SP-1281 Topical Teams in the Life & Teams Topical Physical Sciences Towards New Research Applications in Space New Towards

SP-1281 Topical Teams in the Life & Physical Sciences: Towards New Research Applications in Space /o ESTEC, PO Box 299, 2200 AG Noordwijk, The Netherlands Contact: ESA Publications Division c 5433 (31) 71 565 3400 - Fax (31) 71 565 Tel. sp1281cover 8/2/05 1:51 PM Page 1 Page PM 1:51 8/2/05 sp1281cover Contents.qxd 8/2/05 1:38 PM Page 1

SP-1281 June 2005

Topical Teams in Life & Physical Sciences Towards New Research Applications in Space Contents.qxd 8/2/05 1:38 PM Page 2

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Contents

Foreword 5

Physical Sciences Vibrational Phenomena in Near-Critical Fluids and Granular Matter 6 D. Beysens & P.Evesque

Thermophysical Properties of Liquids: Modelling and Non-Metallic Materials 24 H.-J. Fecht et al.

Solidification in Multicomponent Multiphase Systems (SIMMS) 36 S. Rex & U. Hecht

Ices in the Universe: Answers from Microgravity 52 H.J. Fraser et al.

Zeolite Synthesis in Microgravity 78 R. Aiello et al.

COSMIC: Combustion Synthesis under Microgravity Conditions 86 G. Cao et al.

Macromolecular Crystallisation in Microgravity 94 SP-1281 ‘Topical Teams in Life & Physical Sciences: Towards New Research Applications in Space’ A.Tardieu et al. ISBN 92-9092-974-X ISSN 0379-6566 Microencapsulation Processes 102 T.L. Whateley & D. Poncelet Edited by Andrew Wilson ESA Publications Division Instabilities in Lean Gas-Phase Combustion 108 K. Schneider et al. Coordination Benny Elmann-Larsen Directorate of Human Spaceflight, Life Sciences Microgravity & Exploration Cartilage Engineering and Microgravity 114 R.Toffanin et al.

Published by ESA Publications Division Fluid and Electrolyte Balance and Kidney Function Research in Space 120 ESTEC, Noordwijk,The Netherlands P. Norsk et al.

Price €50 Space Motion Sickness and Stress Training Simulator 136 using Electrophysiological Biofeedback Copyright © 2005 European Space Agency C. Gadeau et al.

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contents foreword

Foreword

Eye-Hand Coordination: Dexterous Object Manipulation 148 The concept of scientific Topical Teams (TTs) This ESA Special Publication contains in New Gravity Fields evolved in the context of ESA’s human reports submitted in 2004 by TTs that were J.L.Thonnard et al. spaceflight programme a decade ago.The initiated around 1998, most of which have purpose was to support scientists in since submitted proposal(s) to ESA’s Muscle Physiology 164 establishing forums grouped around Announcements of Opportunity, either as M. Narici et al. selected topics to prepare ESA’s future individual coordinators for a team, or as a scientific directions and specific areas of team originating in a TT setting Low-Back Pain in Microgravity: Causes and Countermeasures 174 focus.The basic idea was to allow scientists C.J. Snijders & C.A. Richardson of similar scientific orientation, approaching The success of these Topical Teams in the a scientific focus from different viewpoints, to AO peer review process demonstrates a very Shielding against Cosmic Radiation on Interplanetary Missions 184 meet and exchange views and experience, high return on investment, in terms of quality M. Casolino et al. with the primary goal of developing of the scientific projects, industry support to coherent and mature research approaches. them, European synergy and the likely impact Preservation of Samples during Space Experiments 200 Likewise,TTs would identify industries of the research.This publication F.J. Medina et al. interested in teaming with leading scientists, demonstrates the significant outcome of and would attempt initial steps to involve these efforts. It should also be stressed that Gravity-Sensing and Plant Development in Space 210 those industries.They could then submit the IMPRESS Integrated Project, kicked-off in M. Pagès et al. research programme proposals in response November 2004 and co-funded at a level of to Announcements of Opportunity released EUR40 million by ESA and the European by ESA and define the instrumentation Commission, is the long-term result of the required to support the research incubation and definition of research programme. In doing so, scientists were programmes within Topical Teams. encouraged to seek funding from various national and European sources to reach a In total, more than 400 scientists from a critical mass rapidly. multitude of disciplines in Life and Physical Sciences have been involved in Topical Teams Over time, more than 50 Topical Teams over a period of 10 years. have seen the light of day. A large number of them have successfully submitted one or I hope that this publication gives you a more research programme proposals. good impression of the effectiveness of the A number of members of these TTs or even Topical Teams in gathering the best European entire TTs have gone on to develop projects scientists and industries together, and in that qualify for partial funding by ESA under focusing their research efforts in life and the Microgravity Applications Programme physical sciences in space. (MAP).This has been to their own scientific benefit as well as to that of their industry Daniel Sacotte partners.The contents of these projects are Director, Human Spaceflight, the core of the Research Plan that constitutes Microgravity and Exploration the basis of the European programme for Life and Physical Sciences in Space – the ELIPS programme.

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Report of the Vibrational Phenomena in Near- ESA Topical Team in Physical Sciences Vibrational Phenomena

Critical Fluids and Granular Matter Contributors: D. Beysens, Grenoble (F) P.Evesque, Paris (F)

Often, experiments are performed under 1. Rotational Vibration microgravity because of their sensitivity to Whereas translational vibration affects only gravitational effects, which means they are heterogeneous media, rotational vibration also sensitive in space to inertial effects and also works on homogeneous fluids, meaning g-jitter. Any movement by an astronaut or that it also operates in space.To illustrate the experiment is efficiently transmitted by the problem, consider a spinning cup of coffee. spacecraft structure; this vibration may At the start of rotation around its main axis, perturb other experiments. Knowledge, the coffee near the wall rotates with the wall, prediction and minimisation of vibration is a while the central part moves less. On necessity for controlling space experiments. stopping rotation, the outer part stops but whole end of the cell (centre-right photo). Fig. 1.Left: the experiment on rotational vibration on Earth,from The natural mechanical noise of a spacecraft, the central part continues. Hence there is a Although they cannot be seen on the Selin et al.(2002).Centre left: the mean flow generated with a which is probably non-homogeneous and dephasing of the motion that depends on photos, there is also a narrow vortex localised water-glycerine mixture at the end of a rectangular cavity below ϕ the threshold ( o = 0.165 rad; Rep = 68.4).Centre right: the mean non-isotropic, can largely be avoided by the distance to the centre of the cell. in the boundary layer thickness of each ϕ flow obtained above the threshold ( o = 0.165 rad; Rep = 70.7). positioning and orienting experiments Rotational vibration can induce boundary, associated with each macroscopic Right: the speed of the permanent flow V = va/ν (in reduced unit) carefully. inhomogeneous flow that may act as a vortex and rotating with its opposite sign. as a function of the Reynolds number.The structure and intensity Any apparatus moves as a whole with random force and provoke ‘over-diffusion’. This example shows that rotational of the average flow depend on the dimensionless number ω Ω ν ϕ Ω ν random rotation and translation in the frame When the boundary is non-circular, the vibration can change mixing properties and =a / ,which is determined by the parameter Rep = o a / of the space laboratory. If the part sensitive interaction of the flow with the walls perturb the measurement of diffusion and V = va/ν. a = width of rectangular cavity; ν =viscosity; ϕ Ω π to gravity is composed of different fluids, for depends on time and space in an coefficients. It has long been known and o = angle of rotation; /(2 ) = frequency of rotation. example, it will behave as heterogeneous inhomogeneous way. Under these studied with a square geometry; the fluids submitted to translation and rotation conditions, a permanent flow is induced that rectangular geometry is now under vibrations.The accurate control of such an depends on the square of the amplitude of investigation (Selin et al., 2003). experiment requires knowledge of the six vibration at low speed. An example is given Another noteworthy effect is the levitation different components of vibration in Fig. 1 (Selin et al., 2003).The left part of of heavy particles by rotational vibration (3 translational, 3 rotational) because it can Fig. 1 shows a long rectangular cell of width (Fig. 2), a phenomenon recently discovered be viewed as a rigid device within a moving 2a, much larger than its length, L: L >>2a.The (Kozlov et al., 1996; Kozlov, 1996; Ivanova et laboratory. cell is filled with liquid and rotated al., 1998; Kuzaev et al., 2003).When a periodic The effects of rotational vibration and periodically.The centre photos show the rotation is imposed on a toric sector filled translational vibration are treated here pattern of the permanent flow in the left end with liquid and containing a heavy particle, separately. Rotational vibration acts even on of the cell.These flows are permanent, the particle is attracted towards the axis of homogeneous fluids, where it generates superimposed on a periodic rapid flow.They rotation. On Earth, this occurs above a given periodic flow. It is an unavoidable are produced by the interaction of the rapid threshold only when the toric axis is inclined phenomenon that can be studied on Earth. inhomogeneous flow with the boundaries. to the vertical, because gravity stabilises the By contrast, translational vibration affects When the rapid flow is smaller than a particle on the bottom. Fig. 2.Left:The cavity,a sector of a cylinder,is filled with liquid and only heterogeneous fluids. On the ground, threshold, the steady flow pattern remains Typical results are shown on the right of contains a heavy sphere; it rotates around its axis,which is inclined these heterogeneities are stratified and symmetric (centre-left photo), consisting of a Fig. 2, working at constant angular rate and to the vertical.The ball drops to the lowest point when the cavity is at rest,but it levitates and touches the ceiling when the vibration oriented by gravity, which is not true in macroscopic vortex in each corner.The increasing (decreasing) the frequency of speed is high enough (Kozlov et al., 1996).Right: the position of microgravity. spatial averaging of these vortex flows on vibration for four different liquid viscosities. the ball (L/h) versus the frequency (f) in water (a), 1 cSt, ϕ the whole cell is 0. Above a threshold, a The threshold of levitation is different from o = 0.100 rad; in water-glycerine solutions, (b): 1.62 cSt, ϕ ϕ bifurcation occurs and one permanent the threshold of falling, creating a hysteretic o = 0.113 rad; (c): 90.1 cSt, o = 0 .104 rad; (d): 276 cSt, ϕ vortex dominates the others and invades the behaviour.This leads to the prediction that o = 0.063 rad).

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Fig. 3.The position of the steel sphere near to the borders of the Fig. 4.Attraction by the wall and deformation of a hydrogen annulus just before rising (a,c) and just before falling (b,d) in bubble vibrated under magnetic compensation of gravity ϕ water (a,b) (1 cSt, o = 0.100 rad) and in water-glycerine (T–Tc = 0.2K, a = 0.6 mm, f = 20 Hz). ϕ solution (c,d) (90.1 cSt, o = 0.184 rad) (From Kozlov et al., 1996.)

important, not only for discovering new here, beyond simply admitting that the fluid lines is formed.This transition is due to the phenomena but also for evaluating the effect is submitted in the bulk to a periodic increase of dissipation near the critical point. of the unavoidable vibrations of space acceleration. This is a unique example of strong coupling stations and spacecraft mechanical A number of theoretical aspects have between two different critical point structures, which sometimes considerably been considered in some detail by the Perm phenomena: the critical point of interface perturb fluid- and material-science group in Russia (Gershuni et al., 1998).The instability and the thermal critical point of the centre of rotation will attract all heavy experiments. suppression of a uniform steady gravity field the liquid-vapour phase transition. Under particles. Fig. 3 provides images recorded just The investigation of the behaviour of is mandatory for evaluating the phenomena weightlessness, the effects can be markedly before levitation and falling. inhomogeneous materials vibrated under induced by vibration. Only a very few different and concern not only the shape and Clearly, the main effects owing to rotation zero mean gravity has begun only recently. experiments have been conducted to date localisation of the gas-liquid interfaces, but can be studied on Earth and appear even in However, significant results have already been on the behaviour of fluids vibrated under also the evolution and morphology of the homogeneous systems.They are: the obtained, as reviewed below.The review weightlessness. drop pattern during phase transition. generation of a periodic flow; the generation begins with fluids, where the critical point Far from the critical point, the vapour of a permanent convective flow; and the plays an important role, since simply 2.1.2 Interface Deformation and Localisation phase in weightlessness takes the shape of a generation of a centripetal force for heavy changing the distance to the critical point On Earth, the usual effect of vertical spherical bubble in the absence of vibration. heterogeneity when the fluid is modifies properties in a scaled, universal way. vibrations is to modulate the effective gravity When applying translational vibration, heterogeneous.These effects, however, are The effect of vibrations on granular matter via the time-dependent acceleration applied parametric forcing stimulates the vibration of obviously also present in microgravity, where are then discussed. to the system. Considering a two-fluid system eigen modes of deformation of the bubble. they are strengthened in comparison to (liquid-liquid, liquid-gas), this generates This vibration also induces a periodic motion other gravity forces, to the level where they 2.1 Fluids and Near-Critical Fluids under parametric oscillations and waves at of the bubble centre-of-mass, which cannot be neglected. Vibration frequency f/2 when the vibration frequency generates in turn an average flow whose 2.1.1 Why Vibrating Fluids under is small, the restoring force being either resultant always corresponds to an attraction 2.Translational Vibration Weightlessness? gravity or capillary. But rapid vertical of the bubble by one of the walls (Fig. 4) Translational vibrations act on Vibrations applied to mechanical systems can vibration can also stabilise the inverted (Lyubimov et al., 2001; 2004).The stationary inhomogeineities, which generally tend to induce destabilisation or stabilisation, equilibrium (Wolf, 1969), with the heavier state of such a system thus comprises a ρ direct the interfaces perpendicularly to the depending on the characteristic features of liquid (density 1) on top, when the speed of vapour phase at the wall, more or less excited acceleration direction.The inhomogeneities the vibrations: the frequency f (or the angular vibration 2πaf is large enough: according to whether the frequency is near or can be due to the granular structure of frequency ω =2πf ), the amplitude a and the not to a resonance.This is sketched in Fig. 4. ρ ρ π ρ ρ matter itself, as in an assembly of hard beads, direction of vibration. Many equilibrium and ( 1 – 2)(2 af ) > ( 1 + 2) g/2 Experiments were carried out under or to density inhomogeneities, as those non-equilibrium phenomena can be affected magnetic compensation of gravity in H2 induced in a simple fluid by temperature by the presence of high-frequency vibrations. The problem of parametric oscillation (Wunenburger et al., 2000), and in a sounding

gradients, or inhomogeneities created by the The periodic acceleration can have a becomes more intricate on Earth in the rocket with CO2. By varying the distance to coexistence of two phases (e.g. liquid and marked influence on the behaviour of a fluid vicinity of the critical point. A plane liquid- T–Tc from the critical point (Tc = 33K for H2 vapour). In a simplified manner, vibrations near its critical point. Different phenomena vapour layer vertically vibrated parallel to and 300K for CO2), the difference in density δρ ρ ρ σ can play the role of artificial gravity, inducing are under consideration: induced thermal gravity displays two different regimes (Fauve = L – V and the interfacial tension can flows and structuring the gas-liquid instabilities analogous to Rayleigh-Bénard et al., 1992). Far from the critical point, a be modified.These two quantities tend interfaces, and eventually helping to control convection, and ordering of the gas-liquid square wave-pattern deformation is formed towards zero near the critical point according δρ 0.325 the fluids in space. interface below the critical point.The (the usual Faraday instability). At a to the power laws ~(T–Tc) and σ 1.24 The phenomena associated with question of how the acceleration can be temperature T0 close to the critical ~(T–Tc) . vibrations are a rich collection so far poorly transmitted to the compressible fluid through temperature (Tc – T0 ~ 20mK for CO2), a When acceleration is parallel to the investigated. However, the subject is a mechanical boundary layer is not discussed transition to a new pattern configuration of interface, a Kelvin-Helmholtz-like instability is

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Fig. 5.Typical frozen reliefs formed at the interface between two Fig. 6.Gas-liquid phases, fluids (oil and fluorinert), due to rapid horizontal vibration under which show up under 1 g as a gravity.(From Ivanova et al., 2001). vapour phase above the liquid phase separated by a flat meniscus,and under weightlessness as a vapour bubble surrounded by a liquid phase (a),can order in a different way when submitted to vibration: (b) frozen waves under 1 g (from Wunenburger et al., 1999); The experiments conducted on a fluid- (c) gas-liquid ordering under weightlessness.(From fluid equilibrium (Wunenburger et al., 1999) Beysens et al., 1998.) in the vicinity of the critical point of the gas- liquid transition are consistent with this model (Fig. 6b), with the velocity (aω) as the relevant parameter governing the instability. This generalises the domain of application of the modelling to hyper-compressible systems. Fig.7.The spreading of the Similar reliefs have been obtained hot boundary layer during experimentally at the liquid-sand interface the heating of the thermistor (Th1,supported by a thread). observed (Gershuni et al., 1998; Wolf, 1969), (Ivanova et al., 1996) and at the interface a: without vibration (hot with the interface modulated as a ‘frozen’ roll between two miscible liquids of different region underlined in white; b: wave pattern (Figs. 5 & 6b).This phenomenon, densities (Legendre et al., 2003), i.e. when can act as a kind of artificial gravity to fluid then becomes extremely sensitive to under low frequency; c: under which corresponds to the formation of waves capillary forces are zero. In these cases, the localise the liquid and vapour phases vibration as the critical point is approached. high frequency vibration, on the sea under the influence of wind, has relief is stabilised by gravity , and its height perpendicular to it, whatever the initial Measurements of flow velocities where convection rolls form (from Garrabos et al., 2004). been poorly investigated so far where the cannot grow too much over its configuration (emulsion of vapour droplets performed in the Mir space station in CO2 ‘wind’ (the gas phase) exhibits a periodic wavelength, so that both its height HR and or a unique vapour drop).These are and SF6 confirm this expectation. A heat flux velocity relative to the ‘sea’ (the liquid).The its wavelength λ are proportional and vary preliminary studies of the phenomenology of was sent into the fluid from a point-like λ ω 2 instability mechanism is due to the relative as HR ~ ~(a ) /g , (Ivanova et al., 1996). one- or two-phase fluids subjected to source (thermistor). Depending on the motion of two fluids induced by vibration. This demonstrates the drastic effect of oscillatory accelerations under oscillation velocity, two regimes of heat A perturbation becomes unstable if the gravity. weightlessness, and still almost nothing is propagation are observed: (i) at low velocity (aω) is larger than the threshold The only available study under known about these phenomena.The frequency, heat is convected during one velocity weightlessness concerns preliminary data stratification of sedimenting particles in oscillation period to form symmetrical hot gathered in a sounding rocket experiment liquid has been also observed (Evesque, layers perpendicular to vibration ω ρ ρ 3 ρ ρ ρ ρ σ ρ ρ (a )0 ={( 1 + 2) /[ 1 2( 1 – 2)]}{ g/( 1 – 2)} (Beysens et al., 1998).Three samples at 1997). (configuration hot-cold-hot, Fig. 7b), and (ii), different gas volume fraction and distance at high frequency, heat is transported by Here, σ is the gas-liquid surface tension and from the critical point were vibrated at 2.1.3 Vibrational Thermal Effects convection rolls perpendicularly to the ρ is the fluid density.This destabilisation is due different amplitudes (0.1-5 mm) and When a fluid under vibrational acceleration is direction of oscillation (opposite to the increasing effect of the Bernoulli-type frequencies (0.1-60 Hz). Although the initial subjected to a thermal gradient in the configuration, cold-hot-cold, Fig. 7c). pressure arising from the velocity difference state of the sample is a vapour drop Rayleigh-Bénard configuration, convection between gas and liquid. emulsion or a unique drop, the final state is starts at conditions corresponding to a 2.1.4 Phase Transition and Nucleation under Fig. 5 shows typical results obtained on the same: vapour and gas phases form vibrational Rayleigh number Vibration ω ρ ∆ 2 η Earth at different amplitudes and frequencies alternate layers perpendicular to the Rav =[a (∂ /∂T)p Te] /2 D larger than a few Now consider the general problem of phase for viscous fluids.The growth of the relief acceleration vector (Fig. 6c).The instability thousand (Gershuni et al., 1998). (Here, ∆T is transition and the liquid-gas transition.The

height Hr is predicted to be critical (Gershuni et develops as liquid fingers from the cell walls, the temperature difference between two critical point (Fig. 8) is defined by its λ η al., 1998) at constant wavelegth c.This occurs and coalesces with the droplets in the bulk fluid layers separated by the distance e, is coordinates (pc,Vc,Tc).Working at constant λ only in the vicinity of the threshold (Hr << c), and/or with the fingers that have grown the shear viscosity and D is the thermal temperature on a gas (or liquid) phase and while a period-doubling mechanism has been from the opposite side. diffusivity coefficient.) As the temperature of increasing (decreasing) the pressure allows us observed far from the threshold (Ivanova et al., These observations suggest that, under the fluid moves closer to the critical to compress (dilate) a gas (or liquid) until a λ –1.9 2001) when Hr and c become proportional. some circumstances, a periodic excitation temperature, Rav diverges as (T – Tc) .The first drop of liquid (bubble of gas) is formed

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Fig.8.Fluid phase diagram in the plane (p,V).The vertical arrow Fig.9.Phase transition under vibration (a = 0.3 mm, f = 20 s–1) in indicates a thermal quench through the critical point; the other hydrogen under magnetic compensation of gravity.Lm is the arrow corresponds to an isothermal compression. distance between domains.a: after a thermal quench to 1mK below the critical point,at critical density.The arrows indicate the area where the growth accelerates.The interconnected pattern of bubbles is shown in the insert.b: 100 mK quench below the critical point,at non-critical density.The bubbles order in columns perpendicular to the direction of vibration.(From Beysens et al., 2004)

proportion. But they separate at the same Magnetic compensation (Wunenburger et time in the whole volume, so they form two al., 2000) was used to study the effect in intermixed continua, as a porous material hydrogen of a vibration during the liquid- invaded by gas (the porous material is here vapour transition. At critical density, after a

the liquid). Under gravity, bubble and drop thermal quench from T > Tc to T < Tc, mechanical excitation. Dynamical decoupling coalescences force the separation via hydrogen separates in interconnected of the particles and the surrounding media is spontaneous gravitational drainage; the droplets and bubbles with the same volume achieved by using a low-pressure/low-density

system stratifies and the vapour ends on top fraction (Fig. 9).The pseudo-period Lm of the fluid, such as air at atmospheric pressure or of the liquid and the interface is flat and network evolves as (Beysens & Garrabos, even vacuum. In such a fluid, the solid σ η horizontal. In microgravity, there are only 2000) Lm =b( / )t.Here,t is time after particles can be considered as isolated bodies capillary forces.The separation time quench, η is the shear viscosity of shearing between each collision. One of the most increases, no stratification occurs and and b is a universal constant (~0.03). interesting properties is the dissipative nature intermixing remains with a typical ‘pore’ size Under vibration, the growth remains linear. of the particle-particle interactions (inelastic

Lm.The growth process is due to a chain However, the slope increases when the size of collisions).The usual techniques and results of reaction of coalescence: each coalescence the domains reaches the viscous boundary statistical mechanics can then be used to η ρω 1/2 when T < Tc; the pressure remains constant at induces another by the flow it induces in its layer (2 / ) (~100 mm here; Fig. 9a).The analyse the thermo-statistics of a dissipative this stage and the second phase neighbourhood. Growth is thus limited by vibration then accelerates the growth of the gas. progressively invades the system.When this flow.This flow is itself limited by viscosity, domains by inducing a shear flow of shearing, σ η T > Tc, there is no difference between gas and such as Lm ~( / )t. as in the critical liquid mixtures subjected to a 2.2.1 Low Gravity for Granular Media liquid and there is no jump in density at a Here, t is time, η is the shear viscosity (the flow with a uniform gradient of velocity (Chan From an experimental point of view, in order σ definite pressure pb(T). friction) and is the gas-liquid interfacial et al., 1998). to study the properties in a steady state, it is In contrast, working at constant volume tension – a reduced force.The process ends At non-critical density, the drops or necessary to bring to the gas a steady leads to different kind of processes. In the when a single ‘pore’ is formed that bubbles are no longer interconnected. Mutual amount of kinetic energy that balances the

neighbourhood of Tc, the fluid above Tc and corresponds to a bubble surrounded by interactions are then exerted, attraction in the dissipative losses. Mechanical vibrations are a both phases below Tc exhibit large liquid if the liquid wets the sample walls.The direction perpendicular to the vibration, common way of keeping the ‘temperature’ of fluctuations (at the origin of the ‘critical correlation length ξ of fluctuations is the repulsion in the parallel direction, which order such a macroscopic gas constant. On Earth, opalescence’), with large amplitude and large natural lengthscale of the phase separation the domains in columns (Fig. 9b).The the energy of the particles depends on their length scales (characterised by a correlation process, and the relaxation time τ is the appearance of a characteristic wavelength is a altitude, and stratification occurs at all level of length ξ), and large relaxation time τ (at the natural timescale of the phase separation robust phenomenon, since it is also observed vibrations. Observation of a ‘phase transition’ origin of the critical ‘slowing down’). dynamics.Then the phase transition with solid balls vibrated in a liquid in granular media is therefore uncertain, and ξ depends on T – Tc, via a universal critical dynamics can be put under a universal, (Wunenburger et al., 2002). experimental tests of theoretical predictions ξ∝ –ν ν τ ξ τ exponent: (T – Tc) ; = 0.63; depends on scaled function: Lm/ ~(t/ ). problematic. Although it is possible to τ∝ –3ν T – Tc,via (T – Tc) . If now V is far from Vc, the proportion of 2.2 Granular Matter immerse the particles in a liquid of When cooling below Tc, nucleation the two phases are different and the phase Although studied for several centuries comparable density, this induces a strong proceeds on these fluctuations through a separation proceeds under weightlessness because of their industrial applications, dynamical coupling between the particles ‘generalised nucleation’ process, and no through coalescence of the domains granular media have only recently received and the fluid, leading to liquid-like behaviour

meta-stability occurs near Tc. (drops/bubbles) induced by Brownian attention from physicists. Granular media of the granular media (Ivanova et al., 1996; Consider first the case where cooling is motion, such that the typical distance Lm exhibit a wide range of behaviour: solid-, gas- Kozlov, 1992; Evesque, 1997). For instance, ρ ρ 1/3 performed at V = Vc (density = c).The between domains grows as Lm ~ t . Here and liquid-like, depending on the dynamic vibrations perpendicular to the gravity vector cooling from above Tc to below Tc forces the also, scaling permits a universal form to be coupling of the particles with the produce the patterning of the interface ξ τ 1/3 system to separate into two phases of equal found: Lm/ ~(t/ ) . surrounding media and the intensity of the shown in Fig. 5 at the interface between

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Fig. 10.‘Gas-liquid’transition for granular matter subject to vibration under microgravity conditions aboard ESA’s MiniTexus-5 in 1998.a: gas behaviour (G).b: cluster behaviour (C).In the most dilute case (a), the particles move erratically and their distribution is roughly homogeneous in space.In the denser cases (b), a ‘motionless’dense cluster (in black, C) is surrounded by regions of lower particle density.(From Falcon et al., 1999.)

ε from the microgravity experiments.The Fig.11.The two compartments of a box are connected via a slit.The box is vibrated and contains Ntot beads.Variation of the asymmetry (Ntot ) ε observation of such a dissipative collapse of the bead-distribution between the two sides at equilibrium, measured via (Ntot )=N1/Ntot –1/2=1/2–N2/Ntot.Left: at fixed total Γ ω2 Γ has important consequences in astrophysics, number of beads Ntot = 460 as a function of acceleration =a ,in units of g.Right: at a given acceleration = 2.6 g, as a function of the total number of beads N in both compartments.(From Jean et al., 2002.) particularly for the analysis of the formation tot of planetary rings. During this low-gravity experiment (Fig. 10b), the formation of a dense cluster of particles was observed when the number of particles in the cell was large enough.This ‘liquid’ or cluster regime is requires the local equilibrium of pressure, – a gas with particles having a characteristic λ characterised by a low speed and a small i.e. L >> c. So, this experiment proves the mean free path larger than the sample liquid and sand.This proves the efficiency of free mean path; it is in equilibrium with a failure of this hypothesis and it size is in a Knudsen regime, for which the Kelvin-Helmholtz instability type. fraction of the particles in a ‘gaseous’ regime demonstrates that all the previous sounds do not propagate in a classical Vibration parallel to gravity may favour (high speed, large free mean path). It occurs theoretical descriptions of this manner. jumps of particle density, may align the above a well-defined threshold in the phenomenon to be unrealistic, because particles perpendicularly to the vibration and number density of particles (Fig. 10) that they were based on the continuum These behaviours are probably related to may stop the sedimentation (Evesque, 1997). corresponds to about one layer of beads in approach (Goldhirsch & Zannetti, 1993). other strange behaviour of granular matter In contrast, a low-gravity environment the cell at rest. Fig. 10a shows the behaviour This, then, was a key experiment in the on Earth, as will be shown in the next section eliminates stratification, even at high-density of the homogeneous gas of beads when the physics of granular media. using the example known as ‘Maxwell’s ratios, and produces an effectively isolated number density n is smaller. Demon’ with sand. gas of particles. The difference between the two kinetic – there is also a periodic depletion of balls At the moment, it seems that the only way regimes (homogeneous and clustered) also near the wall, which moves back from the to simulate the clustering process and the 2.2.2 The Isolated Dissipative Gases of seemed apparent in the pressure signals. In gas (and from the cluster when it exists). pressure-temperature dependence is to Particles the dilute case, the pressure of the granular This means that the speed of the wall aω introduce an anomalous variation of the The first experiment with slightly dissipative gas scales like the 3/2 power of the vibration is larger than the typical speed of the restitution coefficient. Hence much more granular media was flown aboard the CNES speed.This is quite surprising, because basic grains. In the terminology of sound in work needs to be carried out to reach a microg-Caravelle in 1991 (Worms, 2000). It argument predicts a power of 2. It seems gases, this means that excitation of the gas deeper understanding. tested the PV =nRT law of a perfect gas using that this result can only be explained with is supersonic.This means hyperbolic a collection of macroscopic stainless steel some special dependence of the collision- equations and discontinuities of density 2.2.3 Maxwell’s Demon spheres. Its purpose was mainly pedagogical restitution coefficient upon speed. and speeds, if continuum formalism is Divide a box in half with a partition that and showed reasonable agreement between Later work has improved the used. includes a slit (Fig. 11). Fill each side with a pressure and temperature equivalence and understanding of this experiment (Evesque, layer of identical grains and vibrate the box with the Boltzmann statistics. 2001a; Evesque et al., 2001; Evesque & – simulating (Evesque, 2001b) the dynamics vertically (amplitude a, frequency ω/(2π), The first experimental evidence of a phase Adjémian, 2002). Noting in Fig. 10: of a single ball leads to a mean typical acceleration Γ = aω2/g). At some point, the transition in a granular gas was provided by a speed of the ball larger than the speed of sand empties from one side into the other. MiniTexus-5 sounding rocket experiment in – clustering occurs as soon as the number the wall, which is in contradiction with the Typical results are shown in Fig. 11, where 1998 (Falcon et al., 1999). Although this of layers of grains in the box at rest is above.That the excitation is supersonic the difference of population ratio ε, where ε collapse was predicted by numerous larger than 1.This indicates that clustering demonstrates that the dissipation is =(N1 – N2)/[2(N1 + N2)], is plotted versus the λ theoretical and numerical studies, it had occurs when the free mean path c of a stronger than obtained in 1-D modelling. total bead number Ntot = N1 + N2 at constant never been observed in three dimensions, grain between two grain-grain collisions is This is an effect of rotation, which excitation Γ (Fig. 11, right), and versus the and the 2-D results are strongly perturbed by smaller than the cell side L. However, to increases dissipation in 2-D and more so in excitation Γ at constant total bead number

boundary collisions as one can deduce now describe the gas of beads as a continuum 3-D. Ntot (Fig. 11, centre).They show that

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Fig.13.‘Gas’(G),‘solid’(S) and ‘laser’(L) behaviour for granular a bc matter under vibration in microgravity (ESA Maxus-5, 1 April 2003).a = 0.3 mm, f = 60 Hz).In the most dilute case (G), the particles move erratically and their spatial distribution is almost uniform.In the denser case (S), an ‘immobile’cluster with some crystalline order is surrounded by regions of smaller density.When the particles do not interact with each other (L), a coherent motion is observed with velocity larger than the wall speed.

Fig.12.The flow j of beads through a slit when the box is vibrated and submitted to g.L eft (a): the experimental set-up.Centre (b): the number N(t) of beads remaining in the box as a function of time t,at constant acceleration.Right (c): flow j = –dN(t)/dt as a function of the number of reduction of the kinetic temperature of the beads for different accelerations.The bead number is measured via the number of layers covering the box floor at rest.The inclined line grains and of the efficiency of the mechanical corresponds to the location of j(n) maxima with n.When two similar boxes are connected via a slit,the distribution remains equal in each box if excitation before n = 1. Exactly as the ‘granular j(n) increases with n.The equal distribution becomes unstable if j(n) decreases when n increases,so the denser box fills up and the other gas’ experiment, it exhibits a reduction of empties until j(n1)=j(n2) and n1 +n2 = 2n.(From Jean et al., 2002.) kinetic energy under the same condition. The linear variation of j(n) vs. n at small n is in contradiction of previous simulations and theoretical descriptions using the continuum approach (Eggers, 1999). It shows that the population is dissymmetric below some Fig. 12b shows a strong acceleration of the hypotheses used in these simulations are Γ acceleration threshold c at constant Ntot,or emptying process at the end. Of course, the inadequate (Jean et al., 2002).Thus the Γ above some Ntot,c at given acceleration .The flow decreases and then stops at the very theoretical description of these phenomena transition looks ‘critical’,which means that ε end when the bead number becomes too and their simulation do not describe the varies quite rapidly near the thresholds Γ and low.This is why j starts increasing with n experiments correctly.

Ntot,c, i.e. with a vertical tangent, but that there when n is small, and why j passes a maximum shows the reduction of the dimensionality of ε Γ is no jump of just above the threshold. at nmax, which depends on , most likely 2.2.4 Billiards in Microgravity the phase space, which jumps from 13-D Hence ε seems to vary rapidly but linearly (Fig. 12c). As described above, granular gas exists only (which is the number of degrees-of-freedom continuously. However, this is not strictly These results explain the experiment of in quite dilute conditions. In the limit of fixed for a 3-D ball with time-dependent excitation: certain owing to the small number of beads Fig. 11. For two joined half-boxes, equilibrium L and ρ→0, it corresponds to the case of 3 positions, 3 angles, 3 speeds, 3 rotation

involved in the experiment, which introduces occurs when j1 = j2 and N1 + N2 = Ntot,or vibrating a single billiard ball. Simulations on speeds, time) to 1-D or 3-D space, fluctuations and finite size effects. n1 + n2 =2ntot.This leads to: a 1-D box showed that the particle speed was corresponding to the motion of a point at Nevertheless, the result is surprising. It is always larger than aω and sometimes much constant speed, under periodic excitation.

probably related to the previous experiment – when ntot is such that j is increasing with n, larger; this is in contradiction to Fig. 10. Reduction of dimensionality is classic in of clustering of gas in microgravity and to the system of equi-partition is stable. Furthermore, a 3-D experiment in dissipative systems with dissipation.This

dissipation. In order to study the behaviour, – as soon as ntot > nmax, the equi-partition is weightlessness aboard a parabolic aircraft explains in particular chaotic strange consider only half of the box and perform an unstable because j decreases when n flight with one ball in a fixed 3-D box and a attractors. However, it turns out to be experiment similar to that of Fig. 11, at increases. Consider a small fluctuation δn vibrating piston confirms that v > aω.Better,it peculiarly efficient in the case here. 3-D

different acceleration and starting with a large around the point n1 = n2 = ntot,then showed intermittent resonance, during which simulations have also been performed with a δ δ number of beads N1 (Fig. 12).This permits us n1 = ntot + n and n2 = ntot – n.It imposes the ball performed a round-trip per period Discrete Element code from J.J. Moreau and δ to study the dynamics of the emptying j1 < j2 so that the real difference n’ a time synchronously with the vibration, so that confirmed the experimental finding. δ ω π ω process. Measuring the number N1(t) of grains t later increases according to v ~ L / >> a , and during which the In classic billiard theory applied to δ δ δ remaining in the box as a function of time t n’= n +(j2 – j1) t/N0. trajectory aligned along a single periodic statistical mechanics, the real shape of the (Fig. 12b) provides the flow j1 =–dN1/dt of the path parallel to the vibration direction. It thus cavity plays a significant role in the beads through the hole, from which j1 versus It can also be shown that the nature of the corresponds exactly to 1-D simulations. ergodicity/non-ergodicity of the problem. In N1 can be plotted. If N0 is the number of beads asymmetry of the curve j(n) around the Intermittency of the stabilisation is also particular, spheres should not present stable corresponding to a single layer of grains maximum nmax controls the nature observed in 1-D simulations, the motion orbits. It would be interesting to demonstrate covering the bottom of the box, j1 versus the (transcritical, critical or subcritical) of the becoming fully synchronous only at large that such a cavity would also result in the number of layers n1 = N1/N0 can be plotted, as bifurcation. amplitude but completely erratic at very destabilisation of the resonant trajectories, shown in Fig. 12c. Repeating the experiment These results are coherent with clustering small amplitude.This synchronisation is an hence improving the ergodicity of the at different accelerations produces typical of granular gas in microgravity because the important result because it demonstrates the dynamics. In the same way, adding some hard results as in Fig. 12c. decrease of j(n) demonstrates the strong intermittent breaking of the ergodicity. It also convex fixed obstacles to the cavity should

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also improve the ‘quality of ergodicity’.This is 3. Perspectives for the International the interfacial tension, and to determine the the temperature evaluated by the speed of perhaps why using a few balls, instead of Space Station (ISS) coalescence laws of dispersed two-phase the particles. one, may change the qualitative nature of the It is a fact that nobody knows exactly the fluids when submitted to such oscillating For this purpose, systematic experiments dynamics and force the problem of granular effects of vibrations on inhomogeneous accelerations. A goal of this study will be to have to be done to determine the number- gas to be rather ergodic. However, this media in weightlessness.The achieve sufficient knowledge of the ordering density threshold where the collapse occurs remains to be demonstrated. phenomenology is still lacking. Non-linear mechanism to be able to control and predict and the influence of the shape of the Another conclusion is the ‘catastrophic’ vibration may induce new forces that may the localisation of the fluid interfaces under container and its orientation compared to influence of dissipation during grain-grain help to control the flow of fluids in space. microgravity conditions. the direction of vibration. Also, an collision in granular-gas mechanics.The They could then be used for phase Another objective is to understand how improvement of the apparatus and of the normal restitution coefficient was thus separation of heterogeneous media in vibrations can induce ordering mechanisms detection of particle motion can be gained

measured; it is quite large (vout/vin = 0.95-0.9) weightlessness. So it is most likely that this in a disperse system, such as a metastable easily by introducing stereo-imaging.The and rather independent of speed vin. So it study may produce new processes in applied gas-liquid dispersion. It should be interesting influence of the coupling between the cannot explain Fig. 10. In fact, this effect was science and technology. to analyse the effect of alternating surrounding fluid through viscosity or explained when we understood why the For the future, the Topical Team proposes accelerations on phase separation in the compressibility also needs to be studied in linear trajectories parallel to vibration are to enlarge the preliminary investigations that same way as the effect of shear on phase detail, as should be the perturbing effect of stabilised: any transverse component of the were performed with fluids and granular separation kinetics, i.e. in terms of the electrostatic forces. In this sense, an ball speed will force the ball to rotate in one materials.The basic need is for a vibration anisotropic law of domain growth, domain exhaustive programme of ground-based direction, say spin +, at one wall due to apparatus providing an amplitude range of deformation, growth acceleration and final experiments combining various fluids, among collision rules, and in the other one, say 0.1-50 mm and frequency range of 0.1- equilibrium state. them supercritical fluids and granular media, spin –, at the opposite wall.This much 100 Hz, with maximum acceleration in the Understanding these effects will not only should be carried out in order to extend the improves the dissipation; hence it blocks range 1-10 g. help in the control of gas-liquid interfaces recent theoretical and experimental results rotation and transverse motion. and the enhancement of heat transfer in on fluidised granular media. An extended In 3-D, this effect can be generalised to 3.1 Fluids and Near-Critical Fluids microgravity, but it will also give information range of excitation intensities and longer ball-ball collisions, because collision rules fix The first objective is to understand the on the spurious and destabilising effects of experiments should allow the kinetic of the the ball spin at the end of each collision from coupling between heat transfer and high- the ISS structure vibrations on the numerous collapse process to be investigated. the impact parameter at the beginning of frequency vibrations. Since no buoyancy experiments using heterogeneous media. Improvements in the detection of the the collision (mainly ball translation speeds forces exist in microgravity, the only possible For rotational vibration, it seems that most particles and larger sample cells should also and position of the contact point). Following heat-transfer mechanisms at rest are thermal of the research can be performed on the permit the formation of multiple clusters to collisions occur with different impact diffusion (and the piston effect for near- ground, since the same effects will be be detected and their coalescence studied. In parameters, so an important part of the spin critical fluids). A well-controlled method to observed there. parallel, the pressure fluctuations should be energy is lost during each collision.This effect investigate this phenomenon is to use a measured and modelled in order to is stronger in 3-D than in 2-D, and it does not single-phase fluid under a thermal gradient, 3.2 Granular Matter determine the energy of the granular matter. exist in 1-D. Hence, it can be understood why submitting it to controlled oscillatory An intensive study of the dissipative collapse Another subject of interest is the dissipation looks quite large in 3-D acceleration.The main effect of high- is the natural goal of the research segregation mechanism of binary mixtures experiments on granular gas – much larger frequency vibrations would be to restore programme on granular matter, in order to (particle species of different sizes, shapes or than in a 1-D case. It is rather strange that no convection, behaving as in normal gravity. build an experimental phase diagram of densities). On Earth, segregation is frequently simulation on granular gas or granular fluids Concerning the behaviour of a two-phase granular matter under vibration. From a observed, but there is no unified theory for has ever demonstrated and studied this fluid, the main scientific objectives are to statistical mechanics point of view, vibrations this phenomenon, and even the pertinence effect; simulations simply do not take care of understand the interface deformation and are used to maintain the kinetic energy of of the description in terms of minimisation of this phenomenon.This, then, is a direct result ordering/organisation mechanisms, the ‘gas’,whereas the granular pressure is interaction energy is still an open question. of space research. particularly the role of the density ratio and measured by simple pressure sensors and This hot scientific problem is presently the

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object of a few microgravity experiments DOI: 10.1140/epje/i2002-10082-4. Ivanova, A.A., Kozlov,V.G. & Evesque, P.(2001). Beysens, D. & Roux, B. (2004).Vibration funded by the US and Japanese space Evesque, P., Beysens, D. & Garrabos,Y.(2001). Interface Dynamics of Immiscible Fluids Effect on Critical Fluid in Weightlessness agencies in an industrial context. Since the Mechanical Behaviour of Granular-Gas and under Horizontal Vibrations. Fluid Conditions; (preprint). experiment by NASA consists of shearing a Heterogeneous-Fluid Systems Submitted Dynamics 36(3), 362-368. Selin, N.V., Kozlov, V.G. & Evesque, P.(2003). rather dense binary granular mixture in low to Vibrations in Microgravity. J. de Physique Jean,P.,Bellenger,H.,Burban,P.,Ponson,L.& Experimental Study of Convection in gravity, the experiments proposed here to IV France 11(6), 49-56. Evesque, P.(2002). Phase Transition or Rectangular Cavity Subject to vibrate a granular medium are Falcon, E.,Wunenburger, R., Evesque, P., Maxwell’s Demon in Granular Gas. Poudres Nontranslational Vibration. In Proc. 30th complementary. Fauve, S., Chabot, C., Garrabos,Y.& & Grains 13(3), 27-39. Summer School ‘Advanced Problems in Beysens, D. (1999). Cluster Formation in a http://www.mssmat.ecp.fr/sols/ Mechanics’ (APM 2002), St. Petersburg References Granular Medium Fluidised by Vibrations in Poudres&Grains/poudres-index.htm (Repino), IPME RAS, Russia, pp577-583. Beysens, D. & Garrabos,Y.(2000).The Phase Low Gravity. Phys. Rev. Lett. 83, 440-443. Kozlov,V.G. (1996). Solid Body Dynamics in Wolf, G.H. (1969).The Dynamics Stabilization Transition of Gas and Liquids. Physica A Fauve, S., Kumar, K., Laroche, C., Beysens, D. & Cavity with Liquid under High-Frequency of the Rayleigh-Taylor Instability and the 281, 361-380. Garrabos,Y.(1992). Parametric Instability of Rotational Vibration. Europhys. Letts. 36(9) Corresponding Dynamics Equilibrium. Beysens, D.,Wunenburger, R., Chabot, C. & a Liquid-Vapor Interface Close to the 651-656. Z. Physik 227, 291-300. Garrabos,Y.(1998). Effect of Oscillatory Critical Point. Phys. Rev. Lett. 68, 3160-3163. Kozlov,V.G., Ivanova, A.A. & Evesque, P.(1996). Worms, J.C. (2000). CNES Experiments on Accelerations on Two-Phase Fluids. Garrabos,Y., Beysens, D., Lecoutre, C., Mean Dynamics of Body in Cavity,Subject Microgravity Airbus. Planet 6/CNES, Microgravity Sci.Technol. 11, 113-118. Polezhaev,V. & Emelianov,V. (2004).Thermal to High Frequency Pendular Vibrations. In PV=nRT, Une Loi Physique Réputée Simple. Beysens, D., Chatain, D., Evesque, P.& Behaviour of a Vibrated Near-Critical Fluid Proc. 2nd European Symp. on Fluids in Space, Video (Distribution: Planet 6, c/o Garrabos,Y.(2004). High-Frequency under Weightlessness; (preprint). Naples, 22-26 April 1996 (Ed. A.Viviani), J.C. Worms, 12 rue de l’Espérance, F-67400 Vibrations Speed up Phase Transition Gershuni, G.Z. & Lyubimov, D.V. (1998). Thermal Jean Gilder Congressy srl, Naples, Italy, Illkirch, France). under Weightlessness; (preprint). Vibrational Convection, John Wiley & Sons, pp578-582. Wunenburger, R., Carrier,V. & Garrabos,Y. Chan, C.K., Perrot, F.& Beysens, P.(1998). New York, USA. Kuzaev, A.F., Ivanova, A.A. & Evesque, P.(2003). (2002). Periodic Order Induced by Effects of Hydrodynamics on Growth: Goldhirsch, I. & Zannetti, G. (1993). Clustering Viscosity Dependence of the Behaviour of Horizontal Vibrations in a Two- Spinodal Decomposition under Uniform Instability in Dissipative Gases. Phys. Rev. a Heavy Sphere in a Cavity Filled with Dimensional Assembly of Heavy Beads in Shear Flow. Phys. Rev. Lett. 31, 412-415. Lett. 70, 1616. Liquid and Subject to Rotary Vibration. In Water. Phys. Fluids 14, 2350-2359. Eggers, J. (1999). Sand as a Maxwell Demon. Kozlov,V.G. (1992). Experimental Investigation Proc. 30th Summer School ‘Advanced Wunenburger, R., Chatain, D., Garrabos,Y.& Phys. Rev. Lett. 83, 5322-5325. of Vibrational Convection in Pseudoliquid Problems in Mechanics’ (APM 2002), Beysens, D. (2000). Magnetic Evesque, P.(1997). Sablier Inversé. Pour la Layer. Rev.Proc.1st Int.Symp.on Hydromech. St. Petersburg (Repino), IPME RAS, Russia, Compensation of Gravity Forces in (p-) Science 239, 94. & Heat/Mass Transfer in Microgravity. (6- pp297-302. Hydrogen near its Critical Point: Evesque, P.(2001a). Comparison between 14 July 1991, Perm-Moscow), Gordon & Legendre, M., Petitjeans, P.& Kurowski, P. Application to Weightless Conditions. Phys. Classical-Gas Behaviours and Granular-Gas Breach, USA, pp57-61. (2003). Instabilités entre Fluides Miscibles Rev. E 62,460-476. Ones in Micro-gravity. Poudres & Grains Ivanova, A.A., Kozlov,V.G. & Evesque, P.(1996). par Forcage Oscillant Horizontal. C.R.A.S. Wunenburger, R., Evesque, P.,Chabot, C., 12(4), 60-82. Patterning of Liquefied Sand Surface in a Mécanique 331, 617-622. Garrabos,Y., Fauve, S. & Beysens, D. (1999). Evesque, P.(2001b).The Thermodynamics of a Cylinder Filled with Liquid and Subjected Lyubimov, D.V., Lyubimova,T.P.& Shklyaev, S.V. Frozen Wave Induced by High Frequency Single Bead in a Vibrating Container. to Horizontal Vibrations. Europhys. Letts. (2001). Behaviour of a Drop (Bubble) in a Horizontal Vibrations on a CO2 Liquid-Gas Poudres & Grains 12(2), 17-42. 35(3), 159-164. Pulsating Flow near Vibrating Rigid Interface near the Critical Point. Phys. Rev. E http://www.mssmat.ecp.fr/sols/ Ivanova, A.A., Kozlov,V.G. & Evesque, P.(1998). Surface. In Proc. 1st Internat. Symp. on 59, 5440-5445. Poudres&Grains/poudres-index.htm Dynamics of a Cylindrical Body in Liquid- Microgravity Research & Applications in Evesque, P.& Adjémian, F.(2002). Stress filled Sector of Cylindrical Layer under Physical Sciences and Biotechnology,ESA Fluctuations and Macroscopic Stick-Slip in Rotational Vibration. Fluid Dynamics l.33(4), SP-454, pp805-811. Granular Materials. Eur. Phys. J. E 9, 253-259, 488-496. Lyubimov, D.V., Lyubimova,T.P., Meradji,S.,

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Topical Team Members

Dr.D.Beysens Dr.Y.Garrabos B. Le Neindre K.S. Rezkallah CEA-ESEME, ESPCI-PMMH, 10 Rue Vauquelin, University Bordeaux I, ICMCB-CNRS, UPR 9048, Laboratoire d’Ingéniérie des Matériaux et des Department of Mechanical Engineering, F-75231 Paris Cedex, France. 87 Avenue du Dr. A. Schweitzer, F-33608 Hautes Pressions, Institut Galilée, Université University of Saskatchewan, Saskatoon, Email: [email protected] Pessac Cedex, France. Paris Nord, Av. J. B. Clément, Saskatchewan, Canada S7N 5A9. Email: [email protected] F-93430 Villetaneuse, France. Email: [email protected] Dr.P.Evesque Email: [email protected] UMR 8579 CNRS, Lab MSSMat, Ecole Centrale Prof.W. Grassi D. Routier de Paris, Grande Voie des Vignes, F-92295 University of Pisa, Facolta di Ingegneria,Via Dr.L.Liggieri NOVESPACE, 15 rue des Halles, F-75001 Paris, Chatenay-Malabry Cedex, France. Diotisalvi 2, I-56126 Pisa, Italy. CNR Consiglio Nazionale delle Ricerche, IENI - France. Email: [email protected] Email: [email protected] Istituto per l’Energetica e le Interfasi, Sezione Email: [email protected] di Genova,Via de Marini 6, I-16149 Genova, Dr.C.Bartscher Prof. Hegseth Italy. B. Roux Kayser-Threde GmbH,Wolfratshauser Str. 48, University of New Orleans, Dept. of Physics, Email: [email protected] University of Marseille, IRPHE-IMT,Technopole D-81379 Muenchen, Germany. New Orleans, LA 70148, USA. de Château-Gombert, F-13451 Marseille Email: [email protected] Email: [email protected] D. Lyubimov cedex 20, France. IRPHE-IMT,Technopole de Chateau-Gombert, F- Email: [email protected] N. Bergeon Prof.A.Ivanova 13451 Marseille Cedex 20, France. L2MP,Faculte de St. Jerome - Case 151, Perm State Pedagogical University, Dept. of Email: [email protected] J.Tabony Avenue Escadrille Normandie Niemenn, Experimental Physics, 24 Sybirskaya Street, Laboratoire Résonance Magnétique en F-13397 Marseille, France. 614600 Perm, Russia. T. Lyubimova Biologie Métabolique, Département de Email: [email protected] Email: [email protected] University of Marseille, IRPHE,Technopole de Biologie Moléculaire et Structurale, Château-Gombert, F-13451 Marseille cedex Direction des Sciences du Vivant, B. Billia Prof.M.Kawaji 20, France. Commissariat à l'Energie Atomique L2MP,UMR CNRS 6137, Universite d’Aix- University of Toronto, 200 College Street, Email: [email protected] Grenoble, 17 rue des Martyrs, F-38054 Marseille, Campus de Saint Jérôme, Case Toronto MSS 1A4 Ontario, Canada. Grenoble Cedex 9, France. 142, F-13397 Marseille Cedex 20, France. Email: [email protected] R. Marcout Email: [email protected] Email: [email protected] EADS Space Transportation France, 66 route de Prof.V.G. Kozlov Verneuil BP 3002 F-78133 Les Mureaux S. van Vaerenbergh Prof.I.Egry Perm State Pedagogical University, Dept. of cedex, France. Microgravity Research Centre, Chemical DLR, Center of Excellence ZEUS, Linder Experimental Physics, 24 Sybirskaya Street, Email: [email protected] Physics Department, Université Libre de Hoehe 5, D-51170 Cologne, Germany. 614600 Perm, Russia. Bruxelles, Av. F.D. Roosevelt 50, Email: [email protected] Email: [email protected] V. Nikolayev B-1050 Bruxelles, Belgium. CEA/Grenoble, 17 rue des Martyrs, F-38054 Email: [email protected] V.M. Emelianov C. Lecoutre Grenoble Cedex 9, France. Institute for Problems in Mechanics, Russian ICMCB-CNRS, 87 Avenue Dr. A. Schweitzer, Email: [email protected] V.Volpert Academy of Sciences, pr.Vernadskogo 101, F-33608 Pessac Cedex, France. Univ. Lyon 1, Dept. of Numerical Analysis, Moscow, 117526, Russia. Email: [email protected] A. Passerone F-69622 Villeurbanne, France. Email: [email protected] ICFAM-CNR, University Genova, Genova, Italy. Email: [email protected] Prof. J.C. Legros Email: [email protected] E. Falcon Free University of Brussels, Microgravity D. Wagner Laboratoire de Physique, École Normale Research Center (MRC), Chem. Phys. E.P.Dept V. Polezhaev EADS Launch Vehicles, 66 route de Verneuil, Supérieure de Lyon, UMR 5672, 46 allée - CP 165/62, Avenue F.D. Roosevelt 50, Institute for Problems in Mechanics, Russian BP 3002, F-78133 Les Mureaux, France. d’Italie, F-69007 Lyon, France. B-1050 Brussels, Belgium. Academy of Sciences, Moscow, Russia. Email: [email protected] Email: [email protected] Email: [email protected] Email: [email protected]

Prof.S.Fauve G. Putin Ecole Normale Superieure, 24 rue Lhomond, Perm State University, 15 Bukireva str., F-75005 Paris, France. Perm 614990, Russia. Email: [email protected] Email: [email protected]

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physical sciences

Report of the Thermophysical Properties of ESA Topical Team in Physical Sciences Thermophysical Properties of Liquids: Liquids: Modelling and Non-Metallic Modelling and Non-Metallic Materials Contributors: H.-J. Fecht, Ulm (D) (Coordination) Materials R.Wunderlich, Ulm (D) I. Egry, DLR-Cologne (D) F.S. Gaeta, MARS Center Napoli (I) F.Gori, Roma (I) N. Greaves, Aberysthwyth (UK) A. Leipertz, Erlangen (D) 1. Motivation for the Research F.Millot, Orléans (F) In general, properties such as mechanical K.C. Mills, London (UK) strength, creep, wear resistance and ductility, A. Passerone, Genova (I) as well as the chemical, magnetic and S. Seetharaman, Stockholm (S) electronic characteristics, of a material are B.Vinet, Grenoble (F) determined by the atomic structure and Stefan Will, Bremen (D) chemical composition and the number and kind of defects produced during the synthesis process. For high-precision castings, controlling the structure during the liquid-to- unwanted crystallisation events, it is even solid phase transition – which can cover up possible to produce completely new to 10 orders of magnitude in length scales, materials with controlled amorphous (glassy) from the atomic, nanoscopic, microscopic to or nanocomposite structures. macroscopic – is absolutely crucial for quality Fig. 1.The temperature distribution during the casting of a car During melt processing, the crystal control and the design of advanced materials engine block. nucleation and growth are controlled by the for specific technological applications. thermophysical properties of the melt. For The production and fabrication of alloys, example, the heat flow and fluid flow are together with the casting and foundry characterised by dimensionless numbers, Fig. 2.The viscosity of pure iron is known to an accuracy of only industry, generate considerable wealth high accuracy of geometric shape are such as the Peclét number, the Prandtl about 50% within Europe. For example: important. As an example, Fig. 1 shows the number, the Rayleigh number and the simulated temperature distribution during Marangoni number.The basis for – 10 million tonnes of total castings within the casting of a car engine block, which will understanding and predicting transport the European Union (EU) are worth benefit from knowledge of these precise phenomena lies in the accurate knowledge thermophysical data for industrial materials €18 billion per year; thermophysical properties. of the thermophysical properties, which are often insufficient because of the inherent – steel production within the EU is worth The issues involved are the modelling of define these dimensionless numbers. difficulties stemming from the high about €7 billion per year; filling and the temperature distribution on However, for most advanced materials, the temperatures involved and the chemically – investment castings in 1997 were worth cooling. From these, the residual strain at thermophysical parameters needed for the aggressive nature of the melts against any €1.1 billion; critical parts can be calculated.This directly simulation of heat flow and fluid flow during container. – the annual worldwide production of nickel affects product reliability and the solidification remain unknown because of alloys is about 13 000 t, worth optimisation of mass, which in turn affects inherent experimental limitations. For 2. State of the Knowledge €170 million; fuel consumption. More advanced issues instance, viscosity measurements reported Most properties of materials (metal, non- – worldwide production of copper alloys is include modelling of the solidification for pure iron – the basis for any steel metals, ceramics, polymers, composites) of 15 million tonnes per year; microstructure and phase formation for production – vary by about 50%, as shown in technological interest and industrial use are – worldwide production of titanium alloys is further improvement of the mechanical Fig. 2. determined by their microstructure. 100 000 t per year. properties. In order to apply computational design Controlling the microstructure is, in turn, very Through the improvements in numerical tools for describing the heat-flow balance important for quality control and the design Against this background, the numerical methods and the control of fluid flow and and fluid dynamics, and the resulting of new advanced materials for specific simulation of casting and solidification cooling conditions, it is possible to optimise microstructure of a casting, reliable applications in aerospace, energy conversion, processes is being increasingly used as a tool the defect and grain structure as well as thermophysical and related properties are transport, microelectronics, etc. For example, for the microstructural optimisation of high- stress distribution at critical patches of required as input parameters. However, for in the aerospace and electric power quality castings, where process reliability and components. Moreover, through controlling quality optimisation, the precision of the industries, the need for single-crystal turbine

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General Perspectives

The liquid phase of materials at high temperature is of considerable interest to the casting, welding and solidification industries. Basic physical research such as structure Fig. 3.The scull-melting (cold crucible; left) technique and and thermodynamic properties, electromagnetic levitation (right) of highly specialised materials. including phase transitions.

alloys. Figure 3 shows the principles of the Applied research and industrial processing. scull-melting (cold crucible) technique and Thermodynamic and transport electromagnetic levitation of highly properties for process modelling. specialised materials. Most investigations require containerless Based on the successful development of processing techniques: gas film containerless processing and diagnostics levitation, acoustic, electrostatic and methods in space, high-precision electromagnetic. measurements at high temperatures of critical and reactive melts are becoming possible by avoiding any chemical reaction of the specimen with its environment.The required high accuracy can, however, be As a consequence, numerical simulation achieved only with the following: programs of industrial casting and solidification processes have been – extended periods of processing time established as a valuable tool in improving (> 10 000 s); process reliability, quality control and high blades offering increased thermal fatigue In general, thermodynamic calculations – ultra-high vacuum conditions (better than accuracy of geometric shape. However, for strength and creep resistance is obvious. can predict thermophysical properties of 10–8 torr); further quality optimisation, the availability However, the reproducibility of single-crystal alloys and simple materials based on known – minimised levitation forces and thus and accuracy of the thermophysical property growth of sufficiently large blades, in properties of the pure substituent phases. controlled heating and reduced liquid data used as input parameters are generally particular for stationary turbines, is rather Such calculations are, however, usually convection in comparison with 1 g gravity insufficient.There are no such data for most limited and needs improvement. restricted to binary or ternary alloys at low conditions on Earth; commercial materials or there are only values In particular during melt processing, such alloying levels and are based on poorly – sophisticated analytical tools. with intolerable error widths. as casting, welding, single-crystal growth and established assumptions concerning the Inspection of the industrial problems directional solidification, the crystal mixing behaviour. This is possible only under conditions of outlined here indicate that the following nucleation and growth are controlled by the Some data can be obtained more or less microgravity either aboard a Space Shuttle or thermophysical property data are needed to thermophysical properties of the melt. accurately by conventional methods. High- the International Space Station (ISS). Based overcome the problem and establish a Besides the general importance of the precision measurements, however, on on the positive experience with recent long- reliable mathematical model of the process: thermophysical properties of multi- chemically highly reactive melts and fluids at term space missions and several hundred component alloys for controlling the the temperatures of interest require hours of processing time, new scientific – ‘freckle’ and ‘white spot’ formation require solidification and casting processes, accurate containerless processing using non-contact methods and hardware modifications are a knowledge of the melting range, fraction knowledge of such data is also important for diagnostic tools. By eliminating the contact being developed that will allow the precise solid and density, and enthalpy of fusion fundamental science. For example, the between the melt and its crucible, accurate determination of much-needed temperature- and thermal conductivity are needed to analysis of phase transformations, fluid surface nucleation control and the synthesis dependent data for highly reactive melts. model heat and fluid flow; stability and dynamics, fundamental laws of materials free of surface contamination This will allow considerable improvements in – thermal conductivity, specific heat and such as dendrite and pattern formation, and becomes possible. For metallic melts, current materials-processing technologies, as enthalpy of fusion data are needed to fundamental studies of kinetics, transport electromagnetic levitation is a well-suited well as the development and application of overcome the problem of the metal and structure formation in physics and containerless technique. new advanced materials, such as glassy solidifying before the mould is filled; biology, all require the accurate knowledge To some extent, such technologies have supermetals and other lightweight/high- – the problem of ‘burn on’ requires a of the thermophysical properties controlling already been adopted to melt processing of strength materials with controlled knowledge of the metal’s surface tension; them. highly reactive materials, such as titanium micro/nanostructures. – to predict locations of shrinkage porosity

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in a casting, melting range, fraction solid, – transport (engine components, weight Here, the most important parameters enthalpy of fusion, density, specific heat reduction); (1-5) are directly related to solidification and thermal conductivity are all required; – energy technologies (wear-resistant processes. On the other hand, it is also – to predict the locations of gas porosity coatings, land-based gas turbines); recognised that these data are generally requires reliable data for the surface – sports (golf clubs, materials with low weight unavailable for most commercial alloys.The tension, melting range, fraction solid and / high strength / low modulus of elasticity). empirical database to be developed will be the diffusivity of gas in the metal. incorporated into software already in use. Furthermore, a questionnaire distributed Existing software platforms and the Fig. 4.Using microgravity offers advantages. The accurate knowledge and high- within European industry by the Topical Team integration of software developers will precision measurements of the revealed the urgent need for high-quality data facilitate industry acceptance and full thermophysical properties of liquids is of themophysical properties.The responses utilisation of the technologies. necessary for the numerical modelling of clearly indicate that: industrial processes where the solid-liquid 3. Expected Results, Space Experiments phase transformation plays a crucial role. – the companies are dissatisfied with the and Future Impact Examples of these industrial processes have amount of data available for commercial Whereas electromagnetically-based been identified: materials; techniques can be used on Earth, – such data are needed for: microgravity offers a number of advantages, – casting processes (Al-, Fe-, Mg-,Ti-alloys); – computer modelling of solidification as shown in Fig. 4. – crystal growth of poly- and single- processes; The influence of microgravity conditions crystalline materials (turbine blades & – gaining a better understanding of the on the measurement of certain discs, semiconductors, ceramics); process; thermophysical parameters can vary.The – glass production (metallic and non- – improved process control; reduction of the levitation forces in metallic); – improved product quality; microgravity leads either to a significant – rapid prototyping; – 90% of the returns indicated enthusiasm for improvement in accuracy or makes the – spray forming and powder production; participating in any future property- measurement possible in the first Fig. 5.Electromagnetic positioning and heating of a quiescent – surface laser modification; measurement programme. place. liquid drop with magnetic fields. – welding (conventional, laser, electron). The advantages of electromagnetic Accurate knowledge of the following levitation under microgravity are: Several fields of applications for the properties is considered to be important, in materials and processes can be defined for order of priority: uncoupling of heating and positioning coils. As a result of the necessity to obtain the following industries: This allows a quiescent liquid drop at accurate thermophysical properties of 1. melting range; constant temperature (< 1K variation), selected commercial materials in the liquid – aerospace (reduced-emission gas 2. fraction solid/fraction liquid; impossible in 1 g (Fig. 5); state, the following objectives of future space turbines); 3. heat capacity and enthalpy; minimum heat input caused by positioning. experiments have been identified: – biomedical technologies (lightweight, 4. density; This allows processing and property high-strength replacements of human 5. surface (interfacial) tension; measurements in ultra-high vacuum 1. develop microgravity techniques to body parts); 6. thermal conductivity and diffusivity; conditions, impossible in 1 g; measure very accurate values of – information technology (high-speed 7. viscosity; reduced magnetic pressure. This leads to thermophysical properties of commercial computing, optical data transmission); 8. emissivity, optical properties; undeformed, spherical liquid drops; alloys for heat flow and fluid flow – nanotechnology (ultra high-strength 9. diffusion coefficients; reduced electromagnetic stirring. There is no modelling; materials); 10. electrical conductivity. turbulent flow in the sample. 2. measure thermophysical properties of

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Fig. 6.The MSL-EML facility and some principles of thermophysical property measurements.(EADS)

Scientific precursor experiments were fluid flow phenomena occuring in liquid conducted in the TEMPUS containerless samples processed under microgravity versus processing facility during the Spacelab IML-2 1 g conditions.These new materials include: and MSL-1 missions. It has been demonstrated that the reduction of – non-metallic materials (oxides, glasses, ...); positioning forces in microgravity leads – semiconductors (Si, Ge, highly-doped either to a significant improvement in the semiconductors, intermetallics); fluids when the unique microgravity advantages over alternative levitation accuracy or makes the measurement – composites (metal/metal, metal/ceramic); environment of space is necessary, in methods through the direct coupling of the possible at all. During 200 h of measurement – functional/smart materials (super- particular using the ISS and developing or electromagnetic field with the sample.The time using non-contact diagnostic tools, conductors, giant magnetostrictive improving specific experiment facilities; considerably reduced electromagnetic thermophysical data were obtained over a materials, permanent magnets); 3. further possible topics include drop-tower power input allows processing under ultra- temperature range and with a precision – slags (steel production). processing, electromagnetic, electrostatic, high vacuum conditions with a much- previously unattainable.These new acoustic and gas-film levitation, as well as extended temperature range (700-2700K) experiment techniques can clearly be Further discussions with a number of the development of a special thermal and better temperature control extended to measure the thermophysical researchers in academia and industry in the analysis furnace using modulation (measurements better than 0.1K) of a properties of liquid materials that are of US and Japan have revealed a strong interest calorimetry and/or new laser-flash quiescent liquid sample in comparison to commercial interest, and they open a new in a major international cooperative effort methods; electromagnetic levitation under 1 g.As an field of research into high-precision using different kinds of containerless 4. carry out terrestrial measurements to example, Fig. 6 shows the advanced MSL- thermophysical property measurement and processing and non-contact measurement indicate the magnitude of corrections for EML (Materials Science Laboratory - its application for high-precision numerical methods for applications-oriented high- problems such as convection; ElectroMagnetic Levitator) facility which is modelling of industrial solidification precision thermophysical properties.This 5. provide a scientific basis for modelling the being developed to fly aboard the ISS. processes. necessitates a further coordination effort on thermophysical material properties in the The precise measurements of The development of an international an international basis. stable and undercooled liquid; thermophysical data, especially in the liquid containerless processing laboratory aboard 6. provide a database for numerical state, are considered to be a prime goal in the ISS using electromagnetic, electrostatic 4. The Way Ahead involving ESA modelling of materials processing; order to improve the modelling of and acoustic levitation methods is highly Installations, Carriers and Opportunities 7. determine the sensitivity of model solidification processes important to desirable in this regard. In particular, the The roadmap consists of three phases in a predictions to the values of various industry. Although the standard ground- development of a variety of positioning long-term research programme: properties imported into the model; based techniques appear to work for several devices under different controlled 8. disseminate the results of the materials, they cannot be applied with atmospheres and with new diagnostic tools Phase 1: Terrestrial Precursor Experiments measurement programme to European confidence to reactive melts at high will allow the investigation of a wide range of i select commercial alloys for industry; temperatures because of contamination and materials with varying degrees of electrical measurement based on the advice and 9. demonstrate the usefulness and exothermic reactions from the crucibles conductivity. steering provided by the industrial importance of microgravity research to required to hold liquid samples against In the early stage, the Topical Team on partners; industry. gravity. New scientific methods and Thermophysical Properties has concentrated ii carry out terrestrial precursor apparatus developments are now available on the processing of metallic materials of experiments in the first 2 years, including High-precision measurements on that eliminate containers. Further increases commercial interest, such as Ni-based drop-tower experiments; chemically highly reactive melts require in accuracy will be possible by carrying out superalloys and Fe-,Ti- and Cu-alloys. In the iii critically evaluate existing theories; containerless processing using non-contact these measurements in the microgravity meantime, the TT has defined new classes of iv carry out a sensitivity analysis, diagnostic tools. Electromagnetic levitation is environment of space under ultra-high of non-metallic materials of interest and new demonstrating the effect of differences in a containerless technique that offers several vacuum conditions. data-based modelling efforts of heat and thermophysical properties on modelling

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grain size (microstructure) and shrinkage Relation to Other Projects defects; i casting of lightweight γ-TiAl turbine CONCLUSIONS v define experiments that take full blades is a key issue of the EC-FP6 advantage of the benefits of IMPRESS Integrated Project, requiring What kind of project? Gas film levitation (ground-based, microgravity; extensive modelling of casting and Levitation techniques for non-metallic and Grenoble, F) vi model the fluid flow in 1 g and solidification in order to overcome metallic specimens Acoustic levitation (ground-based, Canada) microgravity within a levitated drop by problems with product reliability which Measurement of thermophysical properties support of the team being established. hitherto have prevented the application Modelling of magnetic fields Which instrument technology would be of this material on a larger scale in needed? Phase 2: Short-Duration Microgravity energy production and aviation. Based on what ground-based research? Peripheral equipment for electromagnetic Experiments Containerless processing levitation (temperature, volume, i carry out pilot microgravity experiments ii bulk metallic glasses and glass- Solidification (crystallisation/glass emissivity measurements, etc) in available facilities (drop-towers, crystalline composite materials have formation) parabolic flights). However, these facilities promising properties for application as What potential applications? are not sufficient to reach the main goal functional and structural materials. How long a perspective? Casting processes (Fe-, Ni-,Ti-, Al-, Mg-alloys, owing to limited microgravity durations; Exploitation of this potential requires 10 years refractories, metal-matrix composites) ii develop models and methods for the understanding of the formation of the Crystal growth of poly- and single- evaluation and interpretation of solidification microstructure and of the Which space relevance? crystalline materials (turbine blades & microgravity experiments on specific basic thermodynamic properties of the Reduction of internal flow discs, semiconductors, oxides) samples; liquid phase.This topic is addressed in Ultra-high vacuum conditions (makes Glass production/wires/fibres (metallic and iii model the effects of compositional the EC-BMG (Bulk Metallic Glass) RTN precise measurements possible) non-metallic) changes (e.g. the effect of oxygen) on project. Rapid prototyping surface and bulk properties. What facility can potentially be used? Spray forming and powder production Electromagnetic levitation (metals, heavily Surface modification by spraying Phase 3: ISS Experiments doped semiconductors) techniques i carry out systematic experiments on Electrostatic levitation (ground-based JAXA, commercial alloys aboard the ISS using Japan; Caltech, USA) Advanced TEMPUS (and possibly alternative contained or containerless processing facilities); ii test and improve existing numerical models used in casting and foundries and secondary refining industries; iii theoretical and numerical predictions will be compared with the results of well- defined experiments both on the ground and in-flight.

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Topical Team Members The team members are all leading researchers Prof. Ivan Egry Prof. Dr.-Ing. Alfred Leipertz Prof. Dr. Seshadri Seetharaman in the broad field of thermophysical properties DLR Institut für Raumsimulation, D-51140 Köln, Lehrstuhl für Technische Thermodynamik, Department of Metallurgy, KTH Royal Institute of fluids and applications in materials science Germany. Friedrich-Alexander-Universität Erlangen- of Technology, S-10044 Stockholm, Sweden. and engineering. Furthermore, their expertise Tel: +49 2203 601-2844 Nürnberg, Am Weichselgarten 8, D-91058 Tel: +46 8 790-8355 covers different classes of materials, in Fax: +49 2203-61768 Erlangen, Germany. Fax: +46 8 790-0939 particular: Email: [email protected] Tel: +49 (0)9131-85-9900 Email: [email protected] Fax: +49 (0)9131-85-9901 – metals; Dr. F.S.Gaeta Email: [email protected] Dr. Bernard Vinet (also representing Dr. P.Desré, – metallic alloys (crystalline and glass); MARS Center, Microgravity Advances Research and Dr. Garandet, Dr. Praizay) – ceramics; Support,Via Comunale Tavernola, I-80144 Dr. Francis Millot Laboratoire de la Solidification et de ses – electronic materials and semiconductors. Capodichino-Napoli, Italy. Centre de Recherche sur les Matériaux à Haute Procédés, CEA/CEREM Département d’Etudes Tel: +39 81 234-4527 Température, Centre National de Recherche des Matériaux, 17 rue des Martyrs, F-38054 The science team has a long history of Fax: +39 81 234-7100 Scientifique (CRMHT/CNRS), 1D avenue de la Grenoble Cédex 9, France. microgravity experiments, such as: Email: [email protected] Recherche Scientifique, F-45071 Orléans Tel: +33 (0) 4 7688-4099 Cédex 2, France. Fax: +33 (0) 4-7688-5117 – IML-2, Space Shuttle STS-94; Dr. Fabio Gori Tel: +33 2 3825-5683 Email: [email protected] – EuroMir-94; Dipartimento di Ingegneria Meccanica, Università Fax: +33 2 3863-8103 – EuroMir-95; di Roma ‘Tor Vergata’,Via di Tor Vergata, I-00133 Email: [email protected] Prof. Dr. Stefan Will – MSL-1, Space Shuttle STS-97; Roma, Italy. Technische Thermodynamik,Wärme- und – several parabolic flights; Tel : +39 06 7259-4670/7129 Prof. Ken C. Mills Stofftransport, FB 4 Produktionstechnik, – drop-tube processing (short and long tubes). Fax : +39 06 2021-351/7259 Imperial College London, Queens Road, Universität Bremen, Postfach 330440, Email: [email protected] Teddington, Middlesex TW11 0LW, London, UK. D-28359 Bremen, Germany. Tel: +44 171 549-6759 Tel: +49 (0) 421-218-2229 Prof. Hans J. Fecht (Coordination) Prof. Neville Greaves Fax: +44 171 594-6758 Fax: +49 (0) 421-218-7555 Ulm University, Faculty of Engineering, Albert- Department of Physics, University of Wales, Email: [email protected] Einstein-Allee 47, D-89081 Ulm, Germany. Aberysthwyth, Ceredegion SY23 3BZ, UK. Dr. Alberto Passerone Tel: +49 30 314-22831 Email: [email protected] ICFAM-CNR,Via de Marini 6, I-16149 Genova, Italy. Fax: +49 30 314-23035 Tel: +39 010 6475-714 Email: [email protected] Fax: +39 010 6475-700 Email: [email protected]

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Report of the Monotectic: an alloy that separates into two distinct immiscible Solidification in Multicomponent ESA Topical Team in Physical Sciences liquids. Aluminium-lead is an example. Solidification in Multicomponent Eutectic: an alloy with the lowest possible freezing point of any Multiphase Systems (SIMMS) possible mixture of the components. Plumber’s solder (lead-tin) is Multiphase Systems (SIMMS) an example. Contributors: Peritectic: an alloy where a liquid has reacted with a solid to produce S. Rex & U. Hecht, ACCESS e.V., Aachen (D) another solid. Steel is an example.

Fig. 1.Multiphase The multiphase microstructures that evolve in industrial practice, so R&D efforts are research groups from European universities microstructures in (top) the during the solidification of multicomponent directed towards avoiding the formation of and industry in order to build sound commercial Al-alloy A357 alloys are attracting widespread interest for detrimental minority phases and controlling background knowledge for the definition of (deep etched) and (bottom) a industrial applications and fundamental the amount and distribution of beneficial future experiments in microgravity. ternary Al-Cu-Ag alloy used research.Thermodynamic databases are now minority phases. for investigations of eutectic well-established for many alloy systems. Academic interest in multiphase 2. Multiphase Solidification in cell formation (cross-section close to cell tips). Thermodynamic calculations provide all the solidification of multicomponent materials Multicomponent Alloys required information about phase equilibria, focuses on the morphological stability and The microstructures that evolve during forming an integral part of both dedicated the nature and dynamic behaviour of multiphase growth in eutectic, monotectic or and comprehensive microstructure models. multiphase patterns during coupled peritectic reactions are known to show a Among the latter, phase-field modelling has growth.The higher number of degrees of variety of features, depending not only on emerged as the method of choice. freedom and/or the higher number of the phase diagram and the material Solidification experiments are intended to phases in comparison to binary alloys make properties of the alloy under consideration trigger model development or to serve as this a highly challenging field of but also on the growth kinetics and hence benchmarks for model validation. For investigation. the solidification process. Examples include benchmarking, microgravity conditions offer Figure 1 shows the multiphase aligned lamellar or rod-like microstructures a unique opportunity for avoiding buoyancy- microstructures formed during solidification typically achieved during coupled growth, induced convection and buoyancy forces in of a commercial aluminium alloy and where the spacing and its spatio-temporal bulk samples. However, diffusion and the eutectic cells in a ternary alloy, illustrating evolution depend on the growth conditions. free-energy of interfaces and its anisotropy the two aspects outlined above. In multicomponent alloys, the additional need to be determined.The measurement of To handle the industrial and the more degrees of freedom and/or the higher chemical diffusivities in the liquid state can fundamental aspects of multiphase number of phases lead to new equally benefit from microgravity microstructure evolution in multicomponent morphological features, including 2-phase experiments. alloys, close interaction between cells and dendrite-like 2-phase fingers. thermodynamics, thermophysical property Multicomponent alloy thermodynamics and determination and microstructure growth kinetics are needed to understand 1. Introduction investigation is essential throughout the those microstructures that resemble binary Microstructure formation is of major stages of nucleation and growth. All these alloys.The following sections give a brief increases significantly, and reading the importance in solidification research. It is areas of research rely on experimental and introduction to thermodynamic data and diagram is no longer straightforward. highly dependent on alloy composition and modelling techniques.This report discusses computations, and then describes regular, Computational thermodynamics is a process parameters. For binary alloys, the thermodynamic data and computational coupled growth in ternary eutectic alloys and powerful means of tackling these problems. dedicated models and comprehensive thermodynamic tools, as well as the multiphase solidification in subsequent They cover the creation of thermodynamic simulation tools have been developed for experimental and modelling techniques and reactions along the solidification path of databases based on the CALPHAD method predicting microstructure formation and their recent results in the field of multicomponent alloys. (Kaufman & Bernstein, 1970; Saunders & have been successfully validated. For alloys microstructure evolution during Miodownik, 1998) and their use in calculation with three or more components, solidification.The report reflects the 2.1 Computational Thermodynamics of phase equilibria. microstructure formation during discussions within the ‘Solidification in Constructing and reading phase diagrams for Industrial demand influences the solidification is less well understood, Multicomponent Multiphase Systems binary alloy systems is relatively simple. availability of comprehensive especially in cases where multiphase (SIMMS) Topical Team.The Team was However, with an increasing number of multicomponent databases.Today, databases reactions occur along the solidification paths established and funded by ESA with the alloying elements, the amount of data are available for Fe-base alloys, Ni-base of the alloys.These cases are most common intention of stimulating interaction between required to construct a phase diagram superalloys, Al-base light alloys,Ti- and TiAl-

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Fig. 2.Univariant and a b nonvariant reactions shown in the projection of the liquidus surface on the Gibbs triangle for (a) a simple ternary eutectic alloy system A-B-C, and (b) the alloy system Al-Cu-Ag (Witusiewicz et al., 2004).In (b),in addition to the univariant and nonvariant eutectic reactions in the Al-rich corner base alloys, solders and a few others such as kinetics for 1-D systems. Chemical potential of the system, several quasi- peritectic and peritectic slag and geochemical systems. For ternary gradients are used as the driving force to reactions can be and quaternary systems, some handle diffusion.This method allows distinguished. thermodynamic descriptions – often more diffusion against composition gradients than one for a given system – are available in (uphill diffusion) to be treated.The capability the literature. If available, thermodynamic and limitations of the software are databases combined with numerical codes demonstrated by a variety of DICTRA (Sundman et al., 1985; Eriksson & Hack, 1990; simulations for steels (Inden, 2002). Other multicomponent alloys (Section 2.2.2). known as the ternary eutectic point).The Chen et al., 2002; Davis et al., 1990; Lukas et solidification models that have been Investigations into the latter are strongly reactions are: al, 1982) can be used to calculate total Gibbs successfully coupled to thermodynamic driven by industrial demand. Assessing all the energy minima (thermodynamic equilibria) calculations are microsegregation models achievements is beyond the scope of this UV1: Liquid →α(A) + β(B) + Liquid’ for any composition, temperature and (Kraft & Chang, 1997).These take into report; the potential of selected experimental UV2: Liquid →α(A) + γ(C) + Liquid’ pressure, and so are highly effective for account solid-state or back diffusion and and computational tools for application UV3: Liquid →β(B) + γ(C) + Liquid’ handling complex phase equilibria. Highly kinetic effects related to dendrite tip purposes are pointed out instead. NV: Liquid →α(A) + β(B) + γ(C) instructive reviews on applications of undercooling and dendrite arm coarsening, computational thermodynamics can be while approximating a dendrite arm to a 2.2.1 Coupled Growth in Ternary Eutectic Many real ternary systems exhibit found in Kattner et al. (1996), Kattner (1997) sphere, a cylinder or a plate in order to allow Alloys univariant and nonvariant eutectic reactions and Ågren et al. (2002). a 1-D formulation of the equations. Recently, The Gibbs phase rule at constant pressure in certain parts of the system, as can be seen As many industrial R&D projects make use the considerable progress in coupling reads f = c – p + 1, where f is the number of in the Al-rich corner of Cu-Al-Ag in Fig. 2b, of thermodynamic computations on a day- thermodynamic calculations and phase-field degrees of freedom, c the number of calculated with the database assessed by to-day basis, it is evident that models allows the simulation of components and p the number of phases in Witusiewicz et al. (2004). thermodynamic computations are the most microstructure evolution during the system. So, increasing the number of When considering these phase diagrams, advanced tool for tackling solidification of solidification of multicomponent multiphase components means the system will increase two main topics emerge: multicomponent multiphase materials. alloys.This makes modelling of 2-D and even the degrees of freedom for a given number However, they convey no information on the 3-D microstructures possible, without an of phases, or increase the number of phases – in steady-state growth, the solid/liquid local arrangement of the phases in the aprioriassumption of the shape of the for a given number of degrees of freedom. interface of univariant eutectics is prone to microstructure, such as the size distribution growing solid phases. More details are given For a ternary system (c = 3), this means that morphological transitions from planar to and morphology of the individual phases, in Section 2.3. 2-phase equilibria (p = 2) are bi-variant with cellular and dendrite-like patterns, much and the neighbourhood relationships of the two degrees of freedom, 3-phase equilibria like in single-phase solidification of a multiphase pattern.These features are 2.2 Microstructure Evolution during (p = 3) are univariant, and 4-phase equilibria binary alloy (that is also univariant). dependent on the growth kinetics. It is Multiphase Solidification (p = 4) are nonvariant. A simple ternary Stability limits and morphological therefore an essential step to couple Key aspects of microstructure evolution eutectic alloy system is characterised by transition thresholds for composite thermodynamic calculations to other during multiphase solidification of three univariant eutectic reactions and one eutectic interfaces are challenging, owing microstructure evolution models to multicomponent alloys can be divided into: nonvariant eutectic reaction. Figure 2a shows to the interplay between the diffusive understand better and, eventually, (a) the stability and dynamic behaviour of a scheme of the liquidus projection of a instabilities of the eutectic pattern itself. quantitatively predict microstructures in morphological patterns at a multiphase simple ternary eutectic system, where the – simultaneous growth of three solid phases multicomponent alloys. (‘composite’) solid/ liquid interface during three univariant eutectic reactions are from the ternary liquid in nonvariant The DICTRA (Diffusion Controlled steady-state coupled growth of eutectic marked with UV1, UV2, UV3 and the eutectic reaction gives rise to complex Transformations) kinetic software is the first alloys (Section 2.2.1); and (b) multiphase nonvariant reaction with NV (NV is the alloy patterns like periodic arrangements of to integrate thermodynamic calculations microstructures that evolve in successive composition with the lowest freezing point duplex structures. Quadruple points and with diffusion-controlled transformation reactions along the solidification path of of any possible mixture of components; also triple lines also appear. Especially

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a

interesting topics are pattern selection theoretical attempt to analyse the stability of Fig. 3. Microstructures observed for coupled eutectic growth in based on the interplay between solute a lamellar eutectic interface in the presence ternary Al-Cu-Ag alloys shown in cross-sections after directional diffusion and the free energy of hetero- of a low content of a ternary impurity. In the solidification in a temperature gradient G ~ 27 K/mm. interfaces and all questions related to vicinity of the binary eutectic point, they a: planar growth in Al-Cu15.5 at%-Ag9.04 at% at v = 0.085 mm/min.b: cellular growth in Al-Cu13.6 at%-Ag 10.3 at% at oscillatory or tilted growth modes, known extended the linear stability analysis of v = 0.156 mm/min.c: Al-Cu 13.6at%-Ag 16.4at% at from eutectics in binary alloys. Datye & Langer(1981) to a ternary eutectic b v = 0.14 mm/min.In these images,taken by a scanning electron groove.The analysis provides the full linear microscope with back-scattered electrons,the brightness is Figure 3 shows eutectic microstructures stability spectrum of the steady-state proportional to the Ag content of the phases.The white phase in (c) observed during unidirectional solidification lamellar eutectic front in 2-D. One of the is Ag2Al, the grey phase in (a), (b) and (c) is the Al-solid solution of bulk Al-Cu-Ag alloys. interesting conclusions is that, for very small and the black phase is Al2Cu.The white margins of the eutectic cells in (b) are Al-solid solution rich in Ag due to segregation. Univariant eutectic growth attracted much concentrations of the ternary impurity, interest in the early 1970s (Durand-Charre & interlamellar diffusion is a significant Durand, 1972; Fehrenbach et al., 1972; Sahm capillary force stabilising the solid/liquid & Lorenz, 1972; Garmong, 1971), driven by interface. Moreover, in a transient regime the idea of growing in situ composite before morphological break-up, oscillatory materials with aligned microstructures that modes with long wavelengths appear as a cells persisted up to high growth velocities, would give superior mechanical properties, result of the interplay between the Mullins- probably due to a specific orientation of the α for example. Experimental work was Sekerka instability and the resulting local (Al) and Al2Cu lamellae. dedicated to determining the stability limit changes of the eutectic spacings. Crystalline anisotropy and anisotropy for planar coupled eutectic growth in Recently, Akamatsu & Faivre (2000) resulting from the geometric arrangement of univariant reaction and to characterising the studied the initial stage of destabilisation c the eutectic pattern play an important role 3-phase eutectic patterns emerging during and cell formation in thin transparent during cell formation and growth of eutectic

nonvariant growth. Assuming that, as analogue samples of CBr4-C2Cl6 with cells in array. Future experiments and proposed by Mullins & Sekerka (1964), an different low concentrations of naphthalene modelling will explore this aspect in more instability causes the transition from planar as the third component. At the eutectic detail. to cellular eutectic growth, a constitutional solid/liquid interface, travelling waves Nonvariant eutectic growth has been supercooling criterion for defining the occurred prior to the formation of eutectic investigated in quite a number of alloy stability limit for planar univariant eutectic cells.Two-phase structures (fingers) were systems (Rinaldi et al., 1972; Cooksey & growth was proposed (Rinaldi et al., 1972; found locally, intermediate to cell formation. Hellawell, 1967; Mollard et al., 1974), with the McCartney et al., 1980). The cellular structure was found to be main aim of identifying the different types of Similar to a Mullins-Sekerka instability for unsteady, possibly because the interfacial 3-phase eutectic patterns. A systematic a single-phase solid, this approach is properties show low anisotropy. classification of possible phase arrangements formulated in terms of the third, segregating In bulk samples, additional phenomena based on the phase diagram, the diffusion component for the univariant eutectic arise from the 3-D nature of the eutectic and mobility of the individual components and reaction. It agrees reasonably well with cellular pattern. Based on unidirectional the free energy of all hetero-interfaces (three experimental observations, but it does not solidification experiments with different Al- solid/liquid and six solid/solid interfaces) is consider the most interesting aspect of the Cu-Ag alloys, Hecht et al. (2004) argued that plane of the lamellae rather than pending, although several approaches have morphological destabilisation of a planar the primary instability of an initially planar perpendicular to the lamellae. Elongated cells been proposed (Cooksey & Hellawell, 1967; eutectic interface: the interplay between the eutectic interface consisting of α(Al) and were found to result from this break-up Lewis & Notis, 2002). Recently, Himemiya &

eutectic pattern and the instability. Al2Cu lamellae (see univariant reaction process that only in a later stage transformed Umeda (1999) published 3-phase eutectic Plapp & Karma (1999) made the first labelled ‘1’in Fig. 2b) occurred within the into regular cells. In some grains, elongated growth models for the ideal lamellar pattern

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and constructed ‘rod+hexagon’ and multiphase reactions in the terminal stages superalloy and compared the results with field model for ternary alloys, including the ‘semiregular brick-type’ patterns, following of solidification. In most industrial processes measurements of microsegregation in thermodynamic data via an apriori the procedure applied by Jackson and Hunt the cooling rates are high, such that solid- unidirectionally solidified samples. Phase- calculated tie-line map of the ternary phase (1966) for binary eutectics, under the state or back-diffusion is ineffective and field simulations are able to handle diagram. Chen et al. (2004) reported on assumption that the diffusion fields for the complete mixing is achieved in the liquid circumstances when different phases solidify directly linking the Ti-base thermodynamic individual components simply superpose on through the overlap of the diffusion fields at different locations in space, i.e. situations database from CompuTherm and the kinetic each other. from neighbouring dendrites.This situation where 1-D microsegregation models are software DICTRA to a 2-phase field model for The question emerging from these is well described by the Scheil-Gulliver inadequate. It remains a long-term goal to modelling growth of precipitates in the pattern-selection aspects is what patterns approximation for solute partitioning (Scheil, link microstructure simulations based on ternary system Ti-Al-V. Cha et al. (2001) will be selected during coupled growth when 1941; Gulliver, 1922).Therefore, phase-field models to macroscopic reported on coupling thermodynamic data forcing the alloy to grow in 2-D confinement, thermodynamic calculations in the Scheil solidification modelling. to a 2-phase field model. i.e. when the formation of quadruple points approximation yield valuable information The only model that presently applies to within duplex structures is prohibited. In this about the solidification sequence, including 2.3 Phase-field Modelling of Multiphase multiphase transformations in regard, comparative 2-D and 3-D the type and amount of phases formed and Microstructures multicomponent alloys is based on the investigations of pattern selection and its the composition of these phases. Many Since phase-field models emerged as the multiphase-field model, initially developed spatio-temporal evolution will be the applicational questions can thus be handled method of choice for complex microstructure for unary alloys by Steinbach et al. (1996; method of choice for future work. with computational thermodynamics; evolution problems, a vast variety of models Steinbach & Pezolla, 1999).This model was For both univariant and nonvariant indeed, thermodynamic software is now an has been proposed. Recent reviews (Ode at later extended to binary alloys (Tiaden et al., eutectic growth, the availability of established tool in many industrial R&D al., 2001; Chen, 2002; Boettiger et al., 2002) 1998) and to multicomponent alloys (Grafe et thermodyamic equilibrium data is mandatory departments. However, the Scheil provide a guide through this field.The al., 2000; Böttger et al., 2000). For whenever morphological transitions or the approximation does not apply to all extension of multiphase-field models from multicomponent alloys, coupling the phase- relationship between spacings and processes. For example, directional binary to multicomponent alloys is rather field model to thermodynamic databases and undercooling is adressed. For the latter, solidification of single-crystal turbine blades new: Plapp & Karma (2002) developed a calculations is also possible, directly or analytical models for univariant growth from Ni-base superalloy, and other slower eutectic phase-field model for binary indirectly. An application of this model to (McCartney et al., 1980; DeWilde et al., 2004) processes. For these situations, eutectics with a ternary impurity and nonvariant eutectic solidification is shown in and for nonvariant growth (Himemiya & microsegregation models are better. Since simulated the formation of eutectic colonies Fig. 4, where initial qualitative 3-D Umeda, 1999) can be applied. However, apart the first analytical model for a ternary alloy in 2-D.They achieved good agreement with simulations of 3-phase nonvariant eutectic from thermodynamic data, diffusion data, (Mehrabian & Flemings, 1970), many their earlier stability analysis (Plapp & Karma, growth in Al-Cu-Ag are shown. including off-diagonal terms and interfacial numerical models of microsegregation have 1999) regarding the destabilisation of the Phase-field theory is also well suited for energy data, are required.Today, these data been developed.They were reviewed by initially planar lamellar front due to long- the continuum modelling of nucleation. Such are rather scarce, but results from ongoing Kraft & Chang (1997).The models usually wavelength modes. A striking similarity to an approach has been used to describe work in different groups are expected in the employ a 1-D approximation of the dendrite 2-D experiments (Akamatsu & Faivre, 2000) eutectic solidification in a binary model near future for selected alloy systems. Until arm geometry as plate, cylinder or sphere has been achieved. system (Elder et al., 1994; Drolet et al., 2000). then, data from corresponding binary alloys and solve the multicomponent diffusion Several phase-field models for A similar technique has been applied for must suffice. equations coupled to a solidification model multicomponent alloys have been proposed simulating the nucleation of primary and to thermodynamic data. recently based on coupling of the phase-field dendritic particles with different 2.2.2 The Solidification Path and Multiphase In the future, phase-field simulations are equations to thermodynamic databases and crystallographic orientations (Gránásy et al., Microstructures also expected to contribute to this topic. equilibrium calculations. Qin et al. (2003) 2002).This approach has been extended to In many multicomponent commercial alloys, Warnken et al. (2002) computed proposed a direct linking to thermodynamic describe the nucleation and growth of the growth of the primary phase, which microsegregation during dendritic calculations for a 2-phase field model. eutectic phases during equiaxed causes segregation, is followed by solidification of a 5-component Ni-base Kobayashi et al. (2004) proposed a 2-phase solidification. Figure 5 shows the simulated

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a a

multi-grain structures obtained for components from the liquid will flow into solidification of hypo-eutectic, eutectic and and accumulate in the depressed areas, hyper-eutectic Ag-Cu melts, reproduced from increasing the curvature; Lewis et al. (2004). – buoyancy forces induce motion of solid- phase particles inside the liquid.This holds 3. The Benefits of Research under for primary-phase particles growing from Microgravity the undercooled liquid after nucleation on b b Experimental investigations on sample foreign seeds, such as TiB2, but also for systems containing a liquid phase are known secondary-phase particles in divorced to benefit from the unique environment of eutectic growth. On Earth, particle motion space.The continuous state of freefall on a and the associated alteration of the solute stable orbiting platform provides near- fields around growing particles affect the weightlessness not only to the astronauts, experimental results. but also prevents any convection created by density differences in the liquid (buoyancy- Taking full account of the effects of driven convection), sedimentation and thermo-solutal convection and buoyancy hydrostatic pressure variations. forces within the frame of microstructure Buoyancy-driven convection is critical in models for multicomponent multiphase the measurement of chemical diffusivities in alloys is beyond the reach of today’s models. liquid alloys, as well as in the determination The overall strategy, then, is experimentally of thermophysical properties.These data are to achieve diffusive growth conditions in a important for microstructure formation in few benchmark space experiments and to c multicomponent alloys, which is the subject check model calculations against these c of the Topical Team looking at the experiments. thermophysical properties of liquids. The alternative of using very thin or quasi- Buoyancy is critical for solidification 2-D sample geometries to reduce convective experiments in multiphase multicomponent effects on the ground appears to be an alloys for two reasons: interesting technique, especially in view of the comparison with 2-D model calculations. – buoyancy-driven convection can alter the Here, wall effects owing to wetting may solutal field ahead of a growing solid/ hinder application to a wide range of liquid interface and thus affect the different alloy systems. Of course, all morphological features of the growing inherently 3-D processes remain unresolved. multiphase solid.This can be considerable The post-mortem analysis of thin metallic for univariant eutectic growth in Bridgman samples is a more delicate, but feasible, task. solidification of alloys that segregate a In this regard, the use of organic low-density component, such as Si for multicomponent alloys that allow in situ (α)Al-Al Cu eutectics in ternary Al-Cu-Si observation of microstructure evolution are Fig. 4.Qualitative 3-D phase-field simulation of nonvariant Fig. 5.Equiaxed solidification in (a) hypo-eutectic,(b) eutectic and 2 eutectic growth in Al-Cu12at%-Ag18 at% showing (a) the three (c) hyper-eutectic Ag-Cu liquids at 900K as predicted by the phase- alloys.Whenever the overall solid/liquid future research topics for microgravity α phases Ag2Al (white),Al2Cu (dark grey) and (Al) (light grey) field theory (Lewis et al., 2004).The figures show orientation interface is curved because of even small conditions, where thick cells can be used. together, (b) only Ag2Al (white) and Al2Cu (dark grey) and (c) only maps, where different colours stand for different crystallographic radial temperature gradients, high-density In conclusion, experiments under Ag2Al (white). orientations in the laboratory frame.

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microgravity conditions offer a unique the ISS will use ESA’s Solidification & of initially hypo-eutectic and hyper-eutectic References opportunity for obtaining experimental results Quenching Furnace (SQF) insert, which is alloys.The weightlessness is needed to avoid Ågren, J., Hayes, F.H.Hoglund, L., Kattner, U.R., in diffusive growth conditions to serve as likely to be the first to use the multi-user buoyancy-driven thermosolutal convection Legendre, B. & Schmid-Fetzer, R. (2002). benchmarks.The facilities used for space Materials Science Laboratory (MSL) facility, in the melt and buoyancy-induced motion of Applications of Computational experiments – both isothermal and gradient integrated in NASA´s Materials Science the growing multiphase solid. Thermodynamics. Z. Metallkd. 93, 128. furnaces – generally provide a very high level Research Rack (MSRR-1) in the Station’s Akamatsu, S. & Faivre, G. (2000).Traveling of performance and control. Even if all the ‘Destiny’ US laboratory module.The launch of 5. Conclusions and Perspectives Waves,Two-Phase Fingers and Eutectic desirable experimental features cannot be this furnace insert is sheduled for 2006 with Within the SIMMS Topical Team, the Colonies in Thin-Sample Directional offered because of safety constraints, the the first ESA MSL flight increment. Different discussions about solidification in Solidification of a Ternary Eutectic Alloy. space furnaces are extremely well- facilities are under consideration for the multicomponent multiphase systems were Phys.Rev.E61, 3757. characterised and equipped with unidirectional solidification experiments based on the experience of the partners from Boettiger, W.J.,Warren, J.A., Beckermann, C. & comprehensive diagnostics.With this, the with organic ternary alloys. Either the ESA industry and academic institutions. For Karma, A. (2002). Phase-field Simulation of quality of the experimental results is generally Directional Solidification Insert (EDSI) being industrial purposes, the interest is directed at Solidification. Ann. Rev. Mater. Res. 32, 163. very high. developed by ESA for the DECLIC (Dispositif multiphase microstructures evolving in Böttger, B., Grafe, U., Ma, D. & Fries, S.G. (2000). pour l’Étude de la Croissance et des Liquides successive steps of phase formation along Simulation of Microsegregation and 4. The Next Steps in Space and Joint Critiques) facility, or a suitable modification the solidification path of multicomponent Microstructural Evolution in Directionally Research Projects of the NASA Pore Formation & Mobility alloys during casting, welding and brazing. Solidified Superalloys. Mat. Sci. & Tech.16, In parallel with the formation of the SIMMS Investigation (PFMI), presently installed in From a more fundamental point of view, 1425. Topical Team in 1999, a joint research proposal Destiny’s Microgravity Science Glovebox interest is focused on the morphological Cha, P.-R.,Yeon, D.-H. & Yoon, J.-K. (2001). was submitted by some of the team members (MSG), will be used. In both cases, these stability and dynamic behaviour of A Phase Field Model for Isothermal to an ESA Announcement of Opportunity.This experiments might be launched in 2007. multiphase patterns during steady-state Solidification of Multicomponent Alloys. research proposal, focusing on the Until then, the preparatory ground research coupled growth in unidirectional Acta Mat. 49, 3295. Solidification along the Eutectic path in programme will be continued and solidification. Naturally, these two focal points Chen, L.Q. (2002). Phase Field Models for Ternary Alloys (SETA), was approved and highly expanded. differ slightly with respect to their immediate Microstructure Evolution. Ann. Rev. Mater. recommended by ESA´s European peer panel. Nationally-funded projects have been set goals, but their common ambition is to Res. 32, 113. The research into the eutectic solidification of up by partners of the Topical Team. Examples achieve reliable microstructure models that Chen,Q.,Ma,N.,Wu,K.& Wang,Y.(2004). ternary alloys includes univariant and are two research projects within the national integrate multicomponent thermodynamics. Quantitative Phase-Field Modeling of nonvariant eutectic growth. Presently, the ‘Schwerpunktprogramm’ on Phase Phase-field modelling emerged as the Diffusion-Controlled Precipitate Growth and experimental investigations focus on coupled Transformation in Multicomponent Melts of method of choice, since it can handle almost Dissolution in Ti-Al-V. Scripta Mat. 50, 471. eutectic growth, especially on the formation of the Deutsche Forschungsgemeinschaft all types of phase transitions and alloy Chen,S.-L.,Daniel,S.,Zhang,Z.,Chang,Y.A.,Yan, eutectic cells and the cellular pattern. Future (DFG), dedicated to eutectic and monotectic systems.The partners agreed that X.-Y., Xie, F.-Y., Schmid-Fetzer, R. & Oates,W.A. tasks will include divorced eutectic growth in a growth in ternary alloys. experiments under microgravity conditions (2002).The Pandat Software Package and its ternary univariant alloy, which has already The first space experiment, however, free of buoyancy-driven convection and Applications. Calphad 26, 175-188. have been observed in space experiments emerging from the SIMMS Topical Team will buoyancy forces can serve as benchmarks for Cooksey, D.J.S & Hellawell, A. (1967).The (Hecht et al., 2001). be a solidification experiment on the model verification. However, an important Microstructures of Ternary Eutectic Alloys in The preparatory investigations on the Maxus-6 sounding rocket, scheduled for future task remains to provide reliable data the Systems Cd-Sn-(Pb,In,Tl), Al-Cu- ground are being performed using metallic Al- launch in late 2005.This Unconstrained on diffusivities (mobilities) in the liquid and (Mg,Zn,Ag) and Zn-Sn-Pb. J. Inst. Met. 95, Cu-Ag and Al-Cu-Si samples, and transparent Eutectic Solidification in Ternary Alloys the free energy/ anisotropy of the interfaces. 183. organic ternary alloys. Space experiments are (UNESTA) experiment will investigate Multicomponent diffusion couples in the Datye, V. & Langer, J. S. (1981). Stability of Thin planned with both metallic and organic equiaxed growth in undercooled liquid Al- liquid state would benefit from microgravity Lamellar Eutectic Growth. Phys.Rev.B24, samples.The metallic experiments onboard Cu-Ag alloys, following the solidification path experimentation. 4155.

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Davis, R.H., Dinsdale, A.T., Chart, T.G., Barry, T.I. of Rapid Cooling upon the Constitution of Kraft, T. & Chang, Y.A. (1997). Predicting Rinaldi, M.D., Sharp, R.M. & Flemings, M.C. & Rand, M. (1990). Application of MTdata Binary Alloys. Metallic Alloys, Griffin, Microstructure and Microsegregation in (1972). Growth of Ternary Composites from to the Modeling of Multicomponent London, UK, 120. Multicomponent Alloys. JOM 49, 20. the Melt: Part II. Metall.Trans. 3, 3139. Eequilibria. High Temp. Sci. 26, 251. Hecht, U.,Witusiewicz, V.T. & Rex, S. (2001). In Lewis, D., Allen, S., Notis M.R. & Scotch, A. Sahm, P.R.& Lorenz, M. (1972). Strongly DeWilde, J., Froyen, L. & Rex, S. (2004). Int. Conf. on Solidification Science and (2002). Determination of the Eutectic Coupled Growth in Faceted-Nonfaceted

Coupled Two-Phase [(Al)+(Al2Cu)] Planar Processing, 2001, Bangalore, India,(Eds. Structure in the Ag-Cu-Sn System. J. Eutectics of Monovariant Type. J. Mater. Sci. Growth and Destabilization Along the B.K. Dhindaw et al.), Science Publisher Inc., Electronic Mat. 31, 161. 7, 793. Inivariant Eutectic Reaction in Al-Cu-Ag 61. Lewis, D., Pusztai, T., Gránásy, L.,Warren, J.A. & Saunders, N. & Miodownik, A.P.(1998). Alloys. Scripta Mat., in press. Hecht, U.,Witusiewicz, V.T., Dervermann, A. & Boettinger, W.J. (2004). Phase Field Models CALPHAD, Elsevier Science, New York. Drolet, F., Elder, K.R., Grant, M. & Kosterlitz, J.M. Rex, S. (2004). Formation of Eutectic Cells in for Eutectic Solidification. J. Metals,in print. Scheil, E. (1941). Bemerkungen zur (2000). Phase-Field Modeling of Eutectic Ternary Al-Cu-Ag Alloys. Advanced Eng. Lukas, H.L.,Weiss, J. & Hening, E.-T. (1982). Schichtkristallbildung. Z. Metallkd. 34, 70. Growth. Phys. Rev. E 61, 6705. Mat., submitted. Strategies for the Calculation of Phase Steinbach, I. & Pezolla, F.(1999). A Generalized Durand-Charre, M. & Durand, F.(1972). Effects Himemiya,T. & Umeda, T. (1999).Three-Phase Diagrams. Calphad 6, 229. Field Method for Multiphase of Growth Rate on the Morphology of Planar Eutectic Growth Models for a McCartney, D.G., Hunt, J.D. & Jordan, R.M. Transformations using Interface Fields. Monovariant Eutectics: MnSb-(Sb,Bi) and Ternary Eutectic System. Materials Trans. JIM (1980).The Structures Expected in a Physica D 134, 385. Mn-Sb-(Sb,Sn). J. Cryst. Growth 13-14, 747. 40, 665. Simple Ternary Eutectic System: Part I Steinbach, I., Pezzola, F., Nestler, B., Elder, K.R., Drolet, F., Kosterlitz, J.M. & Grant, M. Inden, G. (2002). Computational Theory. Metall.Trans. A 11, 1243. Seesselberg, M., Prieler, R., Schmitz, G.J. & (1994). Stochastic Eutectic Growth. Phys. Thermodynamics and Simulation of Phase Mehrabian, R. & Flemings, M.C. (1970). Rezende, J.L.L. (1996). A Phase Field Rev. Lett. 72, 677. Transformations. In Calphad and Alloy Macrosegregation in Ternary Alloys. Metall. Concept for Multiphase Systems. Physica D Eriksson, G. & Hack, K. (1990). ChemSage – A Thermodynamics (Ed. P.E.A.Turchi et al.), Trans. 1, 455. 94, 135. Computer Program for the Calculation of TMS Annual Meeting, Seattle,WA, USA, Feb Mollard, F.,Lux, B. & Hubert, J.C. (1974). Sundman, B., Jansson, B & Anderson, J.O Complex Chemical Equilibria. Metall.Trans. 17-21, 2002,TMS,Warrendale, PA, USA, 107. Directionally Solidified Composites Based (1985).The Thermo-Calc Databank System. B 21, 1013. Jackson, K.A. & Hunt, J.D. (1966). Lamellar and on Ternary Eutectic Ni-Ni3Al-Ni3Ta Calphad 9, 153. Fehrenbach, P.J., Kerr, H.W. & Niessen, P. Rod Eutectic Growth. Trans.Met.Soc.AIME (gamma-gamma’-delta). Z. Metallkd. 65, Tiaden, J., Nestler, B., Diepers, H.J. & (1972). Unidirectional Solidification of 236, 1129. 461. Steinbach, I. (1998).The Multiphase-Field Monovariant Eutectic Cu-Mg-Ni Alloys. Kattner, U.R., Boettinger, W.J. & Corriell, S.R. Mullins, W.W. & Sekerka, R.F.(1964). Stability Model with an Integrated Concept for J. Cryst. Growth 16, 209 (1996). Application of Lukas’ Phase Diagram of Modelling Solute Diffusion. Physica D 115, Garmong, G. (1971).The Directional Programs to Solidification Calculations of a Planar Interface during Solidification of a 73. Solidification of Al-Cu-Mg Monovariant Multicomponent Alloys. Z. Metallkd. 87, 522. Dilute Binary Alloy. J. Appl. Phys. 35, 444. Warnken, N., Böttger, B., Ma, D.,Vitusevych, V., Alloys. Metall.Trans. 2, 2025. Kattner, U. R. (1997).The Thermodynamic Ode, M., Kim, S.G. & Suzuki, T. (2001). Recent Hecht, U., Fries, S.G. & Dupin, N. (2002). Grafe, U., Böttger, B.,Tiaden, J. & Fries, S.G. Modeling of Multicomponent Phase Advances in the Phase-Field Model for Microstructure of a 5-component Ni-base (2000). Coupling of Multicomponent Equilibria. JOM 49, 14. Solidification. ISIJ Int. 41, 1076. Model Alloy: Experiments and Simulation. Thermodynamic Databases to a Phase Kaufman, L. & Bernstein, H. (1970). Computer Plapp, M. & Karma, A. (1999). Eutectic Colony In Materials for Advanced Power Field Model: Application to Solidification Calculation of Phase Diagrams with Specific Formation: A Stability Analysis. Phys.Rev.E Engineering 2002, 29 September – 2 October and Solid State Transformations of Reference to Refractory Materials, Academic 60, 6865. 2002, Liege, Belgium (Eds. J. Lecomte- Superalloys. Scripta Mater. 42, 1179. Press, New York. Plapp, M. & Karma, A. (2002). Eutectic Colony Beckers et al.), Jülich: Forschungszentrum Gránásy, L., Börzsönyi,T. & Pusztai, T. (2002). Kobayashi, H., Ode, M., Kim, S.G., Kim, W.T. & Formation: A Phase Field Study. Phys. Rev. E Jülich, 315. Nucleation and Bulk Crystallization in Suzuki, T. (2003). Phase-Field Model for 66, 061608. Witusiewicz, V.T., Hecht, U. & Rex, S. (2004). Binary Phase Field Theory. Phys. Rev. Lett. Solidification of Ternary Alloys Coupled Qin, R.S. & Wallach, E.R. (2003). A Phase-Field The Ag-Al-Cu System: II.Thermodynamic 88, 206105-1. with Thermodynamic Database. Scripta Model Coupled with a Thermodynamic Evaluation of the Entire System. J. Alloys Gulliver, G.M. (1922).The Quantitative Effect Mat. 48, 689. Database. Acta Mat. 51, 6199. Comp., submitted.

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Topical Team Members

Dr.S.Rex (Coordinator) &U.Hecht Prof.L.Granasy Prof.L.Ratke A. Ludwig ACCESS e.V., Intzestrasse 5, D-52072 Aachen, Research Institute for Solid State Physics and DLR, Linder Hoehe, D-51147 Cologne, Germany. Simulation and Modelling of Metallurgical Germany. Optics (RISSP), P.O. Box 49, HU-1525 Budapest, Tel: +49 2203 601 2098/2356/2667 Processes, Department of Metallurgy, Tel: +49 241 8098007 Hungary. Fax: +49 2203 61768 University of Leoben, Franz-Josef-Str.18, Fax: +49 241 38578 Tel: +36 1 3922222 ext. 3371 Email: [email protected] A-8700 Leoben, Austria. Email: [email protected] Fax: +36 1 3822219 Tel: +43-3842-402-2220 Email: [email protected] C. Sigli Fax: +43-3842-402-2202 Dr.D.Camel PECHINEY CRV, 725, rue Aristide Bergès, BP 27, Email: [email protected] CEA/DTA/CEREM/SPCM - CENG, Section G-U. Gruen F-38341 Voreppe Cedex, France. Solidification & Cristallogenese, 17 Avenue Hydro Aluminium Deutschland GmbH, R&D, Tel: +33 476 57 8107 Dr.R.Montanari des Martyrs, F-8054 Grenoble Cedex 9, P.O. Box 2468, D-53014 Bonn, Germany. Fax: +33 476 57 8099 University of Rome II, Dept. of Mechanical France. Tel: +49 228 5522123 Email: [email protected] Engineering,Via della Ricerca Scientifica, Tel: +33 4768 8422 3 Fax: +49 228 5521991 I-00173 Rome, Italy. Fax: +33 4768 8511 7 Email: [email protected] B. Sundman Tel: +39-06-72597182 Email: [email protected] KTH Stockholm, Dep.Mat.Sci. and Engineering, Fax: +39-06-2021351 Dr.A.A.Howe SE-10044 Stockholm, Sweden. Email: [email protected] G. Faivre Corus Research Development & Technology, Tel: +46 8790 6211 Directeur de Recherche CNRS, UMR CNRS 7588/ Swinden Technology Centre, Moorgate, Fax: +46 810 0411 M. Plapp Gr.de Phys. des Solides, Couloir 23-13, 2 Place Rotherham, South Yorkshire S60 3AR, UK. Email: [email protected] Laboire PMC, Ecole Polytechnique, F-91128 Jussieu, F-75251 Paris Cedex 05, France. Tel: + 44 1709 825328 Palaiseau, France. Tel: + 33 1442 7639 9 Fax: + 44 1709 825337 Guests Tel: +33 1 6933 4664 Fax: +33 1435 4287 8 Email: [email protected] Y.Bienvenue Fax: +33 1 6933 3004 Email: [email protected] Ecole des Mines des Paris, Centre des Materiaux, Email: [email protected] Dr.-Ing H-A Kuhn BP 87, F-91003 Evry Cedex, France. Dr.L.Froyen Wieland-Werke AG, Zentrallabor und Entwicklung, Tel: +33 1 6076 3035 Dr. B.Vinet Catholic University of Leuven, Dept. MTM, Graf-Arco Strasse 36, D-89079 Ulm, Germany. Fax: +33 1 6076 3150 Laboratoire de la Solidification et de ses Kasteelpark Arenberg 44, B-3001 Leuven, Tel: +49 731 944 37 05 Email:[email protected] Procedes, CEA/CEREM, Dept. des Technologies Belgium. Fax: +49 731 944 30 93 p. les Energies Nouvelles, 17 avenue des Tel: +32 1632 1277 http://www.wieland.de A. Buchholz Martyrs, F-38054 Grenoble Cedex 9, France. Fax: +32 16321 992 Corus Research, Development & Technology, Tel: +33 4387 8409 9 Email: [email protected] B. Legendre P.O. Box 10000, 1970 CA Ijmuiden, Fax: +33 4387 8511 7 Universite Paris-Sud XI, Rue Jean-Baptiste- The Netherlands. Email: [email protected] Clément, F-92296 Chatenay-Malabry Cedex, Tel: +31 251 497651 France. Fax: +31 251 470445 Tel: +33 1 4683 5457 Email: [email protected] Fax: +33 1 4683 5454 Email: [email protected]

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Report of the Ices in the Universe: Answers from ESA Topical Team in Physical Sciences Physico-Chemistry of Ices in Space

Microgravity Contributors: H.J. Fraser, Strathclyde (UK) (Coordination) P.Ehrenfreund, Leiden (NL) J. Blum, Braunschweig (D) J.H.E. Cartwright, Granada (E) E. Hadamcik, Paris (F) A.C. Levasseur-Regourd, Paris (F) S. Price, London (UK) The research detailed in this report focuses models, or interpret remote observations of F.Prodi, Bologna (I) on icy particles, spanning key hot topics in such icy nanoparticles, for example with A. Sarkissian, Paris (F) astronomy and the atmospheric sciences, Earth observation satellites or ground- and R. Seurig, Kayser-Threde GmbH, Munich (D) including: space-based telescopes, accurate data on the – star formation; physical interactions of icy particles are also – cometary science; required.These include understanding the – origins of life; mechanisms and physics governing – cloud formation; aggregation processes, or coagulation of ESA’s ELIPS programme, as well as the data – polar stratospheric clouds and cirrus iced particles, and the formation of porous needs of many ESA directorates, including formation; regolith.The interplay between Human Spaceflight and Science.The results – radiative forcing of the Earth’s climate; electromagnetic radiation and icy particles is of this research will be invaluable for Fig. 2.The evolution of icy particles, from the interstellar – icy nano-particles; paramount to the interpretation of remote- interpreting data from ongoing and planned medium to planetary atmospheres,showing the key water-ice – atmospheric aerosols. sensing data, and requires a significant effort ESA missions, such as Rosetta, Mars Express, phases and grain sizes at each stage.a: icy mantles form on dust particles in interstellar clouds,through sublimation from the gas in experiments studying light-scattering, Venus Express, Smart-1 and Herschel. phase,or by reactions on the grain surfaces.b: as dense cores In all of these research fields, the chemical back-scattering and polarisation effects, as within interstellar clouds collapse,icy grains are incorporated and physical interactions of nanoparticles well as the spectroscopy of icy nanoparticles into the coldest regions of the disc.Closer to the protostar, icy need to be understood at a molecular level across the whole spectrum. 1. Overview mantles are evaporated and reform as the disc cools.c: over a and bulk level. In the Earth’s atmosphere or This report highlights the prospects of Icy layers are known to cover dust particles in few million years, the dust aggregates, forming planetesimals on aerosol particles, a liquid-like water layer studying icy nanoparticles using existing, the cold regions of the interstellar medium, and subsequently planets.The remaining planetesimals form the population of comets and asteroids,the surfaces of which forms at the surface and governs the planned and future facilities on Earth, in and to drive a rich chemistry in energetic may be covered with regolith and ices.d: many planets and chemistry that subsequently occurs. extraterrestrial missions, and utilising the star-forming regions (Fig. 1). Ices have also moons within the Solar System are known to have ices on their Laboratory and theoretical studies are microgravity environment of the been detected on lines-of-sight towards surfaces and in their atmospheres.On Earth, icy particles form in required to simulate the chemical processes International Space Station (ISS).The extra-galactic sources.Within dusty discs various clouds from water vapour and super-cooled liquid water. in a variety of astronomical and atmospheric scientific benefits of such studies are far- surrounding newborn stars, the aggregation These icy grains are a key constituent of polar stratospheric clouds, which play a major role in the chemistry of Earth’s upper environments.To build comprehensive reaching: in such an interdisciplinary field, of ice-covered dusty particles plays a role in atmosphere. the data will impact many disciplines, the formation of planetesimals and cometary Reproduced from Ehrenfreund et al.(2003), by permission of including materials physics, fundamental nuclei.The polar caps of terrestrial planets, Elsevier Science. physics, atmospheric chemistry and dust grains within the rings of Saturn and exobiology. As such, there is significant Jupiter, and most of the outer Solar System overlap between the aims of this research moons have icy surfaces or icy regoliths. community and the more general aims of Smaller bodies, such as comets and Kuiper Galaxy and Solar System. In low-temperature Belt Objects (KBOs), contain a significant astronomical environments, water-ice is

fraction of icy materials. Icy particles are also present in its amorphous form, IASW (Fig. 2a & Fig. 1.This reflection nebula, consisting of gas and dust,is present in planetary atmospheres and play 2b).The solid-ice phases form either from illuminated by light from a nearby newborn star (centre-left).The an important role in determining the climate vapour deposition of gas-phase H2O object is about 1500 light years from Earth, in a region where and the environmental conditions of Earth. molecules, or chemical reactions between H many stars are being born.The dark ‘keyhole’is a dense molecular Water-ice seems to be everywhere in space and O atoms, at the surfaces of the cold dust cloud,gas and dust blocking the light from behind.Such regions and is by far the most abundant ice in the grains (Fig. 3). Crystalline phases of water ice, are the molecular cauldrons of our Universe,from which stars, planets and possibly life can form.They are the key to answering Universe. Ic, have also been observed in several space many of mankind’s questions from the dawn of time. Figure 2 summarises the distribution and environments (including circumstellar shells, (NASA/The Hubble Heritage Team/STScI) physical properties of icy particles in the moons, Saturn’s rings and comets), indicating

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Fig. 3.The growth, processing and destruction of icy particles in space.Typically,the grains are very small, only nano- to micron- sized, yet they play a significant role in the chemical evolution of star-forming regions.

that these environments are, or have been at coverage, see Ehrenfreund et al. (2003). A key some time, under higher temperature and/or goal was to determine whether a dedicated pressure conditions (Fig. 2c). In planetary ‘ice’ experiment insert could be made for the atmospheres, the icy particles can be ‘existing’ hardware proposed for flight on the crystalline or amorphous: the ISS.The ‘International Microgravity Plasma, thermodynamically most stable phase of ice Aerosol and Cosmic dust Twin’ ( IMPACT)

on Earth is hexagonal ice, IH.A third facility will house the ‘Interactions in Cosmic population of super-cooled particles may and Atmospheric Particles Systems’ (ICAPS) also be present, formed by rapid cooling and ‘International Microgravity Plasma

from the liquid phase, IHSW (Fig. 2d). Facility’ (IMPF). A new insert on this facility Many open questions remain, related to will support multidisciplinary studies on the the formation, structure and evolution of icy growth of icy particles, aerosol microphysics, particles in the Universe.These particles ice hydrometeors, light-scattering properties range in size from just a few nanometres to of solid icy particles, the physics and many millimetres or centimetres in diameter. chemistry of icy particle aggregates. Some answers are expected only from Studying ices in microgravity conditions will studying ices in reduced- and microgravity provide fundamental data on the nature of conditions, particularly under experimental extraterrestrial and atmospheric ice particles, conditions that are impossible to reproduce improving knowledge on the physical and on Earth.This report reviews the scientific chemical processes prevailing in different background to icy particles in the Universe, environments. highlighting some recent ground-based experiments on ice and dust, as well as 2. Scientific Background to the crystalline forms.The presence of pathways (Ehrenfreund & Fraser, 2003). related experiments performed under 2.1 The Icy Universe crystalline ices infers that the pressure and Regulatory mechanisms, such as selective reduced-gravity and microgravity conditions. Ices are observed throughout the Universe: temperature conditions under which they thermal desorption, cosmic ray sputtering, The remainder of the report focuses on the on planetary bodies and their atmospheres, formed were somewhat higher than the photodesorption, sublimation, bulk diffusion Topical Team activities, which have moons, comets, in the interstellar medium prevailing conditions during amorphous ice and grain explosions return molecules back investigated the advantages of studying the (ISM) and in protoplanetary discs. Different formation. It can also be an indicator of to the gas phase (Fig. 3).The physical and physics and chemistry of molecular ices in molecular species are found as ices, such as pressure, stress or elevated temperature on chemical evolution of interstellar icy grain

microgravity conditions; for more detailed H2O, CO2,CO,CH3OH, NH3 and CH4.‘Ice’ refers the ice itself, driving the phase change from mantles is determined by the local to any solids that condensed from their an amorphous to a crystalline form. environment, which can be quiescent or An agglomerate is a cluster or collection of particles and/or aggregates, volatile gas counterparts at temperatures dominated by shocks (including high joined, for example, at their corners or edges, but not necessarily strongly below the freezing point of water (273K). 2.1.1 Interstellar Space temperatures) and UV irradiation. bound together.The total surface area is not significantly different from the Each of these ices can exist in a number of In cold, dense regions of the ISM, ices are sum of the individual surface areas. An aggregate is an ensemble of crystalline or amorphous solid phases, formed by efficient accretion of atoms and 2.1.2 The Formation of Stars and Planets interacting particles, joined via surface-to-surface contact, with a total surface typically represented on a pressure- molecules from the interstellar gas onto Dense interstellar clouds are star nurseries. area smaller than the sum of the surface areas of the individual particles. temperature phase diagram. Amorphous ices carbonaceous or silicate dust particles. Once Star formation occurs via the gravitational When aggregates or agglomerates are iced, their total surface area may exhibit no long-range molecular order. adsorbed on the surface of such interstellar collapse of an individual rotating clumpy increase or decrease depending on the thickness and regularity of the icing. Provided that the temperature is low enough grains, small molecules and atoms diffuse molecular core within the dense cloud, within Icy aggregates, icy agglomerates and iced aggregates of particles/ to prevent molecular rearrangement, the across the surface layer and form more an evolutionary period of ~106-7 years. It is agglomerates of particles are relevant to the science outlined in this report. amorphous ices are metastable with respect complex molecules via catalytic reaction assumed that, in the local vicinity of the new

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The ISS is an invaluable research platform for studying the Solar System, such as comets and Kuiper Belt hydrometeors are mostly characteristic of the than a few seconds. Open questions remain physics and chemistry of icy nanoparticles. Objects, are composed predominantly of icy troposphere, though they also appear in the therefore as to whether ices produced in material (Schmitt et al., 1998). Collisions mesosphere, and in the stratosphere, where terrestrial laboratories are good analogues star (within 5 AU), thermal desorption between asteroids, KBOs and interplanetary PSCs are formed in the polar regions, and are for ices produced in a variety of space dominates the chemistry and all ices are dust all lead to the formation of fluffy at least partially composed of crystalline environments. evaporated. Further out in the protostellar regolith on the surfaces of these small water-ice (Prodi & Levi, 1978; Prodi et al., disc, where temperatures are low enough, bodies, some of which may later be covered 1982). Studies on hail growth have provided 2.2.1 The Advantages of Microgravity volatile species may recondense, forming a in ice. Saturn’s ring system is very bright interesting results on ice accretion processes In microgravity, it would be possible to form, new generation of icy grains beyond the (albedo 0.2-0.6) and contains a mixture of that are relevant to icing effects beyond our manipulate and study physical and chemical snowline. Eventually, as the protostellar disc innumerable rocky and icy particles. Here, we own atmosphere, as well as being directly interactions in clouds of a single population evolves to a mature solar system, such icy focus on these low-gravity environments. For applicable to structural icing, as on aircraft of icy particles over much longer timescales particles are expected to aggregate, forming a discussion of planetary ices per se, consult wings and electrical cables (Prodi et al., than on Earth. Experimental results over the cometary nuclei, protoplanets and asteroids. the review articles in Schmitt et al. (1998). 1991). last few years indicate that the diversity of Turbulent mixing of these particles between amorphous water-ice in the Universe is far the inner and outer regions of the Solar 2.1.4 Earth’s Atmosphere 2.2 Ices in Microgravity and Reduced- greater than most astronomers or System has been postulated as a reasonable Icy particles also exist in planetary Gravity Conditions atmospheric scientists previously explanation for the presence of crystalline atmospheres, including that of Earth.These The current understanding of extraterrestrial contemplated. Given the range of extreme silicates in comets (Bockelee-Morvan et al., particles play a vital role in Earth’s climatic ices relies entirely on comparisons between conditions under which icy particles are 2002). system, through their radiative properties data accrued from laboratory studies (on forming in the Universe, it is quite possible and significance to meteorology (WMO, Earth, at 1g) and remote observations of ices that ice structures exist where the ices have 2.1.3 The Solar System 1998), and are important in atmospheric via telescopes and planetary missions using been under conditions difficult to recreate on Molecular ices are also widespread in the chemistry, where heterogeneous reactions at spectroscopy, IR, light-scattering, polarisation Earth. Furthermore, experiments on Solar System.They cover the poles of the the ice surface can be a source or scavenger and albedo measurements. Understanding of aggregation processes or on light-scattering terrestrial planets: Mars has permanent ice of molecules, and are related to the dramatic icy particles in Earth’s atmosphere has been properties of small particles or their caps at both poles, composed mostly of solid ozone depletion over the Antarctica assimilated through a combination of remote aggregates are ideally suited to reduced- carbon dioxide. Hydrogen-rich regions have (Solomon et al., 1986).The formation, sensing, radiative transfer modelling and gravity and microgravity conditions also been identified near the poles with chemistry and evolution of icy particles laboratory experiments. Experiments that (Levasseur-Regourd, 1998). Specifically, gamma-ray spectroscopy, indicating within polar stratospheric clouds (PSCs) are evaluate the physical and chemical experiments in microgravity will improve subsurface ice, probably in the form of water. far from understood or quantified. Cirrus properties of the ice surface or bulk are scientific knowledge beyond what can be Most of the outer Solar System bodies are clouds, sometimes originating from aircraft generally performed with thin-film ice layers, achieved by ground-based environments covered with ices, predominantly water-ice, contrails, reflect solar radiation back to space supported by a chemically inert substrate, because: although more volatile species can be and/or trap terrestrial IR radiation, rather than icy particles.The latter have been trapped on (and in) bodies such as Triton and substantially affecting Earth’s radiative studied in flowing systems and supersonic – no weight-induced compaction occurs in Pluto under very low-temperature conditions budget (Ramaswamy et al., 2001). In addition, jets, where small clouds of icy grains are low-density ice aggregates or ice-aggregate (< 60K) (Ehrenfreund & Fraser, 2003; Schmitt Earth’s atmosphere includes a great variety continuously generated and pumped away, layers. This has been demonstrated in et al., 1998). A number of Jupiter’s Galilean of iced particles called ice hydrometeors: or particles are prevented from previous studies of the formation of highly moons have been visited by several elementary crystals, snowflakes, graupels and sedimentation by up-flows of cold, damp air. porous dust aggregates, which are spacecraft. In particular, Europa’s icy surface hailstones. Dew is produced by diffusion of However, none of these methods is capable compacted when gravity overcomes the has been studied in detail to establish water vapour onto cold surfaces and objects, of generating a single family of size- inter-particle rolling-friction forces (Blum & whether there is a subsurface ocean. A large and rime (hoarfrost), an ‘icy dew’,is formed at distributed icy particles whose physical and Wurm, 2000). On the molecular scale, more number of small bodies formed in the outer sufficiently low surface temperatures. Ice chemical evolution can be studied over more ordered layer organisation and a reduction

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Fig.4.Scanning electron microscope image of a fractal dust agglomerate consisting of monodispersed,spherical SiO2 particles of 0.95 mm radius.It formed via differential sedimentation in a laboratory experiment.Reproduced from Ehrenfreund et al. (2003), by permission of Elsevier Science.

Only one previous study of water-ice under microgravity and may also play a role in determining of applications in astronomy, atmospheric conditions has been conducted, aboard Skylab in 1973! the reactivity and ionisation potential of sciences and exobiology, and the clear the surfaces of the icy particles. advantages of conducting at least some in defect sites can also result in – no separation between different ice particle studies on a microgravity platform, it is crystalline ices forming structures that sizes or shapes occurs. Compared with somewhat surprising that there are currently more closely resemble theoretical terrestrial levitation experiments with, for no European Union, national or models. Such materials can display example, aerodynamic or electrostatic internationally funded projects focused on different optical properties, different levitation techniques, no separation the physical and chemical properties of physical properties, and larger void between different ice particle sizes or molecular ices formed under microgravity volumes than those grown on Earth shapes occurs under reduced-gravity conditions. A thorough search of the ESA, (Ahari et al., 1997).These differences, conditions (for example, owing to NASA and MICREX microgravity research resulting entirely from the strength of variations in surface-to-mass or charge-to- database revealed only one previous study of the gravitational field, are attributable to mass ratio) in ice-cloud aggregation water-ice under microgravity conditions, the different transport regimes that experiments. aboard Skylab in 1973! (Otto & Lacy, 1973). dominate solid formation in the presence – no particle alignment occurs. In ice cloud This study focused on surface melting of ices and absence of gravity. In particular, the experiments under microgravity in the absence of convection currents.The that low-speed collisions in ensembles of suppression of convection and conditions, non-spherical particles will be Japan Aerospace Exploration Agency (JAXA) particles lead to the rapid growth of fractal dominance of surface tension effects are formed that will not align in any specific and Japanese Space Forum are funding dust aggregates, as seen in Fig. 4.The degree particularly important in substances orientation. Conversely, in the laboratory, research into the effects of gravity on the to which the ensemble can be described as whose crystal structure is determined by the ice particles will be aligned because of growth of ice crystals in thin cells from the fractal depends on the relative speed weak interlayer, or intermolecular, their sedimentation speed and the solution phase (Nagashima & Furukawa, between the aggregates in the dust clouds. interactions. Since this is the case for ices, interaction with ambient gas (Wurm & 2000).This research provides key insights At the earliest stage of planetesimal one would expect ices formed in Blum, 2000; Kraus & Blum, 2004). For into non-linear and non-equilibrium formation, where Brownian-motion microgravity or reduced gravity also to understanding the formation of comets, phenomena in solution, but it does not dominates (Blum et al., 2000; Krause & Blum possess structures with different physical KBOs and icy moons, it is mandatory to address questions concerning condensation 2004), the resulting aggregates are less properties from those grown on Earth. perform aggregation experiments with icy of ices from the gas phase. irregular than later planet-formation stages, – icy particles are isolated and free-floating particles, both in the laboratory and under where differential sedimentation and gas long enough for their spectroscopic and long- and short-duration microgravity 3.2 Aggregation Studies turbulence dominate (Wurm & Blum, 2000; optical properties to be measured conditions. Over the past few years, considerable Blum et al., 1998). Measurements on dust (Levasseur-Regourd, 1998; Levasseur- progress has been made, through a aggregates formed under ballistic Regourd & Hadamcik, 2001). Microgravity 3. Previous Experiments on Ices and combination of laboratory, reduced-gravity aggregation require long-duration conditions allow light-scattering Particle Aggregation and microgravity experiments, in microgravity conditions, as shown with the measurements of low-concentration 3.1 Overview understanding the formation of decimetre- Cosmic Dust Aggregation Experiment particle clouds, without any multiple A detailed and extensive review of recent sized dust agglomerates in the young Solar (CODAG). In this experiment, a cloud of

scattering being induced by results from laboratories and reduced-gravity System (Blum, 2000; 2004; Blum & Scräpler micron-sized SiO2 particles was dispersed in sedimentation. During aggregation, size- and microgravity experiments, together with 2004). It is now clear that micron-sized a rarefied gas atmosphere.Without the discrimination effects between particles the status of ices research in interstellar, silicate particles adhere to one another effect of gravity, the dust grains were and convective heat-transfer processes planetary, cometary and atmospheric through van der Waals forces (Heim et al., subjected to Brownian motion only.This are suppressed. In microgravity, surface- sciences, was published by the Topical Team 1999) and that the speed threshold for irregular thermal motion leads to ballistic tension effects are particularly prevalent in 2003 (Ehrenfreund et al., 2003). Given the sticking is typically a few m/s (Poppe et al., low-speed collisions (typically < 10–3 m/s), during melting and hyper-quenching, significance of ices research to a wide range 2000). Dust-cloud experiments have shown resulting in the grains sticking to each other

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Fig. 5.a: comet nuclei, built up of ices and dust,partially evaporate near their perihelion and give rise to comae and tails of gas,ions and dust particles (A. Dimai, Col.Druscie Obs.).b: polarisation images of the coma of Hale-Bopp at a 43° phase angle reveal differences in the physical properties of the dust,with a lower polarisation in the inner coma, which, together with a change in the polarisation colour,suggests the presence of icy particles.c/d: the colour of the polarisation phase curves retrieved mostly from the outer coma is typical of very fluffy (possibly fractal) dust aggregates of submicron grains that are possibly remnants of more compact particles after sublimation of their icy mantles. Reproduced from Ehrenfreund et al.(2003), by permission of Elsevier Science.

and forming extremely open fractal 4. Requirements for the Next 5-7 Years aggregates (Blum et al., 2000; 2002). 4.1 Planetary Ices 4.1.1 Science Supporting Missions 3.3 Light-Scattering Experiments Most of ESA’s Solar System missions in the The PROGRA2 instrument (Propriétés coming years have some direct or indirect Optiques des Grains Astronomiques et relation with ices in space.This is because ices Atmosphériques; Worms et al., 1999; 2000) are found almost everywhere in the Solar has been used to measure polarimetric phase System, and especially on bodies of interest curves in reduced-gravity from about 70 for astrobiology and the origins of life. samples, with different parameters such as size of grains or aggregates, refractive index Missions to Mars and the packing density of the aggregates. Carbon dioxide ice has been detected in The results have illustrated that the Mars’ polar caps and the polar atmosphere. polarisation of the light scattered by (non- The water-cycle on Mars allows deposition of icy) dust particles is a sensitive diagnostic to frost on mid-latitude rocks and regolith (the structural differences between the particles. layer of unconsolidated pulverised rock As light-scattering effects vary with the material).The gamma-ray spectrometer wavelength of light, it is imperative to repeat carried by NASA’s Odyssey orbiter, launched many measurements over the full visible in 2001, established that there is a wavelength region. Colour effects are a widespread distribution of water-ice, buried fundamental parameter in remote to a depth of at least a metre and mixed with observations, so light-scattering rocky material. By January 2004, ESA’s Mars measurements eventually have to be made Express and NASA’s Mars Exploration Rovers at least three wavelengths (UV-IR) for had arrived to begin observations. In addition comparison with the remote observations. to the detection of carbon dioxide ice at both water-ice. ESA’s SMART-1 mission was launched in 1997, entered orbit around For example, laboratory measurements, poles, the spectral signature of water-ice has launched in September 2003, heading Saturn in July 2004. Cassini carries optical performed at two wavelengths on clouds of been observed at the South Pole by three towards a polar orbit around the Moon by instruments to study the planet’s ring system, levitating particles with PROGRA2 (Worms et Mars Express instruments for the first time. mid-2005 with a 300 km perilune and from UV to near-IR. Huygens is designed to al., 1999; 2000) showed that grey compact OMEGA, a combined camera and IR 10 000 km apolune. High-resolution imaging analyse Titan’s atmosphere and surface,

dust particle aggregates induce a blue spectrometer, mapped the water-ice of the south polar region is planned. including CH4 ices, in January 2005.This polarisation colour, whereas mixtures of fluffy distribution over the South Pole. SMART-1 should provide significant mission will provide significant information aggregates of the same sub-micron-sized information on the existence of ices in the on ices in the many different environments grains, which agglomerate in highly porous Missions to the Moon surface polar regions, which will require surrounding the giant planets, which will structures, usually induce a red polarisation It has been suggested, although never firmly further modelling and laboratory require further modelling and laboratory colour (Levasseur-Regourd, 1999; Levasseur- demonstrated, that volatile molecules measurements for accurate interpretation. measurements for accurate interpretation. Regourd et al., 2001).The blue polarisation released by cometary impacts could be colour observed in the vicinity of cometary gravitationally trapped in permanently Missions to the Giant Planets Missions to Comets nuclei could therefore be a clue to the shadowed areas in the lunar polar regions. Ices are everywhere in the regions around Cometary nuclei are built up of ices (mostly

presence of large compact particles hovering The surface and subsurface of the large the giant planets, including their moons and H2O, but including ices such as CO and CO2) above the nucleus, or of freshly ejected icy Aitken crater basin near the south pole could rings. Following the Galileo results, the and dust particles or boulders that particle aggregates. thus consist of a regolith containing some Cassini/Huygens ESA/NASA mission, aggregated during the epoch of planetary

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formation (Fig. 5). Observations from tiny icy solid or regolith surfaces is a cornerstone have never yet been investigated under There is a clear niche for a well-defined experimental grains in the coma of the bright and active to many of the scientific aims of this report. conditions similar to those in the outer solar programme focused on the physics and chemistry of icy comet C/1995 O1 Hale-Bopp indicate water- As all terrestrial, and most spacecraft, nebula. particles in cometary environments. ice in both amorphous and crystalline phases. observations of icy planetary bodies are Determination of the deuteration fraction of performed using emitted or scattered Simulating Cometary Nuclei – the chemical effects of aggregating icy water from in situ and remote observations in electromagnetic radiation, a clear Cometary nuclei (Fig. 5) are very small bodies particles or icing particle aggregates; the comae of 1/P Halley, C/1996 B2 Hyakutake understanding of the generation and with diameters that rarely exceed 10 km.This – spectroscopic properties of the icy and C/1995 O1 Hale-Bopp suggests that alteration of radiation scattered, emitted or equates to surface escape velocities of nanoparticles; cometary water-ice formed in the cold reflected from the surface regions of these < 10 m/s. Consequently, their formation – condensation and subsequent interstellar medium.This point is still a hot bodies is required.The first step in filling this mechanism is completely different to that of evaporation of ices on model ejecta dust topic because there are still no data missing link between observations of remote the comparatively large icy moons or ice- grains; concerning the nuclei. ESA’s Rosetta mission, bodies and their surface properties will be covered planets and the large KBOs. Since – the thermal- and UV-processed evolution launched in March 2004, is heading for a conducted on the ICAPS experiment insert of they never reach the critical mass, cometary of cometary grains through simulations of rendezvous with 67P/Churyumov- IMPACT (Levasseur-Regourd, 2003).This nuclei are not thought to form by model grains in a variety of comae Gerasimenko in 2014.The orbiter experiments experiment will be equipped to make light- gravitational accretion but by agglomeration, conditions. are devoted to imaging, spectroscopy (UV to scattering measurements, but only at a process involving low-speed (< 100 m/s) microwave), spectrometry, radar sounding of temperatures at or above the ambient collisions.They are held together by cohesive These questions are of the utmost the nucleus structure and physical properties background. For true icy-particles surface forces such as van der Waals forces or importance not only in the formation of of the cometary dust.The lander experiments experiments, a microgravity experiment hydrogen bonding. Many details in the cometesimals and in improving knowledge are devoted to imaging (visible, IR), platform is required. theory of comet formation are still of the origin of comets, but they may also spectrometry (α,protons,X-rays),imaging, unresolved.Thus, a clear niche exists for a help in analysing data from the Rosetta monitoring of the surface and subsurface, and Impact Studies and Aggregation well-defined experimental programme to mission in 2014, improve understanding of to sophisticated chemical and isotopic Over their lifetimes, a multitude of physical determine: the origins of KBOs, the icy moons of the analysis.The observations inside the coma are processes alter the surfaces of small Solar outer Solar System, and possibly even the planned to be performed from almost the System bodies.The most prominent are – cohesive forces between ice grains; cores of the giant planets. Again, many of cometary aphelion to perihelion, and from the impact processes, although in bodies with – the stickiness of icy grains in mutual low- these experiments can be conducted outer coma to the innermost coma.They will atmospheres, weathering by wind and/or speed collisions; effectively only in a microgravity research allow the changes in the properties of the precipitation may also be relevant. Realistic – agglomeration behaviour of micron and facility. dust particles, including the sublimation of samples can be used to simulate various nanometre-resized ice particles; embedded water-ice and other volatiles, to be surface regions: impact experiments will – the early stages of agglomeration, that is, 4.2 Interstellar Ices accurately documented.The analysis of the then help to reveal the long-term evolution quasi-mono-dispersed growth of fractal 4.2.1 Science Supporting Missions nucleus surface and subsurface will allow a of icy surfaces subjected to bombardments aggregates; Data from ESA’s Infrared Space Observatory, significant proportion of the cometary ices to by, for example, the interplanetary meteor – the runaway growth stage, in which larger operational from 1995 to 1998, made an be defined, both chemically (parent flux. External (Sun) or internal (volcanism, agglomerates sweep up and (non- important contribution to our understanding molecules) and physically (ice structure). tidal effects) effects can be experimentally gravitationally) accrete small ice grains; of the ice chemistry in the interstellar simulated by heating the sample surface.To – restructuring and fragmentation medium and the Solar System.The next IR 4.1.2 Laboratory (Ground-Based) date (as illustrated in Section 3), the entire thresholds of icy agglomerates; satellite, NASA’s Spitzer Space Telescope, was Experiments experimental focus discussed has been on – the importance of sintering effects in launched in August 2003 and is returning Light-Scattering Experiments the agglomeration of refractory dust aggregation processes; valuable data. Spitzer is a cryogenically- An extensive experimental programme to particles.The mutual interactions between – the physical effects of sintering on particle cooled IR (3-180 µm) observatory, with a study light-scattering and thermal emission of micron-sized icy particles and agglomerates size, light-scattering etc; 85 cm-diameter telescope; its estimated

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A link can be traced between molecules and species formed also amorphous). In some regions, cubic than thin films, including experiments on ice hydrometeors are ESA’s EarthCARE in pristine interstellar ices, through star and planet crystalline ice has also been observed.The aggregation processes, chemical reactivity, (Fourier spectrometer) and Europe’s Metop formation and possibly to the formation of life itself. final composition of any ice mantle depends heat capacity or light-scattering properties, (IR Atmospheric Sounding Interferometer strongly on the prevailing physical require long-duration (minimum 6-8 h) spectrometer). All these missions will require lifetime is 5 years.The NASA/DLR conditions when the ice was formed. Icy levitating clouds of particles. Again, they are laboratory data on, and theoretical modelling Stratospheric Observatory for IR Astronomy particles in the ISM are governed by best conducted on a dedicated facility on a of, icy particles, to fully elucidate their (SOFIA), successor to the Kuiper Airborne accretion, diffusion, reactions on the surface microgravity platform. observations. Observatory, will debut in 2005 as the world’s and desorption of species into the gas phase. largest airborne observatory, able to observe None of those processes is currently well 4.3 Atmospheric Ices 4.3.2 Laboratory (Ground-Based) at 5-300 µm using a 2.5 m-diameter mirror. understood.The underlying grain surface 4.3.1 Science Supporting Missions Experiments ESA’s Herschel Space Observatory, to be material plays a crucial role and determines In March 2002, ESA launched its advanced Since the air in our atmosphere is being launched in 2007, will be the only space the structure and behaviour of accreted ice Envisat polar-orbiting Earth observation continuously mixed, it is extremely difficult to facility ever developed to cover the far-IR to layers. Laboratory experiments of surface-ice satellite.Three instruments are directly follow the evolution of icy particles in the sub-mm range (80-670 µm).Towards the end interactions therefore have the highest involved in atmospheric science: SCIAMACHY atmosphere with any precision. As with the of this decade, the NASA/ESA James Webb priority.The structure of the bulk ice and any is performing global measurements of trace planetary sciences, a lack of knowledge of Space Telescope (JWST) will be able to restructuring processes due to thermal and gases in the troposphere and stratosphere; the optical properties, including scattering, penetrate the dusty envelopes around radiation processing have significant MIPAS is a mid-IR Fourier transform emission and reflection of optical radiation, newborn stars and take a closer look at the relevance for the trapping and release of spectrometer returning high-resolution for irregular particles (and icy particles in stars themselves.The largest gain in volatiles within the ice matrix. Interstellar ices gaseous emission spectra of Earth’s limb; particular) adds an uncertainty to sensitivity and spatial resolution at mid-IR are a complex mixture of many molecular, GOMOS is providing altitude-resolved global interpretations of observational data. wavelengths will be provided by a camera atomic, ionic and radical species, so a large ozone mapping and trend monitoring. Consequently, developments in light- and spectrometer. number of laboratory experiments will be However, these instruments are not scattering theory are required, together with All these observational missions will, necessary to measure physical parameters dedicated to particle observations, but experimental data on light scattering from among other topics, study the processes by such as sticking probability, binding energies interpreting their observations requires the icy particles, and aerosols resembling the which stars, the surrounding protoplanetary and desorption kinetics of simple and more retrieval of the optical, geophysical and atmospheric hydrometeors and particles. discs and planets are made.They will provide complex ice mixtures or layers, accurately physical properties of the clouds and their Optical monitoring of the formation and a wealth of data for observational astronomy, and empirically. icy constituents, through a combination of evolution of these particles in a controlled unsurpassed by limited wavelength-range Experiments that evaluate the physical laboratory and observational work. environment will certainly help us to observations from the ground, where the and chemical properties of the ice surface or Vertical profiles of abundance and understand their microphysical and optical advent of high-sensitivity and high- bulk are generally performed with thin-film physical properties of water and ice properties. Consequently, there is a resolution instruments on 8 m-class ice layers, supported by a chemically inert hydrometeors are being investigated by the significant need for laboratory work on ices telescopes is revolutionising our substrate, rather than isolated particles.With Tropical Rainfall Measuring Mission (TRMM), under atmospheric conditions, directly understanding of the role of icy particles in such experiments, it is very difficult to equipped with a precipitation radar and relevant to Earth-observation studies, the Universe. develop a picture of how chemical reactions passive microwave sensors. It has already atmospheric chemistry and meteorology. proceed on icy particles in the ISM. Particle provided significant insights into Large, ground-based laboratory facilities 4.2.2 Laboratory (Ground-Based) size effects, diffusion rates and surface precipitation systems in tropical regions.The have been developed in Europe, concerned Experiments roughness effects (such as steps and Global Precipitation Measurement mission is mainly with tropospheric and marine Water ice is the most abundant condensed dislocations and defects on the particle being planned by ESA, NASA and JAXA to particles, soot and sulphate particles solid in the ISM, dominated by the surface) play a key role in affecting the extend these TRMM capabilities beyond the exhausted from aircraft or burning, and icy abundance of its amorphous phase (and, by outcome of chemical reactions. Any tropics.Two other missions that can particles in cirrus clouds and PSCs.These inference, most other condensed species are experiments involving icy particles rather contribute to investigations of atmospheric include the University of Cambridge,

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The realisation of the experimental programme outlined methods by which the scientific results could particles with speeds much less than terrestrial laboratory).When icy layers are here will involve the use all types of ESA microgravity and be obtained without exploiting microgravity 1 m/s; added to dust particles, their mass can reduced-gravity facilities. or reduced-gravity experiments, and then – all experiments investigating ice increase significantly, leading to seeking to identify where ground-based morphology changes under reduced- sedimentation. In advance of using an Department of Chemistry, UK; Aida Chamber, studies are entirely unable to answer the gravity conditions expensive platform such as the Space Karlsruhe, Germany; ISAC-CNR, Italy; and scientific question to hand. All levitation Station for these long-duration experiments, EUPHORE,Valencia, Spain. Studies conducted techniques – including electrostatic, These experiments therefore fall into two all available microgravity platforms, from in these ground-based laboratories have aerodynamic and magnetic – use gravity- categories: short-duration drop-towers to parabolic limited temperature, pressure and timescale counteracting forces that are not flights, and all ground laboratory techniques ranges, concentrating on: proportional to the mass of the particles.The – those studying icy particles; such as random positioning machines, and frictional forces are proportional to the – those studying the role of gravity itself in particle suspension in traps, air-flow or liquid – homogeneous and heterogeneous ice surface area of the particles, so levitation the formation of amorphous and should be used. Of course, not all methods nucleation mechanisms; works for only one narrow range of particle crystalline ice structures. are suitable for icy particles research. Certain – surface chemical reaction kinetics (uptake sizes. Furthermore, if icy coatings are methods, such as particle suspension, which coefficients of heterogeneous chemistry); irregular, a scenario could be imagined When considering the icy particles, it is simulate well the interaction between icy – ice crystal growth; where the surface area of a particle increases important to distinguish between particles and the air (gas) for atmospheric – light-scattering from cirrus clouds and more rapidly than its volume or mass; experiments involving particles that science studies are not well suited to PSCs.; consequently, levitation conditions would aggregate or form regolith and are then recreating icy particle behaviour in low- have to be rapidly altered to sample the subjected to icing, and those that begin by density space environments.Technology can However, there is significant scope to same subset of size-distributed icy particles using icy particles to form icy particle limit certain experiments from using extend such work, particularly, as with and regular particles. In short, levitation aggregates or regolith. In this vein, it will be random positioning machines or being interstellar ice particles, in regimes where techniques are not applicable here. interesting to compare similarities and placed in or near high magnetic or electric particle clouds are required for long periods. The realisation of the experimental differences between an aggregate of icy fields. Drop-towers, parabolic flights and This includes determining particle size programme will involve all types of ESA particles and an iced aggregate of particles. If sounding rocket flights offer an excellent effects, diffusion rates and surface roughness microgravity and reduced-gravity facilities: current theories are correct, the former first step towards dissecting icy particle effects (such as steps and dislocations and short-duration drop-tower flights (typically should more closely resemble the aggregates behaviour in reduced-gravity conditions, but defects on the particle surface) on the less than 10 s), sounding rocket, and Space from which cometary nuclei are formed, their relatively short duration (from a few outcome of chemical reactions. Station experiments when microgravity aerosol particles and iced hydrometeors, seconds to a few minutes) is usually durations above 10 min are required. while the latter should resemble the icy insufficient to grow, observe and react icy 5. Ices Research Outlook The following groups of experiments can regolith on the surfaces of outer Solar particles before sedimentation, gravitational 5.1 Microgravity and Reduced-Gravity be performed only under microgravity System bodies, asteroids and in fragments of forces or convection interactions set in.The Experiments conditions: planet formation, and interstellar dust. ISS offers a unique opportunity to study Section 4 shows that, from the range of both the physics and chemistry of icy missions in planetary, interstellar and – all experiments involving escape speeds 5.2 Experiments aboard the ISS particles in long-duration microgravity atmospheric sciences where icy particles of much less than 1 m/s; There is a significant scientific benefit to environments. have scientific relevance, there is a clear need – all experiments involving particle studying icy particles in microgravity in for laboratory and theoretical data to ensure accelerations of < 1 g; cases where very low speeds are needed 5.2.1 A Dedicated Icy Particles Microgravity that maximum scientific benefit and – all experiments involving long-term (which are otherwise overwhelmed by Experiment understanding are gained.This Topical Team observations of ice clouds with a broad gravitational settling) or where extremely A dedicated icy particles experiment has worked to identify possible ice size distribution; fragile agglomerates are studied (which may onboard the ISS would have two major experiments, first considering all possible – all experiments involving collisions among collapse under their own weight in the scientific objectives:

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Microgravity experiments on ices fall into two categories, physical processes that begin in the facilities (down to 10–10 mbar). ICAPS’ lowest A dedicated icy particles experiment insert for IMPACT those studying icy particles and those studying the effects of interstellar medium, progress into the temperatures are expected to be around 250- would offer a unique opportunity to study ice structures and gravity on ice morphologies. protosolar nebula, and then finally result 280K; a few experiments might be possible on particle aggregation, with a plethora of subsequent in the formation of cometary nuclei and icy regolith, grains and aggregates coated applications. small Solar System bodies. Long-duration with ice, although these are likely to focus on – to investigate the amorphous ice microgravity conditions are essential to shock-freezing of water or ice crystal growth structures obtained when water-ice is follow these changes, to ensure that one from condensation, leading to quite different – an experiment insert using all the gas- grown from both vapour and liquid single dust population is observed ice phases and structure than those of and data-handling hardware available in phases under microgravity conditions. continuously, and to avoid any interest in vapour deposition and interstellar IMPACT could be built to reach Simple in situ mass-measurement sedimentation effects as particles medium and cometary science.The pressure temperatures of 100K rather than 270K. techniques and porosity measurements aggregate, or as ices are accreted onto in ICAPS will reach only 10–3 mbar, suitable for With temperature control down to 100K, would allow the morphology of the ice and sublimated from the ‘sample’ grains. It recreating atmospheric conditions, but quite crystalline and hyper-quenched ice particles to be determined, and their is also important to have the flexibility to different to the ambient pressure in space phases could be obtained, rather than just structure compared for the first time with repeat the experiment in cycles, in order environments. ICAPS also focuses on physical the thermodynamically stable hexagonal the structures of amorphous thin films to compare the results. instead of chemical behaviour, and is ices. Referring back to Fig. 2, it is clear that grown in the laboratory.The growth therefore ill-equipped to look at chemical a plethora of scientific questions related mechanisms involved form an interesting 5.2.2 The ICAPS Facility reactions. For ice studies, a number of to the physical behaviour of icy particles basic physics problem, with hydrogen ESA’s Columbus module will accommodate alternative diagnostic tools will be required. in all regions of the Universe could then bonding, surface tension, crystallisation the IMPACT (International Microgravity be addressed, from cometary systems, to and nucleation kinetics competing to Plasma, Aerosol and Cosmic dust Twin) 5.2.3 Steps to Achieving the Facility PSCs and aerosol chemistry. influence the final structure of the icy facility, to house the ICAPS (Interactions in Since temperatures of only 270K will be – an experiment insert using all the gas- particles. Once it is possible to grow icy Cosmic and Atmospheric Particles Systems) attained by ICAPS, the scientific return on icy and data-handling hardware available in particles from liquid or vapour phases, in and IMPF (International Microgravity Plasma particles experiments is rather limited. IMPACT could be built to reach amorphous or crystalline forms, the whole Facility. ICAPS (http://www.icaps.org) is now in However, as a first step, a few shock freezing temperatures of 10K and pressures of wealth of further physics and chemistry Phase-B of development. Its objectives are to experiments will allow the unimpeded study 10–10 mbar, equipped to study chemical experiments is accessible. characterise the interaction physics of small of the physical behaviour and attributes of icy and physical processes. Such a facility is – to follow the aggregation of icy grains into solid and liquid particles in an ambient grains, and the comparison of in-vacuum, the ideal solution or ‘Rolls Royce’ bigger structures (e.g. flakes) and the gaseous atmosphere, with electromagnetic microgravity results with those obtained, for experiment for ice particle studies in behaviour of such particles after ice radiation, and with other particles in their example, in suspended air flows of small microgravity conditions.With direct sublimation. If aggregated ice-coated dust vicinity.The central research topics particles. modifications, an ICAPS ices insert for grains are heated up slowly, as in the Sun- highlighted for this facility include the Major scientific gains, in terms of the IMPACT, capable of working at low passage of a comet, does the ice melt and physics of protoplanetary discs, aerosol and microgravity-based experiments having a pressure and temperature, and equipped thus force the aggregate to shrink haze physics, regolith and light-scattering in direct application in astronomy and for chemical and physical analysis, would together, to form a dense clump? Or does particulate media.The experimental atmospheric sciences, will be achieved by be able to address the roles of icy the ice sinter together forming an even programme includes investigations of modifying the temperature and diagnostic particles in all the different space and more consolidated ice-dust aggregate? Or aggregation, regolith and aggregate capabilities of ICAPS.This could be achieved atmospheric environments shown in does the ice evaporate and drag the dust collision, as well as cloud experiments. In its by a single new experimental insert to ICAPS, Fig. 2. Already, preliminary work by the grains along by aerodynamic friction? Or current configuration, however, ICAPS is not within the IMPACT facility (see next section) ICAPS contractors, Kayser-Threde and does the ice evaporate and leave a dust suitable for the ice studies described here, or in a two-step process where technological Nubila (Phase-A, Phase-A/B bridging and aggregate with basically unaltered which require cryogenic temperatures down stumbling blocks can be offset against Phase-B), shows that a second-generation morphology? This is representative of the to 10K and in some cases low-pressure scientific benefits: ices insert could use the existing IMPACT

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Fig. 6 (far left).Front view and 3-D rack-mounted housing view of hardware arrangement to accommodate an ices insert aboard the ISS in the IMPACT- IMPF/ICAPS research facility.

Fig. 7 (left).Infrastructure overview for an ices insert aboard the ISS in the IMPACT- IMPF/ICAPS research facility.

(Figs. 6 & 7 were produced as part of the preliminary work package by the ICAPS contractors, Kayser-Threde and Nubila.)

suitable for the sticking of species to form molecules) can be grown in a free jet icy mantles; expansion of warm water vapour. – contact nucleation, where a super-cooled liquid droplet is contacted by a foreign Technically, some of these methods could surface; for example, shock initiates be adapted for use in microgravity, but the nucleation; question remains how to form ice particles – nucleation by immersion freezing when that are neither supercooled nor in crystalline

there is a nucleation centre at the centre ice phases. It may be possible to use cold SiO2 of an icy particle and a droplet in liquid spheres as a starting model for nucleation phase forms around it and freezes in a centres for icy particle growth in cometary temperature-dependent process. nuclei or interstellar medium conditions. Starting with a mono-dispersed sample could The formation of ice crystals under simplify the theoretical modelling and data microgravity conditions is also technically interpretation from such experiments. difficult. In the laboratory they are formed by Growth of ice nanoparticles from water infrastructure and a combined 24-Panel 5.3 New Experimental & Technological a variety of methods: clusters is a key area that warrants further Unit drawer (Figs. 6 & 7). It is unlikely that Requirements investigation. such experiments would require During these investigations, the Team – warm liquid water is sprayed into cold air, significantly greater data-processing or discovered some key technical and scientific and below 230K super-cooling leads to 5.3.2 Water Vapour in Microgravity gas-handling requirements, making ices drivers to which no simple solutions or full the formation of icy particles; Conditions in microgravity an exciting prospect for understanding could be found.With this in – homogeneous nucleation requires 400% To get gas-phase water vapour in future ISS experiments. mind, the Team has highlighted certain super-saturation of the surrounding gas. If microgravity is also non-trivial and requires technical drivers that warrant further the gas is then expanded, icy particles of some technology input. One option might be

Further in the future, it may be possible to investigation, and will be required if the ices around 1-10 µm can be produced, at to transport H2O in the form of hexagonal ice combine an ices insert with a plasma or insert for IMPACT is to be realised. pressures resembling those of Earth’s melt an ice cube and warm it until gas-phase trapping facility, to allow the charging of icy atmosphere; water vapour is obtained, and then use the

particles to be studied – of direct relevance 5.3.1 Nucleation Processes – to generate a nucleation centre, cold water warm gas as an H2O source. However, some in mesosphere, stratospheric and interstellar The formation of icy particles from different is sprayed onto a liquid N2 probe.The nucleation processes require cold H2O physics and chemistry of icy particles, as well nucleation processes should be investigated. droplets are super-cooled and then a vapour, so this method could not be as thunder cloud electrification.This offers It is not clear which nucleation processes shock wave (such as popping bubble universally applied. During parabolic flight, it an interesting synergy between the work of dominate in atmospheric, planetary or packing), triggers nucleation, and ice might also be possible to use the vapour this Topical Team and the IMPF scientists. An interstellar medium conditions, or whether crystals formed on the cold probe can be pressure of water: water samples can be ices infrastructure aboard the Space Station one process might be affected more by shaken free; prepared with vacuum above, which then fills

would be widely used by both the gravitational forces than another.The key – under atmospheric conditions, icy with H2O vapour at a maximum of 15.9 mbar astronomy and atmospheric science processes to study are: particles can be grown in an updraft of partial pressure. If the gas phase and vapour communities, as well as for basic physics and cold air, which flows to counter the effects phase are separated by a shutter during a chemistry research, providing answers to – condensation of vapour onto a nucleation of downward acceleration owing to reduced-gravity aircraft parabola, then the some of the fundamental questions centre for direct formation of an icy gravity, at least for a subset of the icy vapour can be transported directly into the concerning the formation and evolution of mantle.The nucleation centre has to be particles; vacuum chamber and used for ice growth. the Solar System, and the chemical colder than the condensation temperature – very small icy clusters (a few nm diameter However, such a method would not work in evolution of Earth’s upper atmosphere. and the chemical surface has to be and consisting of a few hundred microgravity conditions, where the best

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Charging of icy particles may be especially important in cometary and ISM conditions.This is readily unknown.This requires further consideration, asteroids, moons). Such experiments are vital thunderclouds and the ISM, yet the effects of charging on obtainable using turbopump technology, testing and thought, but clearly starts to link to comprehending observations of comets, aggregation and chemical behaviour are entirely unknown! which is already planned for other experiment the activities of this Topical Team with those outer Solar System bodies, icy planets and icy facilities on the ISS. There is a technological of the IMPF community and their research moons. Optical monitoring of the formation solution is probably to use a slow-release problem when trying to maintain a cloud of into dusty plasmas. Indeed, the synergy and evolution of atmospheric particles in a sponge to hold liquid water with a vapour particles under microgravity and low-pressure between the needs of an ice experiment in controlled microgravity environment should pressure above it. Further investigations in conditions for long periods so that chemical parabolic flight or onboard the ISS and the help to understand the microphysics of these this field are required. processing or aggregation studies can be IMPACT facility have become very clear, and particles and to characterise their optical made. Assuming that all the particles are at warrant further study. properties without being hampered by the 5.3.3 Low-Temperature Experiments rest in the system, that the vacuum pumping sedimentation and airflow found in a ground It is clear from the work of this Team and the does not exert a force on them, and that 6. Conclusions laboratory. Microgravity is also important in ICAPS Phase-A and -A/B studies that photophoretic and thermophoretic forces do Many open questions remain to be answered investigating the scavenging of particulate obtaining low temperatures in microgravity not affect them, then their residence time in before we can fully comprehend ice-particle and gaseous pollutants by ice hydrometeors and reduced-gravity conditions poses a the chamber, dictated by gravitational forces morphologies and the physico-chemical in clouds. technological challenge. Although cryogenics becomes a factor. If the ISS provides a behaviour of icy particles in different The ISS offers a unique opportunity to can be used, they are an expensive, limited microgravity field of no better than 1 µg environments. More knowledge is required to conduct long-duration microgravity and crew-intensive method of cooling.This (which happens to be equivalent to the understand the agglomeration of ice and dust experiments on icy particles, applicable to a Team had a significant input into the ICAPS gravitational field at the surface of a small into planetesimals, and then to describe how vast range of interdisciplinary fields, and to Phase-A, encouraging development of a comet of low density, or a 10 m-diameter these assemblies subsequently formed the assist in addressing many unanswered facility with as low a temperature as possible. asteroid) and we assume that the cloud planets and other small bodies in the Solar questions in these areas. In particular, it would If a cloud of particles rather than a simple chamber has a radius, s, of about 0.1 m, then System.The formation and evolution of help to understand the basic physics substrate needs to be cooled, then the we can estimate the time it takes a particle at atmospheric icy particles is far from being associated with the formation of amorphous problems associated with cooling a large the centre of the icy cloud to reach the side understood; this is a dominant source of water-ice from the gas and liquid phases, and body without affecting the surrounding walls of the chamber and stick: uncertainty for radiative and chemical to identify the key chemical and physical experimental apparatus must also be environmental models. Studies under processes governing the formation and considered. Ideally, the Team would like to t = (2s / g)–1/2 microgravity conditions will allow us to evolution of the Solar System and Earth’s reach 10K for all of its science requirements, elucidate the underlying physics governing atmosphere and climate. but it recognises that this might be giving a residence time in the chamber per water-ice formation from the vapour and solid prohibitive. It suggests that if 200K can be particle of about 1 min.This clearly suggests phases. Once formed, the chemical reactions Acknowledgements reached as a first step, and then 100K, then that such an experiment would require ultra and the physical behaviour of these icy The authors acknowledge the sponsorship of different science questions could be high-vacuum technology to be coupled with particles will offer a key insight into many ESA for the Topical Team ‘Physico-Chemistry of addressed in these regimes. a secondary trapping device, such as an unanswered problems in astronomy and Ices in Space’,ESTEC contract 15266/01/ NL/JS. electrostatic or magnetic Paul trap or simple atmospheric chemistry. Experiments on the The laboratory work and previous 5.3.4 Pressure Range Requirements hexapole trap. Alternatively, higher pressures ISS will allow us to study the evolution of the microgravity studies described here are/were A new facility or experiment suitable for ice are required. If a trap is used, it is necessary to light-scattering properties during the supported by ESA, DLR, CNES, NOVA and studies would also need to operate over a investigate the effects of charging the icy condensation or sublimation of ices on SRON.The authors acknowledge technical range of pressures, from ambient to around particles in the clouds. Charging of icy sub-micron dust grains (representative of assistance from Kayser-Threde GmbH, and 1-0.1 mbar (for atmospheric science) and particles may be especially relevant in cosmic grains), micron grains (cometary dust), thank C. de Bergh, R. Delhez, G. Kroesen, J. van about 0.1-0.01 mbar for icy regolith studies, thunderclouds and the interstellar medium, aggregates with different packing densities Loon, J. Ovarlez, L. Schriver-Mazzuoli and to very low pressures, of at least 10–6- but the effects of charging on aggregation and sizes (cometary dust aggregates), and J.C. Worms for scientific input during the 10–10 mbar for studies of icy particles in and chemical behaviour are entirely high-porosity regolith (cometary nuclei, Team’s work.

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Light Schmitt, B., de Bergh, C. & Festou, M. (1998). Rev. 92, 265-278. Astrochemistry (Eds.V. Pirronello & Scattering Measurements on Dust Solar System Ices, ASSL 227, Kluwer Blum, J. (2004). Grain Growth and J. Krelowski), NATO ASI Series, Kluwer Aggregates, from Maser 8 to ISS. ESA Academic Publisher, Dordrecht,The Coagulation. In Astrophysics of Dust (Eds. A. Academic Publishers, Dordrecht,The SP-454, 797-802. Netherlands. Witt, G. Clayton & B. Draine), ASP Conf. Ser. Netherlands, 317-356. Nagashima, K. & Furukawa,Y. (2000). Solomon, S., Garcia, R.R., Rowland, F.S. & 309, 369-391. Ehrenfreund, P., Fraser, H.J., Blum, J., Interferometric Observation of the Effects Wuebbles, D.J. (1986). On the Depletion of Blum, J. & Münch, M. (1993). Experimental Cartwright, J.H.E., Garciá-Ruiz, J.M., of Gravity on the Horizontal Growth of Ice Antarctic Ozone. Nature 321, 755-758. Investigations on Aggregate-Aggregate Hadamcik, E., Levasseur-Regourd, A.C., Crystals in a Thin Growth Cell. Physica D WMO (1999). Scientific Assessment of Ozone Collisions in the Early Solar Nebula. Icarus Price, S., Prodi, F.,Sarkassian, A. (2003). 147, 177-186. Depletion: World Meteorological 106, 151-167. Physics and Chemistry of Icy Particles in Otto, G.H. & Lacy, L.L. (1973). Ice Melting Organization Global Ozone Research and Blum, J. & Schräper, R. (2004). Structure and the Universe. Planet. & Space Sci. 51, 473. (SD16-TV111).The Microgravity Research Monitoring Project Report N°. 44,WMO, Mechanical Properties of High-Porosity Heim,L.,Blum,J.,Preuss,M.& Butt,H.-J. Experiments (MICREX) Database, NASA. Geneva, Switzerland. Macroscopic Agglomerates Formed by (1999). Adhesion and Friction Forces Poppe,T., Blum, J. & Henning,Th. (2000). Worms, J.C., Renard, J.B., Hadamcik, E., Random Ballistic Deposition. Phys.Rev.Lett. between spherical Micrometer-Sized Analogous Experiments on the Stickiness Levasseur-Regourd, A.C. & Gayet, J.F. 93, 115503. Particles. Phys.Rev.Lett.83, 3328-3331. of Micron-Sized Preplanetary Dust. (1999). Results of the PROGRA2 Blum, J. & Wurm, G. (2000). Experiments on Krause, M. & Blum, J. (2004). Growth and Form Astrophys. J. 533, 454-471. Experiment: An Experimental Study in Sticking, Restructuring and Fragmentation of Planetary Seedlings: Results from a Prodi, F.& Levi, L. (1978). Crystal Size in Ice Microgravity of Scattered Polarized Light of Preplanetary Dust Aggregates. Icarus Sounding Rocket Microgravity Grown by Accretion. J. Atm. Sc. 35(11), by Dust Particles with Large Size 143, 138-146. Aggregation Experiment. Phys.Rev.Lett. 2181-2189. Parameter. Icarus 142, 281-297. Blum, J.,Wurm, G., Poppe,T. & Heim, L.-O. 93, 021103. Prodi, F., Levi, L., Franzini, A. & Scarani, C. Worms, J.C., Renard, J.B., Hadamcik, E., Brun- (1998). Aspects of Laboratory Dust Levasseur-Regourd, A.C. (1999). Polarization (1982). Crystal Size and Orientation in Ice Huret, N. & Levasseur-Regourd, A.C. (2000). Aggregation with Relevance to the of Light Scattered by Cometary Dust Grown by Droplet Accretion in Wet and Light Scattering by Dust Particles with the Formation of Planetesimals. Earth, Moon & Particles. In Composition and Origin of Spongy Regimes. J. Atm. Sci. 39(10), 3201- PROGRA2 Instrument – Comparative Planets 80, 285-309. Cometary Materials (Eds. K. Altwegg et al.), 2312. Measurements between Clouds under Blum, J. et al. (2000). Growth and Form of Space Sci. Rev. 90, 163-168. Prodi,F.,Levi,L.,Nasello,O.B.& Lubart,L. Microgravity and Layers on the Ground. Planetary Seedlings: Results from a Levasseur-Regourd, A.C. (2003). Laboratory (1991). Morphology and Density of Ice Planet. Space Sci. 48, 493-505. Microgravity Aggregation Experiment. Studies of Icy Regolith, in Relation to Accreted on Cylindrical Collectors at Low Wurm, G. & Blum, J. (2000). An Experimental Phys. Rev. Lett. 85, 2426-2429. Observations of Minor Bodies in the Outer Values of Impaction Parameter: Rotating Study on the Structure of Cosmic Dust Blum,J.,Wurm,G.,Poppe,T.,Kempf,S.& Solar System. Earth, Moon, Planets 92(1-4), Deposits. Quart. J. Roy. Met. Soc. 117, 783- Aggregates and their Alignment by Kozasa, T. (2002). First Results from the 337-343. 801. Motion Relative to Gas. Astrophys. J. 529, Cosmic Dust Aggregation Experiment Levasseur-Regourd, A.C. & Hadamcik, E. Ramaswamy,V., Boucher, O., Haigh, J., L57-L60. CODAG. Adv. Space Res. 29, 497-503. (2001). Clues to the Structure of Hauglustaine, D., Haywood, J., Myhre, G., Wurm, G., Blum, J. & Colwell J. (2001). Bockelee-Morvan, D., Gautier, D., Hersant, F., Meteoroids, from Dust Light Scattering Nakajima,T., Shi, G.Y. & Solomon, S. (2001). Aerodynamic Sticking of Dust Hure, J.-M. & Robert, F.(2002).Turbulent Properties. In Meteoroids, ESA SP-495, 587- Radiative Forcing of Climate Change. In Aggregates. Phys. Rev. E 64, 046301-1 - Radial Mixing in the Solar Nebula as the 594. Climate Change 2001: The Scientific Basis. 046301-9.

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Topical Team Members

Prof.J.Blum Prof. A.C. Levasseur-Regourd Institut für Geophysik und Extraterrestrische Universite P.et M. Curie, Paris VI, 4 Place Jussieu, Physik,Technische Universität Braunschweig, F-75005 Paris, France. Mendelssohnstr. 3, D-38106 Braunschweig, Service d’Aéronomie/CNRS, Route de Gatines, Germany. BP 3, F-91371 Verrières le Buisson, France. Email: [email protected] Email: [email protected]

Dr. J.H.E. Cartwright (from February 2003) Prof.S.Price Instituto Andaluz de Ciencias de la Tierra, Department of Chemistry, University College Laboratorio de Estudios Cristalográficos, London, 20 Gordon Street, London, Facultad de Ciencias, Av. Fuentenueva s/n, WC1H 0AJ, UK. E-18002 Granada, Spain. Email: [email protected]

Prof.P.Ehrenfreund Prof.F.Prodi Astrobiology Group, Leiden Institute of Institute of Atmospheric and Ocean Sciences,Via Chemistry, Leiden University, Einsteinweg 55, P.Gobetti, 101, C.A.P.I-40129 Bologna, Italy. 2300 RA Leiden,The Netherlands. Email: [email protected] Email: [email protected] Dr. A. Sarkissian Dr.H.J.Fraser Service d’Aéronomie/CNRS, Route de Gatines, Department of Physics, University of BP 3, F-91371 Verrières le Buisson, France. Strathclyde, 107 Rottenrow East, Glasgow, Email: [email protected] G4 0NG, Scotland, UK. Email: [email protected] Prof. D.E.Williams (until April 2002) Department of Chemistry, University College Dr.E.Hadamcik London, 20 Gordon Street, London, Service d’Aéronomie/CNRS, Route de Gatines, WC1H 0AJ, UK. BP 3, F-91371 Verrières le Buisson, France. Email: [email protected] Prof.W. Holländer (since February 2003) Fraunhofer-Institut für Toxikologie und Prof. J. Garcia-Ruiz (until February 2003) Experimentelle Medizin, Nikolai-Fuchs- Instituto Andaluz de Ciencias de la Tierra, Straße 1, D-30625, Hannover, Germany. Laboratorio de Estudios Cristalográficos, Facultad de Ciencias, Av. Fuentenueva s/n, E-18002 Granada, Spain.

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Zeolite Synthesis in Microgravity Report of the ESA Topical Team in Physical Sciences Zeolite Synthesis in Microgravity

Contributors: R. Aiello, Univ. of Calabria, Italy G. Artioli, Univ. of Milan, Italy L.Carotenuto,MARS Center,Naples,Italy C. Colella, Univ. of Naples, Italy P.Norby, Univ. of Oslo, Norway J. Sterte, Univ. of Luleå, Sweden

1. Introduction natural zeolites are known (Coombs et al., This report summarises the outcome of 1997); about ten are being used in activities performed by the authors as environmental applications (Colella, 2002). thermodynamically metastable, but their members on the Topical Team appointed by Most zeolites are synthetic, often without synthesis routes must necessarily depart ESA on ‘Zeolite Synthesis in Microgravity’.The any natural counterpart. Figure 1 shows an from the thermodynamic equilibrium. Fig. 1.Structure of zeolite A (LTA).Crystal composition: Team’s efforts focused on: example of zeolite structure, illustrating the Therefore, the nucleation and growth Na12(Al12Si12O48)·216H2O.Crystals are synthesised from clear extensive microporosity at the molecular processes of the zeolite crystals are solution with batch composition: 8.6Na2O-0.18Al2O3-SiO2-150H2O. – coordination of the research groups and level that is the basis of their peculiar dominated by kinetics and they are rather integration of their complementary properties. sensitive to small variations in the control expertise; Microporosity plays an important role in a parameters and boundary conditions.This – identification of possible applications to large number of technological and industrial sensitivity means the results are only weakly the most suitable zeolite synthesis systems involve industrial partners in the research fields, such as catalysis (oil cracking, octane- repeatable. It is therefore difficult to deepen for investigation under microgravity plan; number busting, production of fine our understanding of the synthesis process conditions; chemical modelling of the – identification of scientific problems to be chemicals), ion exchange (hardness just by analysing the final products. In synthesis process; addressed using the microgravity abatement in detergents, heavy-metal addition, the early stages of synthesis are Prof. G. Artioli, Univ. of Milan, Italy; Prof. environment, and definition of a research concentration and removal from waste particularly relevant in determining the path P. Norby, Univ. of Oslo, Norway: in situ time- plan; waters), molecular sieving (linear/branched of the entire process. resolved kinetic studies of zeolite crystal – definition of a European research paraffin separation, gas purification, For these reasons, the Team’s research growth by synchrotron WAXS and SAXS, programme on specific aspects of zeolite oxygen/nitrogen separation from air, and all approach is based on in situ monitoring of Atomic Force Microscope; synthesis that includes joint ground-based kinds of dessication processes).There is the complete process using non-invasive Prof.J.Sterte,Univ.of Luleå,Sweden: and microgravity experiments. promising potential for air purification diagnostics.Whenever possible, time- deposition of thin zeolite layers on aboard the International Space Station and, resolved diffraction or spectroscopic different substrates; A brief description of the zeolite systems in general, on manned spacecraft for long- techniques are employed in order to Dr. L. Carotenuto, MARS Center, Italy: fluid and their possible applications are presented, duration flights. characterise the crystallisation kinetics from dynamic modelling and numerical followed by the activities and results As a consequence, there is huge interest in the crystal-structural point of view. Optical simulation of the synthesis, development obtained by the Team. studying the process of synthesising zeolites. techniques can also follow particle growth in and utilisation of optical diagnostics; Understanding it better could yield a transparent samples, so clear solutions are preliminary definition of space 2. Zeolites number of advantages: particularly suitable for such investigations. experiments. Alumino-silicate zeolites are a large group of Several important zeolite types can be crystalline compounds with microporous – the optimisation of large-scale readily synthesised from clear-solution Continuous coordination between these structure.There are both natural and production; systems, although the detailed interpretation groups has promoted the exchange of synthetic types. More than 60 types of – the development of new synthesis paths; of the crystallisation mechanisms is still open information and monitored the progress of – the production of new zeolite structures, to debate. work. Presentation and discussion of results, Zeolites are a family of alumino-silicate compounds, either tailored for specific applications. definition of research activities and mineral or synthetic, with a structure characterised by an array 3. Integration of Expertise assignment of tasks have been performed at of intersecting channels and cages of molecular dimensions. In spite of the large research effort The Team is formed by groups offering joint meetings.These activities have created That is why they are often referred to as microporous devoted in the past to the understanding of complementary expertise: an integrated team, leading to: exchange of materials. This ‘open’ structure is responsible for the main zeolite crystallisation mechanisms, the expertise among the groups; joint laboratory properties of zeolites, which can behave as heterogeneous synthesis route of many microporous Prof. R. Aiello (Coordinator), Univ. of Calabria, experiments; joint design and execution of catalysts, selective adsorbents and cation exchangers. compounds is still not fully known.This is Italy; Prof. C. Colella, Univ. of Naples synchrotron experiments; joint papers and largely because many important zeolites are ‘Federico II’,Italy: study and optimisation of congress presentations.

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4. Contacts with Industries reasons, the Team has decided to focus its been obtained, as described below. steps in the preparation procedure and in A number of industries involved in zeolite research activities on the zeolite deposition Gravity effects on deposition are not various sequences: production have been contacted, to process, in the belief that it will also be negligible. For example, in the case of films investigate which innovations have the best highly attractive to industrial partners once grown by seeding, the change of orientation – creation of nuclei or seeds of the desired potential for commercialisation. In particular, the basic knowledge has been in the film could be due to secondary molecular sieve; it has been investigated whether industry consolidated. nucleation or to the attachment of crystals – concentration of nuclei or seeds at an has any interest in improving the bulk formed in the bulk and transported to the interface or in a confined volume; production of zeolites, either simply 5. Deposition of Zeolite Films surface by sedimentation and convection. In – facilitation of growth and inter-growth of improving the production yield or increasing As discussed above, one of the most addition, undesirable changes in film nuclei or seeds into a macrostructure. the quality of the product. Unfortunately, promising new fields for technological thickness that vary with the substrate there proved to be little interest. In fact, bulk applications is the deposition of position inside the reactor could be From a practical point of view, the production of zeolites is targeted on oil- microporous crystalline films on substrates attributable to small temperature and/or synthesis approaches can be divided into cracking and detergents, and they are of various types.The development and compositional changes at the interface two categories: already produced from cheap materials. Any optimisation of film-deposition techniques owing to natural convective flows. improvement would not yield an economic would allow the integration of the zeolite This is why microgravity experiments, – direct synthesis or crystallisation (either in benefit sufficient to justify industry properties (molecular sieving, catalytic which allow synthesis conditions otherwise the liquid or vapour phases); involvement in a research programme. activity, etc.) with those of the substrate. impossible on Earth, would provide further – synthesis utilising pre-deposited seed However, there is a demand for nano- Of course, the performances of these insights into the fundamental mechanisms crystals. structure zeolites – materials specifically devices could be optimised if the zeolite underlying zeolite film deposition.The designed and prepared in a controlled crystals are oriented to expose the desired understanding of such mechanisms is Although a vast amount of research has manner to overcome the limitations of structural channels of their porous structure necessary to produce films with the desired been performed in this area, the bulk has existing materials (Sterte et al., 2002; Caro et to the substrate and to the external orientation, homogeneity and thickness. focused on a relatively limited number of al., 2000). As an example, a great amount of environment, forming homogeneous layers A number of strategies have been zeolite-substrate combinations. Further research is now devoted to zeolite with finely controlled pore distribution. In adopted in order to prepare primarily development is called for in order to find membranes for catalytic reactors, where the addition, the ability to prepare thin layers 2-dimensional (films or coatings) but also methods for the preparation of new simultaneous catalysis and separation would allow fast response times and higher 1- and 3-dimensional macrostructures of interesting combinations and also for improve the conversion in equilibrium- reagent fluxes. Much research investment is molecular sieves.The majority of the improved control of the properties of limited reactions. now devoted to microporous membrane methods developed are a result of a search existing combinations. Both of these Chemical sensors are also of great interest, systems, aiming at controlling the for controlled preparation of films intended developments would be strongly facilitated using zeolite films, with their structural deposition conditions and film properties. for use in membrane applications.The by an improved understanding of the basic channels of molecular dimensions, together The Luleå University of Technology group preparation of molecular sieve films and mechanisms involved in the various steps of with the possibility of tailoring the chemical has grown thin and well-oriented zeolite coatings for this purpose has been treated in the preparation.The central topic in this environment inside the channels. layers on different substrates through a number of recent review articles (e.g. context is a better knowledge of the basic These new devices are based on the innovative synthesis techniques. Jansen et al., 1994; Bein, 1996; Matsukata & nucleation and growth mechanisms involved deposition of thin, compact and oriented Despite the large research effort, the Kikuchi, 1997; Coronas & Santamaria, 1999; in the crystallisation of the molecular sieves. layers of zeolite microcrystals on various controlled growth of thin oriented zeolite Tavolaro & Drioli, 1999 – probably the most substrates, including steel, alumina and films has still not been fully achieved, comprehensive). 6. Main Research Activities and Outcomes silicon wafers, and gold. Completely new particularly for low-silica zeolites.There, the Despite the fact that the adopted The results described here are summarised processes have to be developed, and presence of gel-like phases appears to strategies may not appear to have much in from the papers cited below.The activities laboratory experiments have produced interfere with the oriented growth of common, most contain the following stages, concerned synthesis from clear solutions, in encouraging preliminary results. For these zeolite crystals, although partial results have which can be carried out as one or several order to include optical diagnostics for in situ

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measurements.The Team activities focused during ageing of the solution at room composition and crystal orientation.To this on the following objectives: temperature; end, experiments are investigating the – only zeolite LTA forms during the hydro- influence of control parameters, particularly – clarifying the role of the amorphous phase thermal synthesis, when the amorphous temperature effects. in the initial stages of crystallisation; phase, formed during ageing of the A method has been developed using a Fig.2.Atomic Force Microscopy images of zeolite A film deposited – investigating the influence of the different solution at room temperature, is removed two-temperature synthesis procedure to on a silicon substrate.a: deflection mode; b: height mode.The physico-chemical parameters on the prior to crystallisation; distinguish between the nucleation and diagram shows the height profile along the line in the upper image. deposition of thin zeolite films. – dynamic light scattering (DLS) showed growth phase of the crystallisation and thus that particle aggregation/flocculation to model the crystallisation process.This 6.1 Crystallisation Mechanisms starts immediately after mixing of the method is based on the finding that the Many studies performed on the reagent solutions, even though the nucleation process can be stopped by a rapid crystallisation of microporous materials in solution appears visually clear; increase in temperature. A large temperature Fig. 2.The film is compact, the crystals are recent years focused on the very important – the phase that forms in the early stage of rise after a period of nucleation at a lower mostly oriented, but they show irregular Al-free silicalite system (MFI topology).They the synthesis process is amorphous, as temperature results in a number of crystals morphology and rounded shape. concluded, on the basis of experimental shown by combined DLS and synchrotron that increases with time up to a limit evidence, that crystal growth proceeds by X-ray diffraction (XRD) experiments; corresponding to the time at which the 7. Conclusions direct addition of structural building blocks – kinetic data from XRD indicate that nucleation phase would be completed at the On the basis of these findings, the Team has of considerable size (20-30 nm) (Kirschhock heterogeneous nucleation occurs during initial temperature.The number of crystals elaborated a research programme on zeolite et al., 1999). Our studies focused on Al- and synthesis, probably at the gel-solution formed is thus correlated with the number of film deposition that includes microgravity alkali-containing systems, and led us to interface. nuclei present in the original solution at the experimentation. A proposal was submitted conclude that zeolites and microporous time when the temperature was raised. A in January 2001 to ESA in response to the materials synthesised from such solutions All these results indicate that gel plays a consequence of this method of some International Announcement of Opportunity invariably nucleate through interface crucial role in synthesis from clear solutions. practical use is that it can be used for rapid issued in 2000, identifying methods and reaction at a gel/solution interface, and that In particular, they suggest that the final preparation of very small (< 50 nm) colloidal facilities for the microgravity experiments. As the gel phase plays a fundamental role in the phases obtained from the synthesis depend molecular sieve crystals with a high yield. pointed out by the peer review, further on- process. on mechanisms involving the gel.Therefore, Moreover, this work has shown that the ground research is needed to deepen our Recent detailed findings on zeolite phases more detailed investigations on the role of nucleation and growth kinetics are highly understanding of the role of different

synthesised in the Na2O-SiO2-Al2O3-H2O gel formation in clear solutions are needed, dependent upon the silica source used in the parameters (in particular the temperature) on system can be summarised as: in order to be able to control the final synthesis and on the ageing of this silica primary and secondary nucleation and on synthesis product. source. It has also contributed to the other crystal growth. In addition, more detailed – Nuclear Magnetic Resonance (NMR) on part of our work in a more direct manner: the models of the whole process are needed to liquid phase provided no evidence that 6.2 Crystallisation on a Substrate preparation of highly crystalline samples of support the definition of industrial processes. zeolite A (LTA; Fig. 1) (Baerlocher et al., Advances have also been made in deposition certain zeolites, such as ZSM-5, is facilitated Microgravity data are crucial for model 2001) formation starts from aggregation techniques.The Luleå University of by a two-stage temperature process. validation. of large sub-units; Technology group has developed a method In parallel, preliminary experiments have The Topical Team approach promoted by – FAU and GIS zeolites co-crystallise using seeds for preparing ultra-thin zeolite investigated the possibility of suppressing ESA has been extremely proficuous.The together with zeolite A.Their growth films. Current efforts are being devoted to secondary nucleation by imposing a different points of view of the groups, owing proceeds after the end of the hydro- improving the method’s capabilities, temperature gradient. Optical thickness of to their different expertises, has stimulated thermal treatment (between 60°C and increasing flexibility, the range of materials the solution has been monitored by new ideas and innovative approaches. 80°C), and their crystallisation seems to be and in particular the overall quality of the interferometry. As an example, a zeolite A film Contacts with industries have helped to focus related to the amorphous phase formed films – uniformity of thickness, structure, deposited on a silicon substrate is shown in the research on highly innovative topics.

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References Catalysis and Separation. Studies in Surface Nazionale AIC, Parma, 18-21 Settembre Baerlocher, Ch., Meier, W.M. & Olson, D.H. Sci. & Catalysis, 85, 215. 2001; Abst. Book, 95. Topical Team Members (2001). Atlas of Zeolite Framework Types. Matsukata, M. & Kikuchi, E. (1997). Zeolite Grizzetti, R., Artioli, G., Carotenuto, L. & IZA Special Publication, Elsevier,The Membranes: Synthesis, Properties, and Piccolo, C. (2001). Studies of the Zeolite A Prof. Rosario Aiello Netherlands. Prospects. Bull. Chem. Soc. Jpn. 70, 2341. Synthesis by Simultaneous Synchrotron Dipartimento di Ingegneria Chimica e dei Bein, T. (1996). Synthesis and Applications of Sterte, J., Hedlund, J. & Tosheva, L. (2002). X-ray Diffraction and Dynamic Light Materiali, Università della Calabria,Via Pietro Molecular Sieve Layers and Membranes. Options for the Design of Structured Scattering. 9° Convegno SILS, Firenze, Italy, Bucci, I-87030 Rende (CS), Italy. Chem. Mater. 8, 1636. Molecular Sieve Materials. Studies Surface 5-7 Luglio 2001. Prog. Abstr., 51. Email: [email protected] Caro, J., Noack, M., Kolsch, P.& Schafer, R. Sci. & Catalysis 142, 423. Grizzetti, R. & Artioli, G. (2002). Kinetics of (2000). Zeolite Membranes – State of Their Tavolaro, A. & Drioli, E. (1999). Zeolite Nucleation and Growth of Zeolite LTA from Prof. Gilberto Artioli Development and Perspective. Microp. Membranes. Adv. Mater. 11, 975. Clear Solution by In Situ and Ex Situ XRPD. Dipartimento di Scienze della Terra, Università Mesop. Mat. 38, 3-24. Microp. Mesop. Materials 54, 105-112. ‘A. Desio’,Via Botticelli 23, I-20133 Milano, Colella, C. (2002). Application of Natural Publications of the Team Grizzetti, R., Artioli, G., Carotenuto, L., Italy. Zeolites. In Handbook of Porous Solids Aloi, D.,Testa, F., Pasqua, L., Aiello, R. & Piccolo, C., Norby, P.& Carsughi, F.(2002). Email: [email protected] (Eds. F. Schüth, K.S.W. Sing & J.Weitkamp), Nagy, J.B. (2002). Improved Synthesis Simultaneous Synchrotron Wiley-VCH,Weiheim, Germany, 2, 1156- Procedure for Fe-BEA Zeolite. Studies SAXS/WAXS/DLS In-Situ Studies of the Dr. Luigi Carotenuto 1189. Surface Sci. & Catalysis 142, 469-476. Crystallization of LTA zeolite. X Convegno MARS Centre,Via E. Granturco 31, I-80146 Coombs, D.S., Alberti, A., Armbruster,T., Artioli, G., Grizzetti, R., Carotenuto, L., SILS, Roma, 11-13 Luglio 2002. Abst. P22, Napoli, Italy. Artioli, G., Colella, C., Galli, E., Griece, J.D., Piccolo, C., Colella, C., Liguori, B., Aiello, R. & Abst.Vol. 60. Email: [email protected] Liebau, F., Mandarino, F., Minato, H., Frontera, P.(2002). In situ Dynamic Light Grizzetti, R., Artioli, G. & Carsughi, F.(2002). Nickel, E.H., Passaglia, E., Peacor, D.R., Scattering and Synchrotron X-Ray Powder Time Resolved In-Situ Studies of the Prof. Carmine Colella Quartieri, S., Rinaldi, R., Ross, M., Diffraction Study of the Early Stages of Crystallization of Linde Type A Zeolite by Dipartimento d’Ingegneria dei Materiali e della Sheppard, R.A.,Tillmanns, E. & Vezzalini, G. Zeolite Growth. Studies Surface Sci. & Combined SAXS/WAXS Techniques. SAS Produzione, Università ‘Federico II’,Piazzale V. (2002). Recommended Nomenclature for Catalysis 142, 45-52. 2002, XII International Conference on Tecchio 80, I-80125 Napoli, Italy. Zeolite Minerals: Report of the Candamano, S., Frontera, P., Crea, F.& Aiello, R. Small-Angle Scattering,Venezia, 25-29 Email: [email protected] Subcommittee on Zeolites of the (2004). In Situ Deposition of FAU-type August 2002. Abst. AP11, Abst.Vol. 90. International Mineralogical Association, Zeolite Layer on Cordierite Support. Topics Subotic, B., Aiello, R., Bronic, J. & Testa, F. Prof. Poul Norby Commission on New Minerals and in Catalysis 30, 369-373. (2002). Modeling of Crystal Growth at Early Kjemisk institutt, Kjemibygningen, Sem Sælands Mineral Names. Can. Mineral. 35, 1571- Caputo, D., de Gennaro, B., Liguori, B.,Testa, F., Stages of Analcime Synthesis from Clear vei 26, N-0371 Oslo, Norway. 1606. Carotenuto, L. & Piccolo, C. (2000). Solutions. Studies Surface Sci. & Catalysis Email: [email protected] Coronas, J. & Santamaria, J. (1999). Catalytic A Preliminary Investigation on Kinetics of 142, 423-430. Reactors Based on Porous Ceramic Zeolite Crystallisation using Optical Prof. Johan Sterte Membranes. Catalysis Today 51, 377. Diagnostics, Mat. Chem. Phys. 66, 120-125. Division of Chemical Technology, Luleå Kirschhock, C.E.A., Ravishankar R., Jacobs, P.A. Frontera, P.,Testa, F., Crea, F.& Aiello, R. (2005). University of Technology, S-97187 Luleå, & Martens, J.A. (1999). Aggregation Zeolite LTA Deposition on Silicon Wafer. Sweden. Mechanism of Nanoslabs with Zeolite J. Porous Mater., in press. Email: [email protected] MFI-type Structure. J. Phys. Chem. B 103, Grizzetti, R., Artioli, G., Carotenuto, L. & 11021-11027. Piccolo, C. (2001). Study of the Zeolite A Jansen, J. C., Kashchiev, D. & Erdem- Synthesis by Simultaneous Synchrotron Senatalar, A. (1994). Preparation of X-ray Diffraction and Dynamic Light Coatings of Molecular Sieve Crystals for Scattering. Atti del XXXI Congresso

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Report of the COSMIC: Combustion Synthesis ESA Topical Team in Physical Sciences Combustion Synthesis under Microgravity under Microgravity Conditions Conditions (COSMIC) Contributors: G. Cao, Cagliari (I) (Coordination) R. Licheri, Cagliari (I) R. Orrù, Cagliari (I) J. De Wilde, Leuven (B) I. Agote, Donostia-San Sebastian (E) L. Froyen, Heverlee (B) A.E. Sytschev, Chernogolovka (RU) The research described in this report will Synthesis’ (SHS). It permits thre creation of a A.S. Rogachev, Chernogolovka (RU) have significant influence on self- increase the understanding of fundamental variety of advanced materials such as F.Preud’homme, Kruibeke (B) propagating combustion synthesis aspects of self-propagating combustion ceramics, intermetallics, composites, solid L.Vautmans, Kruibeke (B) processes. Interesting results have been synthesis processes and synthesis of solution and functionally graded materials recently obtained in the USA, Japan, materials that cannot be formed under (Merzhanov & Borovinskaya, 1972; Munir & Canada and Russia, while this field remains normal gravity conditions. Self-propagating Anselmi Tamburini, 1989; Merzhanov, 1995; almost unexplored in Europe. Performing combustion synthesis processes involve Hlavacek & Puszynski, 1996; Varma et al., experiments in microgravity will allow us several stages that are significantly affected 1998).The SHS method is receiving likely to provide increased control of the to investigate self-propagating by gravity: melting of reactants and products, increasing attention for its simplicity, short reaction front, with a consequent combustion synthesis processes without spreading of the melt, droplet coalescence, reaction time, simple equipment, low-energy improvement in the microstructure of the the masking effects of gravity-induced diffusion and convection, buoyancy of solid requirements and the possibility of synthesised product. In addition, flows.The research will address how particles and densification of liquid products. obtaining complex or metastable phases. microgravity experiments lead to advances in interfacial energies, capillary spreading, High temperatures in the combustion wave The broad objective of the research in this understanding fundamental aspects of mass transport in porous media and generate liquids that are subject to gravity- field is to understand the mechanisms of combustion and structure formation during Marangoni flows affect the process driven flow. In this context, the removal of self-propagating combustion synthesis self-propagating combustion synthesis. Since dynamics and phase formation and such gravitational effects is likely to provide reactions under conditions where gravity- self-propagating combustion synthesis structure evolution; increased control of the reaction front, with a related effects are suppressed. Self- technology has the potential to prepare – suitable systems for welding purposes. consequent improvement in the propagating combustion synthesis processes advanced materials and net-shape articles Joining by self-propagating combustion microstructure of the synthesised product. In are characterised by highly exothermic with tailored physical and mechanical synthesis reactions is a promising method addition, microgravity experiments will lead reactions that may propagate upon ignition properties in one step and has extremely low for space platforms. to advances in understanding fundamental in a self-sustained manner without requiring external energy requirements, it is well-suited aspects of combustion and structure additional energy. Specific features of this for use on space platforms. 2. State of the Knowledge formation during self-propagating synthesis technique are high combustion Important issues to be addressed are: It is known that several parameters affect combustion synthesis. Since self-propagating temperatures, short synthesis times and combustion synthesis reactions. For instance, combustion synthesis technology has the simplicity of technological facilities. – the dynamics of self-propagating reaction stoichiometry, green density, potential to prepare advanced materials and The research described in this report will combustion synthesis processes in the reactants particle size, thermal conductivity, net-shape articles with tailored physical and increase the understanding of fundamental absence of gravitationally-induced ignition temperature, heating and cooling mechanical properties in one step, and has aspects of self-propagating combustion buoyancy and phase-separation effect. rates, physical state of reactants, and the extremely low external energy requirements, synthesis processes and the synthesis of This fundamental aspect of the work gravity field are demonstrated to have an it is well-suited for use on space platforms. materials that cannot be formed under includes the analysis of ignition, wave important effect on final product normal gravity conditions. Self-propagating speed and temperature and conversion morphology and properties. Specifically, combustion synthesis processes involve profile; stoichiometry (including the use of dilutents 1. Motivation for Research several stages that are significantly affected – the phase formation and structure or inert reactants) affects the exothermicity Self-propagating high-temperature reactions by gravity: melting of reactants and evolution in self-propagating combustion of synthesis reaction and, therefore, the are characterised by the fact that, once products, spreading of the melt, droplet synthesis processes.This research has dynamics of the combustion process. In ignited by an external energy source, they coalescence, diffusion and convection, practical as well as fundamental particular, the addition of inert reactants propagate as a combustion wave through buoyancy of solid particles and densification implications. It is planned to investigate leads to heat subtraction and, consequently, the reacting mixture without requiring of liquid products. High temperatures in the the role of gravity on product formation to a decrease in combustion temperature. additional energy.The reaction has been combustion wave generate liquids that are (nature of the product, composition of The green density of the reacting sample also exploited to establish the technique known subject to gravity-driven flow. In this context, phases, homogeneity of the phases and influences SHS processes, because it affects as ‘Self-propagating High-temperature the removal of such gravitational effects is grain size). Gravity has been shown to system reactivity as well as the thermal

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Table 1. Summary of research into self-propagating combustion synthesis reactions under microgravity conditions. Fig. 1.Experimental set-up for self-propagating combustion synthesis under microgravity conditions (parabolic flights). top: general view; centre: sample holder; bottom: ignition phase of the combustion process.

affected by gravity. In particular, generated liquid and gaseous species will be subject to gravity-driven fluid flow and vapour transport and convection, which are likely to affect both SHS reaction stability and morphology of product phases significantly. The importance of investigating the effect of gravity on these phenomena in order to identify the detailed mechanism of reaction evolution and structure formation is clear. Specifically, low-gravity experiments, in conjunction with direct comparisons with data from equivalent ground-based experiments, can reveal the general mechanism of combustion and structure formation without the disturbing effect of gravity. Interesting results have been recently obtained in the USA, Japan, Canada and Russia (Table 1). It has been shown that products with finer and more uniform microstructures are typically obtained under low-gravity conditions (Shteinberg et al., 1991; Moore et al., 1992; Odawara et al., 1993; Goroshin et al., 1994; Hunter & Moore, 1994; Lantz et al., 1995; Odawara et al., 1995; Mukasyan et al., 1997a; Mukasyan et al., 1997b; Odawara, 1997;Yi et al., 1998; 2000; Merzhanov et al., 1998; Merzhanov et al., 2000; Odawara, 2000; Medda et al., 2001).

conductivity of the compact. Similar Mukasyan et al., 1997b; Odawara, 1997; 3. Most Recent Campaigns during the Belgian ‘Odissea’ Soyuz mission of considerations can be made for other Merzhanov et al., 1998;Yi et al., 1998; Within the framework of the ESA- November 2002 as part of COSMIC. operating parameters. However, gravity has Merzhanov et al., 2000; Odawara, 2000; coordinated COSMIC (Combustion Synthesis In order to investigate the mechanism of been shown to play an important and Axelbaum & Moore, 2001; Medda et al., 2001). under Microgravity Conditions) project, the structure formation during combustion specific role in self-propagating high- Combustion synthesis and the related results obtained during a parabolic flight synthesis reactions, in addition to classical SHS temperature synthesis reactions (Karataskov structure formation mechanisms involve campaign sponsored by ESA in March 2002 experiments using free-standing cylindrical et al., 1985; Merzhanov & Yukhvid, 1990; several stages, including melting of reactants and related to the combustion synthesis of pellets (Fig. 1), combustion front quenching Shteinberg et al., 1991; Moore et al., 1992; and products, spreading of the melt, droplet TiB2-xTiAl and TiB2-xTiAl3 intermetallic experiments using conical samples placed Odawara et al., 1993; Goroshin et al., 1994; coalescence, diffusion and convection, matrix composites are discussed. inside a copper block were also conducted. Hunter & Moore, 1994; Lantz et al., 1995; buoyancy of solid particles, and densification A microgravity experiment was performed Similar experiments were performed under Odawara et al., 1995; Mukasyan et al., 1997a; of the liquid product, most of which are aboard the International Space Station (ISS) terrestrial conditions for comparison.

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Fig. 2.Experimental set-up for self-propagating combustion synthesis under microgravity conditions (ISS).Top: COSMIC reactor ensemble mounted in the MSG,together with the MSG video camera on the camera baffle and the experiment control electronics box; upper/centre: inner view of the COSMIC reactor ensemble: COSMIC reactors mounted on the experiment ensemble base plate; lower/centre: COSMIC reactor ensemble: outer view with camera baffle and MSG video camera; bottm: external view of a single COSMIC reactor.

As expected, under both microgravity References Condizioni di Microgravità. La Metallurgia and ground conditions, it is found that the Axelbaum, R.L. & Moore, J. (2001). Italiana 7-8, 45-52. combustion temperature and front Microgravity Combustion for Materials Medda,E.,Orrù,R.,Cao,G.,Fry,J.,Guignè,J.Y.& propagation speed decrease as the system Synthesis. In Microgravity Combustion, Fire Zell, M. (2001). Effects of Microgravity on exothermicity is reduced, i.e. when the In Free Fall (Ed. Howard D. Ross), Academic High-Temperature Self-Propagating aluminide/diboride molar ratio is increased. Press, San Diego, USA, pp479-523. Reactions. In Proc. 1st Int. Symposium On However, it is observed that front De Wilde,J.,Froyen,L.,Orrù,R.,Cao,G., Microgravity Research In Physical Sciences propagation speed is lower under Beloki, I.A., Sytschev, A.E., Rogachev, A.S., And Biotechnology, ESA SP-454, 299-306. microgravity conditions.The extinction of Jarvis, D. J.,Vautmans, L., Preud’homme, F., Merzhanov, A.G. & Borovinskaya, I.P.(1972). the combustion front occurs consistently Licheri, R. (2003). Self-Propagating High- Self-Propagated High-Temperature earlier when the reaction is performed Temperature Synthesis of Al-Ti-B in the Synthesis of Refractory Inorganic under reduced gravity conditions. ISS: Reactor Design and Preliminary Compounds. Dokl. Akad. Nauk 204, 366-369. For ISS experiments (Fig. 2), a dedicated Evaluation. Int. J. SHS 12, 165-177. Merzhanov, A.G. & Yukhvid,V.I. (1990).The Self- reactor ensemble was designed and used in Goroshin, S., Lee, J.H.S. & Frost, D.L. (1994). Propagating High Temperature Synthesis in the Microgravity Science Glovebox (MSG) on Combustion Synthesis of ZnS in the Field of Centrifugal Forces. In Proc. 1st the Station.The experiment was also Microgravity. 25th Int. Symposium On US-Japanese Workshop Combustion performed on the ground. Six samples with Combustion, Combustion Inst. Pittsburg, Synthesis,Tokyo, Japan, pp1-22. a relatively high green density of 65%TD PA, USA, pp1651-1657. Merzhanov, A.G. (1995). History and Recent were successfully processed in space.The Hlavacek,V. & Puszynski, J.A (1996). Chemical Developments in SHS. Ceramics Internat. 21, influence of the composition on the Engineering Aspects of Advanced 371-379. combustion process was examined. Materials. Ind. Eng. Chem. Res. 35, 349-377. Merzhanov, A.G., Rogachev, A.S. & Preliminary results on the self-propagating Hunter, K.R. & Moore, J.J. (1994).The Effect of Sytschev, A.E. (1998). SHS in Space. First combustion synthesis of titanium Gravity on the Combustion Synthesis of Experiments. Dokl. Russ. Akad. Nauk. 362(2), diboride/titanium aluminides composites Ceramic and Ceramic-Metal Composites. 217-221. can be described briefly. Combustion wave J.Mater. Synth. Proc. 2(6), 355-365. Merzhanov, A.G., Sanin,V.N. & Yukhvid, V.I. velocity and temperature decrease as the Karataskov, S.A,Yukhvid,V.I. & (2000). Peculiarities of Structure Formation aluminide/diboride content is augmented Merzhanov, A.G. (1985). Regularities and of High Caloric Systems during Combustion owing to the corresponding decrease of the Mechanism of Combustion of Melting under Microgravity. Dokl. Russ. Akad. Nauk. exothermicity of the system.When the Heterogeneous Systems in a Field of Mass 371(1), 94-97. reaction is performed under reduced Forces. Fizika Gorenia I Vzriva 6, 41-43. Moore, J.J., Feng, H.J., Hunter, K.R. & Wirth, D.G. gravity, it seems that the combustion front Lantz, C.C.,Tefft, P.A.,Moore, J.J. & (1992). Combustion Synthesis of Ceramic proceeds more slowly than in the ground Readey, D.W. (1995). Self Propagating and Metal-Matrix Composites. In Proc. 2nd experiments. Accordingly, combustion front Synthesis of Ceramics in a Microgravity Int. Microgravity Combustion Workshop, quenching experiments revealed that the Environment. In 7th Int. Symposium On NASA CP-10113, Cleveland, OH, USA, pp157- extinction of the combustion wave occurred Experimental Methods For Microgravity 162. earlier in microgravity.This behaviour may Materials Science (Ed. R.A. Schiffmann), Mukasyan, A.S., Pelekh, A.,Varma, A. & result from the fact that, under low-gravity TMS Publications,Warrandale, PA, USA, Rogachev, A. (1997a). Effects of Gravity on conditions, thermo-gravitational pp41-44. Combustion Synthesis in Heterogeneous phenomena, which could promote the Licheri, R., Orrù, R., Cao, G.,Wilde, J., Beloki, Gasless Systems. AIAA J. 25(12), 1821-1828. propagation of the combustion front, are I.A., Jarvis, D.J. & Froyen, L. (2003). Sintesi Mukasyan, A.S., Pelekh, A. & Varma, A. (1997b). limited. Autopropagante ad alta Temperatura in Combustion Synthesis in Gasless Systems

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under Microgravity Conditions. J. Mater. Manerbino, A. & Schowengerdt, F.D. (2000). Synth. Proc. 5(5), 391-400. Gravity Effects on Combustion Synthesis Topical Team Members Munir, Z.A. & Anselmi-Tamburini, U. (1989). of Glasses. In Proc. 1st Int. Symposium on Self-Propagating Exothermic Reactions: Microgravity Research & Application In Giacomo Cao (Team Coordinator) Iñaki Caro Calzada, the Synthesis of High-Temperature Physical Science & Biotechnology,ESA Roberto Orrù, Manuel Gutierrez Stampa, Materials by Combustion. Mater. Sci. Rept. 3, SP-454, pp277-284. Alberto Cincotti, Federico Ibarreta Lopez 277-365. Roberta Licheri, INASMET, P/M & Ceramics Dept., Camino de Odawara, O., Mori, K.,Tanji, A. & Yoda, S. (1993). Antonio Mario Locci, Portuetxe 12, E-20009 San Sebastian, Spain. Thermite Reaction in a Short Microgravity Massimo Pisu, Tel: +34-943-316247 Environment. J. Mater. Synth. Proc. 1(3), 203- Nicola Lai, Fax: +34-943-217560 207. Alessandro Concas Email: [email protected] Odawara, O., Kanamaru, N., Okutani,T., Dipartimento di Ingegneria Chimica e Materiali, Nagai, H., Nakata,Y. & Suzuki, M. (1995). Università di Cagliari, Piazza d’Armi, I-09123 Claudio Zanotti, Combustion Synthesis of GaP,InP,and Cagliari, Italy. Piero Giuliani, (Ga,In)P under Microgravity Environment. Tel: +39-070-6755058 Francesca Passaretti Int. J. SHS 4(2), 117-122. Fax: +39-070-6755067 IENI-CNR,Via Cozzi 53, I-20215 Milano, Italy. Odawara, O. (1997). Microgravitational Email: [email protected] Tel: +39-02-66173310 Combustion Synthesis. Ceramics Internat. and Fax: +39-02-66173307 3, 273-278. CRS4 Center for Advanced Studies, Research and Email: [email protected] Odawara, O. (2000). Combustion Synthesis of Development in Sardinia, Parco Scientifico e TiB2-based Fine Composite Compounds. In Tecnologico, POLARIS, Edificio 1, I-09010 Pula, Pekka Lintula, Proc. 'Spacebound 2000', 8th Canadian Italy. Pekka Ruuskanen, Microgravity Conf., 14-17 May 2000, Tel: +39-070-9250255 Pertti Lintunen, Vancouver, Canadian Space Agency. Fax: +39-070-9250216 Marko Vainio Shteinberg, A.S., Scherbakov,V.A., Email: [email protected] VTT Manufacturing Technology, P.O. Box 1731, Martynov, V.V., Mukhoyan, M.Z. & FIN-33101 Tampere, Finland. Merzhanov, A.G. (1991). Self-Propagating Ludo Froyen, Ph: +358-3-3163762 High-Temperature Synthesis of High- Lili Van Vugt, Fax: +358-3-3163799 Porosity Materials under Zero-g Rudy Devos, Email: [email protected] Conditions. Sov. Phys. Doklady 36(5), 385- Jimmy De Wilde 397. Department MTM, KU Leuven,W. De Croylaan 2, Jacques Guigne’ Varma, A., Rogachev, A.S., Mukasyan, A.S. & B-3001 Leuven, Belgium. GUIGNE’ International Ltd., 685 St.Thomas Line, Hwang, S. (1998). Combustion Synthesis of Tel: +32-16-321277 Site 21, Box 13, R.R. #1, Paradise, Newfoundland, Advanced Materials: Principles and Fax: +32-16-321992 Canada A1L 1Cl. Applications. Adv. Chem. Eng. 24, 79-226. Email: [email protected] Fax: 709-895-3822 Yi, H.C.,Woodger,T.C., Moore, J.J. & Guignè, J.Y. Email: [email protected] (1998). The Effect of Gravity on the Combustion Synthesis of Metal-Ceramic Composites. Metall. and Mater.Trans. B. 29b,889-897. Yi, H.C., Guignè, J.Y., Moore, J.J., Robinson, L.A.,

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Report of the Macromolecular Crystallisation in ESA Topical Team in Physical Sciences Fundamental Aspects of Macromolecular Microgravity Crystallisation in Microgravity Contributors: A.Tardieu, Paris (F) J.M. Garcia-Ruiz, Armilla (E) J. Drenth, Groningen (NL)

This report describes the crucial position of Otálora et al., 2001) that the quality of the structure of biological macromolecules in more fully the crystal growth process, with biological macromolecules (mainly proteins) microgravity environment provided in atomic detail is by X-ray diffraction on a the goal of obtaining crystals of biological in the life sciences. If their structures are Shuttle missions (where most of the crystal of the material.This is the starting macromolecules faster and of higher quality. known, their mechanisms of action can be experiments were performed) does not allow point for the Topical Team. Growing crystals explained. Structure determination is mainly a full exploration of the effects of of biological macromolecules is essential in 3. State of the Knowledge by X-ray diffraction, and crystal growth is an microgravity on crystallisation. It is therefore order to determine their structures via X-ray The structural determination of biological essential element of this process.The normal expected that ESA’s Protein Crystallisation diffraction.The crystal structure provides not macromolecules greatly contributes to procedure for obtaining crystals is trial-and- Diagnostic Facility (PCDF) can correct this only information on the architecture of the advances in life sciences.The bottleneck in error, but this is unsatisfactory for theoretical situation once it is commissioned aboard molecules in atomic detail but also on the these structural studies is the growth of high- and practical reasons. Fundamental studies ESA’s Columbus module. molecular packing and interaction.This is quality crystals. Although there is much on Earth are based mainly on theories Industry does not embrace space as a important information because a large fundamental knowledge for growing small developed for small compounds and colloids. crystallisation environment for various number of biological processes depend on molecules, this is not true for biological This is not completely realistic because of reasons.This background probably explains the interaction of macromolecules of the macromolecules. It has been suggested that differences in physical properties: the the hesitation of granting agencies to same or different type. gravity lowers the chance of obtaining well- interaction between biological support such studies.This has a negative It is clear that crystal growth is an ordered crystals.This parameter can be macromolecules is short-range and between effect on the progress in this field. essential step towards determining the avoided in space, leading to a better small compounds long-range. Colloids are structure of biological macromolecules.The understanding of the growth process.The isotropic, whereas biological macromolecules 2. Motivation of Research crystals need not be very large; with modern primary purpose of this Topical Team is to are highly anisotropic. Much effort is devoted to the life sciences in instrumentation and synchrotron radiation a study the crystallisation process of biological Gravity is a parameter in crystal growth. order to unravel the processes in living cells. size of 0.1 mm is sufficient, together with a macromolecules on the ground and in space Removal of this parameter in space could Our understanding of these processes is good degree of order for the molecular and, in addition, to recommend improved improve crystal quality and extend our deepened at an ever-increasing speed as a packing in the crystal.The quality of the procedures for practical purposes. knowledge of the growth process. result of advanced biochemical and crystalline order determines the accuracy of This process can be divided into two steps: Unfortunately, crystal growth experiments in biophysical techniques.The outcome is an the final molecular model. Crystallisation is, nucleation and growth. Nucleation starts space have so far given ambiguous results improvement in the quality of life by the at the moment, the limiting step in the from a supersaturated solution. Such a design or improvement of drugs that process. solution is unstable; it is in a non-equilibrium interfere with reactions in the cell. Many parameters determine the success state. It will move to the equilibrium state: the 1. Introduction In the pharmaceutical and chemical of crystallisation experiments: purity of the crystalline state in equilibrium with the The crystallisation of biological industry, classical chemical reactions are preparation, solvent composition, pH, saturated solution.This process begins with macromolecules (mainly proteins) is of being increasingly replaced by reactions additives, precipitating agent, and aggregation of the macromolecules. Small crucial importance in the life sciences. catalysed by biological macromolecules. temperature and, perhaps, gravity.The aggregates are unstable and disintegrate but Fundamental studies on Earth have greatly They are more specific (fewer byproducts) normal crystallisation procedure has been if they reach a critical size they are stable and contributed to a better understanding of the and often safe energy. A complete for a long time to follow a trial-and-error grow to macro-size crystals. It has been crystallisation process. By contrast, the understanding of those biochemical approach. An enormous number of different shown for the conversion from non- contribution to this subject by microgravity reactions is possible only if the structure of conditions are screened in order to locate equilibrium to equilibrium in many other experiments is so far limited. Indeed, the molecules involved is known in atomic optimal conditions for crystal growth.This systems and from scattering studies that opportunities for producing protein crystals detail. often has reasonable success but the nucleation occurs in, or close to, attractive in space have yielded ambiguous results. Although these details can be obtained scientific background is far from satisfactory. regimes – in solutions where spontaneous However, it has been demonstrated by under certain conditions using nuclear It has become clear that more rational fluctuations occur in the solute European teams (Riès-Kautt et al., 1977; magnetic resonance, the most general and approaches can be pursued. Space is an concentration. In the Team’s approach, these García-Ruiz & Otálora, 1997; Snell et al., 1997; quickest way to determine the molecular additional parameter to help understand fluctuations provide the means for bringing

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The best crystals are believed to grow at the critical anisotropic. Protein nucleation is, therefore, most cases crystallised by changing the ionic Crystals are essential for determining the structure of temperature. more complicated than nucleation of strength, the pH or the dielectric constant, or biological macromolecules by X-ray diffraction. colloids.The aggregation of the first by increasing the concentration of polymer

the macromolecules together for molecules, forming protein nuclei, can have a that provokes a depletion attraction. In the out to be true, then it requires Tc to be aggregation. 3-D structure completely different from the batch method, this is performed by mixing determined by a fast technique not Nucleation of macromolecules is, in macro-crystal structure.The participants in the protein solution with the precipitant requiring too much sample. Such a fast principle similar to the nucleation of small our Topical Team applied ingenuously solution.The Topical Team has performed method has not yet been proposed but molecules. However, there is a difference designed experiments using light scattering, studies on the mechanisms involved in the would be extremely valuable. owing to the large size of the low-angle X-ray scattering (static and time- mixing of protein and precipitating solutions. 2. look for the best crystallisation conditions macromolecules. At certain conditions of resolved), electron microscopy, It is most probable that the differences in when polymers are the precipitating temperature and macromolecular interferometry, atomic force microscope, nucleation behaviour observed in the agents in order to determine whether the concentration, the solution separates into calorimetry and even nuclear magnetic nucleation studies reported so far can be optimal conditions are also close to the one solution with a low concentration and resonance, providing a wealth of information explained by the nature of mixing. phase separation induced by the polymer. one with a high concentration (Fig. 1).These on the kinetics of the nucleation process and 3. study in detail the mixing of protein and solutions have a limited lifetime, are unstable on subsequent crystal growth. Many of the 4. Expected Results precipitating solutions in different protein and after a certain time move to the final experiments were supported by computer Crystals are essential for determining the crystallisation techniques. Detailed stable (crystalline) state.There is growing simulation studies. After nucleation, growth structure of biological macromolecules by knowledge of the dynamics of mixing of evidence that the best crystals grow at a proceeds to the final macro-crystal.The more X-ray diffraction.The crystal structure tells us these solutions under the microgravity

temperature near the critical temperature Tc ideal the arrangement of the molecules in about the molecular architecture in atomic level/noise scenario provided by the (Fig. 1). the crystal, the higher the accuracy of the detail and about molecular packing.The International Space Station can then be The liquid/liquid phase This view on nucleation of biological final molecular model obtained by X-ray most popular method for finding the best obtained. separation curve of the protein lysozyme plotted in a macromolecules has been adapted from diffraction. Illuminating images of the crystallisation conditions is by screening a 4. study in far more detail the effect of temperature versus lysozyme experience with small molecules and from growth process have been obtained with an large number of them.The trend is to impurities by crystallising from solutions Φ concentration diagram. a is studies on colloids.The latter consist of large atomic force microscope.They show the continue this approach, while fully with known amounts of impurities added the low concentration branch, Φ particles, like proteins, but they are isotropic, incorporation of impurities and the addition automating the process.The understanding deliberately. A weak point might be that b is the high concentration branch. whereas protein molecules are highly of molecules to growth steps or to of the physics behind the growth process the effect is highly specific for different spontaneously formed nuclei on a crystal would contribute to reducing the number of proteins. face. Scientists in the USA (Caylor et al., 1999; experiments in a screening by predicting 5. microgravity could be helpful in the long Thomas et al., 2000; Chernov, 1997; 1998) what the best conditions could be for run.The PCDF would first provide detailed proposed the idea that impurities in the obtaining crystals of the highest quality in knowledge of nucleation and growth. protein preparation are preferentially the shortest possible time. Then crystals of the highest possible absorbed in the growing crystal in the very The Topical Team has formulated the quality could be produced once the need beginning of the growth process. following steps as a practical approach: for high throughput is removed. Subsequently added layers to the crystal are then of a purer composition than the crystal 1. providing the preparation is reasonably 5. Space Experiments and Future Impact centre.This has not been completely verified. pure and the conditions do not denature An evaluation of the studies of protein It is the experience that impurities in the the protein, the optimal conditions are crystallisation in space was published by preparation have, in general, a detrimental expected to be at a temperature close to García-Ruiz et al. (2001). A review by Vergara

effect on crystal growth and quality. the critical temperature Tc of the et al. (2003) summarises the results of protein Microgravity experiments can also be liquid/liquid phase separation (Fig. 1).This crystallisation experiments exclusively relevant for mixing. Protein solutions are in should be studied in more detail. If it turns obtained with the Advanced Protein

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Space can still play a role in basic research into biological taking from a few hours to several weeks. References Correlation with Accelerometer Data. Acta macromolecular crystallisation. The benefits of microgravity Therefore, drop towers, parabolic flights and Caylor, C. L., Dobrianov, I., Lamay, S.G., Crystallog. D53, 747-755. have not been fully exploited. sounding rockets are not suitable except for Kimmer, C., Kriminski, S., Kinkelstein, K.D., Thomas, B.R., Chernov, A.A.,Vekilov, P.G. & testing instrumentation. Free-flying space Zipfel,W.,Webb,W.W.,Thomas, B.R., Carter, D.C. (2000). Distribution Coefficients Crystallisation Facility (APCF), the most vehicles and the ISS are the only options.The Chernov, A.A. & Thorne, R.E. (1999). of Protein Impurities in Ferritin and advanced instrument for crystallisation roadmap the Team foresees for ESA involves: Macromolecular Impurities and Disorder Lysozyme Crystals; Self-Purification in experiments in space.The protein in Protein Crystals. Proteins 36, 270–281. Microgravity. J. Crystal Growth 211, 149- crystallographic community at large does not – speed up the commissioning of PCDF. Chernov, A.A. (1997). Protein versus 156. share the optimistic view of Vergara et al. From the user’s point of view and Conventional Crystals: Creation of Defects. Vergara, D.C., Lorber, B., Zagari, A & Giegé, R. (success rate 26%). Leaving aside economically it is an unhealthy situation if J. Crystal Growth 174, 354-361. (2003). Physical Aspects of Protein Crystal considerations on the growth process itself, the period between design and Chernov, A.A. (1998). Crystal Growth and Growth Investigated with the Advanced the comparison of the quality of different commissioning of an instrument is Crystallography. Acta Crystallogr. A54, 859- Protein Crystallization Facility in Reduced- protein crystals is not a trivial matter and can excessive. Although there is no 872. Gravity Environment. Acta Crystallogr. D59, be achieved only by X-ray evaluation of a spectacular new approach for the García-Ruiz, J.M. & Otálora, F.(1997). Crystal 2-15. statistically significant number of crystals. crystallisation of proteins on the horizon, Growth Studies in Microgravity with the The perception of crystallisation in space such a danger always exists and would APCF.II. Image Analyses Study. J. Crystal is affected by the long delay between devalue the instrument.The Team also Growth 182, 155-167. submission of the proposal for an experiment encourages the support of ESA for full García-Ruiz, J.M., Drenth, J., Ries-Kautt, M. & and its materialisation.This is due to several testing of the PCDF on the ground before Tardieu, A. (2001). A World Without Gravity – precautions inherent to space experiments. using it in space. Research in Space for Health and Industrial Using space is out of the question for high- – to obtain crystals of superb quality it is Processes, (Ed. G. Seibert et al.), ESA throughput structure determination, mandatory to have a convection-free SP-1251, ESA Publications Division, ESTEC, certainly for industries where confidentiality environment. As demonstrated by The Netherlands. also plays a role. Unfortunately, the previous studies, neither the Shuttle nor Otálora, F., Novella, M.L., Gavira, J.A.,Thomas, B reluctance by industry also reduces the the ISS provides such an ideal setting.The & García-Ruiz, J.M. (2001). Experimental enthusiasm by granting agencies to support Team suggests exploring the use of 15- Evidence for the Stability of the Depletion crystallisation studies of macromolecules on day unmanned flights. For this, the Team Zone around a Growing Protein Crystal Earth and in space. proposes an inexpensive (low fabrication under Microgravity. Acta Crystallogr. D57, Space can still play a role in basic cost, no crew time required, easy 412-417. research.This is true for PCDF,which allows implementation, low mass and small Riès-Kautt, M., Broutin, I., Ducruix, A., the study of crystallisation unhindered by volume) fully autonomous crystallisation Shepard, W., Kahn, R., Chayen, N., Blow, D., gravity effects, and for specific proteins facility.The Granada Crystallisation Facility Paal, K., Littke,W., Lorber, B.,Théobald- where high throughput is not required. It is is a candidate: it meets these Dietrich, A. & Giegé, R. (1977). the Team’s conviction that the benefits of requirements and has been demonstrated Crystallogenesis Studies in Microgravity microgravity have not been fully exploited. to work properly aboard the ISS. with the Advanced Protein Crystallization Further experiments in microgravity should – to keep in mind the need for a highly Facility on SpaceHab-01. J. Crystal Growth provide more evidence to support this view. automatic, ground-controlled 189, 79-96. crystallisation facility for the ISS, if Snell, E.H., Boggon,T.J., Helliwell, J.R., 6. Roadmap for ESA Flight Carriers possible at reasonable cost. It could cater Moskowitz, M.E. & Nadarajah, A. (1997). The crystallisation of biological for specific proteins that do not require a CCD Video Observation of Microgravity macromolecules is a rather slow process, high-throughput system. Crystallisation of Lysozyme and

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Topical Team Members

Dr. Luc Belloni Dr. Stéphanie Finet Dr. Joseph Martial Dr. Patrice Vachette Service de Chimie Moléculaire, CEA/SACLAY, E.S.R.F., 6 rue Jules Horowitz, B.P.220, F-38043 Institut de Chimie B6, Université de Liège, B-4000 IBBMC, Bâtiment 430, Université Paris-Sud, F- F-91191 Gif-sur-Yvette Cedex, France. Grenoble Cedex, France. Start Tilman, Belgium. 91405 Orsay Cedex, France. Tel: +33 1 69 08 48 18 Tel: +33 4 76 88 26 82 Tel: +32 4 366 3311 Tel: +33 1 69 15 71 32 Fax: +33 1 69 08 66 40 Fax: +33 4 76 88 23 25 Fax: +32 4 366 2968 Fax: +33 1 69 85 37 15 Email : [email protected] Email : [email protected] Email: [email protected] Email: [email protected]

Dr. Luigi Carotenuto Dr. Richard Giegé Dr. Javier Pérez Dr. Stéphane Veesler MARS Center, via E, Gianturco 31, I-80146 Napoli, Institut de Biologie Moléculaire et Cellulaire, CNRS, SWING - Synchrotron SOLEIL, L’Orme des Merisiers Centre de Recherche en Matière Condensée et Italy. 15 rue René Descartes, F-67084 Strasbourg BP 48 Saint-Aubin, F-91192 Gif-sur-Yvette Nanosciences, CNRS-Campus de Luminy, Tel: +39 81 6042480 Cedex, France. Cedex, France. Case 913, F-13288 Marseille cedex 09, France. Fax: +39 81 6042100 Tel: 33 38 84 17058 Tel: +33 1 69 35 96 19 Tel: +33 6 62 92 28 66 Email: [email protected] Fax: 33 38 86 02218 Fax: +33 1 69 35 94 56 Fax: +33 4 91 41 89 16 Email: [email protected] Email: [email protected] Email: [email protected] Prof Hervé Delacroix Equipe de Bioinformatique, Centre de Dr. Juan Manuel Garcia-Ruiz Dr. Marie Claire Robert Prof Dr. Sevil Weinkauf Génétique Moléculaire, CNRS-P11, F-91198 Laboratorio de estudios Cristalográficos, Edificio Laboratoire de Minéralogie Cristallographie de Technische Universitaet Muenchen, Gif-sur-Yvette Cedex, France. BIC, Parque Tecnologico de Ciencias de la Salud, Paris, Case 115, 4 Place Jussieu, F-75252 Paris Lichtenbergstr. 4, D-85748 Garching, Tel: +33 1 69 82 37 48 Av. Innovacion 1, E-18100 Armilla (Granada), Cedex 5, France. Germany. Fax: +33 1 69 82 37 40 Spain. Tel: +33 1 44 275217 Tel: +49 89 289 13517 Email: [email protected] Tel: +34 958 750599 Fax: +33 1 44 273785 Fax: +49 89 289 13513 Fax: +34 958 750597 Email: [email protected] Email: [email protected] Prof Dr. Jan Drenth Email: [email protected] University of Groningen, Laboratory of Prof Dr.Wolfram Saenger Ingrid Zegers Biophysical Chemistry, Nyenborgh 4, 9747 AG Pr. Dr. Pierre-Paul Knops-Gerrits Institut für Kristallographie, Freie Universität Institute of Molecular Biology & Biotechnology, Groningen,The Netherlands. Département de chimie, Université Catholique de Berlin,Takustr. 6, D-14195 Berlin, Germany. VUB-ULTR, Building E, 4.16, Pleinlaan 2, Tel: +31 50 3634382 Louvain, Bâtiment Lavoisier, Place Pasteur n°1, Tel: +49 30 838 3412 B-1050 Brussels, Belgium. Fax: +31 50 3634800 B-1348 Louvain-la-Neuve, Belgium. Fax: +49 30 838 6702 Tel: +32 2 6291932 Email: [email protected] Tel: +32 010 47 24 39 Email: [email protected] Fax: +32 2 6291936 Fax: +32 010 47 28 36 Email: [email protected] Prof Arnaud Ducruix Email: [email protected] Dr. Annette Tardieu Faculté de Pharmacie, Case 48, 4 Avenue de Laboratoire de Minéralogie-Cristallographie, l'Observatoire, F-75270 Paris cedex 06, Dr. Michael Kokkinidis CNRS-P6, Case 115, 4 Place Jussieu, F-75252 France. Institute of Molecular Biology and Biotechnology, Paris Cedex 05, France. Tel: +33 1 53 73 98 36 Vassilika Vouton, 71110 Heraklion, Crete, Tel: +33 6 22 06 17 63 Fax:+33 1 53 73 99 25 Greece. Fax : +33 (0)1 44 27 37 85 Email: [email protected] Tel: +30 81 39 4455 Email : [email protected] Fax: +30 81 39 4351 Email: [email protected]

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Report of the Microencapsulation Processes ESA Topical Team in Physical Sciences Interfacial Studies of Emulsions Used in Industrial Microencapsulation Processes

Contributors: T.L.Whateley, Glasgow (UK) D. Poncelet, Nantes (F)

Microencapsulation by solvent evaporation is runs the two largest encapsulation pilot market method for encapsulating food a novel technique to enable the controlled plants for these applications. Food industries ingredients such as aromas, probiotics, delivery of active materials.The controlled are working increasingly with powders, flavours and vitamins. release of drugs, for example, is a key which are easier to store, handle and The two methods may appear quite challenge in the pharmaceutical industries. transport than fresh food. However, many different to the layman, but they share many Although proposed several decades ago, it fragile and volatile ingredients need to be aspects.This Topical Team is dealing remains largely an empirical laboratory encapsulated before they are incorporated. principally with solvent evaporation because Fig. 1.Surface pattern obtained on polylactic acid microcapsules process.The Topical Team has considered its The controlled release of drugs is a key its observation is simpler; in spray drying, the obtained by solvent evaporation. critical points and the work required to challenge for most pharmaceutical droplets move rapidly and the whole process produce a more effective technology – better industries. Similar comments apply to the takes only a few seconds. However, the control of the process for industrial cosmetics and agrochemical fields. conclusions of the research will be production, understanding of the interfacial There are many encapsulation methods, extrapolated to spray drying. dynamics, determination of the solvent such as interfacial polymerisation, simple evaporation profile, and establishment of the and complex coacervation, spray coating and 2. Fundamental Aspects of Encapsulation relation between polymer/microcapsule spray drying. Careful selection is required to by Solvent Evaporation structures.The Team has also defined how meet the objectives. A typical and effective Analysis of the literature on microcapsule microgravity experiments could help in method is to disperse the active ingredients production by solvent evaporation reveals a better understanding microencapsulation by (as solute, powder or immiscible liquid) in a surprisingly large number of publications. solvent evaporation, and it has proposed a polymeric solution.The mixture is then However, authors have concentrated on two strategy for a collaborative project on the dispersed into droplets and the solvent is aspects: selection of the polymer as the topic. evaporated to form to solid micro spheres matrix, and testing the controlled release entrapping the active ingredient.The solvent either in vitro or in vivo. Moreover, most of the Fig. 2.Evaporation site versus pressure during the is generally a volatile organic solvent.This research has been performed on a very small microencapsulation process.P: pressure above the reactor; 1. Introduction technology is quite expensive and difficult to scale. Ps: saturation pressure of the solvent. Microencapsulation involves a large number scale up; it is essentially a batch process. It is There is, then, an important gap in of processes that entrap an active material in used mainly in the pharmaceutical industry, knowledge on the physico-chemical and mainly spherical particles in order to particularly for producing microcapsules engineering process of encapsulation by immobilise it, protect it, control its release composed of biodegradable polymers solvent evaporation.The difference between solvent A. However, industrially, the ratio of and provide new physical properties or (essentially polylactic; Fig. 1).The drug this process and simple solvent evaporation dispersed phase to continuous phase will be functions.The applications of microcapsules release can be modulated with a high is too great to allow simple extrapolation. maximised, limiting the extraction. are wide-ranging but little known to the degree of freedom and the material is quite The Team has identified a range of questions At the laboratory scale, evaporation is public; in most cases, microcapsules are tools biocompatible. and areas to research, as outlined below. performed at room temperature under that provide specific properties or simplify ‘Spray drying’ involves spraying in hot air atmospheric pressure.The process can take production. using water as the solvent. It is a typical 1.Where does evaporation take place? hours. In industrial schemes, the pressure is Most large industries are involved in method in the food industry, similar from a Consider a polymeric solution in volatile reduced and sometimes the temperature encapsulation either as producers or users. process point of view to drying to produce solvent A dispersed in solvent B. In many raised. A flow of inert gas may be pumped For example, one of the largest food powders.The technique is cheap, both cases, scientists have not really taken the through the reactor to entrain solvent A. manufacturers is 3M, with a large range of in investment terms (as reactors already exist miscibility between these two solvents into Evaporation takes place in a few minutes products such as encapsulated inks, glues or in industry) and running costs (continuous consideration.The dispersed phase is often a Preliminary studies have shown that the catalysts. Detergents for washing machines process). Even if the efficiency of the large volume of solvent B. Solvent extraction site of evaporation depends on the operating include encapsulated enzymes. Genencor encapsulation is not perfect, it is the major may then take place before evaporation of conditions at atmospheric pressure in the

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The conditions are critical for producing the required However, as the concentration of solutes in 4. Microcapsule structure and polymer It will be possible to improve our understanding of the structure of microcapsules. the droplet decreases, the diffusion of the selection process and to optimise the production of microcapsules. solvent may become the limiting factor. Rapid evaporation at the droplet surface There is a high risk of bubble formation may provide a quick increase of the polymer reactor and the room temperature. Solvent A directly inside the droplets. concentration in the vicinity of the surface. the loss is due to the coalescence/breakage will diffuse through solvent B and evaporate Preliminary experiments show that, at This may result in precipitation and then cycles; rapid evaporation quickly fixes the at the liquid surface (Fig. 2a). fixed pressure, the rate of evaporation formation of a skin/membrane around the matrix and avoids such loss. When the conditions are such that decreases quickly during the process. At droplets.This structure will strongly affect diffusion becomes the limiting process (lower low pressure, 90% of the solvent is the transfer of the solvent and then reduce 3.Why Carry Out Studies in Microgravity? pressure), the system may enter ebullition. removed in a few minutes but the rate of the process efficiency. The brief analysis above shows that better Gas bubbles start to form in the continuous evaporation then decreases exponentially. In some cases, however, it might have knowledge of the processes involved in phase (Fig. 2b). Unfortunately, there is little information beneficial effects. In the case of volatile microencapsulation by solvent evaporation is If the pressure decreases even further, the available for modelling this phenomenon. active ingredients, forming a skin still needed to improve not only the quality and bubble forms on the surface of the dispersed permeable to the solvent but with a performance of the encapsulated products phase droplet (pre-microcapsules) (Fig. 2c), 3. Interfacial turbulence and internal flows molecular cut-off lower than the active but also the cost and efficiency of the creating disturbances on the droplet surface. Removing 80-90% of the volume of a ingredient molecular mass will allow the production. While the pressure is very low, the bubble droplet assumes the transfer of this active ingredient to be retained during the Observation of the process on Earth is may form inside the dispersed droplet, volume to the surface of the droplets. How formation of the microcapsules.This, for difficult and microgravity would open new leading to very porous microcapsules. does this affect the structure of the example, explains the high yield of investigation possibilities. In ground It is clear that the conditions are critical for capsules? How could this influence the encapsulation of flavours by spray drying. experiments, mixing is required to maintain producing the required structure of the distribution of the active ingredients in the The type of polymer used to form the the emulsion during the microcapsule microcapsules (generally non-porous). capsules? Internal flows may either matrix affects the process. If the formed skin formation.The speed range of the droplets in However, lower pressure speeds up the promote or hinder the transfer of the is largely permeable, solvent will pass the reactor is 2-5 m/s. In such emulsions, the process and thereby reduces cost.There is a active ingredient to the surface.The through the membrane with little effect on large droplet size distribution is difficult to compromise to be made between physical state of the active ingredient the resulting capsules. If the skin is quite observe, and the evolution of droplet size or performance and quality of capsules, but no (solute, liquid, solid) or its size (molecular impermeable, the process will slow and the structure cannot be recorded. Moreover, model exists to help the process engineers in size, droplet diameter) may largely droplet contract, generating a ‘raisin’ visual observations are limited to the external defining it. influence its movements. structure. If really impermeable, the droplet layer of the batch. In microgravity, normal While evaporation takes place on the may form inside the microcapsules, creating dynamic coalescence/droplet rupture is 2. Solvent evaporation profile droplet surface, interfacial turbulence a very porous and open structure. eliminated. Monodisperse and spherical Returning to our initial emulsion, the affects the interfacial transfer rate by a droplets could be produced and observed dispersed phase is composed of the active factor of 2-3. Local variation in interfacial 5. Double emulsion process during the overall process of solvent ingredients (a few percent), the polymer tension, polymer concentration or In a number of applications, the active evaporation and encapsulation. (generally less than 10% to avoid too-high temperature may result in micro-flows near ingredients are in an immiscible phase In microgravity experiments, droplets can viscosity) and a majority of solvent (up to the surface, owing to the Marangoni effect, dispersed inside the polymeric solution.The be photographed dynamically to follow 90%). During evaporation, the droplet will and lead to the surface pattern observed process thus involves a double emulsion extraction/evaporation of solvent, also reduce its volume by a factor of up to 10. experimentally.These micro-flows may (active ingredient / polymeric solution / allowing observation of the dynamics of At the starting point, when solvent is the themselves affect the evaporation and play continuous phase). Some results show that surface turbulence and surface pattern main component, transfer to the continuous an important role in the transfer of the the encapsulation yield strongly correlates formation. As no mixing is required to phase and evaporation is easy, and controlled solvent versus the diffusion, affecting the with the duration of the mixing process maintain the emulsion, the shear and mainly by the mass transfer at the interface. risk of bubble formation inside the beads. during the second emulsion. A large part of turbulence could be modulated around the

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droplets, applying different flow patterns.The Topical Team Members effects controlling the mass transfer (diffusion in droplet, convection, etc.) could Dr.T.L.Whateley Prof.O.Alpar then be observed independently. Using Dept. of Pharmaceutical Sciences, SIBS, Centre for Drug Delivery Research,The School of specific tracers, internal flows or temperature University of Strathclyde, Glasgow, G4 0NR, Pharmacy, University of London, fluctuations on the surface can be observed. Scotland, UK. 29-39 Brunswick Square, London WC1N 1AX, From all of these data, using numerical Tel: +44 141 552 4400 UK. simulation and computational fluid dynamics Fax: +44 141 552 6443 Tel: +44 207 753 5928 to connect them with ground experiments, it Email: [email protected] Fax: +44 207 753 5942 will be possible to improve our Email: [email protected] understanding of the process and to Prof.D.Poncelet optimise the production of microcapsules by ENITIAA, Rue de la Géraudière BP 82225, Prof. Dr.T. Kissel solvent evaporation both in terms of quality F-44322 Nantes Cedex 3, France. Philipps-University Marburg, Dept. and production performance. Tel: +33 2 51 78 54 25 Pharmaceutics & Biopharmacy, Fax: +33 2 51 78 54 67 Ketzerbach 63, D-35032 Marburg, Germany. 4. Developing a Research Programme from Email: [email protected] Tel: +49 6421 282 5881 the Topical Team Fax: +49 6421 282 7016 From Topical Team discussions, several Prof. P.Colinet projects have been considered. Some of the Microgravity Research Centre, Université Libre Industrial Partners members have joined the ESA-funded de Bruxelles, Service de Chimie Physique E.P., Dr.K.Eichler ‘Convection and Interfacial Mass EXchange’ C.P.165/62, 50 av. F.D. Roosevelt, Glatt GmbH, Binzen, Germany. (CIMEX) project led by Prof. Colinet. It is B-1050 Bruxelles, Belgium. Email: [email protected] investigating heat and mass transfer Tel: +32 2 650 31 41 phenomena through interfaces between a Fax: +32 2 650 31 26 Dr.G.Rees liquid and a gas or between two immiscible Glaxo SmithKline, Middlesex, UK. liquids. Bristol Myers Squibb has shown a real Prof. C. Ward Email: [email protected] interest in the CIMEX programme and may Director,Thermodynamics and Kinetics even extend it into an industrial project. Laboratory, Dept. Mechanical & Industrial Dr. D. Bain, Quintiles, UK. The Team may join its efforts with those of Engineering, University of Toronto, 5 King’s the Topical Team on ‘Emulsion Science and College Road,Toronto, Canada M5S 3G8. Dr. J.Taihades Technology’,led by R. Miller, together with Email: [email protected] Astrium, 31 avenue des cosmonautes, F-31402 the MAP project ‘Fundamental and Applied Toulouse cedex 4, France. Studies in Emulsion Stability’,led by Prof. T. Coakley Tel: +31 05 62 19 66 72 A. Passerone. School of Biosciences, Cardiff University, Email: [email protected] Despite the difficulties in matching with PO Box 915, Cardiff CF10 1TL,Wales, UK. its objectives, a project in response to the 6th Tel: +44 29 2087 4287 Dr N. Suter Framework Programme of the European Fax: +44 29 2087 4305 Nisco Engineering AG, Dufourstrasse 110, Commission is being investigated. Email: [email protected] CH-8008 Zurich, Switzerland. Email: [email protected]

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Report of the Instabilities in Lean Gas-Phase ESA Topical Team in Physical Sciences Numerical & Experimental Studies of Combustion Instabilities in Lean Gas-Phase Combustion Contributors: Fig.1.A candle in the microgravity of a drop tower.The teardrop K. Schneider, Marseille (F) (Coordination) shape of 1 g (first frame) relaxes towards a sphere. H. Bockhorn, Karlsruhe (D) Ch. Eigenbrod, Bremen (D) D. Emerson, Daresbury (UK) P.Haldenwang, Marseille (F) S. Hoffmann (D) D. Roekaerts, Delft (NL) Lean burning is the burning of fuel-air phenomena (Ronney, 1999; Eigenbrod et al., P.Ronney, Los Angeles ( USA) mixtures with less than the chemically- 1997). Owing to the absence of buoyant W.Triebel, Jena (D) balanced (stoichiometric) mixture. It convection, which on Earth generates M.Tummers, Delft (NL) produces a significant increase in fuel convection and strongly influences the efficiency and reduction in pollution. reaction zone, other transport mechanisms, However, the limits and control of lean such as Lewis-number effects or radiation, burning are still not well understood.This is can be investigated in detail.To elucidate dropped to create microgravity, the the motivation behind the study of these questions, microgravity experiments teardrop shape relaxes towards a sphere. instabilities in lean gas-phase combustion within the mix of theoretical and numerical Moreover, the candle flame, like many under microgravity conditions via direct studies are indispensable. Experiments are others, produces an unsteady ‘flicker’ at 1 g, numerical simulations and comparison of the typically performed in a combustion whereas in microgravity this flicker is results with experimental data.The goal is to chamber containing a quiescent, premixed eliminated. Hence the study of flames gain fundamental insights in order to identify lean-gas mixture with a reactant of small becomes much easier. and understand the intrinsic chemical and Lewis number. A point ignition leads to a Figure 2 shows the results from a high- fluid dynamical mechanisms responsible for flame that rapidly breaks up into cells. In resolution direct numerical simulation of a Fig.2.Instabilities of spherical flame structures.High-resolution these instabilities.The potential of this some cases, steady spherical flame balls form premixed lean hydrogen-air flame in direct numerical simulation showing temperature isosurfaces. microgravity combustion research includes that are not supported by any source of microgravity (Gerlinger et al., 2000). (Gerlinger et al., 2000). the development of technology that would reactants or sink of products in their centres. Temperature isosurfaces are shown at reduce pollution and fire and explosion The conceptual importance of such a different instants in order to highlight the hazards, improve hazardous waste configuration resides in the possibility of 3-D instabilities induced by local incineration and increase efficiency of the investigating flammability limits. In general, perturbations. An open question for the conversion of chemical energy to electric these limits depend to a very large extent on behaviour of spherical flames is the pattern power or motive force.The results from this the experiment hardware, whereas the formation when they split into cells. Figure 2 fundamental research will thus benefit flame-ball experiment may provide a limit shows that the initial pentagonal structure chemical engineering and power generation. that is practically device-independent. first grows continuously and then splits at Its wide range of applications in industry the five preferred locations triggered by the includes lean-burning car engines. 2. Examples initial perturbation. Gradual splittings then Figure 1 (first frame) shows a candle lit in create a pentagon of five balls; these do not Earth gravity.The flame quickly forms a change positions or shape for a long time. 1. Motivation for Research teardrop shape caused by the hot air rising Figure 3 shows the results from numerical The design of efficient, low-pollution and cold fresh air flowing in behind to keep simulation of the interaction of a spherical combustion engines and the assessment of it burning. However, this airflow also flame structure in a premixed lean mixture fire and explosion hazards in, for example, obscures many of the fundamental with an adiabatic wall under microgravity chemical plants and mine shafts require a processes that we aim to understand in conditions (Roussel et al., 2003; 2004).The profound knowledge of the behaviour of order to control combustion for heating, fire- figure shows the temperature (left), the lean premixed-gas flames, i.e. those near safety and pollution. In the microgravity chemical reaction rate (middle) and the extinction or stability limits. Under these environment of an orbiting spacecraft or a adaptive grid used in the numerical conditions, the flames are highly sensitive to drop tower, gravitational effects are computation (right) at different times.The disturbances such as buoyancy-induced eliminated and many combustion processes reaction rate gradually decreases when the turbulent flow. Microgravity is thus a suitable are slowed down.The last three frames of flame reaches the wall. At later times, the Fig.3.Interaction of a flame ball with an adiabatic wall at low environment for investigating these Fig. 1 show that, when the capsule is front curvature is modified through Lewis number (Roussel et al., 2003; 2004).

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tangential diffusion.This phenomenon has – development of ignition devices and the gains in knowledge of combustion: it allows These new techniques can be used for combustion research similarities to capillarity effects in fluid combustion chamber design; experimenters to establish controllable in drop towers, on parabolic flights and aboard the mechanics. – development of laser diagnostics to meet conditions for the precise examination of International Space Station. the experimental requirements. accepted but unverified theories, and to 3. Expected Results, Space Experiments and develop fresh insights into elementary method that has to be implemented in the Future Impact 3.1 Relevance for Microgravity phenomena that are hidden in ground-based 3-D computer code. Also clarified will be the The objective of the research group is to Gravitational forces on Earth hamper the combustion processes. link between flame balls with turbulent study the transient behaviour of lean gas- combustion and conversion of chemical combustion, and simulations that study the phase combustion under microgravity matter in many different ways such that 4. Roadmap response of the flame structures to vortical conditions, including ignition-extinction experiments provide no fundamental 4.1 Direct Numerical Simulations with structures and homogeneous isotropic phenomena of reactive mixtures, by means insights. As exothermic chemical reactions Simple Chemistry turbulent flow fields. of numerical simulations and experiments. intrinsically involve production of high The transient behaviour of premixed gases The participating teams have temperatures, the density changes and will be studied by direct numerical 4.2 Numerical Simulations with Complex complementary knowledge to address the thereby triggers buoyant motion, which simulation of flame structures under Chemistry different questions. Applications in the vastly complicates the execution and microgravity conditions.The numerical code For the numerical simulation of lean flames context of homogeneous combustion are the interpretation of experiments. Furthermore, is a fully parallel implementation on with complex chemistry, 1-D spherically main consideration.The behaviour of the effects of buoyancy are strongest in the massively parallel computers with 256 symmetric flames involving methane, H2+CO spherical flames is studied in order to gain highest temperature regions, where the processors.The developed code is the only and other mechanisms are being considered. fundamental insights into the flammability chemical reactions take place. Buoyancy available tool to perform simulations of such Different radiation models are incorporated, behaviour of premixed gas flames near their causes these reaction zones (where our large-scale microgravity problems (Gerlinger such as the optically-thin model and a extinction limits.The project is based on the understanding is most limited) to collapse et al., 2000). Issues being addressed include narrow band model.This allows the study of strong interplay between theoretical into very thin sheet-like regions, the modelling of the ignition source and the the near-limit structure of lean flames and predictions using asymptotic stability theory, unresolvable by existing techniques such as resulting number of spherical flames will yield information concerning the numerical simulations with different level of laser diagnostics, under normal gravity produced for a given ignition source. ignition, ignition limits and burning velocity. complexity and experiments under conditions. Additional complications arise Whether and to what extent the predictions The 1-D code works with the optically-thin microgravity conditions.The following from the onset of turbulent convection of the stability limits of 3-D flame structures radiation model, which considers only heat projects are therefore being pursued: being triggered by buoyant motion.This based on asymptotic analyses agree with the loss due to emission of radiation from the yields unsteadiness at a wide range of numerical simulations and experiments will gas; work needs to be done to add the – development of 3-D computer codes for temporal and spatial scales. Finally, buoyancy also be investigated.The influence of narrow band model, which includes direct numerical simulation of flame causes particles and drops to settle, complex chemistry on the evolution of the absorption and re-emission of radiation. instabilities in lean mixtures; inhibiting studies of heterogeneous flame balls and their stability properties will After, different detailed chemistry studies are – development and validation of complex reactions important to catalysts, incineration be checked. being performed.The code will be reaction mechanisms for lean mixtures; and power-generation technologies.The The influence of the Lewis number for subsequently extended to 2-D axisymmetric – development of the mixture generation effects of buoyancy thus seriously limit our mixtures of different species is another point spherical flames to investigate the flame and homogenisation system through the ability to conduct the experiments needed of research.The open question is whether stability with respect to curvature-induced definition of studies and preparatory to advance our understanding of chemical and how the lowest Lewis number present in perturbations and to the formation of cellular experimental projects; reactions in technical devices and, in the mixtures determines the behaviour of structures (the local extinction effects). particular, to conduct experiments that can the evolution of the spherical flame Microgravity offers the potential for major gains in our be directly compared to numerical structure.The interaction of spherical flame 4.3 Experiments and Exchange of Data knowledge of combustion. simulations. structures with each other and the walls will The proposed experiments aim to obtain Microgravity offers the potential for major be simulated using a volume-penalisation basic data for comparison with the numerical

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models of lean premixed gaseous flames parabolic flights and the International discussed above. Microgravity conditions are Space Station. Synergy effects to and from Topical Team Members essential, as otherwise laminar propagating new terrestrial applications are lean flames are strongly affected by foreseeable. Prof. Kai Schneider (Coordinator) Dr. Stefan Hoffmann buoyancy driven by natural convection. Laboratoire de Modélisation et Simulation Siemens-KWU, D-45466 Mülheim a.d. Ruhr, Besides this, the facility will enable the lean References Numérique en Mécanique, UMR 6181 - CNRS Germany. flammability limits and flame propagation Eigenbrod, Ch., König, J. & Triebel,W. (1997). et Universités d’Aix-Marseille, Centre de Tel: +49 208 456-2790 velocities of gaseous pre-mixtures to be Recent Developments and Applications of Mathématiques et d’Informatique, Université Fax: +49 208 456-2319 measured. For methane/air mixtures, these the Combustion Diagnostics at Bremen de Provence, 39 rue Joliot-Curie, F-13453 Email: [email protected] values have been proved to be leaner than Drop Tower. Proc. 4th Int. Microgravity Marseille Cedex 13, France. under terrestrial conditions.This part of the Combustion Workshop, NASA Conference Tel: +33 4 91 11 85 29 Prof. Dirk Roekaerts project will be performed in close Publication 10194, Cleveland, 317. Fax: +33 4 91 11 35 02 Shell Global Solutions, PO Box 38000, 1030 BN collaboration with the ESA Microgravity Gerlinger, W., Schneider, K. & Bockhorn, K. Email: [email protected] Amsterdam,The Netherlands. Applications Project (MAP) combustion (2000). Numerical Simulation of Three- Tel: +31 20 630 3270 project on ‘Combustion Properties of Partially Dimensional Instabilities of Spherical Prof. Henning Bockhorn Fax: +31 20 630 2235 Premixed Spray Systems’ (CPS). Particularly Flame Structures. Proc.Combust.Inst.28, ICT, Universität Karlsruhe, Kaiserstr. 12, D-76128 Email: [email protected] interesting here is the development of 793-799. Karlsruhe, Germany. advanced laser diagnostics for inflight König, J., Eigenbrod, Ch., Bolik,T., Rath, H.J., Tel: +49 721 608 2120 Prof. Paul Ronney application on the CPS project (Triebel, 1998). Gerber, D., Müller, D. & Triebel,W. (1998). Fax: +49 721 608 4820 USC, Los Angeles, CA 90089-1453, USA. Current methods are 2-D laser-induced Observation of Two Stage Autoignition of Email: [email protected] Tel: +1 213 740-0490 emission (LIE) techniques like laser-induced n-Heptane Fuel-Spheres by LIF of Fax: +1 213 740-8071 fluorescence (LIF), particle image velocimetry Formaldehyde. 27th. Symp. (Int.) on Christian Eigenbrod Email : [email protected] (PIV), and Rayleigh- and Mie Scattering for Combustion,The Combustion Institute, ZARM, Universität Bremen, Am Fallturm, http://carambola.usc.edu/sofball temporally- and spatially-resolved Boulder, Colorado, USA. D-28359 Bremen, Germany. measurements of species concentrations and Ronney, P.D. (1999). A Perspective on the Role Tel: +49 421 4078 Prof.Wolfgang Triebel temperature fields (König et al., 1998). of Microgravity in Combustion Research. Fax: +49 421 2521 IPHT Jena, Helmholtzweg 4, D-07743 Jena, Enhancements towards 3-D diagnostics Combust. Flame 116, 317. Email: [email protected] Germany. through tomographic spectroscopy will be Roussel, O., Schneider, K.,Tsigulin, A. & Tel: +49 3641 302602 developed to a prototype status where Bockhorn, H. (2003). A Conservative Fully Dr. David Emerson Fax: +49 3641 302603 applicable.The reaction zones of spherical Adaptive Multiresolution Algorithm for CLRC Daresbury Laboratory, Daresbury, Email: [email protected] flames can then be investigated. For gaseous Parabolic Conservation Laws. J. Comput. Warrington,WA4 4AD, UK. fuels considered in the MAP project, OH and Phys. 188(2), 493-523. Tel: +44 1925 603221 Dr. Mark Tummers CH are the most interesting species.There are Roussel O. and Schneider K. (2004). Numerical Fax: +44 1925 603634 Delft University of Technology, Faculty of two important points to note with the Study of Spherical Flame Structures Email: [email protected] Applied Physics, Lorentzweg 1, 2628 CJ Delft, application of high-resolution LIF techniques: Interacting with Adiabatic Walls using an The Netherlands. Adaptive Multiresolution Scheme. Prof. Pierre Haldenwang Tel: +31 15 278 2477 – the time-resolved, 2-D spatial resolution Combustion Theory and Modelling, Université de Provence, 38 rue Frederic Joliot- Email: [email protected] close to the diffraction limit will allow submitted. Curie, F-13451 Marseille cedex 20, France. characterisation of the interaction Triebel,W. (1998). Laser Diagnostics of Tel: +33 491 118 551 mechanisms between flames and vortices; Combustion Processes under Short-Term Fax: +33 491 118 502 ZARM: www.zarm.uni- – the developments will commonly apply to Microgravity Conditions. Space Forum 4, Email: [email protected] bremen.de/combustion.html combustion research in drop towers, 121.

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Report of the Cartilage Engineering and ESA Topical Team in Life Sciences Cartilage Engineering and Microgravity: Innovative Scaffolds for Microgravity Chondrocyte Encapsulation

Contributors: R.Toffanin,Trieste (I) (Coordination) A. Bader, Leipzig (D) A. Cogoli, Zurich (CH) C. Carda,Valencia (E) P.Fantazzini, Bologna (I) L. Garrido, Madrid (E) The complex effects of mechanical forces and Despite its simple appearance, this tissue S. Gomez, Cadiz (E) growth factors on articular cartilage hides various modifications in respect of the L. Hall, Cambridge (UK) development still need to be investigated in original cartilage that make it a singular I. Martin, Basel (CH) order to identify optimal conditions for structure.The articular cartilage is, in fact, E. Murano,Trieste (I) articular cartilage repair. Strictly controlled stratified. Classically, four distinct layers are D. Poncelet, Nantes (F) in vitro studies under modelled or space described, from the surface to the interior: R. Pörtner, Hamburg (D) microgravity conditions can improve our tangential, transitional, radial and calcified, understanding of the fundamental role of respectively. In each, the distribution, form gravity in articular cartilage development. and size of the chondrocytes, the content of The main objective of this Topical Team is to proteoglycans and the density and course of nonexistent in situ, but it is latent. It has been use modelled microgravity as a tool to the type II collagen fibrils differ. More than documented that chondrocytes isolated from elucidate the fundamental science of this, these layers vary in thickness and the cartilage are capable of proliferating in cartilage regeneration. Particular attention is, definition from one articulation to another, in culture, and of expressing, under controlled therefore, given to the effects of physical accordance with the loading they support conditions, their cartilaginous phenotype forces under altered gravitational conditions, and the congruence of their surfaces.The (essentially, capable of producing Fig. 1.a: articular cartilage,stained with toluidine blue to applied using controlled bioreactor systems, extracellular matrix is not uniform and two proteoglycans and type II collagen).When demonstrate acid proteoglycans.b: articular cartilage,stained on cell metabolism, cell differentiation and basic compartments, known as territorial and these chondrocytes are cultured in isolation, with silver to demonstrate the collagen network.c: articular cartilage; ultrastructural aspect of a chondrocyte.d/e: cartilage tissue development. Specific attention is also interterritorial, can be distinguished.The until their confluence, or else are seeded in cultured under modelled microgravity conditions in a random directed toward the potential advantages of territorial matrix directly encapsulates the biodegradable scaffolds, solid fragments of a position machine (RPM) for 2 weeks; stained with toluidine blue. using magnetic resonance methods for the chondrocytes, either isolated or in isogenic cartilage-like tissue are obtained.To what f/g: control cartilage cultured in a static flask at 1 g for 2 weeks; non-destructive characterisation of scaffolds, groups, and is easily distinguished by the extent is this engineered tissue similar to the stained with toluidine blue.h: cartilage cultured under modelled chondrocytes-polymer constructs and tissue intense staining of the proteoglycans original? So far, none of the studies on microgravity conditions in an RPM for 4 weeks; stained with engineered cartilage. (Fig. 1a).The interterritorial matrix cartilage engineering has created a toluidine blue.i: control cartilage cultured in a static flask at 1 g for 4 weeks; stained with toluidine blue.Bar = 10 µm in a, b,e,g, constitutes the greater part of the functional tissue that fully regenerates the h, i; bar = 2 µm in c; bar = 50 µm in d,f. extracellular matrix, and the fibrillar natural properties of articular cartilage, even 1. Articular Cartilage component is predominant in this after several months in vivo. Articular cartilage is one of the types of compartment (Fig. 1b). Blood vessels (and Mechanical loading together with growth hyaline cartilage that persists throughout nerves) are absent from the articular factors certainly play a major role in articular adult life. Basically, it comprises chondrocytes cartilage, and, for this reason, the cartilage regeneration. Mechanical forces, extracellular matrix, in terms of incorporated in an extracellular matrix chondrocytes live in a hypoxic medium. presented to cells by fluid shear or direct glycosaminoglycan content and consequent composed mainly of water, collagen II fibrils, However, it is active cells that synthesise, manipulation of the surface, can influence increase in both static and dynamic and proteoglycans.The collagenous network process and degrade the extracellular matrix, cell function at multiple levels. For example, compressive stiffness of the constructs. gives the tissue tensile strength and hinders and are capable of responding to variations the effects of continuous and intermittent Pioneer studies of in vitro cultivation of the expansion of the viscoelastic in their surroundings. Ultrastructurally dynamic compression on chondrocyte chondrocytes on synthetic polymer scaffolds, proteoglycan molecules that provide (Fig. 1c), they are well endowed with the biosynthesis have been characterised in under conditions of modelled microgravity compressive stiffness. Cartilage matrix endoplasmic reticulum, Golgi apparatus, cartilage explants and chondrocyte-seeded and space experiments, indicate that building blocks are synthesised, organised ribosomes, lysosomes and mitochondrias. In scaffolds. In particular, long-term alternate microgravity significantly affects the and maintained by a sparse population of short, they have all that is necessary for the day intermittent dynamic compression has development of cartilaginous tissue in cell chondrocytes. As cartilage is avascular, production of collagen II, proteoglycans, been proved to stimulate chondrocytes culture systems. However, the mechanism by chondrocyte nutrition has to rely upon the glycoproteins and metalloproteinases.Their seeded onto hydrogel scaffolds in which microgravity alters phenotype diffusion of nutrients from the synovial fluid. capacity for proliferation is practically accelerating maturation of proteoglycan-rich modulation, matrix production and

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basic science and clinical studies. In coefficients (D-values). In particular, the T2- particular, magnetic resonance imaging values reflect variations in the concentration Fig. 2.2-D spin-echo MR images (TR = 1500 ms,TE = 20 ms) of (MRI), which provides high-resolution and of water and proteoglycan, whereas the MT- the distal interphalangeal (DIP) joint of a healthy 23-year-old high-quality anatomical information without values are related to the concentration of the man, measured at 2.4 Tesla, slice thickness 1.0 mm, in-plane ionising radiation, can be repeatedly used to collagen fibres. Figure 2 clearly shows how resolution 75 x 150 mm without (left) and with magnetisation Fig. 3.Proton MR image showing a cross-section of two samples of transfer (right). track changes without deleterious effects. the magnetisation transfer method can be Very recently, space agencies such as NASA used to evaluate the collagen content of biodegradable polymer substrates immersed in a phosphate and ESA have considered the development articular cartilage (and of skin). Similarly, the buffered solution (polymer in green, medium in blue) and separated by a thin glass cover (red).The open porosity of the of dedicated low-mass MRI systems for the spatial distribution of T2-values can also be substrate (blue regions within the sample) would facilitate cell aggregation, and chondrocyte hypertrophy International Space Station.With MRI, the measured; progressive loss of preteoglycan infiltration and proliferation, while the polymer strands would after the cartilage phenotype is established, study of physiological alterations in space leads to progressive increases in the T2- provide temporary support as extracellular matrix.In-plane image must still be elucidated and the development and maintenance of values of the water protons from their spatial resolution 117 x 117 µm and 500 µm slice thickness. Using chondrocytes isolated from porcine countermeasures would be significantly normal range (ca. 25 ms) up to ca. 50 ms.The articular cartilage as donors and alginate enhanced. For example, measurements of prospect is that it will be possible in the scaffolds, the experimental activities of the changes in the limbs of astronauts, especially future to calibrate the numerical values of T2- Topical Team have grown cultures under the lower limbs, would confirm the and MT-values to provide maps that show Figure 3 shows a proton MR image of two conditions of microgravity reproduced in a effectiveness of countermeasures on the the spatial concentrations of water, collagen samples of biodegradable polymer random position machine (RPM) or in static human musculoskeletal system in long- and proteoglycans. substrates immersed in a phosphate buffered flasks at 1 g as control.The observed duration spaceflight. In light of the above, it is clear that MRI has solution. MR microscopy can be used in two histology is similar. At 2 weeks, the seeded MRI of the water in a joint can provide the potential to follow the progression of ways when designing porous matrices: chondrocytes are rounded, with spherical anatomical information about all the soft damage, and possibly the repair, of articular nucleus, evident nucleolus and tissues within the synovial sac (articular cartilage in the human knee.This remarkable – to optimise the sample preparation hypertrophied organelles.The chondrocytes cartilage, meniscus, ligaments, synovial fluid) opportunity should lead not only to unique procedures and obtain uniform porous have begun to synthesise and export and surrounding it (muscles, tendons, insight into this important problem, but it matrices (minimum variation in porosity proteoglycans and collagen II, which are vascular structures). Also important, scans of will also provide a rational basis for between the surface and the centre of the progressively accumulated in the interstices water-plus-fat provide insight into the subsequent trials of various repair sample); of the scaffold (Figs. 1d-g). At 4 weeks, this structure of the bone (both cortical and mechanism, whether pharmaceutical or – to control systematically the porosity of accumulation is more evident, as indicated trabecular). Recent developments have led to surgical. Given the above facts, it is now the sample. by the appearance of metachromasia with combinations of scan protocols and image- appropriate to question what further insight toluidine blue (Figs. 1h,i). measurement software such that MRI can be MRI can provide to aid the rational In addition, high-resolution MRI methods used to quantitate the spatial dimensions of development of methods for repairing could allow a more precise estimation of the 2. Nuclear Magnetic Resonance articular cartilage in the human knee. damaged cartilage. substrate mean lifetime and lead to Histological methods are commonly used to Although the early work concentrated on The non-destructive and non-invasive determining mathematical expressions analyse scaffolds and cell-constructs, but total cartilage volumes, it is now feasible to nature of the MR imaging experiment also linking matrix critical attributes (e.g., porosity, non-destructive tools are now required to measure local dimensions, such as plugs. offers a unique opportunity to study in situ pore size and pore size distribution, chemical evaluate the changes occurring in the Hence, MRI provides non-invasive, plug- time-dependent processes (chemical and composition) to tissue infiltration rates.These chemistry and micro-architecture of the biopsy for the human knee. morphological) on the same sample. It has expressions may be used to model (predict) cartilage matrix during ageing in vitro and The relevant MRI parameters include the been shown that it is possible to map the tissue in-growth profiles in porous matrices in vivo.To this end, nuclear magnetic spin-lattice (T1-values) and spin-spin (T2- distribution of water in devices of taking into consideration the resonance (NMR) techniques have proved to values) relaxation times, the magnetisation biodegradable polyesters, both in vitro and micro-architecture of the implant. Moreover, be promising, showing an increasing role in transfer (MT) rates, and the diffusion in vivo, as a function of implantation time. detailed knowledge of the implant-tissue

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interaction in suitable model systems could – establish ties with biotech companies provide the basis for a better understanding dealing with tissue engineering and its Topical Team Members of the MRI appearance of the substrates when human clinical applications; implanted in humans. In turn, this will allow a – continue interactions with aerospace Renato Toffanin (Coordinator) Laurie D. Hall non-invasive management of the cartilage companies involved in the development PROTOS Research Institute, P.O. Box 972, Herchel Smith Laboratory for Medicinal repair in vivo. and construction of International Space I-34100 Trieste, Italy. Chemistry, University of Cambridge School of Station facilities such as the E-mail: [email protected] Clinical Medicine, Forvie Site, Robinson Way, 3. The Topical Team and its Goals Biotechnology Mammalian Tissue Culture Cambridge CB2 2PZ, UK. This Topical Team consists of 11 groups that facility. Augustinus Bader Email: [email protected] bring together multidisciplinary expertise in Chair in Cell Technology and Applied Stem Cell physics, engineering, polymer chemistry and Publications Biology, University of Leipzig, Deutscher Ivan Martin medical sciences.The aim of the Team is to The results of the Topical Team activities Platz 5, D-04103 Leipzig, Germany. Tissue Engineering, Department of Research, use modelled microgravity as a tool to were presented in the dedicated Workshop Email: [email protected] University Hospital, Hebelstrasse 20, understand the fundamental science of ‘Microgravity and Cellular Factors in Tissue CH-8005 Basel, Switzerland. cartilage regeneration in order to produce a Differentiation’ held during the First World Carmen Carda Email: [email protected] functional cartilage engineered tissue.To this Congress on Regenerative Medicine (Leipzig, Department of Pathology, University of Valencia, end, particular emphasis is given to 22-24 October 2004), chaired by a Topical Av. Blasco Ibañez 17, E-46010 Valencia, Spain. Erminio Murano investigating the effect of mechanical forces Team member.The abstracts were published Email: [email protected] PROTOS Research Institute, P.O. Box 972, under altered gravitational conditions, applied in The International Journal of Artificial I-34100 Trieste, Italy. using controlled bioreactor systems, on cell Organs: Augusto Cogoli Email: [email protected] metabolism, cell differentiation and tissue Zero-g Life Tec GmbH,Technoparkstrasse 1, development. Cogoli, A. (2003). Effect of Gravitational CH-8005 Zurich, Switzerland. Denis Poncelet The main objectives of this Topical Team Unloading on Signal Transduction in Email: [email protected] ENITIAA, Rue de la Géraudière, BP 82225, are: Mammalian Cells. Int. J. Artif. Organs 26, F-44322 Nantes, France. 821. Paola Fantazzini E-mail: [email protected] – investigate the specific and interactive Toffanin, R., Murano, E., Cogoli, A., Dept. of Physics, University of Bologna,Viale effects of the parameters that are expected D’Ambrogio, A., Fantazzini, P., Berti Pichat 6/2, I-40127 Bologna, Italy. Ralf Pörtner to influence in vitro cartilage development Garavaglia, C., Gomez, S. & Vittur, F.(2003). Email: [email protected] Department for Bioprocess and Biochemical and function: 1) concentration and spatial Evaluation of the Effects of Simulated Engineering, Hamburg University of distribution of cells and extracellular matrix, Microgravity on Polymer Scaffolds and Leoncio Garrido Technology (TUHH), Denickestrasse 15, 2) biochemical regulatory signals, and Bioconstructs for Cartilage Engineering. Department of Chemical Physics, Institute of D-21071 Hamburg, Germany. 3) physical factors, including applied load Int. J. Artif. Organs 26, 849. Polymer Science and Technology, Spanish E-mail: [email protected] and reduced gravity; Marcos, M., Pérez, E. & Garrido, L. (2003). Council for Scientific Research (CSIC), Juan de – improve encapsulation technologies for the Non-Destructive in situ Characterisation of la Cierva 3, E-28006 Madrid, Spain. construction of biocompatible constructs; Biodegradable Cell Substrates. Int. J. Artif. Email: [email protected] – identify new technology advancements Organs 26, 825. and developments in the field of magnetic Santiago Gomez resonance with potential applications in A review paper entitled ‘Cartilage Department of Pathological Anatomy, University space and on Earth for the characterisation Engineering and Microgravity’ has been of Cadiz, Fragela 9, E-11003 Cadiz, Spain. of bioconstructs and tissue-engineered submitted for publication in the Journal of Email: [email protected] cartilage; Gravitational Physiology.

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Fluid and Electrolyte Balance and Report of the ESA Topical Team in Life Sciences Kidney Function Research in Space Fluid Balance and Kidney Function Contributors: P.Norsk, Copenhagen (DK) N. Juel Christensen, Copenhagen (DK) H.J. Kramer, Bonn (D) N.G. De Santo, Napoli (I) J. Regnard, Besancon (F) M. Heer, Koeln (D)

Fluid and electrolyte regulation in humans is despite more than a hundred years of are connected to the neurohypophysis, which modulated by gravitational stress through a research, the basic mechanisms of this life- secretes the main water-regulating hormone, complex interaction of cardiovascular sustaining system are not fully understood. vasopressin (antidiuretic hormone) reflexes, neuroendocrine variables, physical One reason is that water and salt regulation play significant roles (Norsk, 1996). Finally, the (Robertson & Berl, 1996).The location of the factors and renal function.Weightlessness is are complex and involve elements of several concentration of electrolytes in blood and receptors for detecting fluid volume is still a unique tool to obtain more information on physiological systems, such as the tissue fluids determines the excretion rate of debated but it is generally thought to be integrated fluid volume control. Results from circulation, hormones, nerves and kidneys. water in urine (Robertson & Berl, 1996). If the located in the heart chambers, adjacent space, however, have been unexpected and Another reason is that the methodology and electrolyte concentration is high, this will be vessels and central arteries (Miller et al., unpredictable from the results of ground- experimental procedures have so far been perceived by osmoreceptors in the 1996). In addition, peptides in the heart, brain based simulations.The concept of how inadequate. hypothalamus as thirst, so the fluid intake is and kidneys can be released by nerve activity weightlesness and gravity modulate the With the advent of manned spaceflight, increased and renal water excretion reduced. or, in the case of the heart, directly by regulation of body fluids and associated two possibilities emerged for research into The reverse is true when concentrations of mechanical stretch so that excretion of salt blood components must therefore be revised fluid and electrolyte regulation: electrolytes are lowered. If, for example, a litre can be augmented. and a new simulation model developed. of pure water is abruptly consumed, the As of today, it is fair to state that the There are several main questions to be asked. – weightlessness could be used as a tool to concentration of electrolytes is reduced by qualitative significance of each of the Does weightlessness induce diuresis and stimulate the body in a way that was not 2% and the surplus of water excreted within mentioned systems has largely been natriuresis during the initial hours of possible before; 2-3 h. determined, whereas the quantitative spaceflight, leading to an extracellular and – the methodology for measuring the When salt intake is increased within the significance has not.The systems are intravascular fluid volume deficit? Why are physiological variables could be improved physiological range (e. g. 50 to 250 mmol per sensitive to changes in gravitational stress, so fluid- and sodium-retaining systems by the space programmes. 24 h), not only is the salt retained in the body space research can contribute to the activated by spaceflight, and why are the but also the water so that the concentration quantification of each system in controlling renal responses to saline and water stimuli Weightlessness is unique for understanding of electrolytes is maintained unchanged by extracellular fluid volume and electrolyte attenuated? Can excess sodium be stored in how the body regulates the amount of salt the mechanism described above.Therefore, balance. an hitherto unknown way, in particular and water because the mechanisms of fluid- an increase in salt intake leads to fluid during spaceflight? How can the effects of volume control are sensitive to ‘changes’ in volume expansion.This is sensed by 3. Gravity and Fluid Volume Regulation weightlessness on fluid and electrolyte gravity. During prolonged spaceflight, the cardiopulmonary volume and arterial That the water- and salt-regulating regulation be correctly simulated on the daily fluctuations of blood and fluid along pressure receptors, which, through afferent mechanisms in humans are sensitive to ground? The information obtained from the body axis can be abolished.These nerve signals, inform the central nervous changes in gravitational stress has been space might help us to understand how fluctuations affect the excretion rates of system of the increase in volume.Through an known for decades (Norsk, 1992). Upright gravity degrades the fluid and electrolyte water and salt in the urine, so more efferent link, the kidneys excrete more humans excrete less water and salt in the balance in sodium-retaining and oedema- information can be gained by performing sodium.The urinary excretion rate of water urine than supine humans because the forming states, such as in heart failure. experiments in space. will subsequently increase to prevent the upright position retains as much salt and concentration of electrolytes from water as possible in order to maintain 2. Current Textbook Concept of Fluid and decreasing.Thus, the water-regulating adequate blood pressure to the brain. 1. Introduction Electrolyte Regulation mechanisms are activated primarily by Conversely, the supine body perceives the In order to sustain life, the amount of fluid The water- and salt-controlling mechanisms changes in concentrations of electrolytes in amount of blood and fluid in the heart as and electrolytes in the body is rigorously involve complex interactions between the blood and tissue fluids (Robertson & Berl, exaggerated, and therefore activates the controlled.The control is efficient: fluid and cardiovascular reflexes, fluid- and electrolyte- 1996), and the sodium-regulating water- and salt-excreting mechanisms. electrolytes are kept within narrow limits regulating hormones, and the kidneys. mechanisms by changes in fluid volume The mechanisms of the posture-induced despite large fluctuations in intakes (Miller et Physical factors such as blood pressure and (Miller et al., 1996). changes in urinary water and salt excretion al., 1996). It is, however, surprising that, dilution of the blood with tissue fluid also The osmoreceptors in the hypothalamus are thought to be stimulated primarily by

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Fig. 1.The old concept of how fluid and blood volume is reduced by weightlessness.The hypothesis is based on results from simulation experiments (e.g.head-down bedrest).When changing posture from upright to 6° head-down, blood and fluid from the lower parts of the body are moved towards the heart and head.The heart is distended by an increased blood supply,which,through nerve connections and hormones,induces an increased loss of water and salt in urine.This leads to a reduction in blood volume. When the salt- and water-excreting mechanisms in head-down bedrested subjects are stimulated by infusion of salt solutions or drinking water loads,urine output is still maintained at a high level. fluid-volume receptors in and/or close to the of fullness in the head.This is regarded as a heart.When supine, the heart and nearby consequence of the transfer of blood and vessels are distended as blood moves from fluid from the lower to the upper parts of the the legs towards the head.The opposite is body.The decrease in the volume of the legs 5. Expected Responses in Space the case when upright. During water is a supporting indication. So, from the early During the first decades of manned space- immersion, the movement of blood and fluid days of manned spaceflight, indirect flight, expectations of how physiological towards the upper body parts is more evidence supported the hypothesis that systems would respond to weightlessness pronounced.This leads to augmented blood is moved to the heart, adjacent vessels were based on the results of simulation increases in renal water and salt excretion, and head during weightlessness. experiments.The head-down bedrest which exceed those of a posture change More direct evidence that the blood approach was preferred to water immersion from upright to supine (Norsk, 1992). supply to the heart is augmented in the early because it is more practicable, in particular Even before the beginning of manned stages of a flight was obtained in the 1980s over several days or weeks. Even though it spaceflight, it was expected from water- and 1990s. By imaging the heart chambers has been used to simulate the physiological applied to head-down bedrested humans, immersion experiments that weightlessness via echocardiography, it was observed that, effects of weightlessness (Fortney et al., the urinary excretion rates are maintained at would augment the renal excretion rates of during the initial hours of spaceflight, the 1996), its applicability has never been directly a high level despite reductions in blood water and salt.Water immersion was heart is distended (Watenpaugh et al., 1996). tested.The model was considered to be volume and body fluids (Drummer et al., considered, and is still by some, to be an The heart is even larger than in supine adequate for simulating the effects of 1992; Bestle et al., 2001).This observation analogue of weightlessness. It induces losses humans on the ground.The mechanisms for weightlessness on fluid and electrolyte indicates that it is the augmented urinary of salt six times the level found when the this distension are, however, not as predicted. control, because astronauts usually lose excretion rates of salt and water during the subjects are seated in air; the loss of water is Direct pressure measurements show that the 2-4 kg of body mass within the first days of initial phase of bedrest that account for the more than doubled. So it was expected even pressure in the regions outside the heart is flight (Norsk & Epstein, 1991).This mass-loss fluid and blood volume deficit. before humans went into space that similar decreased.This decreased pressure on the was considered to consist primarily of fluid- and salt-excreting mechanisms would outside surface of the heart augments the electrolytes and fluid. In addition, the volume 6. Water and Sodium Balances in Space: be activated by weightlessness and that the distension and might be caused by a change of blood is reduced by 10-17% (Alfrey et al., Unknown Sodium Storage? astronauts would exhibit renal losses of fluid in the configuration of the lungs and chest 1996); bedrest reduces blood volume by Results from spaceflights of the past 20 years and electrolytes. wall (Watenpaugh et al., 1996). Distension of approximately 10% (Fortney et al., 1996; indicate that the generally accepted scheme the heart early in a flight is therefore not Alfrey et al., 1996).The head-down bedrest (Fig. 1), whereby astronauts lose water and The heart and adjacent vessels are distended during the first only caused by passive movement of blood model was therefore thought to simulate the salt in space, is wrong.There are no hours of a spaceflight. and fluid from the legs to the upper parts of effects of weightlessness. indications that urine output increases in the body, but also because of an anatomical The mechanisms of the augmented space. In fact, there are indications to the 4. Distension of the Heart in Space change in configuration of the chest walls urinary excretion rates of salt and water contrary. During the Apollo lunar flights Considerations on whether the heart is and lungs.This discovery was confirmed by during head-down bedrest are depicted in (Norsk & Epstein, 1991), it was observed that distended by weightlessness are important experiments during parabolic flights Fig. 1. Head-down bedrest induces an the urine outputs were always lower than on because fluid-volume receptors are thought providing 20 s of weightlessness (Videbaek & increase in the blood volume of the heart the ground, even though the astronauts each to reside in the heart and adjacent vessels, Norsk, 1997). and nearby vessels, which, through the lost several kilogrammes of body mass.The and because distension of the heart is Thus, during the initial hours of a flight, mechanisms described earlier, promotes the same was observed during the Skylab flights considered to be the main stimulus for fluid the heart and adjacent vessels are distended. urinary excretion rates of salt and water. A of 1973-74 (Norsk & Epstein, 1991). It was and electrolyte excretion during spaceflight. This should, according to simulation models new state of adaptation is obtained with a suggested that the reason for the low urine In the early studies during the Apollo and on the ground, initiate an increased diminished fluid and blood volume. output during the initial phase of flight was Skylab missions in the 1960s and 1970s, the excretion rate of water and salt in urine, with When water and salt stimuli (e. g. infusion caused by reduced fluid intake and that the astronauts reported ‘puffy’ faces and feelings a resultant loss of body fluid. of salt solutions or drinking water loads) are urine outputs were augmented compared to

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Fig. 2.The concentration of norepinephrine (NE) in blood as an average over a 4 h period in four astronauts during (left) supine conditions on the ground,(centre) upright seated conditions on the ground, and (right) after being adapted to 4-5 days of weightlessness on the Space Shuttle during Spacelab-D2 (Drummer et al., 1993).The highest values were obtained during flight (* indicates a statistically significant change).This was unexpected,because head-down bedrest produces low values.The high NE levels indicate that sympathetic nervous activity is high, with contraction of blood vessels and retainment by the kidney of salt and water.

the intake.This notion has not, however, been – how much sodium can quantitatively be substantiated by direct observations. More taken up by the enormous number of recent studies on the Space Shuttle and the cells: the intracellular compartment? ground.This was not predicted (Norsk et al., Mir space station indicate that output of – how much sodium may be stored in the 1995) by ground-based simulation studies. water and salt in the urine is not increased body in an undissolved, osmotically On Mir during the Euromir-95 and German (Drummer et al., 1993). inactive form? (Does sodium partly Mir-97 missions, Norsk et al. (2000) observed Fluid balances and body-fluid regulation compensate for the considerable calcium that urine production following an oral water in weightlessness differ from those on Earth deficits in bone matrices occurring during load was considerably attenuated.The (Drummer et al., 1993; 2000). All the spaceflight?) attenuation could not be reproduced on the components of water balance (evaporation, ground by simulation of weightlessness with 8. A New Hypothesis oral hydration and urinary fluid excretion) are These mechanisms are unknown to head-down bedrest of up to Three features that cannot be explained by generally reduced. If hydration, nutritional physiological and clinical research and 3.5 months. current textbook descriptions call for a new energy supply and protection of muscle mass explaining the underlying mechanisms may Another unexpected finding in space concept to be developed: are guaranteed, cumulative water balance be fruitful in improving our understanding of during the Spacelab-D2 and Mir-97 missions and total body water content may be stable the human function in space and on Earth. was that sympathetic nervous activity and – urine production and renal sodium during flight. In an investigation by Heer et al. (2000), it release of renin were higher than expected excretion are not increased during the was observed that a huge increase in sodium (Fig. 2) (Norsk et al., 1995; 2000).The initial hours of spaceflight; Explaining the underlying mechanisms of sodium intake of up to 660 mmol/day did not increased sympathetic nervous activity was – the natriuretic and diuretic responses to metabolism may improve our understanding of the human increase extracellular fluid volume or body measured by estimating the concentration of water and salt loads in space are function. mass despite a positive sodium balance.This norepinephrine in blood and urine. Usually, attenuated; was unexpected. How is the extra sodium the activity of this portion of the nervous – sympathetic nervous activity is high in Sodium metabolism, however, is affected stored? Fluid and electrolyte balance studies system is low during head-down bedrest. space. by weightlessness. Activation of sodium- in space might shed light on this surprising There is no apparent reason for the high retaining endocrine systems and a finding. sympathetic nervous activity in space, Firstly, the diminished blood volume in considerable amount of sodium retention because there is no obvious reason for the space cannot be due solely to augmented – without accumulating in the intravascular 7. Surprising Renal Responses to Stimuli in vessels to constrict or for the kidneys to urine production (Drummer et al., 1993; space – may be the chain of events following Space produce less urine.These observations were 2000). Recent investigations indicate that the increased vascular permeability, changes in If the scheme described in Fig. 1 is correct, later confirmed on the Spacelab Neurolab astronauts drink and eat less during flight colloid-osmotic pressure and an exaggerated we would anticipate that the renal responses mission in 1998 (Ertl, 2002). (Drummer et al., 2000). Even though urine extravasation very early in flight. An to water and salt stimuli would be the same The pattern of attenuated urine output of production thereby decreases, it may still be enormous stowage capacity for sodium in in space and in simulation by head-down water and salt in space following stimulation relatively higher than the intake and thus the extravascular space and a mechanism bedrest.This is, however, not the case. During by infusion or oral water loadings and the lead to some fluid loss (Norsk & Epstein, that allows the dissociation between water the Spacelab-D2 mission, an isotonic saline high activity of the sympathetic nervous 1991).The reason for the decreased food and and sodium handling are suggested to solution was infused into the astronauts system fits together. It does not, however, fit fluid intakes is not known. It might be owing contribute to the fluid balance adaptation in (Norsk et al., 1995).The inflight conditions with the expectations from results of the to some degree to space sickness or to some weightlessness.There are several questions were standardised so that, except for head-down bedrest model (Norsk et al., as-yet undetermined disturbances of the to answer: weightlessness, they resembled those of the 2000). Our knowledge of how weight and central nervous system by weightlessness. ground-based control conditions. Renal weightlessness modulate fluid and Secondly, blood volume might be more – how much dissolved sodium is tolerated sodium output was stimulated by the electrolyte regulation in humans is still reduced by spaceflight than by head-down as hypertonic solution in the interstitial infusion but to a much lesser degree than insufficient and should be the focus of future bedrest because weightlessness promotes space and the lymphatic system? when the astronauts were supine on the space research. movement of fluid from blood to the

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Fig. 3.A suggestion for a new hypothesis on how blood volume is reduced during spaceflight.Weightlessness induces immediately after launch 1) a decreased fluid intake,2) absorption of fluid by the interstitial space from the blood compartment owing to lack of compression of the body and inactivation of posture muscles, 3) reduced red cell volume (Johansen et al., 1997), and 4) distension of the heart.These effects all lead to a reduced blood volume.This activates fluid-retaining hormone systems and sympathetic nerves (Fig.2), which lead to secondary low urine responses to water and salt stimuli.According to this hypothesis, the reduction in blood volume is not caused by the kidneys,in contrast to the old hypothesis based on simulation experiments. indicate that bedrest is not an appropriate simulation model. A more reliable model needs to be developed.The mechanisms of the system, and to low urine production.This discrepant effects of weightlessness and new hypothesis is depicted in Fig. 3. bedrest are unknown. As described above, one That the urinary excretion rates of salt and theoretical explanation could be that, during water are attenuated in space following head-down bedrest, the supine body is stimulation by infusion indicate that the continuously compressed by its own weight. blood-volume deficit is not caused by urinary This might modulate the relationship between losses at the beginning of spaceflight. It the heart, fluid- and electrolyte-regulating rather indicates that the urinary attenuations hormones, and the kidneys.That the heart is following infusion are secondary to those of compressed in supine humans is indicated by blood volume contraction (Fig. 3).This is in results from parabolic flights, where it has contrast to the effects of head-down bedrest, been demonstrated that the size of the heart where the augmented urinary responses to promptly increases during weightlessness water and salt infusions indicate that the (Videbaek & Norsk, 1997). interstitial space (Leach et al., 1996).This red cell volume is decreased by spaceflight. initial urinary losses are the primary causes of Whether water immersion for days, weeks or movement might be induced by the total This might also be more pronounced than the volume deficit (Fig. 1). months simulates the effects of weightlessness lack of compression of the body in space. On during simulations on the ground and Even though diuresis and natriuresis have in space remains to be determined. the ground, the body and tissues are thereby contribute to the diminution of never been observed during the initial phase compressed from front to back or from side blood volume and activation of fluid- of spaceflight (Drummer et al., 1993; 2000), it 10. Scientific Questions for Future Space to side, when humans are subjected to, for retaining systems. cannot be excluded that renal excretion rates Research example, head-down bedrest.This Therefore, spaceflight might initially of fluid and electrolytes are in fact Based on the surprising findings of fluid- and compression squeezes the tissues so that produce a fluid- and blood-volume deficit augmented during the initial hours of flight electrolyte-balance studies and renal interstitial pressures are increased relative to more pronounced than that produced by when related to the intakes.This is why, in responses to saline and water stimuli in space, the intracapillary pressures.When this head-down bedrest. In summary, theoretical Fig. 3, it is still hypothesised that the initial the systematic investigation of the hypothesis compression-induced pressure gradient from considerations suggest that the mechanisms distension of the heart during flight can lead depicted in Fig. 3 is proposed.The following the interstitial compartment to blood is for this comprise: to natriuresis and diuresis, e. g. through scientific questions should be the focus of abolished, as in space, fluid moves from increases in atrial natriuretic peptide release. interest: blood to interstitium across the capillary – decreased intake of food and fluids; The reason we do not know if this is the case membrane.This notion is, however, only a – movement of fluid from blood to the is that proper controlled experiments during – does weightlessness induce diuresis and theory and needs experimental confirmation. interstitial space (extravasation); the initial phase of flight have never been natriuresis during the initial hours of Thirdly, muscles for attaining posture – reduced activation of posture muscles, conducted. In order to do so, it is necessary spaceflight, leading to an extracellular and might be less contracted in space than on leading to movement of fluid from blood on the ground to imitate the ambient intravascular fluid volume deficit? the ground, even compared to recumbency to tissues; conditions of launch and the initial hours of – why are fluid- and sodium-retaining systems during bedrest.Therefore, theoretically, lower – a more pronounced diminution of red cell flight: launch accelerations, temperature in activated by spaceflight, and why are the activation of posture muscles could facilitate volume. the spacesuit, fluid and food intake, etc. renal responses to saline and water stimuli fluid transfer from plasma to muscle attenuated? interstitial space and thereby decrease This blood-volume deficit could lead to 9. New Simulation Model – can sodium in excess be stored in an intravascular volume. activation of fluid- and electrolyte-retaining The discrepant effects on the kidneys of hitherto unknown way, in particular during Fourthly, Alfrey et al. (1996) showed that systems, including the sympathetic nervous head-down bedrest and weightlessness spaceflight?

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Fig.5.A scheme of the hypothesis to be tested Fig. 4.Heart-failure patients How can astronauts within the adaptation of exhibit salt- and water- during prolonged fluid and electrolyte retention, with accumulation of spaceflight exhibit the homeostasis to fluid in the tissues (oedema). same physiological weightlessness is depicted. Results of space and parabolic In addition,the equipment patterns as heart-failure flights indicate that the heart is for testing each link of the compressed in supine humans patients without being hypothesis has been added. by gravity; this might degrade sick? Answering this The numbers refer to the the conditions of heart patients. question might reveal equipment described in Investigations in space might new disease mechanisms Section 12.8. reveal to what degree gravity affects the failing heart and of importance for treating how to counteract it. heart failure.

– what is the correct ground-based model patterns.The mechanisms of these for simulating the effects of augmented hormone releases and of weightlessness? sympathetic nervous activity are different in heart-failure patients and weightless 11. Prolonged Spaceflight: A Testbed for astronauts because the astronauts are still Sodium-Retaining Diseases Such as healthy. On the other hand, the activated Heart Failure? hormone secretions and nervous activity development of stimulatory devices is hypothesis is depicted in Fig. 5. In order to The new concept (Fig. 3) that the gravity- might be caused by reduced blood supply to proposed. Finally, a typical experimental test each link of this hypothesis systematic- induced mechanical pressure on the body the arteries; in heart patients because the scenario is presented below, along with a ally, five groups of equipment for monitoring tissues in supine humans has a pronounced heart is weak, and in astronauts because suggestion for a ground-based support nutrients, renal variables, blood constituents, effect on fluid and electrolyte regulation and blood volume is decreased (Fig. 3).Therefore, programme. cardiovascular variables and fluid volume, some of the associated blood components is prolonged spaceflight might provide a respectively, are proposed for development. of relevance for understanding mechanisms testbed for investigating aspects of the 12.1 Scientific Questions and a New of disease. In patients with heart failure, fluid mechanisms of heart disease. Hypothesis 12.2 Nutrient Monitoring and electrolytes are accumulated in the body By comparing cardiovascular, hormonal The main scientific questions to be To evaluate how changes in the intake of because the heart cannot supply the organs and kidney variables of healthy astronauts addressed within the field of fluid and sodium and fluid during spaceflight might with blood as efficiently as in healthy people. on the ground, astronauts in space, and electrolyte balance during spaceflight are account for the decrease in blood volume, The accumulation of fluid leads to oedema heart-failure patients, the following question are: accurate monitoring of food and fluid intake and further deterioration of the condition. A might be answered: how can astronauts is mandatory.The problem is accuracy, vicious circle is thus established. during prolonged spaceflight exhibit the – does weightlessness induce diuresis and because even small methodological errors or Furthermore, heart failure patients might same physiological patterns as heart-failure natriuresis during the initial hours of inaccuracies can produce large mistakes in experience difficulties when supine.This patients without being sick? Answering this spaceflight, leading to an extracellular and the end results.The left link of the hypothesis syndrome might be partly caused by the might reveal new disease mechanisms of intravascular fluid volume deficit? (Fig. 5) concerns space-induced reduction in gravity-induced pressure on the heart.Thus, importance for treatment. – why are fluid- and sodium-retaining food and fluid intake, so hardware for the transverse gravitational stress in supine systems activated by spaceflight, and why nutrient monitoring is required: heart patients might explain some of the 12. Technical Recommendations are the renal responses to saline and water disease patterns.When a patient is upright, To answer the questions posed above, the stimuli attenuated? – food and fluid packages coded for the weak heart has difficulties in maintaining Topical Team recommends to ESA the – can sodium in excess be stored in an contents (e. g electrolytes) and calories; blood pressure to the brain. Gravity is a development of five groups of equipment hitherto unknown way, in particular – barcode reader. burden for heart-failure patients, either for monitoring nutrients, renal variables, during spaceflight? supine or upright (Fig. 4). blood constituents, cardiovascular variables – how can the effects of weightlessness on 12.3 Renal Monitoring Heart-failure patients also exhibit high and fluid volume compartments, fluid and electrolyte regulation be It is mandatory to monitor urine production levels of sympathetic nervous activity and of respectively. It is suggested that the groups correctly simulated on the ground? and electrolyte concentrations in all types of fluid- and sodium-retaining hormones.The are integrated into a Fluid and Electrolyte fluid and sodium balance studies.Therefore, astronauts in space exhibit the same Monitoring System (FEMOS). In addition, the Based on these scientific questions, a new an accurate system for collection of urine and

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measurement of urine volume must be be estimated by injection of non-radioactive – refractometer; The Topical Team recommends the development of developed.To improve accuracy, residual tracers such as Evans Blue for plasma volume – colloid osmometer; instruments for monitoring nutrients, renal variables, blood volume could also be determined after each determination by spectrophotometry, and – spectrophotometer. constituents, cardiovascular variables and fluid volume voiding.This can be done by double-labelled water for estimation of total compartments. echocardiography of the bladder. Finally, the body water by mass spectrometry. Red-cell 12.5 Cardiovascular Monitoring exact times of voiding must be determined. volume can be determined by the As depicted in Fig. 5, one of the basic and limb occlusion plethysmography.Thus, Electrolyte concentrations in urine could radioactive 51Cr, 50Cr or 53Cr method or the hypotheses is that weightlessness induces for monitoring fluid compartments, the be determined by ion-selective electrode carbon monoxide method.The latter involves distension of the heart, which stimulates the equipment could be (prioritised sequence): systems and osmolality by freezing-point the Pulmonary Function System. renal output of sodium and fluid.The heart depression in frozen urine samples after the The constituents of blood can be divided has been shown to be distended during the – multi-segmental multi-frequency flight. However, they could also be into endocrine variables, cell signalling and initial phase of spaceflight. More information, impedance; determined inflight, which requires an physical factors. A common feature is that however, is needed on cardiac output, stroke – limb occlusion plethysmography; onboard osmometer and ion-selective blood must be collected, centrifuged, frozen volume, ventricular ejection fraction and – ultrasound. electrode equipment. Renal function tests and then delivered to the ground for cardiac chamber sizes. It is important to could include determination of glomerular analysis. Some constituents can, however, be know whether arterial filling is compromised 12.7 Stimulatory Devices filtration rate (GFR) and renal plasma flow by analysed inflight: in space; if so, it might explain the attenuated The most likely model for modulating the single shot inulin and paraaminohippuric renal responses. fluid and sodium content in the body during acid (PAH), respectively.The urine samples Hormones: plasma concentrations of Cardiac imaging could be done with spaceflight will probably involve variations in containing these tracers can either be catecholamines, natriuretic peptides, echocardiography and cardiac output daily sodium intake with free access to water. examined in frozen samples brought back to arginine vasopressin, renin-angiotensin- measured by the non-invasive rebreathing By abruptly changing the 24 h intake of Earth or onboard, providing that the aldosterone, and prostaglandines are the technique using the Pulmonary Function sodium, the extracellular fluid volume will be equipment for the analyses is part of the most important and can be estimated by System. Arterial pressures can be measured changed over a few days. A variation in the flight equipment.The lithium method can be ground-based radioimmunoassays. in the brachial artery by non-invasive means 24 h sodium intake within the normal applied for determination of tubular Physical factors: colloid osmotic pressure (oscillometry or auscultation) and peripheral physiological range from, for example, handling of sodium.Thus, the urine- could be determined in a colloid blood flows by e.g. Doppler estimations.Thus, 75 mmol to 250 mmol, will, over 2-4 days, monitoring equipment should constitute the osmometer; protein concentration could the cardiovascular equipment could be induce a 10% increase in extracellular and following (prioritised sequence): be determined in a refractometer; plasma (prioritised sequence): intravascular volume.Varying sodium intake concentration of electrolytes can be is therefore a powerful tool for inducing – urine collection device; measured by an ion-selective electrode – 24 h blood pressure monitoring device; physiological pertubations of extracellular – urine volume measuring system; system; and plasma osmolality by – electrocardiograph (ECG); volume. – freezer for urine storage; freezing-point depression. – Pulmonary Function System (PFS) for Other, more acute, stimulations might also – blood sample collection device; rebreathing; be required in order to address the scientific –centrifuge; Thus, the equipment for analysis of blood – echocardiograph; questions. In this regard, infusion of saline – tracers: injection system (inulin & PAH) and samples could be (prioritised sequence): – ultrasound Doppler system. solutions has been performed before lithium tablets; (Spacelab-D2). By varying the pressure – ion-selective electrode system; – blood sample collection device; 12.6 Fluid Volume Compartment around the lower body and applying – osmometer (e. g. freezing-point – centrifuge (cooling); Monitoring pressure breathing, central, intrathoracic, depression). – freezer for storage of blood samples; Fluid compartment sizes can be estimated by blood volume can be modulated and the – tracers: Evans Blue, double-labelled water; the multi-segmental multi-frequency subsequent renal responses monitored.Thus, 12.4 Blood Constituents Monitoring – ion-selective electrode system; impedance technique.Venous capacitance the following stimulatory devices might be of Plasma and fluid compartment volumes can – osmometer (freezing-point depression); can be measured by ultrasound techniques priority:

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– saline (isotonic, hypertonic) solution Additional equipment (priority 3) be performed. In this way, the size of the Such knowledge could be beneficial for the treatment of infusion systems; 21. ultrasound Doppler system; extracellular fluid volume can be modulated bedridden hospital patients. – lower body negative pressure (LBNP); 22. anti-g suit; in a physiological way. By combining it with – anti-g suit; 23. pressure (+/-) breathing device. oral water loading and/or saline infusions, system in these patients. One question could – pressure (+/-) breathing equipment. the questions can be addressed. be: to what degree does gravity play a role in In Fig. 5, each of the 23 suggested items the pathophysiology of heart failure? 12.8 Fluid and Electrolyte Monitoring has been added to a scheme of the 3. Can sodium in excess be stored in an System (FEMOS) hypothesis, illustrating which items can hitherto unknown way, in particular during 12.10 Ground-based Support Programmes The five groups of equipment and the investigate which links of the hypothesis. spaceflight? Ground-based support programmes should stimulatory devices could be integrated into The same procedure should be followed as include access to simulation models such as: a Fluid and Electrolyte Monitoring System 12.9 Experimental Scenarios in question 2, but with much greater (FEMOS) which would then consist of the To address the four major scientific changes in sodium intake. – head-down bedrest; following, ranked in order of priority (1-23): questions, the following experimental – prolonged head-out water immersion; scenarios might be applied: 4. How can the effects of weightlessness on – manipulation of inthoracic pressure by Mandatory equipment (priority 1) fluid and electrolyte regulation be correctly modulating total body and breathing 1. barcode reader; 1. Does weightlessness induce diuresis and simulated on the ground? pressures. 2. urine sample collection system; natriuresis during the initial hours of flight, The same protocol should be followed in a 3. urine volume monitoring system; leading to fluid volume contraction? population during prolonged bedrest as in Such ground-based programmes should 4. blood sample collection system; Cardiac function, urine output and ingestion an astronaut population in space. be established to evaluate which model is 5. centrifuge; of nutrients should be monitored during the Continuous monitoring of blood pressure the most suitable for simulation of 6. freezer; first few hours following launch.This requires and urine production, with regular weightlessness. By comparing spaceflight 7. blood pressure monitoring system (24 h urine sampling and measurements of urine determinations of cardiac output, can shed results with those from bedrest, light will monitor); volume for at least the first 6 h and light on why the bedrest model is not always probably be shed on how gravity modulates 8. electrocardiograph; simultaneous monitoring of cardiac output applicable. Comparisons of the effects of the cardiovascular system and on the control 9. pulmonary function system; (PFS-rebreathing), stroke volume (PFS, ECG), spaceflight on renal and cardiovascular of renal excretion of electrolytes. Such 10. echocardiograph. blood pressure (24 h) and cardiac chamber variables with those from prolonged knowledge could be beneficial for the sizes (echocardiograhy).The data should be (1 week) head-out water immersion should treatment of bedridden hospital patients. Important equipment (priority 2) compared to similar measurements on the also be considered to evaluate whether this 11. multi-segmental, multi-frequency ground, where the environmental conditions model is more suitable for simulating the impedance system; (temperature, humidity) and intake of food effects of weightlessness. References 12. limb occlusion plethysmography device; and fluid are as similar as possible to flight. Alfrey, C.P.,Udden, M.M., Leach-Huntoon, C., 13. ion-selective electrode system; In addition to these four examples, a Driscoli, T. & Pickett, M.H. (1996). Control of 14. osmometer; 2. Why are fluid- and sodium-retaining variety of experimental scenarios can be Red Blood Cell Mass in Spaceflight. J. Appl. 15. saline (iso- and hypertonic) infusion systems activated by spaceflight, and why envisaged. One could create variations in Physiol. 81, 98-104. system; are the renal responses to saline and water caloric intake on ground and in space to test Bestle, M.H., Norsk, P.& Bie, P.(2001). Fluid 16. refractometer; stimuli attenuated? whether malnutrition is one cause for the Volume and Osmoregulation in Humans 17. colloid osmometer; At different levels of sodium intake, decrease in intravascular volume. Another After a Week of Head-down Bed Rest. 18. tracers (Evans Blue, inulin, PAH, Chrom- continuous monitoring of blood pressure scenario could compare data from space Am. J. Physiol. 281, R310-R317. EDTA, double-labelled water, Li-tablets); with regular estimations of cardiac output with those obtained from ambulatory heart- Drummer, C., Heer, M., Baisch, F., 19. spectrophotometer; simultaneously with determinations of urine failure patients in order to determine the Blomqvist, C.G., Lang, R.E., Maas, H. & 20. LBNP unit. production and renal sodium output should effects of gravity on the cardiovascular Gerzer, R. (1992). Diuresis and Natriuresis

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Following Isotonic Saline Infusion in Control of Extracellular Fluid Volume and In addition to this report, the Topical Team Healthy Young Volunteers Before, During the Pathophysiology of Oedema published a supplementum in the American Topical Team Members and After HDT. Acta Physiol. Scand. Suppl. Formation. In The Kidney (Ed. Journal of Kidney Disease 2001, 38(3), 664-698, 604, 101-111. B.M. Brenner).W.B. Saunders Comp. 5th containing the following papers: Dr. Peter Norsk Drummer, C., Heer, M., Dressendörfer, R.A., ed., 2, 817-872. Department of Medical Physiology,The Panum Strasburger, C.J. & Gerzer, R. (1993). Norsk, P.(1992). Gravitational Stress and Christensen, N.J., Drummer, C. & Norsk, P. Institute, section 12.2.43, University of Reduced Natriuresis during Weightlessnes. Volume Regulation. Clin. Physiol. (Review) (2001). Renal and Sympathoadrenal Copenhagen, Blegdamsvej 3, DK-2200 Clin. Investig. 71, 678-86. 12, 505-526. Responses in Space. Am.J.Kidney Dis. Copenhagen, Denmark. Drummer, C., Hesse, C., Baisch, F.,Norsk, P., Norsk, P.(1996). Role of Arginine Vasopressin 38(3), 679-683. Email: [email protected] Elmann-Larsen, B., Gerzer, R. & Heer, M. in the Regulation of Extracellular Fluid De Santo, N.G., Christensen, N.J., Drummer, C., (2000).Water and Sodium Balances and Volume. Med. Sci. Sports Exerc. 28 (10 Kramer, H. J., Regnard, J., Heer, M., Cirillo, M. Prof. Dr. med. Niels Juel Christensen Their Relation to Body Mass Changes in Suppl.), S36-S41. & Norsk, P.(2001). Fluid Balance and Kidney Department of Endocrinology, Herlev Hospital, Microgravity. Eur. J. Clin. Invest. 30, 1066-75. Norsk, P.& Epstein, M. (1991). Manned Space Function in Space: Introduction. Am. J. University of Copenhagen, DK-2730 Herlev, Ertl, A.C., Diedrich, A., Biaggioni, I. et al. (2002). Flight and the Kidney (Review). Am. J. Kidney Dis. 38(3), 664-667. Denmark. Human Muscle Sympathetic Nerve Activity Nephrol. 11, 81-97. Drummer, C., Norsk, P.& Heer, M. (2001).Water Email: [email protected] and Plasma Noradrenaline Kinetics in Norsk, P., Drummer, C., Röcker, L., Strollo, F., and Sodium Balance in Space. Am.J.Kidney Space. J. Physiol. 538, 321-329. Christensen, N.J.,Warberg, J., Bie, P., Dis. 38(3), 684-690. Prof. Dr. Herbert Kramer Fortney, S.M., Schneider, V.S. & Greenleaf, J.E. Stadeager, C., Johansen, L.B., Heer, M., Heer, M., De Santo, N.G., Cirillo, M. & Medizinische Poliklinik, Universität Bonn, (1996).The Physiology of Bed Rest. In Gunga, H.-C. & Gerzer, R. (1995). Renal Drummer, C. (2001). Body Mass Changes, Wilhelmstrasse 35-37, D-53111 Bonn, Handbook of Physiology, Environmental and Endocrine Responses in Humans to Energy, and Protein Metabolism in Space. Germany. Physiology (Eds. M.J. Fregly & C.M. Blatteis), an Isotonic Saline Infusion during Am.J.Kidney Dis.38(3), 691-695. Am. Physiol. Soc., Bethesda, MD, USA, II, Microgravity. J. Appl. Physiol. 78, 2253- Kramer, H.J., Heer, M., Cirillo, M. & Prof. Natale Gaspare De Santo 889-940. 2259. De Santo, N.G. (2001). Renal Hemo- Cattedra di Nefrologia, Facotta di Medicina, Heer, M., Baisch, F.,Kropp, J., Gerzer, R. & Norsk, P., Christensen, N.J., Bie, P., dynamics in Space. Am.J.Kidney Dis.38(3), Dipartimento di Pediatria,Via Pansini, 5, Drummer, C. (2000). High Dietary Sodium Gabrielsen, A., Heer, M. & Drummer, C. 675-678. pad. 17, I-80131 Napoli, Italy. Chloride Consumption May Not Induce (2000). Unexpected Renal Responses in Norsk, P., Drummer, C., Christensen, N.J., Email: [email protected] Body Fluid Retention in Humans. Am. J. Space. The Lancet 356, 1577-78. Cirillo, M., Heer, M., Kramer, H.J., Regnard, J. Physiol. 278, F585-F595. Robertson, G.L. & Berl, T. (1996). & De Santo, N.G. (2001). Revised Prof. Dr. Jacques Regnard Johansen, L.B., Gharib, C., Allevard, A.M., Pathophysiology of Water Metabolism. In Hypothesis and Future Perspectives. Am. J. Laboratoire de Physiologie, Faculté de Medicine, Siguado, D., Christensen, N. J., Drummer, C. The Kidney (Ed. B.M. Brenner). Kidney Dis. 38(3), 696-698. F-25030 Besancon, France. & Norsk, P.(1997). Haematocrit, Plasma W.B. Saunders Comp. 5th ed., 1, 873-928. Regnard, J., Heer, M., Drummer, C. & Norsk, P. Email: [email protected] Volume and Noradrenaline in Humans Videbaek, R. & Norsk, P (1997). Atrial (2001).Validity of Microgravity Simulation during Simulated Weightlessness for Distension in Humans during Models on Earth. Am.J.Kidney Dis.38(3), Dr. Martina Heer 42 days. Clin. Physiol. 17, 203-210. Microgravity Induced by Parabolic 668-674. DLR-Institute of Aerospace Medicine, D-51170 Leach, C.S., Alfrey, C.P.,Suki, W.N., Leonard, J.I., Flights. J. Appl. Physiol. 83, 1862-1866. Koeln, Germany. Rambaut, P.C.,Inners, L.D., Smith, S.M., Watenpaugh, D.E. & Hargens, A.R. (1996).The Email: [email protected] Lane, H.W. & Krauhs, J.M. (1996). Regulation Cardiovascular System in Microgravity. In of Body Fluid Compartments during Short- Handbook of Physiology, Environmental term Spaceflight. J. Appl. Physiol. 81(1), Physiology (Eds. M.J. Fregly & 105-116. C.M. Blatteis), Am. Physiol. Soc., Bethesda, Miller, J.A.,Tobe, S.W. & Skorecki, K.L. (1996). MD, USA, I, 631-674.

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Report of the Space Motion Sickness and Stress ESA Topical Team in Physical Sciences Space Motion Sickness

Training Simulator using Contributors: C. Gaudeau,Tours (F) (Coordination) J.F.Golding, London (UK) F.Thevot,Tours (F) Electrophysiological Biofeedback Y.Lucas, Bourges (F) P.Bobola,Tours (F) J.Thouvenot,Tours (F)

An important problem in manned spaceflight stimulation then provoke the vestibulo- pathway is clearly involved in mediating organs have different ‘normal’ or visual is the nausea that typically appears during vegetative disturbances, especially in the responses. Increases in circulating levels of behaviour, and conflict depends on coding, the first 3 days and then disappears after hypothalamo-hypophysio-adrenal and stress-related hormones such as epinephrine, context and previous sensory-motor 5 days. Methods of detecting changes in autonomic nerve systems. norepinephrine, antidiuretic hormone, ACTH, experience.The essential conflict must be electrophysiological signals are being Simulation shows a significant increase in cortisol, growth hormone and prolactin have between actual and anticipated sensory studied in order to reduce susceptibility to certain hormones, and can offer improved been found during space motion sickness signals. Reason (1978) proposed a ‘neural space motion sickness through biofeedback understanding of neurophysiological nausea (Kohl, 1985). mismatch’ hypothesis based on the training, and for the early detection of nausea mechanisms. ‘reafference principle’ (Von Holst, 1943). during EVA. A simulator would allow subjects 2.2 Theories on the Origin of SMS to control their body functions and to use 2. Stress and Motion Sickness Different theories on the origin of SMS have fluids movements theory emphasises the biofeedback to control space motion 2.1 Physiological Basis of Motion Sickness been expounded (Miller et al., 1987; Chapeau- perturbations of the electrolytic-fluid sickness and stress. Classical studies (Wang & Chinn, 1956) Blondeau & Chauvet, 1991; Bless, 1979).The compartments at the various levels of the indicated that the cerebellar nodulus and two main theories are: nervous system and of the sensory systems, uvula, portions of the central vestibular in particularly vestibulo-auditory ones, by 1. Introduction system, are involved in susceptibility. In the sensory conflict theory emphasises the the cerebro-spinal and cochleo-vestibular Space motion sickness (SMS) has been central vestibular system, neurons that neurosensorial conflict.This conflict comes fluids system.These migrations of corporeal known since the 1970s to affect astronauts, subserve postural and oculomotor control from discordances between the ingoing fluids must be understood as when the freedom of movement offered by respond to a variety of spatial orientation sensory information and the memorised haemodynamic perturbations when there the Skylab and Salyut missions first made this cues. A brainstem ‘vomiting centre’ identified capital in the consciousness. It is as if the are movements in microgravity. type of susceptibility apparent. In 1969, such by Wang & Borison (1950) and Wang & Chinn central nervous system cannot adjust the sickness affected astronaut Schweickart (1954) receives convergent inputs from a coherent motor and vegetative responses A theory should stress the changes in neuro- during the US Apollo-9 mission. Around 70% variety of central and peripheral sources, such when facing the deficient perceptions. So endocrinal systems which, during external of astronauts were affected on missions, and as the diencephalon and gastrointestinal this mechanism of nausea must be seen as simulations, cause vestibulo-vegetative 67% of crewmembers over 24 American tract.The integrity of the vomiting centre and a defence response of the organism to this problems, at the hypothalamo-hypophysar and Space Shuttle missions.The symptoms of an adjacent ‘chemoreceptive trigger zone’ new environment.That is why SMS is also diencephalic stage. It is important to consider SMS are similar to those of terrestrial motion (CTZ) in area postrema on the floor of the known as ‘general adaptation syndrome’.As the underlying systems involved in the sickness: headache, sickness, lethargy, loss of fourth ventricle is required for motion Claremont (1931) observed, the discrepancy mechanism of space motion sickness. appetite and vomiting. SMS is not only sickness (Wang & Chinn, 1954). Signals between the information provided by one The control of these underlying systems by uncomfortable but can endanger life if originating from the ‘orientation brain’ set of sensations (visual) and that given by the central nervous system requires a certain severe symptoms interfere with decision- somehow traverse, via the cerebellum, to the another set (vestibular) generates motion period of adaptation for the brain to ensure making capacities or occur during EVA. chemoreceptive trigger zone, which in turn sickness symptoms.This is known as the the coordination of the functions in these new Different theories have been proposed activates the vomiting centre. However, ‘sensory conflict hypothesis’.In early conditions and involving all these components. concerning the origins of SMS.The neural different experiences (Miller & Wilson, 1983) statements of the theory, conflict signals Therefore, we can focus our attention on the mismatch theory asserts that a conflict arises indicate that medullary vomiting centres are from various sense organs were said to sensory inputs at the origin of the observing when the integrating processes of the central not discretely localisable. result from a comparison of signals and recording responses and, more particularly, nervous system fail to reconcile incoming The act of vomiting itself involves the provided by different sensory modalities the nauseous states. sensory information and existing memory. somatic musculature (coordination of the (canal-otolith and visual-inertial conflicts). The fluid shift theory claims that SMS is diaphragm, intercostals and abdominal In 1978, Reason (1969; 1975) noted that a 3. Modelling Stress and Motion Sickness caused by an active or passive shift of body muscles). Also, the limbic system and direct intermodality comparison of afferent 3.1 Modelling Techniques fluid to the central nervous system.Vestibulo- associated hypothalamus-pituitary-adrenal information is simply not appropriate, Two techniques of neurophysiologic modelling endocrine changes during external cortex (HPA) neuroendocrine outflow because signals from the various sense have appeared:

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Fig. 1.The relation between the input (skin conductance responses – the application of the fields theory negative slope of one of the input-output per minute > 0.05 µmho) and the motion sickness rating output (modelling the role of the cerebellum).This relationships in the loop. of the GENESYX expert system, developed to compute the motion method allows a finer approach to the sickness rating from bio data. neurophysiologic mechanisms of stress; 3.4 Input-Output Multiples – adhering directly to the scientific literature Technological systems usually have one and experimental data, but using more input and one output, but physiological general modelling of the functioning systems can have several of each. blocks that represent physiological functions (model BCD,Thouvenot) Oman 3.5 The Identification of Feedback (1988). To analyse a biofeedback system, four steps must be followed: Planned work by the Topical Team will investigated by Alvarez (1992), who abundance of data that can help to find a make it possible to integrate these two – identification of components from the intoduced electrogastrography (EGG).The method of reducing SMS using biofeedback. theoretical approaches. literature, each having a pair of stomach, intestine and colon, specifically Motion sickness symptoms recorded functionally-related variables, the input studied with this electrophysical technique, during ESA parabolic flights in 1991 and 1995 3.2 Non-Linear System Representation and the output (Fig. 1).The larger the have also been analysed with were also acquired in 2002 using Unlike in technology systems, the problem of number, the more detail appears in the electroplanchnography (ESG) techniques electrophysiological signals transmitted to modelling physiological systems is not the mathematical model.The number of (Thouvenot, 1998). Because of the proximity the skin’s surface by means of an ELA design of the system, but rather the discovery variables must be sufficient to define the of the digestive viscera in the abdominal MEDICAL portable recording device (Figs. 2 & of its blueprint.The basic difference is that state of the system (Fig. 10). cavity to the thorax, electrical observations 3). technological systems are usually linear, – the variables must be cyclically related. In are difficult to interpret. Moreover, cutaneous whereas physiological systems are almost the steady state, starting with any one electrophysical signals result from 5. Skin Conductance invariably non-linear (Oman, 1982; 1998). variable, it must be possible to trace a electrochemical phenomena indirectly linked Studies of the relationship of electrodermal The process of evolution has removed the functional relationship through all the to physiological functions such as secretions, activity to motion sickness have used skin problem of design arising from non-linear other variables in succession, ultimately mobility and electrolytic fluid transmission. conductance levels and phasic skin systems.The stable systems survived to reaching the starting point. Experimental methods usually involve the conductance.The tonic skin conductance reproduce, while the unstable systems – among the functional relations, there study of signals (or components extracted by level (SCR) measured at the forehead or eventually ended in the death of the must be at least one (or an odd number) spectral analysis) insofar as they are finger sites showed some correlation with organism. However, linearisation sometimes of sign inversions.That is, the slope of an connected with known physiological motion sickness (Golding, 1992; 2000; offers a good approximation in the operating odd number of these steady-state phenomena. Golding & Stott, 1997). range of the system. characteristics must be negative. The normal value of the EGG signal, the Cold sweating together with facial pallor – at least one of these components must basic electrical rhythm of the recording are the most reliable secondary symptoms of 3.3 Homeostasis and Negative Feedback exhibit asymmetrical transmission. activity of the gastric musculature, is motion sickness, the primary manifestations A physiological control system does not approximately 3 cycles/min.Tachygastria, the being nausea and vomiting. Skin always have a well-defined reference input or 4. EGG and ESG Tests abnormally high-frequency EGG observed conductance has been shown to be an an error detector. Regulatory processes are Biofeedback control requires research into during motion sickness, attains objective measure of such sweating using not only essential to life, but have also been the monitoring signals to be used by 4-9 cycles/min (Fig. 9).The functional mass spectrometry of water vapour drawn found at all physiological levels.This is astronauts. Contractile digestive viscera significance of tachygastria, particularly as a from the skin using dry nitrogen gas flow. fundamental to ancient Chinese medicine. generate electrophysical signals that are consequence of motion sickness, remains to It has been demonstrated that the phasic Each physiological variable is controlled by transmitted to the surface through the be studied. components of skin conductance are good negative feedback.This results from the abdominal cavity.The stomach was first Parabolic flights have provided an indicators of motion sickness induced by

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Fig. 4 (above).The forehead position of electrodes to record skin Fig. 2.The positions of skin electrodes for recording conductance during the ESA parabolic flight campaign of 2002. electrogastrographic activity using an ELA MEDICAL device. Fig.5 (top right).The skin conductance analyser and recorder Fig.3 (right).The positions of electrodes for recording developed by Westminster University (UK). electrogastrograms during the ESA parabolic flight campaign of 2002. Fig. 6 (right).The increase of tonic skin conductance during the 2002 ESA parabolic flight campaign indicates the increase of motion sickness.

either cross-coupled or translational motion simulators in the laboratory. The skin of the forehead is the best The visceral mass appears to act as an recording location in terms of motion accelerometer that is sensitive to microgravity sickness, because skin conductance activity variations in reaction against the parietal from other locations, such as fingers or the abdominal wall.The increase of abdominal palms of hands, indicates non-specific compliance (shown by an increase of friction sympathetic autonomic responses to mental conductance, occurs with motion sickness. and of the spring modulus) causes a reduction or emotional arousal such as excitement, These flights are designed to simulate some of tidal motion in the anteroposterior diameter anxiety, sensory stimuli or motor preparatory aspects of the true microgravity space of the lower rib cage.The increase in gastric hormones is released by motion sickness, reflexes (Fig. 4).The skin of the forehead does environment (Fig. 6). If it can be established pressure generates gastric electrophysiological including ACTH/cortisol, as well as the release not respond to such non-specific stimuli but as an useful indicator in-flight, then it will be signals.These phenomena can be of other hormones typically observed in stress will respond by producing bursts of phasic possible to incorporate biofeedback training mathematically modelled. responses, such as growth hormone, thyroid skin conductance activity to the onset of into motion sickness desensitisation. To manage the models, the authors have hormone, prolactin, arginine vasopressin, beta motion sickness (Fig. 5). developed simulation and modelling Expert endorphin, adrenaline and noradrenaline. There have been some conflicting 6. Biomechanical and Neurophysiological Systems.This allows the biochemical internal Golding (2000) has demonstrated that observations of space sickness. For example, Models state, such as cortisol, to be estimated from salivary cortisol, which closely tracks blood Money (1970) concluded that cold sweating Using mathematical software, signals of external data (Fig. 7) and electrophysiological cortisol, peaked 20-30 min after motion and facial pallor reliably followed space acceleration (g) and the abdominal electrical signals. sickness induced by cross-coupled motion. sickness after reviewing Russian reports of ESG for each channel A, B and C using the The results of this non-invasive salivary space sickness in cosmonauts, but Young apparatus shown in Figs. 2&3 are obtained. 7. Salivary Cortisol and Motion Sickness measurement method proved consistent with (2000) suggested that they are absent in Three types of ESG results are then obtained: Motion sickness produces a variety of previous data using invasive blood sampling Space Shuttle SMS, perhaps because of fluid- impulse response, spectral analysis and time autonomic responses, including cold sweating, for cortisol. shift or the low-humidity environment. It has series analysis, which are analysed to model salivation, pallor (peripheral vasoconstriction), thus been of practical and theoretical interest neurophysiological mechanisms of space gastric stasis and changed EGG (Harm, 1990; 8. Biofeedback to use ESA parabolic flights to verify whether motion sickness and stress (Gaudeau et al., Golding, 1992; Golding & Stott, 1997; Gaudeau Previous work (Cowings et al., 1990) at the or not cold sweating, as quantified by skin 1992; 1993; 2005). et al., 1996). A variety of stress-related NASA Ames Research Center developed

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200 192

Fig.7.Grid of clinical states of Fig. 8.Estimated salivary cortisol for biofeedback control of stress 180 174 a subject during parabolic (screen capture).A rating of 100 is normal for an adult not subject 166 163 flight. to space motion sickness.The horizontal axis values indicate the 155 154 155 148 148

parabola number during the flight. 138 140 140 139 136 133 133 126 126 120 140 103 103 100 100 100 100 100 100 100

treatment, drugs will no longer be needed to prevent nausea and sickness.The astronauts will be trained and prepared before flight, 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 which means a reduction of adaptation time.

11. Medical Applications biofeedback and autogenic control that is abdomen itself.The apparatus must stimulate 11.1 General Considerations buses, trains, underground trains and successful in 85% of trained subjects, these three channels; it will be composed of: As normal and pathological subjects, tramcars for whom stress-management reducing reactions to provocative motion humans can learn to self-regulate certain would be necessary. sickness stimuli.The autogenic feedback – a computer system that simulates different parts of their electrophysiological signals training involves learning self-suggestion nauseous situations on a screen, such as a (ECG,EEG,EGC,skin conductance) within a Development of new electrophysiological exercises to regulate physiological responses black and white-striped rotating cylinder, feedback paradigm, using a device providing biofeedback and bioelectrical stimulation to stimuli. Other works have shown that it is the speed of which can be modified and prompt measurements of external equipment for re-education of people with possible to control gastric and digestive programmed; electrophysiological activity.The device’s motor disabilities motricity. Differents studies on the ground – a biomechanical oscillating and rotating display is simple and easy-to-understand, The causes of total motor paralysis are have been carried out by Martin et al. (1993) seat.The rotation has a vertical axis, while like a bar or ball movement on a screen degenerative neuromuscular diseases.The on biofeedback, which is the visualisation of the oscillations are in three axes.This can (Miller, 1988).The training procedure is most frequent is amyotrophic lateral electrophysiological signals, and the be implemented using the EDEN project’s based on the operator-conditioning sclerosis, which involves a steadily apprenticeship, using these signals, of the rotating chair, develop by EADS Launch paradigm. A feedback of the correct progressive degeneration of central and regulation of physiological processes under Vehicles; response serves as a reward.The desired peripheral motoneurones. Attempts to solve the control of the central nervous system. – an electrogastrographic acquisition reaction is systematically shaped; this is a the problem of communication in paralysed This technique will be studied further in system with skin impedance measures.The widely-used training technique in which a patients have led to several strategies that order to allow astronauts to avoid nausea visual stimulation system will be desired motor, physiological or even involve direct communication between the and vomiting by means of specialised superimposed on an electrophysiological biochemical or behavioural objective is brain and a computer, by using computerised equipment adapted to nausea- curve representing electrogastrographic approached step-by-step in successive electrophysiological signals such as EEG.The resistance training. activity. approximations. existing equipment will be adapted to solve The originality of the project is the use of this communication problem. expert systems applied to These measures can be used on the 11.2 Potential Applications electroplanchography, which make it International Space Station. Subjects will be Conception and realisation of devices for anti- 12. Conclusions possible to test the different relations that taught to make their own curves follow the motion sickness and anti-stress training for The members of the Topical Team have can be extracted from tests and which can ‘normal’ ones. No specific method is imposed. civilian and military pilots decided to extend its activities to Dutch, also help to model the effects of stress and The goal of this training is to allow subjects A specific device can be developed in which German and Italian research groups. In SMS (Gaudeau et al., 1996). to control their body functions in ways they the pilot can visualise the amplitude or the addition, the MEDES space medicine institute were unaware of before. frequency of external physiological signals has been contacted to use its jacket for skin 9. Flight Equipment Project and act on corresponding neurophysiologic conductance, electrocardiogram, The Topical Team will develop equipment to 10. Improvement Expected and biochemical states (cortisol, etc). Some electrogastrogram and pneumogram train subjects to control their reaction to This new desensitisation to SMS could have contacts have already been established with measurement on a future parabolic flight and motion sickness and stress.The signals great consequences for space activities. the French Air Force. as a new experiment aboard the involved in this response come from the Although there have been improvements in Specialised equipment can also be International Space Station. vestibular system, the visual system and the the pharmaceutical domain of SMS developed for companies to train drivers of The objective is to study and develop a

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Fig. 9.When motion sickness occurs, the low-frequency gastric Fig. 10.Structured analysis and design technique diagram activity jumps gradually from 3 to 9 cycles/min.This activity is representing the node A-1 of space motion sickness,travel sickness figured here by the large undulations over the characteristic heart and stress modelling. beat signals.(Source : 2002 parabolic flight campain.)

References European Symp.‘Life Sciences Research in Alvarez,W.C. (1922).The Electrogastrogram Space’,Trondheim, Norway, 16-20 June 1996, and What it Shows. J. Am. Med. Assoc. 78, ESA SP-390, ESA Publications Division, 1116-1119. Noordwijk,The Netherlands. Bless,W. (1979). Sensory Interaction and Gaudeau, C., Bobola, P.,Faucheux, S., Human Posture. Ph.D.Thesis, University of Benoist, S., Robert, E.,Tanche, M., Induced Vomiting after Vestibulocerebellar Amsterdam,The Netherlands. Thouvenot, J. & Chauvet, G. (2005). Lesions. In Mechanisms of Motion Induced Chapeau-Blondeau, F.& Chauvet, G.(1991). A Simulation and Modeling of Space Motion Vomiting. Brain Behav. Evol. 23,26-31. Neural Network Model of the Cerebellar Sickness based on Electrophysiological Miller, A.D. & Wilson,V.J. (1983b).Vomiting Cortex Performing Dynamic Associations. Data. Aviat. Space Environ. Med., submitted. Center Reanalysed: An Electrical Biol. Cybern. 55, 201-209. Golding, J.F.(1992). Phasic Skin Conductance Stimulation Study. Brain Res. 270, 54-158. Chauvet, G. (1990).Traité de Physiologie Activity and Motion Sickness. Aviat. Space Miller, A.D.,Tan, L.K. & Suzuki, I. (1987). Control new and effective training system against Théorique.Tome 3 Physiologie intégrative. Environ. Med. 63(3), 165-171. of Abdominal and Expiratory Intercostal SMS and stress and to study the Champ et Intégration Fonctionnelle. Golding, J.F.(2000). Current Work in Motion Muscle Activity during Vomiting; Role of mechanisms of adaptation in microgravity. Masson. Sickness. Proc. Meeting at Hotel Castel La Ventral Respiratory Group Expiratory Once these methods of biofeedback are Claremont, C.A. (1931).The Psychology of Huberdière, Nazelles,Tours, France, 16- Neurons. J.Neurophysiol. 57, 1854-1866. operational, training protocols must take Seasickness. 11, p.86-90. 17 June 2000, pp48-61. Money, K.E. (1970). Motion Sickness into account the subjects’ susceptibilities Cowings, P.S., Naifeh, K.H. & Toscano,W.B. Golding, J.F.& Stott, J.R.R. (1997). Objective Physiology Reviews, 50, 1-39. and personal backgrounds. Different (1990).The Stability of Individual Patterns and Subjective Time Courses of Recovery Oman,C.M. (1988) Motion Sickness: A methods of training and conditioning need of Automatic Responses to Motion from Motion Sickness Assessed by Synthesis and Evaluation of the Sensory to be analysed and created. It is also hoped Sickness Stimulation. Aviat. Space Environ. Repeated Motion Challenges. J. Vestibular Conflict Theory. Can.J. Physiol. Phamacol. that links will be made with new models of Med. 61, 5, 399-405. Res. 7(4), 1-8. 68, 294-303. human consciousness and new theories will Gaudeau, C., Chapeau-Blondeau, F., Harm, D.L. (1990). Physiology of Motion Oman, C.M. (1998). Sensory Conflict Theory be applied to psychophysiology. Chauvet, G. (1992). Detection of Nausea Sickness Symptoms. In Motion and Space and Space Sickness: Our Changing Combining these different aspects will States from ESG Signals during Parabolic Sickness (Ed.G.H. Cramptn), CRC Press, Perspective. J.Vestib Res. 8(1), 51-56. most likely allow us to define new and Flights. ESA Workshop,The Netherlands. Boca Raton, Florida, USA, pp153-177. Oman, C.M. (1982). Heuristic Mathematic effective equipment and techniques that Gaudeau, C., Chapeau-Blondeau, F., Kohl, R.L. (1990). Endocrinology of Model for the Dynamics of Sensory will ensure the good physical health of Combeau, A. & Chauvet, G. (1993). Analysis Space/Motion Sickness. In Motion and Conflict and Motion Sickness. Actes Otho- astronauts aboard the International Space and Modeling of Space Motion Sickness Space Sickness (Ed. G.H. Crampton). CRC laryngology. Supplément 392, 4-42. Station and during long-duration flights. from Electroplanchnograms (ESG) Signals. Press Boca Raton, Florida, USA, pp65-85. Reason, J.T. (1969). Motion Sickness: Some They will also be critical for developing Proc. 5th Eur. Symp. ’Life Sciences Research in Martin, A. (1993). La bioréaction Theoretical Consideration. Int. J. Man-Mach. equipment featuring electrophysiological Space’, 26 September - 1 October 1992, électrogastrographique : intérêt dans les Stud. 1, 21-38. biofeedback to rehabilitate people with Arcachon, France, ESA SP-366, ESA dyskinésis gastroguénales à propos de six Reason, J.T. (1978). Motion Sickness motor disabilities. Publications Division, Noordwijk,The observations. Revue de médecine de Tours Adaptation: A Neural Mismatch Model. J. R. Netherlands. T17. N°8-1. Soc. Med. 71, 819-829. Acknowledgements Gaudeau, C., Serre, A.F., Redouane, M., Miller, A.D. (1988). Motion-Induced Nausea Reason, J.T. & Brand, J.J. (1975). Motion The authors are grateful to O. Guy (ADERSA) Lechrist, A., Robert, E.,Tanche, M., and Vomiting. Chap.5. In Nausea and Sickness. Academic Press, London. and Y. Faisandier (ELA MEDICAL) for their Chauvet, G.,Thouvenot, J. & Kouamé, D. Vomiting: Recent Research and Clinical Thouvenot, J. (1998) L’électrogastrographie contributions, and to the Credit Industriel (1996). An Expert System for Simulation Advances (Ed. R.K. Harding, J. Kucharczyk, & dans son contexte des fonctions et des de l’Ouest (CIO, Nantes, F) for financial and Modeling of Space Motion Sickness D.J. Stewart), CRC Press, Cleveland, USA. interactions viscérales. Editions Médicales support. based on Physiological Data. Proc. 6th Miller, A.D. & Wilson,V.J. (1983a).Vestibular- internationales, Paris, France, 384p.

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Von Holst, E. (1943). Relations between the Central Nervous System and the Peripheral Topical Team Organs. Br. J. Anim. Behav. 2, 89-94. Wang, S.C. & Borison, H.L. (1950).The Vomiting Coordinator Philippe Bobola Industrial Partners Centre: A Critical Experimental Analysis. Claude Gaudeau Laboratoire de Bio-Informatique et de Thierry Palmier Arch. Neurol. Psychiatry, 63, 928-941. Directeur, Laboratoire de Bio-informatique et Biotechnologie, 32-45 rue Emile Zola, F-37000 Fujitsu Siemens Computer, Immeuble Colonnadia Wang, S.C. & Chinn, H.I. (1954.) Experimental de Biotechnologie, 32-45 rue Emile Tours, France. Paris Nord 2, 229 rue de la Belle Étoile, BP 50027 Motion Sickness in Dogs: Functional Zola,F-37000 Tours, France. Tel: +33 2 47 05 27 04 Roissy en France, F-95946 Roissy Charles de Importance of Chemoreceptive Emetic Tel: +33 2 47 05 27 04 Email: [email protected] Gaulle Cedex, France. Trigger Zone. Am. J. Physiol. 178, 111-116. Email: [email protected] Email: [email protected] Wang, S.C. & Chinn, H.I. (1956). Experimental Gilbert Chauvet Motion Sickness in Dogs: Importance of Co-Investigators Institut de Biologie Théorique de l’Ouest, Yves Faisandier Labyrinth and Vestibular Cerebellar. Am. J. J.F.Golding Université d’Angers, 10 rue André Bocquel, ELA MEDICAL Physiol. 185, 617-623. Division of Psychology, Univ. of Wetsminster, F-49100 Angers, France. C.A. La Boursidière Young, L.R. (2000).Vestibular Reaction to 309 Regent Street, London W1B 2UW, UK. Tel: +33 02 41 73 58 40 F-92357 Le Plessis-Robinson Cedex, France Space Flight: Human Factors Issues. Aviat. Tel: +44 020 7911 5000 Email: [email protected] Tel: +33 1 46 01 36 31 Space Environ. Med 71(9, Suppl.), A 100-4. Email: [email protected] Email:[email protected] Jean Claude Pichaud Y.Lucas CHR La Tour Blanche, Service de Médecine Romain Marcout Laboratoire Vision et Robotique, Université Physique et de Réadaptation, F-36100 EADS Space Transportation France, 66 route de d’Orléans, IUT de Bourges Dépt Mesures Issoudun, France. Verneuil BP 3002 F-78133 Les Mureaux cedex, Physiques, 63 avenue de Lattre, F-18020 Tel: +33 2 54 03 56 02 France. Bourges cedex, France. Email: [email protected] Email: [email protected] Tel: +33 2 48 23 80 58 Email: [email protected] Jacques Richalet Romain Cazes ADERSA, 10 rue de la Croix Martre, F-91873 Alexandre Guitton Team Members Palaiseau cedex, France. Florence Mailliez Willem Bles Tel: +33 1 60 13 53 53 Marien Perrot Netherland Aerospace Medical Centre Email: [email protected] Céline Ries (Soesterberg), Department of Work Alexandra Schubnel Environment, Equilibrium and Orientation, Joseph Thouvenot Frédéric Thevot Kampweg 5, P.O. Box 23, 3769 ZG Faculty of Medicine of Tours, Laboratoire de Société de Bioinformatique et de Biotechnologie, Soesterberg,The Netherlands. Physiologie et de Bio-Informatique, 32-45 rue 32-45 rue Emile Zola, F-37000 Tours, France. Tel: +31 346 356 422 Emile Zola, F-37000 Tours, France. Tel: +33 2 47 05 27 04 Email: [email protected] Tel: +33 2 47 05 27 04 Email: [email protected] Email: [email protected] William Bonnet European Stress Management Centre, 6 rue Charles Gilles, F-37000 Tours, France. Email: [email protected]

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Eye-Hand Coordination: Contribution of the ESA Topical Team in Life Sciences Dexterous Object Manipulation in Eye-Hand Coordination Contributors: J.L.Thonnard, Brussels (B) (Coordination) New Gravity Fields A. Smith, Montreal (CDN) A.Wing, Birmingham (UK) J. McIntyre, Paris (F) P.Lefèvre, Louvain-la-Neuve (B) O.White, Brussels (B) The stabilisation of an object manipulated gripping to reduce the consequence of an A.S. Augurelle, , Brussels (B) with the hand depends on applying a erroneous estimate of mass. Alternatively, the J.S. Langlais, , Montreal (CDN) sufficiently strong force with each finger such hand might initially be moved more slowly A.Witney, Birmingham (UK) that sufficient friction is generated to resist than normal to allow more time for G. Blohm, Louvain-la-Neuve (B) the load force acting tangentially to the feedback-based adjustments to grip force. In M. Penta, Brussels (B) Fig. 1.Feedback and feedforward control of a controlled object.a: the feedback control compares the contact surfaces. Gravity normally provides a this regard, a series of experiments has been B. Elmann-Larsen, Noordwijk (NL) realised and the desired trajectories in order to compute an error,which serves to generate the feedback constant force acting on the object designed in order to study the effects of a R.M. Bracewell, Bangor (UK) motor command after a certain delay.b: the feedforward control uses an inverse dynamics model to (depending on its weight) which is change in gravity on the dynamics of S. Stramigioli,Twente (NL) calculate the motor command necessary to realise the desired movement.(Adapted from Kawato, 1999.) adequately taken into account by an prehension, on the kinematics of upper limb appropriate level of grip force.Variations in movements and on eye-hand coordination. inertial forces caused by the subject’s own This report describes the results of some Flanagan & Wing (1993) examined grip force modulation of grip force in anticipation of arm movements over a range of experiments already performed and the modulation as subjects performed either load force implies that the nervous system accelerations also produce synchronous scientific objectives of the experiments that point-to-point or cyclic arm movements with has access to information concerning both changes in grip forces that rise and fall with will be carried out in the coming years. a hand-held load.They found that variations the object mass and the kinematics of the the changes in the tangential load forces on in inertial forces caused by the subjects’ own forthcoming movement, since changes in the fingers.That is, grip force reflects an arm movements over a range of either of these require a different grip force. anticipatory adjustment to the fluctuations in 1. Background accelerations produced synchronous This suggests that the internal models used inertial forces.The modulation of grip force in A stable grip on hand-held objects is of changes in grip forces that rose and fell with to predict load forces and generate anticipation of load force implies that the primary importance to secure lifting and the changes in the tangential load forces on appropriate grip forces are pretty good. It nervous system has access to information moving actions, particularly when the the fingers.The grip forces were modulated remains to be proved, however, whether the concerning the object’s weight, mass and the objects are used as tools. Stabilisation in parallel with the load forces, regardless of entire control process of grip-force kinematics of the forthcoming movement, depends on applying a strong enough grip the object’s surface friction or the frequency compensation is based on feedforward, since changes in any of these require a force normal to each finger-object contact of movement applied to the object.That is, model-based control, or if some components different grip force.This suggests that the surface such that sufficient friction is the grip forces reflected an anticipation of the required grip responses are generated internal models used to predict load forces generated to resist the load force acting adjustment to the fluctuations in inertial through reflex actions. and generate appropriate grip forces are tangentially to the contact surfaces. Studies forces. In this respect, microgravity presents a pretty good. It remains to be proved, of the forces employed in the dexterous A recurring question addressed in studies significant challenge to dexterous object however, whether the entire control process handling of objects using a precision grip of neuromuscular control is that of the manipulation for a number of reasons. First, of grip-force compensation is based on have found that the grip forces are relative contributions of feedforward and the object has no weight.Therefore, a large feedforward, model-based control, or if some optimised to prevent accidental slips, and yet feedback control to the generation of a part of the load forces tangential to the skin components of the required grip responses are not so excessive as to crush a fragile motor command (Fig. 1). are removed. In a modified gravitational are generated through reflex actions. object or to cause muscle fatigue (Johansson An important concept in neuroscience is environment, the anticipatory grip force used Microgravity presents a significant & Westling, 1984; Westling & Johansson, that feedforward control stems from the to support the object would need to be challenge to dexterous object manipulation 1984). Grip force must be greater than ability to predict future states of the system modified. However, whereas the removal of for a number of reasons. Owing to all the weight and the inertial load of the object to based on information from past the weight of the object has an obvious potential deviations from the expected be moved. In order to ensure secure object sensorimotor experiences, current sensory effect on the total load force that might easily characteristics of the load forces, planning manipulation without slip, the grip-load information and the intended action.This be predicted, the anticipation of inertial movement under microgravity conditions force ratio has to be maintained slightly ability to predict the consequences of a forces might also be affected in less obvious might involve a greater reliance on visual, above the minimum required to prevent slip, motor command implies that the central ways. Since there is no perception of weight, tactile and/or memory cues to an object’s according to the friction between skin and nervous system makes use of what is called a the important cues by which the mass of the mass. In addition, there might be over- object (Johansson & Westling, 1984). ‘forward internal model’ (Wolpert, 1997).The object might be inferred prior to movement

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Fig. 2.Frontal view of the experimental set-up.The subject moved Fig. 3.Records of six contiguous cycles the manipulandum up and down between the two elastic bands obtained during the stable period in each 20 cm apart.The grip force was measured by strain gauges, the gravitational phase of the last trial of an NES. load force was calculated from the vertical object acceleration The traces presented are the gravity level (A), measured by an accelerometer. the load force (B), the grip force (C, red line), the slip force (C, black line), the GF/LF ratio (D, blue line) and the slip ratio (D,black line).The difference between the GF/LF ratio and the slip ratio reflects the safety margin.The friction coefficient was 0.5.

Research Announcement (ESA-RA-LS-01- FLIGHT/PF-009).Three new experiments are recommended for ESA’s parabolic flight campaigns over the next 3 years. Described below are the results of the two experiments already performed and the scientific objectives of the three planned would be missing. Furthermore, in the experiments. absence of weight, the momentum of the object will generate tangential forces in 2. Performed Experiments unfamiliar directions (except for highly- 2.1 The Effect of a Change in Gravity on the the first time they executed the task in the about 20 cm apart (Fig. 2), which served to accelerated movements of the object, the Dynamics of Prehension aircraft. guide the endpoints of the arm displacement. weight of the object dominates such that the Experiment team: A.S. Augurelle, M. Penta, The experiments were performed at 0 g,1g net force acting on the object usually has a O. White, J.L.Thonnard Description of the Experiment and 1.8 g during the parabolic flights. Each downward component in normal gravity). All Scientific Objectives These experiments were performed during the subject grasped the instrumented object and these potential deviations from the expected The grip force exerted on a hand-held object 26th and 27th ESA parabolic flight campaigns. started the cyclic movement during the 1 g characteristics of the load forces mean that during cyclic vertical arm movements was The grip-load force coupling was measured phase, about 30 s before the start of the pull- planning movement under microgravity examined at 1 g and at different gravity during cyclic vertical arm movements with an up phase.The movement was performed conditions might therefore involve a greater fields (0 g and 1.8 g) attained during instrumented hand-held object (Fig. 2). It was throughout the whole parabola and 30 s after reliance on visual, tactile and/or memory parabolic flights of an aircraft (Augurelle et equipped with strain gauge transducers to the restoration of the 1 g condition.Thus the cues to an object’s mass. In addition, there al., 2003). A modification of the object's measure the GF applied perpendicularly by the grip force and object acceleration were might be over-gripping to reduce the weight was obtained without modification fingertips on two parallel brass discs, 30 mm in recorded continuously for 120 s, while the consequence of an erroneous estimate of of its mass, and thus its inertia was constant diameter and 30 mm apart, which served as simulated gravity went successively from 1 g, mass. Alternatively, the hand might initially across the different gravitational conditions. the grasping surfaces. An accelerometer to 1.8 g,0g,1.8g, and back to 1 g.Two be moved more slowly than normal to allow By contrast, on the ground, the weight of an mounted on the top of the object recorded subjects were examined per flight. On each more time for feedback-based adjustments object cannot be changed without changing the acceleration along its vertical axis.The flight, the non-experienced subject (NES: no to grip force. its inertial properties.Therefore, the parabolic vertical LF resulting from the gravitational and previous 0 g experience) performed the In this regard, this Topical Team has flight environment offered the unique the acceleration-dependent inertial force was experiment on the first 15 parabolas, and the designed a series of experiments to study the possibility to study the effect of a change in calculated as the product of the mass and the experienced subject (ES) was tested during effects of a change in gravity on the gravity on the grip force (GF)-load force (LF) vertical acceleration of the object as measured the last 15. In this way, the NES experienced dynamics of prehension, on the kinematics of coupling while maintaining the inertial by the accelerometer. microgravity for the first time as the task was upper limb movements and on eye-hand component of the load unchanged.The The subject was seated in a chair with an performed during the first parabola. During coordination.The first experiments were subjects performed cyclic vertical arm attached seat belt. At a signal from the the 15 first parabolas, the ES was not performed between 1999 and 2001 during movements while holding an instrumented experimenter, the instrumented object was specifically involved in a manipulation task. the 26th , 27th and 31st ESA parabolic flight load during ten parabolic flight manoeuvres. grasped between the thumb and index finger campaigns.The results of these experiments Half of the subjects had never experienced of the right hand. Cyclic vertical arm Results have been partly published (Augurelle et al., parabolic flights. It was hypothesised that movements were made at a frequency of The GF-LF coupling in the different 2003; Witney et al., in press; White et al., the GF-LF coupling would be progressively approximately 1 Hz, aided by a metronome. gravitational environments attained during submitted). In order to complete these adapted to a new gravity level in the naive The amplitude of the oscillations was parabolic flights is shown in Fig. 3.These experiments, the Team successfully subjects, while it would be appropriately maintained by limiting the range of movement signals were obtained during the last trial of responded to ESA’s 2001 Life Sciences adjusted in the experienced subjects from to lie within two parallel rubber bands spaced an inexperienced subject. In this typical

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Table 1.The Four Levels of Equivalent Tangential Loads.

parabola, the aircraft’s vertical acceleration was 9.55 ± 0.26 m s–2 at 1 g; 17.07 ± 0.24 m s–2 at 1.8 g and 0.11 ± 0.17 m s-2 at 0 g (Fig. 2A). The load force oscillated around the object weight (dotted line) of 2.5, 4.5 and 0 N at 1, Gravity: gravitation in g (g = 9.81 ms–2); Mass: mass of the object; Distance: object displacement; Additional load: presence (+) or 1.8 and 0 g, respectively (Fig. 3B). absence (-) of the 200 g mass on the arm; a: object acceleration; GL: gravitational load; IL: inertial load; Tangential Load: GL + IL In normal 1 g conditions, the load force reached a maximum at the bottom of the trajectory where the gravitational and the object accelerations were acting in the same grip force modulation was large enough to 0 g and 1.8 g (Fig. 4, NES). By decreasing both direction.The minimum load force occurred prevent slip for any load, suggesting that the the level and the variance of grip force at the top of the trajectory, where the object modulation was not necessary. Peaks of load throughout the ten trials, the NES acceleration was opposed to that of gravity. force were always precisely synchronised progressively tends towards a single GF-LF At 1 g and 1.8 g, the load force was always with a similar peak in the grip force so that relationship across the gravitational positive because the downward acceleration the GF/LF ratio was minimum and highly environments.This process started at the of the object required by the frequency and reproducible at these times (Fig. 3D). In second trial and was achieved after the fifth. amplitude of the movement was always less contrast, when the load force was minimum, Figure 4 also shows that same load force than the acceleration due to gravity. In the GF/LF ratio was more variable and ranges were obtained by varying separately microgravity, the object had to be reached its maximum because the grip was the acceleration of gravity and the accelerated both upwards and downwards not completely released or was even re- acceleration of the object.We observed an because gravity no longer accelerated the increased. overlap in the load force with low object downwards, and thus the load force The adaptation of the GF-LF relationships gravitational acceleration (i.e. 1 g) and high was positive and negative in the lower part in each gravitational condition is shown in object acceleration (i.e. bottom of the arm and in the upper part of the trajectory, Fig. 4 across four representative trials.The left trajectory), and in a high gravitational respectively.The amplitude of the load force column displays typical traces recorded from acceleration (i.e. 1.8 g) with a low object fluctuations was fairly similar across an experienced subject (ES), and the right acceleration (i.e. top of the arm trajectory). gravitational environments (about 3 N), from an inexperienced subject (NES). Even though the upper limb was in different suggesting that the NES in this trial was able Both subjects modulated their grip force simulated gravitational fields, the same to maintain the constraints of the imposed in phase with the load force fluctuations coupling between the grip force and load movement (1 Hz and 20 cm). In each induced by the object acceleration in each force was observed after the information was gravitational phase, the grip force (red line; gravitational condition, starting from their integrated, i.e. from the first trial for the ES Fig. 3C) increased and decreased when the first trial.The ES used the same GF-LF and after the fifth trial for the NES. load force rose and fell, respectively. At 0 g, relationship from the first to their last trial in Fig. 4.The grip force-load force relationship measured during six arm-cycles under three gravity levels during the first, second, fifth the grip force increased again at the top of the aircraft. A near-continuous grip-load 2.2 Do Gravitational Environments Alter the and tenth trials in an experienced subject (ES) (left column) and a the trajectory to prevent the object from force relationship was established across the Grip-Load Force Coupling at the non-experienced subject (NES) (right column).The dotted lines in slipping between the fingers when the different gravitational conditions (Fig. 4, ES). Fingertips? the upper panels represent the object weight in each gravitational object was accelerated downwards.The grip Note that the level of the GF modulation at Experiment team: O.White, J. McIntyre, level.The slip force is presented by a straight line according to the force was always greater than the slip force 0 g remained slightly above that observed at A.S. Augurelle, J.L.Thonnard friction coefficient of each trace.The inset in the left column shows the overlap between the load force ranges observed at 1 g and (black line, Fig 3C), indicating that no 1 g. Conversely, when faced with a new Scientific Objectives 1.8 g.Trial #1 of the NES and the ES corresponded to the first and slippage occurred. Moreover, it was gravitational field for the first time, the NES The relationship between the normal grip the 15th parabolas of the aircraft,respectively. interesting to note that the mean level of the used a dramatically increased grip force at force (Fn) and the tangential force (Ft) was

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Fig. 5.The experimental platform includes (A) two force-torque transducers measuring the full six components of force and torque (Fx,Fy,Fz;Tx,Ty,Tz), (B) a Chronos video-based 3-D binocular eye movement recording system, (C) a 3-D movement tracking system measuring the kinematics of the instrumented object grasped between the fingers and the Chronos helmet (note the LEDs inside the red circles) .

examined while moving an object up and first trials (P1-P5), the task was performed A B C down in different gravitational environments with a 400 g mass displaced by 20 cm at a (White et al., submitted).Through a variety of frequency of 1 Hz (‘400g20cm’). In the second test conditions, the inertial and gravitational series of five trials (P6-P10), the mass was components of the forces acting on the limb reduced by half and the amplitude of were varied independently.The inertial movement was doubled (‘200g40cm’). As the components were modified by varying the frequency of movement was kept the same mass of the load or the mass of the limb (1 Hz), the acceleration was also twice as (ballast weight on the forearm).The weight of great, resulting in an equivalent inertial load the limb and load were varied by varying the but an decreased gravitational load. In the effective gravitational field. In this way, it was last five trials (P11-P15), the 40 cm movement possible to generate equivalent magnitudes was performed with the 200 g mass but a of loads at the fingertips while the ballast brace of 200 g was placed around the agreement with previous works (Goodwin et account for various physical contexts. In other mechanical constraints on the upper limb wrist of the subject (‘additional mass’). In this al., 1998; Flanagan et al., 1999).These results words, subjects are able to identify the and thus the motor commands required to case, the inertial and gravitational show that grip force is not related to the environmental context and select the move the arm were modified. Similarly, components of the load were the same as in muscle commands to the upper limb in a appropriate motor program. certain trials required similar motor the 200g40cm case, but the inertial and simplistic manner. Grip force is adjusted commands to move the arm, but different gravitational components of the arm were specifically to the tangential forces that are 3. Planned Experiments: The Effect of a grip forces to maintain the object safely in increased.Table 1 shows that, among the applied to the fingertips, rather than being Change in Gravity on the Eye-Hand the grasp. nine load conditions, four levels of equivalent tuned to the overall load applied to the limb. Coordination tangential force acting on the fingertips These results further extend the general The Team’s proposal in response to ESA’s Description of the Experiment could be reproduced while the load imposed framework in which the grip-load force 2001 Life Sciences Research Announcement This experiment was performed during the on the upper limb was different owing to coordination is observed. Not only does the was recommended by the evaluation 31st ESA parabolic flight campaign in 2001. different gravity levels. grip-load force coupling reflect a general committee for flight within ESA’s parabolic Five right-handed subjects (aged 30-48 control strategy for any particular grip or campaigns.Three experiments are planned to years), highly experienced in parabolic flights, Results mode of transport (Flanagan & Tresilian, study the effects of a change in gravity on participated in this study.They had to move The main finding was that the magnitude of 1994) but it was shown that this strategy is eye-hand coordination.The first and second an instrumented object up and down the normal force was adequately adjusted for used in different environmental (i.e. experiments examine the role of visual and continuously in the different gravity fields each maximum of load so as to maintain the gravitational) contexts.The similar force ratio tactile feedback, respectively, in sensorimotor (1 g,1.8g and 0 g) induced by parabolic same minimal ratio between the normal observed in the nine loading conditions adaptation to microgravity.The third flights.The imposed movement frequency force and the destabilising tangential load indicates that dynamic constraints such as experiment analyses the grip force control in

was 1 Hz; the object mass was either 200 g or (Fn/Ft) in the nine loading conditions.The gravitational force and inertial resistance of repetitive collisions during parabolic flight to 400 g; the amplitude of movement was subjects were able to maintain this optimal the arm and object are well taken into determine whether gravity is taken into constrained to 20 cm or 40 cm, and an ratio in different contexts of mass, gravity account in the control of precision grip.The account in the prediction of collision load additional mass of 200 g could be secured and upper-limb acceleration. For equivalent precise temporal coupling between the forces. around the forearm.The coordination loads at the fingertips at 1 g or 2 g,the normal force and the tangential load also The equipment for the three experiments between the grip force normal to the surface subjects used the same grip force despite the shows that the load was correctly predicted includes a platform capable of and the tangential load was examined under fact that it required more force to displace and that the normal force was calculated in a simultaneously measuring the dynamics of nine loading conditions (see Table 1). the arm in hypergravity. Furthermore, the feedforward manner based on this precision grip, the kinematics of the upper Each subject performed the task over 15 normal force was modulated with and thus prediction.This suggests that the forward limb and 3-D eye movement (Fig. 5). complete parabolas in the aircraft. In the five anticipated the effects of tangential force, in model predicting the load can be adjusted to The dynamics of precision grip will be

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Fig. 6.Frontal view of the experimental set-up.The subject is Fig. 7.The effect is investigated of wearing little caps covering the secured by a seat belt on a chair,with the instrumented object thumb and index finger on the grip force-load force coupling on grasped,in the frontal plane,between the thumb and the index the continuous manipulation of objects in space. finger of the right hand.On a signal 20 s before the 1.8 g pull-up phase,the subject is requested to move the object continuously in a figure of ‘∞‘.

tends to make the object slip out of the fingers. In order to restrain the object, the normal grip force has to be adjusted to the load force fluctuations.The parameters of movement dynamics (forces and torques) will indicate how the subject is able to anticipate the load force, which depends both on the gravity and the acceleration of delivered 20 s before the 1.8 g pull-up phase, the upper limb. the subject is requested to move the object The kinematics parameters (displacement, continuously in a ‘∞‘ figure trajectory, speed and acceleration) will indicate whether bypassing two horizontal visual targets, one the subject is able to perform the ‘∞’ in each loop of the ‘∞‘ shape (Fig. 6). movements in altered gravitational The subject is instructed to maintain the environments.The intended trajectory could movement constant across each gravity measured by two force-torque transducers implication of visual/cutaneous feedback be programmed inappropriately on the basis phase of the parabola. Moreover, the subject (ATI Mini 40 force/torque sensors, Industrial and of predictive mechanisms in the of an erroneous internal representation of will perform half of the trials with saccades Automation, North Carolina, USA) placed planning and execution of arm movements gravity producing changes in the actual between the targets and half with his gaze under each finger.They measure the full six involving hand-held objects. movement.The question arises as to how the fixed on the midpoint between the targets.

components of force and torque (Fx, Fy, Fz; The three experiments are described grip force applied to the object will be Two subjects will be studied on each flight, Tx, Ty, Tz).The force-torque applied by the below. adjusted according to the tangential load each for 15 parabolas. fingers will be measured according to the force perturbations due to the gravitational fluctuations of the tangential load force 3.1 Role of Visual Feedback in Grip-Load changes and to errors in the trajectory 3.2 Role of Cutaneous Feedback in the Grip- resulting from the gravitational and object Force Coordination during Circular Arm profile.This issue is of particular interest Load Force Coordination during Circular accelerations (Fig. 5A). Movements with a Hand-Held Load in because horizontal load forces remain Arm Movement with a Hand-Held Load The kinematics variables will be recorded Different Gravitational Fields unchanged by gravity modifications, whereas in Different Gravitational Fields by a 3-D movement tracking system Experiment team: O.White, P.Lefèvre, G. Blohm, this is not the case for the vertical Experiment team: A. Smith, J.S. Langlais, (OptoTrak 3020, Northern Digital, Ontario, J.L.Thonnard components. O. White, J.L.Thonnard CDN). Studied will be the displacement, Scientific Objectives Eye movements and the role played by Scientific Objectives angular speed and acceleration of the Eye-hand coordination will be studied by visual feedback when performing this task in It has already been established that after instrumented object grasped and of the varying the arm trajectory of subjects new gravity fields are also of interest. relatively brief exposures (about five episodes upper limb (Fig. 5C). manipulating an object in novel gravity Therefore the gaze behaviour will be studied of 30 s each) to microgravity, subjects learn to In order to investigate eye-hand fields.The coupling between the grip force in order to detect if subjects direct their gaze adapt their grip forces to compensate for the coordination and the influence of visual and the load force will be studied when the to critical landmarks and how these altered tangential forces on the skin feedback on the dynamics of prehension, a vectorial direction of the object acceleration landmarks impinge on the action (Johansson (Augurelle et al., 2003). Since previous studies 3-D eye-movement recording system is is continuously changed in relation to the et al., 2001). (Smith et al., 2002; Saels et al., 1999) had required.The most suitable system is a gravity during a figure of ‘∞’ arm movement. clearly shown that this adaptation to Chronos video-based 3-D binocular eye When one moves an object in the frontal Description of the Experiment unexpected load forces is mediated by movement recording system (Skalar Medical, plane following a figure of ‘∞’ trajectory at a The subject is secured by a seat belt on a cutaneous afferents on the skin of the fingers Delft, NL; Fig. 5B). constant speed, the object is subjected to chair, with the instrumented object grasped, and palm at 1 g, there is every reason to The results of these investigations will the vertical gravitational acceleration and to in the frontal plane, between the thumb and believe that the adaptation to microgravity increase our understanding of the the centripetal acceleration.The load force the index finger of the right hand. On a signal involves the same tactile receptors.This study

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will try to define the minimal tactile spatial by feedback control (Witney et al., 2001). A 4. Perspectives inspired control algorithms in a robot acuity needed to adapt the grip forces problem is then to dissociate the two forms Microgravity provides an excellent installation that operates in different normally used in a 1 g environment to of control in the behavioural record. One environment to assess the properties of the gravitational fields. A number of learning microgravity.The effect of wearing little caps method is to limit analysis to the initial phase motor system.‘Changes’ in gravity can be strategies have been proposed in the field of covering the thumb and index finger (Fig. 7) of an action, say the first 20 ms, which is too considered as perturbations to the robotics for the adaptive control of complex on the grip force-load force coupling on the short a period for feedback correction to be manipulation task.These perturbations are manipulators.The ability of these strategies continuous manipulation of objects will be implemented. An alternative is to study very challenging to the motor system to adapt to novel gravitational environments investigated during parabolic flights.The collisions in which the time period over because they require rapid adaptation to the can easily be tested. Robots implementing caps are made of materials that are evaluated which the load is applied is too short to changing environment.They provide a these algorithms can be trained to perform before parabolic flight for their capacity to allow a feedback loop to operate powerful tool for the analysis of coordination optimally in 1 g.They can then be placed in filter variations in tangential force. (Johansson & Westling, 1988; Turrell et al., underlying dexterous manipulation, as altered gravity fields to see how the control 1999).The proposal is to analyse grip force shown by the studies reviewed above. adapts to the new constraints. Comparisons Description of the Experiment control in repetitive collisions during In the future, we should be able to can then be made between the actions of the The subject is secured by a belt on a chair, parabolic flight to determine the role played investigate the respective roles of robot in the novel environment and the with the instrumented object grasped, in the by gravity in prediction of collision load feedforward and feedback in more complex actions of human subjects faced with the frontal plane, between the thumb and the forces.The task will blend elements of two motor tasks and assess the adaptation same challenge. index finger of the right hand. On a signal paradigms used extensively by Wing in his capabilities of the motor system.This could delivered 20 s before the 1.8 g pull-up phase, previous research: cyclic movement and be done by manipulating visual and haptic 4.2 Studies of Sensorimotor Integration the subject is requested to move the object collision. feedback during motor tasks performed in Through Sensory Conflicts and Virtual continuously in a figure of ‘∞’ trajectory in the microgravity. Using methods of robotics and Reality frontal plan. He is instructed to maintain the Description of the Experiment virtual reality combined with measurements Effective control of movement requires the movement constant across each gravity The subject is secured by a seat belt on a of human motor behaviour, we can explore integration of information from a variety of phase of the parabola.The subject is trained chair with the instrumented manipulandum movement-control strategies.These studies sensory modalities, such as vision, cutaneous at 1 g before the flight campaign.Two grasped between the thumb and the index could also contribute to the design and touch, muscle proprioception and vestibular. subjects will be studied on each flight, each finger of the right hand. He performs a control of robotic arms to be used in These modalities are complementary; the for 15 parabolas. targeted tapping task with the challenging environments such as space. combination of sensors provides more manipulandum while eye movements and Several examples of possible experiments are information than any one modality alone. An 3.3 Grip Force in Controlled Collisions in kinematics of the upper limb are monitored. outlined below. interesting way to study how the central Different Gravitational Fields He briefly taps the manipulandum randomly nervous system calibrates and integrates all Experiment team: A.Wing, J. McIntyre, A.Witney, on surfaces placed above and below the 4.1 Interdisciplinary Studies of Robotics this information from different sources is to R.M. Bracewell, O.White, J.L.Thonnard hand’s neutral position. and Human Motor Control introduce sensory conflicts by which one Scientific Objectives Analyses will include modulation of grip The interaction between neuroscience and sensory modality is perturbed with respect to Studies (see Wing, 1996, for review) have force with collision load force and the timing robotics is two-fold: neuroscience provides the other. Such conflicts can be induced shown that grip force used to overcome load of eye movement relative to tap events.The knowledge about the nervous system that using techniques of virtual reality in which forces and torques in lifting and inertial analyses are expected to show dependence can be used to build anthropomorphic the experimenter can influence the reliability forces and torques in moving is adjusted in of timing and amplitude of peak grip force robots; and anthropomorphic robots are a of sensory information provided to the anticipation of the load (Johansson, 1996; rates on gravitational conditions. A primary powerful platform for experimental subject. For example, one can create a world Wing, 1996; Jenmalm et al., 1998; Wing & focus is on the extent to which there is validation of theories and hypotheses in which a 10 cm movement of the hand is Lederman, 1998). Prediction may not be progressive adaptation over successive formulated by neuroscientists. One can displayed as a 20 cm movement in the visual correct and in many cases predictive cycles after the transition between 2 g and imagine an experiment investigating eye- field; this is a proprioceptive-visual conflict. feedforward control may be supplemented 0 g and between 0 g and 2 g. hand coordination using neurobiologically- Under terrestrial conditions, muscle

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proprioception is important in recalibrating the same trajectory in terms of distance, References Grip when Lifting Rougher or More for the changed visuo-motor relations. Novel velocity and acceleration (Hubbard, 1995; Augurelle, A.S., Penta, M.,White, O. & Slippery Objects. Exp. Brain Res. 56, 550- gravitational environments provide a unique Senot et al., in preparation).This Thonnard, J.L. (2003).The Effect of a 564. experimental manipulation of proprioception phenomenon can be interpreted as a Change in Gravity on the Dynamics of Johansson, R.S. & Westling, G. (1988). for examining the adaptability of such cognitive prediction of the effects of gravity Prehension. Exp. Brain Res. 148, 533-540. Programmed and Triggered Actions to recalibration. on the ball – the subject anticipates that the Flanagan, J.R. & Tresilian, J.R. (1994). Grip-Load Rapid Load Changes during Precision Grip. Vestibular information is another class of ball will accelerate or decelerate depending Force Coupling: a General Control Strategy Exp. Brain Res. 71, 72-86. sensory input which must be integrated with on the direction of movement. On Earth, for Transporting Objects. J. Exp. Psychol. Johansson, R.S.,Westling, G., Backstrom, A. & muscle proprioception. It normally sensation of gravity can easily define the up Hum. Percept. Perform. 20, 944-957. Flanagan, J.R (2001). Eye-Hand contributes to tasks involving whole-body and down directions that are the source of Flanagan, J.R. & Wing, A.M. (1993). Modulation Coordination in Object Manipulation. movement. Consider a task in which one this effect. In microgravity, however, it of Grip Force with Load Force during J. Neurosci. 21, 6917-32. hand is used to provide grip for stabilisation appears that additional cues in the Point-to-Point Arm Movements. Exp. Brain Kawato, M. (1999). Internal Models for Motor when picking up an object with the other environment (such as the direction of Res. 95, 131-143. Control and Trajectory Planning. Current hand at a horizontal or vertical distance of lighting, the spatial layout of the module) Flanagan, J.R., Nakano, E., Imamizu, H., Osu, R., Opinion in Neurobiology 9, 718-727. more than arm’s length. Because of the can nevertheless induce a perception of ‘up’ Yoshioka,T. & Kawato, M. (1999). McIntyre, J., Zago, M., Berthoz, A. & distance, the subject must move the whole and ‘down’ that leads the subject to Composition and Decomposition of Lacquaniti, F.(2001). Does the Brain Model body.The grip used by the stabilising hand anticipate the effects of gravity even though Internal Models in Motor Learning under Newton’s Laws? Nat. Neurosci. 4(7), 693- may then provide an index of prediction of it is no longer present (McIntyre et al., 2001). Altered Kinematic and Dynamic 694. loading caused by whole-body movement. Experiments performed in altered Environments. J. Neurosci. 19, RC34. Saels, P.,Thonnard, J.L., Detrembleur, C. & Manipulating the gravitational field is one of gravitational environments can shed light on Goodwin, A.W., Jenmalm, P.& Johansson, R.S. Smith, A.M. (1999). Impact of the Surface the very few means for modulating the the construction of these cognitive (1998). Control of Grip Force when Tilting Slipperiness of Grasped Objects on Their sensory inputs provided by the vestibular representations and how they affect the Objects: Effect of Curvature of Grasped Subsequent Acceleration. system. control of movement. Furthermore, such Surfaces and of Applied Tangential Torque. Neuropsychologia 37, 751-756. In summary, the ability to perform studies may aid in the conception of J. Neurosci. 18: 10724-10734. Senot, P., Zago, M., Lacquaniti, F.& McIntyre, J. experiments in altered gravity environments countermeasures or tools that might be Hubbard,T.L. (1995). Cognitive How Downward and Upward Trajectories provides a unique opportunity to study provided to astronauts to compensate for Representation of Motion: Evidence for Influence the Timing of Motor Responses vestibular-proprioceptive and visual- the missing stable orientation reference that Friction and Gravity Analogues. J. Exp. in Virtual Ball Catching, (manuscript in proprioceptive sensory integration for motor is usually provided by gravity. Psychol. Learn. Mem. Cogn. 21(1), 241-254. preparation). control. Jenmalm, P., Goodwin, A.W. & Johansson, R.S. Smith,A.M.,Chapman,C.-E.,Deslandes,M., Acknowledgements (1998). Control of Grasp Stability when Langlais, J.-S. & Thibodeau, M.-P.(2002).The 4.3 Interactions between Sensory and This project was supported by a grant to Humans Lift Objects with Different Surface Role of Friction and Tangential Force in the Cognitive Influences on Motor Control Prodex, OSTC (Belgian Federal Office for Curvatures. J. Neurophysiol. 79, 1643-1652. Subjective Scaling of Tactile Roughness. Our ability to function in the physical world is Scientific,Technical and Cultural Affairs), a Johansson, R.S. (1996). Sensory Control of Exp. Brain Res. 144, 211-223. not based exclusively on sensory signals. contract with the Canadian Space Agency Dexterous Manipulation in Humans. In Turrell,Y.N.,Li,F.-X.& Wing,A.M.(1999).Grip Through experience, we create cognitive (RB001336) and an ESTEC Contract Hand and Brain: The Neurophysiology and Force Dynamics in the Approach to a representations of how the world works. For (14725/00/NL/JS Topical Teams). Psychology of Hand Movements (Eds. Collision. Exp. Brain Res. 128, 86-91. instance, a human subject who observes an A.M. Wing, P. Haggard & J.R. Flanagan), Westling, G. & Johansson, R.S. (1984). Factors approaching ball will trigger a interceptive Academic, San Diego, USA, pp381-414. Influencing the Force Control during response earlier for a ball that is falling from Johansson, R.S. & Westling, G. (1984). Roles of Precision Grip. Exp.Brain Res. 53, 277-284. above than for the same ball that is rising Glabrous Skin Receptors and Sensorimotor White, O., McIntyre, J., Augurelle, A.S. & from below, even though both balls follow Memory in Automatic Control of Precision Thonnard, J.L. Do Novel Gravitational

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Environments Alter the Grip-Load Force Coupling at the Fingertips? Experimental Topical Team Members Brain Res., submitted. Wing, A.M. (1996). Anticipatory Control of J.-L.Thonnard, J. McIntyre Grip Force in Rapid Arm Movement. In A.S. Augurelle, C.N.R.S. - Collège de France, Laboratoire de Hand and Brain: The Neurophysiology and O. White, Physiologie de la Perception et de l’Action, 11 Psychology of Hand Movements (Eds. M. Penta Place Marcelin Bertholet, F-75005 Paris, A.M. Wing, P. Haggard & J.R. Flanagan), Unité de Réadaptation et de Médecine France. Academic, San Diego, USA, pp301-324. Physique, Université Catholique de Louvain, Email: [email protected] Wing, A.M. & Lederman, S. (1998). Anticipating Tour Pasteur (5375), Avenue Mounier 53, Load Torques Produced by Voluntary B-1200 Brussels, Belgium. P. Le f è v r e, Movements. J. Exp. Psychol. Hum. Percept. Tel: +32 2 764 53 67 G. Blohm Perform. 24, 1571-1581. Fax: +32 2 764 53 60 CESAME & Laboratoire de Neurophysiologie, Witney, A.G.,Wing, A.,Thonnard, J.-L. & Email:[email protected] Université Catholique de Louvain, 4 avenue Smith A.M. (2001). Feedforward and G. Lemaître, B-1348 Louvain-la-Neuve, Feedback Contributions to Precision Grip. A. Smith, Belgium. In From Basic Motor Control to Functional J.-S. Langlais Email: [email protected] Recovery II (Ed. Gantchev, N.), Sofia, Centre de Recherche en Sciences Bulgaria, Prof. M. Drinov Academic Neurologiques, Pavillon Paul-G.-Desmarais, R.M. Bracewell Publishing House, pp163-176. #4131, 2960 Chemin de la Tour, Université de Centre for Cognitive Neuroscience, University of Witney, A.G.,Wing, A.,Thonnard, J.L. & Montréal, Montréal, Québec, Canada H3T 1J4. Wales, Bangor, Gwynedd LL57 2AS, UK. Smith, A.M.The Cutaneous Contribution to Email: [email protected] Email: [email protected] Adaptive Precision Grip. Trends Neurosci.,in press. A.Wing, S. Stramigioli Wolpert, D.M. (1997). Computational A.Witney Drebbel Institute of Systems and Control, Approaches to Motor Control. Trends Cog. Sensory Motor Neuroscience (SyMoN), University of Twente,Twente,The Sci. 1,209-216. Behavioural Brain Sciences Centre, School of Netherlands. Psychology,The University of Birmingham, Email: [email protected] Edgbaston, Birmingham B15 2TT, UK. Email: [email protected]; [email protected]

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Report of the Muscle Physiology ESA Topical Team in Life Sciences Muscle Physiology

Contributors: M. Narici, Stoke-on-Trent (UK) (Coordination) R. Bottinelli, Pavia (I) J. Zange, Cologne (D) B. Quistorff, Copenhagen (DK) O. Rutherford, London (UK) F.Goubel, Compiegne (F) P.A.Tesch, Stockholm (S)

1. Introduction devise the way ahead for more effective and causes need to be investigated.To this Muscles are a highly dynamic and plastic efficient countermeasures against muscle purpose, molecular biology studies into body tissue.Their role is to execute atrophy in humans flying in space.This will exercise countermeasures. For both gene transcription and translation are movement and support different postures, also improve our understanding of Earth- spaceflight and bed rest, changes in recommended. and they can adapt to changed bound mechanisms. maximum force (F) tend to be greater than metabolic/mechanical demands due to those of muscle size, indicating a decrease in 2.2 Recommendations for the Future loading or unloading over a matter of days to 2. Muscle Anatomical and Physiological F/CSA. Similarly, a disproportionate decrease More data should be obtained using both weeks. In the longer term, this produces a Changes in Microgravity in explosive muscle power with respect to simulated and actual microgravity on the gross build-up or reduction of tissue volume, Preferential postural muscle atrophy is well muscle atrophy is observed. Although the back, neck, thigh and arm muscles. In-flight cross-sectional area and, not least, documented for up to 120 day of bed rest. exact causes of this phenomenon are still not activity and countermeasure intensity, biochemical capacity for energy turnover. The most reliable data are for the calf fully elucidated, in vivo, reduced neural drive, frequency and duration should be regularly There is clearly a ‘short-term’ and a ‘long- muscles (plantar and dorsiflexors) because decreased single fibre specific tension, logged.The latter is an essential step for term’ adaptational capacity. they are based on several observations. Calf alterations in muscle architecture and, as interpreting inter-subject variability.The use Some muscles are active continuously (for muscle atrophy proceeds almost linearly up recent evidence suggests, reduced tendon of 24 h EMG and goniometer recording is example, heart, diaphragm, eye and some to ~40 days of unloading at a rate of stiffness (Reeves et al., 2005) have been highly recommended to monitor muscle postural muscles), while others have periods ~0.5%/day. Recent evidence from the shown to be play a significant role. By and activity and limb movements in-flight. of different durations with no or little activity. Toulouse bedrest study (Reeves et al., 2002) large, little or no change in muscle-twitch Investigators studying muscle atrophy Finally, some muscles are expected to shows that, after 90 days of bed rest, the kinetics is found for Space Shuttle flights and should report both muscle volume and provide a near-maximum dynamic or static plantarflexor cross-sectional area is reduced for various unloading human models.There cross-sectional area. In-flight measurements output for shorter or longer periods. by ~30%.This finding seems quite alarming are controversial data for changes in of muscle size could be preformed aboard For striated muscles, there is a basic because it approaches the limit of 40% fatiguability; both an increase and a decrease the International Space Station, using the common requirement in terms of muscle beyond which a loss of muscle mass is have been reported after actual and Human Research Facility ultrasound feature. function and mechanics even though the clinically considered as a serious health simulated microgravity. Structural, The use of percutaneous electrical or striated muscle tissue of the heart differs concern (Roubenoff & Hughes, 2000). There biochemical and radiological signs of muscle magnetic stimulations is recommended for from general skeletal muscle tissue on is inconsistency in the way atrophy is damage have been observed after bed rest an objective evaluation of maximum decisive functional tasks. As a consequence reported, with some authors using cross- and after reloading of limb-suspended voluntary contraction. Further investigations of the broad spectrum of functionality, one sectional area (CSA) but others muscle animal muscle. on muscle damage during reloading appear can identify significant differences in a whole volume (VOL). Since force is proportional to necessary.The use of integrated techniques array of anatomical and biochemical details, CSA and power to VOL, these dimensional 2.1 Conclusions (using structural biochemical, radiological which in turn make a particular muscle more data should not be combined. For Space Bed rest and limb-suspension are valid and contractile markers) is recommended appropriate for the specific task it has to Shuttle flights lasting up to 17 days, muscle models for studying the effects of given the difficulty of this assessment. More perform. VOL may decrease up to 10%, though inter- muscoloskeletal unloading.There is scanty studies are needed on muscle fatigue The Topical Team for Muscle Physiology subject variability is considerable. Accurate knowledge on the exact causes of muscle during maximal and submaximal has identified and discussed the basic atrophy data for longer spaceflights on the weakness; the most intriguing finding is the contractions, both voluntary and electrically- parameters and functions in relation to the Mir space station are available for only a few decrease in force per unit of muscle cross- elicited. change of loading and activity pattern seen cosmonauts, and range within 6-20% after sectional area. Inter-subject variability, in- during simulated and actual spaceflight. A 180 days. It is most probable that much of flight countermeasures, age and gender may 3. Findings of In Vitro Studies on Whole significant overlap with similar situations on the variation in the degree of muscle atrophy be responsible for the considerable variation Isolated Muscles and Single Muscle Earth can be identified, with clinical among subjects and among missions (even on muscle atrophy among crewmembers. Fibres application as a direct benefit. after taking into account mission duration) However, inter-subject variability is indeed an Most in vitro studies on the effect of For spaceflight, the main goal has been to relates to the type and adherence to in-flight important biological phenomenon and its weightlessness on skeletal muscle have

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been performed on animal muscle samples. – fibre type distribution (by electrophoresis) Spaceflight simulation using bed rest or contain nuclear and mitochondrial encoded There have been very few studies performed and calcium cycling (possibly by newly limb suspension (4-6 weeks), both performed subunits. Simpler model systems like the LDH on human muscles.Two studies have been developed imaging techniques); without exercise countermeasures, results in isoenzyme pattern will probably be easier to done on fibre type distribution of vastus – coordinated expression of myofibrillar a decreased activity of mitochondrial interpretate. lateralis muscle after spaceflight. More proteins and dihidropiridine and ryanodine enzymes and no or only small and varying detailed analysis has been done after bed receptors (by electrophoresis and western changes in the activity of glycolytic enzymes. 5. Neuromuscular Adaptations to rest: fibre type distribution, contractile blot); Muscles of different fibre type composition Weightlessness properties of isolated human muscle fibres – myofibrillar protein density (by react quantitatively different but show the Limited information on changes to the cells (F/CSA), maximum shortening velocity, Ca++ electronmicroscopy) and F/CSA of isolated same qualitative pattern. within the cord is available from rats sensitivity, power output and optimal muscle fibres in vitro; However, more work is needed in this field, following 0 g exposure and hindlimb velocity and stiffness. No information on Ca++ – proteome analysis of muscle samples. in particular in the evaluation of ATP suspension. Minimal changes have been seen uptake and release by sarcolasmic reticulum turnover at different exercise levels in in cell size or oxidative potential to ventral has been collected. A shift towards fast fibres The latter analysis appears particularly relation to actual work output, i.e. possible horn cells in the lumbar spine (most likely was reported after spaceflight, but not after relevant because it provides a comprehensive changes in contraction efficiency. Also, alpha and gamma motorneurones and bed rest. Myofibrillar protein density and view of the changes in a very large number of variations in the pattern of fibre type interneurones). In the cervical region of the number of thin filaments were found to be proteins and reveals still-unknown recruitment must be studied, which cord, more severe adaptations were seen, lower after bedrest. F/CSA of isolated muscle phenomena related to unloading. A ‘small potentially could affect whole muscle energy most probably due to the greater level of fibres was decreased in one bed rest study needle’ biopsy technique should be used metabolism. For future pre- and post-flight or hypoactivity in the forelimbs. Lumbar spinal and unchanged in another study. because it allows more frequent sampling and simulation studies, examination of the ganglia cells showed a reduction in RNA and potentially can be performed in space.The energy metabolism of human muscle by protein content and reduced oxidative 3.1 Conclusions usual needle biopsy technique should still be non-invasive techniques such as 31P-MRS or capacity of the large cells, most likely Human studies are not always consistent used when analysis of single muscle fibres in near-IR spectroscopy will make an essential reflecting a decrease in afferent activity from with animal studies. Information following vitro is required. contribution to documenting the current the spindles during 0 g. Hindlimb suspension spaceflight is very limited. Findings after bed physiological state.This could be especially and electrical silence have consistently rest are not consistent with one another. 4. Biochemistry and Metabolism useful in the validation of countermeasures. caused much smaller, if any, changes to these These might derive from differences in Short-duration spaceflight (5-11 days) without The experimental set-up would involve a neuronal pools and therefore are not a good muscles used and in the bed rest duration. exercise countermeasures does not result in a combination of non-invasive techniques for model of weightlessness. Changes to the Discepancies between animal and human change in mitochondrial enzymes of vastus the examination of energy metabolism and neuromuscular junction, similar to that seen studies might be due to a different lateralis but induces an increase of glycolytic physiological measurements such as following partial or complete denervation, recruitment of skeletal muscles in biped and enzymes in slow fibres but no change in perfusion, hydration, oxygenation and can be seen in rats flown between 7 days and quadruped. glycolytic enzymes in fast fibres. After 3.5- muscle force/power output. Potential 14 days, withthe effects being largest in week and 6-month spaceflights including changes in the fuelling of oxidative predominately slow muscles.Very few 3.2 Recommendations countermeasures onboard the Russian space metabolism by carbohydrates or fatty acids junctions have been studied and the extent Human skeletal muscle samples should be station Mir, non-invasive 31P-MR spectroscopic should by studied, for example, by non- of damage seems incompatible with the fact analysed after long-duration spaceflight and examinations did not show changes in the invasive 1H- and 13C-MRS techniques. that the specific tension of the same muscles bed rest (a month or more).The following aerobic or the glycolytic work capacities of the Studying the effects of microgravity on was unaffected. analyses should be performed: calf muscle. Although the consumption of gene regulation of metabolic enzymes is still A large body of evidence now shows that phosphocreatine at a given workload was at a very early stage but holds great muscle activation is reduced after – protein turnover and especially synthesis significantly increased, muscles weakened by potential. Recent studies have shown the immobilisation and bed rest. As yet, good of myofibrillar proteins (by analysis of spaceflight reached fatigue at higher complexity of microgravity effects, information following spaceflight is lacking. mRNAs); phosphocreatine than in controls. particularly in mitochondrial enzymes, which We have relatively little quantitative

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information on how muscle activity is mechanisms following exposure to 0 g is would appear not to mimic flight, which bGH (not iGH) and IGF-1 release. More changed in either space or bed rest. recommended. would argue against a role for detailed study of the role of muscle afferent Detailed information on the activity hypoandrogenism in this model of muscle stimulation on bGH release and subsequent patterns of muscles during weightlessness is 6. Hormonal Changes atrophy. Ground-based parallels of IGF-1 levels is also required. If shown to be required. The changes considered included: hypogonadism include ageing and the elite important, a number of countermeasures We now have more refined techniques to catecholamines, cortisol, insulin,T3 and T4, endurance athlete. could be explored, including rhGH study control of movement, including testosterone and GH/IGF-1. No single study There is increasing evidence that there treatment.This information will also be Positron Emission Tomography (PET) and has measured all of these, and so a full may be subtle changes to the GH/IGF axis. important in examining the potential magnetic stimulation.These could be used to endocrine profile is not available.This can Previous studies may have been limited by effectiveness of modulating the GH/IGF axis explore the integrity of the normal control lead to difficulties in interpreting results in the type of assay used to measure GH and in ageing. mechanisms following exposure to 0 g.The terms of the catabolic versus anabolic few have measured IGF-1. Further studies elderly also experience postural instability balance. Animal models may be less useful in need to concentrate on bGH (not iGH) and 7. Reflex and Stiffness Adaptations in and altered gait patterns which can pre- this area because the psychological and IGF-1 release. Microgravity dispose them to falling. Research aimed at physical stresses placed on animals will be Changes in stiffness of the musculo-skeletal exploring the mechanisms responsible and very different from those on people.The 6.1 Recommendations for the Future system have consequences for the control of effective countermeasures could have majority of human studies show a decrease A full endocrine profile of catecholamines, movement because stiffness governs the potential benefits for this group in NorAd and variable response in cortisol, insulin,T3 and T4, testosterone and mechanics of the interaction between the adrenaline.The limited data from long flights GH/IGF-1 should be obtained in the same system and its external environment.The 5.1 Recommendations for the Future find raised NorAd. individuals. literature indicates that changes in More studies on changes to the cells within Cortisol is largely unchanged in either Studies should also concentrate on NorAd, mechanical properties and in modalities of the cord should be performed.The time spaceflight or bed rest and therefore is with regular 24 h urine collection and activation can be expected in muscles between landing and the first recovery unlikely to be the major cause of protein accurate documentation of countermeasures hypoactivated by weightlessness. measurement should be minimised.The loss. and activity levels.The use of clenbuterol Furthermore, when considering identification of the precise neuronal pool Results on insulin levels are highly administration, as a countermeasure, could mechanically-induced reflexes it is being studied needs to be identified and variable but there appears to be no human be studied in bedrest conditions. conceivable that changes in stiffness of related to afferent and efferent activity. studies considering the insulin sensitivity of As for insulin, there is a need to study both musculo-tendinous elements take part in Improved microscopy techniques should muscle. Studies are needed of both atrophied and non-atrophied muscles such the reflex adaptation of the hypoactivated enable faster and more accurate examination atrophied and non-atrophied muscles, such as upper versus lower limb; this may muscles. Interrelations between reflex and of NMJs. Electrophysiological studies of as upper versus lower limb; this may discriminate between a systemic and local stiffness changes need to be studied in a synapses need to be carried out to determine discriminate between a systemic and local unloading effect. Unloaded muscles may also large population of astronauts with a better any functional consequences of structural unloading effect. be more sensitive to the effects of T3 and knowledge of countermeasures. changes. Further studies are needed to Overall, the evidence favours an increase future work should explore this in more establish if muscle activation is altered by in thyroid hormone levels.This could play a detail. Measurements of free T3 are required. 7.1 Conclusions spaceflight and bed rest. Extended role in the switch to faster gene expression The effects of spaceflight on the Studies of reflex changes with hypoactivity investigations on the muscle activity pattern seen in real and simulated microgravity. hypothalamic-pituitary-gonadal axis needs to produced conflicting results in humans during spaceflight should be performed Unloaded muscles may also be more be studied in more detail and expanded to using T reflex methodology, whereas an using chronic EMG recordings of activity sensitive to the effects of T3. women.Testosterone replacement could increase in H reflex was often reported and from a selection of proximal and distal, lower Recent evidence suggests a reduction in then be investigated as a potential interpreted in terms of enhancement in and upper limb muscles. testosterone; the effects of spaceflight on the countermeasure, at least during shorter synaptic efficacy. For stiffness changes with The use of PET and magnetic stimulation hypothalamic-pituitary-gonadal axis need to flights. hypoactivity, animal data indicate a decrease to explore the integrity of the normal control be studied in more detail.The bedrest model Further studies need to concentrate on in stiffness of the isolated and tetanised

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muscle, whereas human data indicate an have carried out in-flight exercise using application of lower body negative pressure training can be defined and feasible devices increase in stiffness of the voluntarily different paradigms, yet they suffered from (LBNP), transcutaneous designed. Any countermeasure being activated muscle group. loss of strength upon return to Earth. Since electromyostimulation, intermittent evaluated with regard to its efficacy to these activities were not logged, very little acceleration or other means of producing ameliorate changes in skeletal muscle size 7.2 Recommendations for the Future has been learned about the efficacy of increased muscle stretch or loading appear and function, integrity of the contractile – obtain reflex and muscle stiffness data on exercise countermeasures from past to be less promising. machinery or metabolic profile should also a large population of astronauts; spaceflights. In-flight cycle ergometer study susceptibility to reloading and effects – take into account effects of exercise has been used mainly to maintain 8.1 Conclusions of concurrent aerobic and resistance training. countermeasures; cardiovascular function. Such exercise is not Although muscle atrophy and weakness are – analyse kinetics of parameters during the likely to maintain musculo-skeletal function major concerns of microgravity exposure, the References flight.Without this information, it will be in space, because aerobic exercise use of in-flight countermeasures has so far Reeves, N., Maganaris, C.N., Ferretti, G. & impossible to know if the post-flight reflex programmes typically do not produce been quite lax both in performance and Narici, M.V. (2002). Influence of Long-Term changes are due to weightlessness or to muscle hypertrophy at 1 g.Results from activity logging such that definite Bed Rest on Muscle Architecture and the recovery of gravity conditions; short-duration bed rest or spaceflight studies conclusions on the efficacy of the various Tendon Mechanical Properties. J. Physiol – propose experimental protocols in order also infer aerobic exercise performed up to methods used cannot be drawn. Resistance 543P,S115. to dissociate better central and peripheral 5 times per week did not help to prevent training has been proved to be effective in Reeves, N.D., Maganaris, C.N., Ferretti, G. & neurophysiological adaptations (notably muscle wasting or reduction in muscle preventing muscle wasting during various Narici, M.V.(2005). Influence of 90-day bilateral testings); strength. simulated microgravity models carried out Simulated Microgravity on Human Tendon – continue studies into the effects of In contrast, healthy individuals who were over 14-110 days. Other methods appear less Mechanical Properties and the Effect of simulated or real microgravity in animals confined to bed or subjected to unilateral promising. Resistive Countermeasures. J. Appl Physiol., in order to study, for example, the eventual lower limb unloading for up to 110 days and in Print. plasticity of the sensory receptors. performed various concurrent resistance 8.2 Recommendations for the Future Roubenoff, R. & Hughes,V.A. (2000). exercise were able to maintain muscle Because of the shortcomings of studying Sarcopenia: Current Concepts. 8. Countermeasures in Space: Skeletal protein synthesis, volume and strength.Thus, space crews, spaceflight analogues J. Gerontology. Ser. A, Biolog. Sci. & Med. Sci. Muscle it is evident that unloaded skeletal muscle (prolonged bed rest or unilateral lower limb 55, M716-24. Several approaches have been proposed to benefits from bouts of resistive exercise. unloading) should be employed for future combat the atrophy and deteriorated While this response has been confirmed in a studies aimed at validating the efficacy of function of skeletal muscle that occurs in large number of independent studies various exercise countermeasures to offset space owing to the lack of weight-bearing. It focusing on the quadriceps muscle, it the negative effects of long-duration is safe to say that none of these methods has appears that the more robust triceps surae spaceflight.The evolution of novel molecular been thoroughly evaluated with regard to muscle atrophy observed after simulated techniques and assays for studies of small their efficacy to prevent or ameliorate muscle spaceflight is not entirely offset by the human tissue samples is encouraging and wasting and function impairment in humans exercise paradigms employed so far. should be employed in spaceflight exposed to chronic microgravity. However, Collectively, however, these results suggest simulation studies.This will certainly limit the and regardless of the mechanism(s) that resistive exercise ameliorates or need for studies of lower mammals to responsible for the negative impact of attenuates the negative effects of spaceflight address more mechanistic questions. So far, spaceflight on skeletal muscle, on skeletal muscle. in-flight resistive exercise is undoubtedly the countermeasures to this effect are imperative For various reasons, other proposed most attractive approach to combat the on the International Space Station and other countermeasures, such as the administration global changes in muscle size and function. long-duration space missions. of drugs, aimed at limiting skeletal muscle Thus, future studies should be directed such A large number of astronauts/cosmonauts, protein loss or boosting protein synthesis, that the optimal protocol for resistance

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Topical Team Members

M.V. Narici O.M. Rutherford Institute for Biophysical and Clinical Research Division of Physiology, Shepherd’s House, into Human Movement, Manchester Guy’s, King’s & St Thomas’ School of Metropolitan University, Alsager Campus, Biomedical Sciences, Kings College London, Stoke-on-Trent, UK. Guy’s Campus, London Bridge, London Tel: +44 161 247 5659 SE1 1UL, UK. Fax: +44 161 247 6375 Email: [email protected] F. Goubel Division Biomecanique et Instrumentation, R. Bottinelli Medicale UMR CNRS 6600 UTC, Universite Dipartimento di Medicina Sperimentale, Sezione de Technologie de Compiegne, B.P.20.529, di Fisiologia umana, Universita di Pavia, Pavia, F-60205 COMPIEGNE Cedex, France. Italy. Email: [email protected] Email: [email protected] P. A . Te s c h J. Zange Section for Muscle and Exercise Physiology, DLR Institute of Aerospace Medicine, Köln, Department of Physiology & Pharmacology, Germany. Karolinska Institute, Stockholm, Sweden. Email: [email protected] Email: [email protected]

B. Quistorff Dept. Medical Biochemistry and Genetics, Panum NMR Centre, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen, Denmark. E-mail: [email protected]

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Low-Back Pain in Microgravity: Report of the ESA Topical Team in Life Sciences Causes and Countermeasures Low-Back Pain Contributors: C.J. Snijders, Rotterdam (NL) (Coordination) C.A. Richardson, Brisbane (AUS)

Low-back pain (LBP) is common not only on the pain source is usually very difficult to model developed on the sagittal plane Earth, but also in space.This is remarkable diagnose accurately. For this reason, a mechanics explains iliolumbar ligament because, on Earth, LBP is ascribed mostly to plethora of treatments have been developed tension in flexion and ease of strain by heavy spinal loading.The Topical Team was by various medical disciplines.The challenge erector spinae and multifidus muscle force. established by ESA to answer the question is that treatments for LBP must have The agonist-antagonist model about the ‘What is the aetiology of LBP during flight scientific evidence of their effectiveness. sacroiliac joints (Snijders, 1993) relates back and what countermeasures may be Also reported in literature is that up to muscle dysfunction with pelvic floor muscle Fig. 1.Transverse muscles press the sacrum between the hip bones.This deep-muscle corset for developed?’The starting point for the Team’s 72% of Space Shuttle crewmembers dysfunction (Figs. 2 & 3). lumbopelvic stability is active with gravity loading.Sacroiliac joint (1).Muscles: transverse activities is a biomechanical model experience some form of LBP during flight; abdominal (2), piriformis (3), internal abdominal oblique (4), pelvic floor (5). developed at the Erasmus Medical Centre in 28% of astronauts report moderate to severe 2.2 Microgravity Model Rotterdam (NL) that describes the function of LBP (Thornton, 1987; Fuchs, 1980).This is Microgravity causes a decrease in muscle a deep-muscle corset to stabilise lumbar and remarkable because, on Earth, LBP is mostly performance. It gradually results in strength pelvic joints. ascribed to heavy spinal loading with deficits and decrease in power development, For spaceflight, the hypothesis was detrimental effects on the intervertebral changing mechanical properties, neuromotor formulated that muscle atrophy and discs (Wilke et al., 1999). Still, this concept control and proprioceptive feedback neuroplasticity in the absence of gravity does not explain the causes of 80-90% of LBP (neuroplasticity), with more effects on loading destabilises the lumbopelvic area. cases.Therefore, at Erasmus Medical Centre extensors than flexors (and more in the trunk The outcome of the Team activities is the in Rotterdam (NL), a different approach was and lower limbs). development of a theory for the source of chosen that: So, changing patterns of muscle control as pain in microgravity that identifies in seen in the microgravity model may be particular the iliolumbar ligaments.To help – includes the sacroiliac joints; fundamental issues in the development of Fig. 2.The sacroiliac joints (upper left) link pelvic floor muscle dysfunction with back muscle dysfunction. verify the theory,Team members were – adds the iliolumbar ligament as one of the LBP – improper loading of muscles, loss of involved in the Berlin Bedrest Study and the most important structures at risk; joint stability and muscle protection of joints. Fig. 3.Deep muscle corset being subject to wasting and loss of coordination in the microgravity Dutch Soyuz Mission. Based on the results of – relates low back pain with pelvic floor environment.Comprehensive biomechanical model on sacroiliac joint stability with transversely oriented these studies, countermeasures can be disorders; 2.3 LBP and Microgravity abdominal muscles (transversus abdominis), back muscles (sacral part of multifidus) and pelvic floor developed and implemented. – includes the non-weightbearing situation. The above performance changes result from muscles (coccygeus) (Snijders et al., 1993). changes in the muscle fibres themselves 1. Introduction 2. State of the Knowledge on LBP (histochemical and size) and from changes in Musculoskeletal disorders are the single most 2.1 Biomechanical Model neuromotor activation patterns.The expensive disease in society. Low-back pain The Team members have developed a decrease in performance owing to provides the greatest contribution and, biomechanical model on the transfer of the microgravity has been shown to occur in the despite ongoing research, the incidence of gravity load through the lumbar spine and following trunk and pelvic muscles: LBP and the costs of its influence on society pelvis, with special attention to the sacroiliac multifidus, gluteus maximus, erector spine, continue to rise. For 90% of patients, the joints.The model predicts a significant quadriceps femoris and abdominal muscles. aetiology of the pain remains obscure.The stability effect of deep-muscle forces These muscles are critical for normal 1-year prevalence is 36%, and is increasing. (Snijders et al., 1995, 1998, 2004; Richardson mechanical function of the trunk and pelvis, Based on epidemiologic studies, numerous et al., 2002), which is effective in the and their dysfunction is implicated as one of causes of LBP have been suggested.Various treatment of LBP (Richardson et al., 1999; the causes of LBP.Electrical stimulation is pathological lesions are possible in the 2004).This deep-muscle corset was not known to prevent the loss of muscle different structures of the lumbo-pelvic included in earlier space studies.The above performance that occurs with immobilisation region, but, even with modern technology, model is on the frontal plane (Fig. 1).The and disuse.

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2.4 Posture and Immobilisation 3.1 Berlin Bedrest Study ‘unloading’ as well as the effects of the These results are likely to contribute significantly to knowledge The adopted immobilised posture seen in The four separate measures of vibration exercise, are very encouraging. on the aetiology of LBP both in space and on Earth. astronauts is combined with a constant weightbearing status of the antigravity Based on the measures of lumbo-pelvic maintained flexed spine. Centre-of-mass muscles, developed by the University of stability, the pattern of dysfunction that ‘Yes’,questions about the type and intensity displacements do not remain stable Queensland, were included in the Berlin developed in the lumbo-pelvic muscles for of pain were completed with the use of a during complex postural equilibrium tasks Bedrest Study under the supervision of Team the control subjects at the end the 8-week visual analogue scale. Also asked was if the executed in weightlessness. Furthermore, member C. Richardson and coordinated by bedrest was similar to the pattern of muscle back was painful almost all the time, what in the absence of weight, subjects D. Felsenberg. dysfunction found in previous research on provoked the low-back pain and if it was changed their strategy for producing low-back pain patients.These results are likely possible to relieve the pain.The final question ankle torque during spaceflight, from a Summary of Preliminary Results to contribute significantly to knowledge on was if there was a change in bladder or bowel forward- to a backward-leaning posture The bedrest study involved an 8-week study the aetiology of LBP both in space and on function.The questionnaire was incorporated (Stapley & Pozzo, 1998). Owing to the on 20 subjects, divided equally between the Earth. in the general DSM Delta Physiology over-hydration of the disc tissues, the exercise group and the control group.The As predicted, vibration exercise had a Questionnaire with the schedule: spine becomes extremely lengthened. exercise involved weightbearing under body positive effect on some dysfunctional lumbo- Literature reports spinal length increases load with the addition of ‘whole body pelvic muscles and not on others (e.g. not on Pre-flight: 10±5 days before launch, baseline of 6-9 cm (Thornton et al., 1987; Fuchs, vibration’.When the data collection was lumbar multifidus). Further research is data were collected with the 1980). completed, a meeting was held in Berlin on required to determine the parameters that questionnaire; For the functional motion segments in 5 July 2004 for researchers to discuss the will optimise the effects of vibration exercise In-flight: completion of the questionnaire at the spine, this could refer to a change in preliminary results to date.This meeting did on a dysfunctional lumbo-pelvic muscle the end of every flight day; range-of-motion as well as mechanical not include the 1-year follow-up data, which system.This would allow preventative and Post-flight: for 10±5 days after landing, data restructuring and processes of micro- have not yet been completed for all subjects. treatment strategies for low-back pain in on return to gravity load were collected failure (Kraan et al., 2004). The University of Queensland contribution space and on Earth to be further explored. with the questionnaire. consisted of four tests of lumbo-pelvic 2.5 Related Factors stabilisation: 3.2 In-Space Study As the questionnaire was anonymous, the The influence of micro-failure and During the Dutch Soyuz Mission of April 2004, results of this single case study are presented mechanical overload due to vibration – Magnetic Resonance Imaging (MRI) for a questionnaire on LBP and bowel function in a global form and in consultation with the (launch) and astronaut stress is also the changes in lumbar muscles, including were used.This project was supervised by astronaut. emphasised.Weightlessness does not multifidus; Team member C. Snijders. generate stress when adapted to it. – MRI for estimations of transversus Results Returning from weightlessness to Earth abdominis contractions; Objective and Expectations No pre-flight complaints were recorded. causes stress. After prolonged flights, – MRI for changes in hip/pelvic The aim was to obtain data about the During the first days in-flight, peaking on stress associated with readaptation to musculature; development of complaints during flight on a day 4, back pain bilateral in the region of the gravity is atypical (Grigor’ev & Fedorov, – measurement of changes in levels/ day-to-day basis. Based on the biomechanical iliac crest was recorded, together with 1996). patterns of recruitment of the superficial model it was expected that LBP could constipation. Both complaints disappeared abdominal and lumbar muscles in develop at the site of the iliolumbar ligaments within a few days. Of special interest is that 3. Experiments and Results response to a standard sinusoidal (the iliac crest), and that combined LBP and pain relief was provided by stretching the The projects at issue are: movement task involving the lower limb. constipation could develop. back, i.e. realising a lumbar lordosis. (For this and other information, it was an advantage – Berlin Bedrest Study; The preliminary results show that the Method that the astronaut is a medical doctor.) Along – in-space study; sensitivity of these tests of lumbo-pelvic The questionnaire started with ‘Did you with the pain relief, the constipation – flanking ground studies. stability, to detect muscle changes owing to experience pain today in the lower back?’; if disappeared.

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The results of future studies can have a large impact on in-flight countermeasures and the treatment of LBP pelvic region (neuro-muscular remodelling) hardware. For the ground experiments, countermeasures and the treatment of LBP patients on Earth. patients on Earth. in response to bedrest and vibration exercise. measurement protocols are available, but it is This includes muscle movement and muscle expected that optimisation of several 3.3 Flanking Ground Studies volumes of the deep muscles using magnetic measurement instruments must be executed. Conclusions Ongoing research by Team members are resonance imaging and motor control The Team’s research and development have Combination of the recordings during flight described in the following sections. measures (non-invasive) of the superficial involved close cooperation with the with the unilateral LBP recorded post-flight muscles. companies Enraf Nonius (physiotherapy after 4 days suggests that the in-flight pain Biomechanical modelling and verification market leaders) and Pie Medical (ultrasound (modest, 3 on the VAS-scale) cannot have The biomechanical model predicts that the Intervertebral disc and lumbopelvic ligaments equipment). been caused by trauma during ascent, and action of the transverse fibres of pelvic Simultaneous with increase of injury risk that it cannot have been discogenic. muscles such as transversus abdominis, owing to deep-muscle atrophy, the increase References The answers to the questionnaire support pelvic floor muscles (Pool-Goudzwaard, 2003) of height of the L5-S1 disc is of interest. Disc Desplanches, D. (1997). Structural and the Team’s biomechanical model, as do the and piriformis (Marçal et al., 1999) can stiffen height increase in microgravity has been Functional Adaptations of Skeletal Muscle recorded complaints and the the sacroiliac joints (i.e. force closure) and described extensively (Desplanches, 1997; to Weightlessness. Int. J. Sports Med. 18 countermeasures practised by the astronaut. stabilise and support the pelvis for Hutchinson et al., 1995; LeBlanc, 1995; (suppl. 4): S259-264. A loss of tone in the postural muscle weightbearing, in a similar way to the effects Ledsome, 1997; Styf et al. 1997; Wing et al., Deursen, L.L.J.M. van (2003). Low Back Pain system is expected in microgravity, especially of a belt around the pelvis (Snijders et al., 1991).The Team was able to relate change of and Everyday Activities.Thesis, Erasmus in the transverse abdominal muscles. It is 1998). Muscle physiology forms the basis for spinal length directly with values of Medical Centre, Rotterdam,The shown in LBP patients that these muscles are this research (Morrissey, 1995; Morrissey et al., intradiscal pressure (Van Deursen, 2003; Van Netherlands. inhibited after a few days of pain. Inhibition 2002). Deursen et al., 2004). It also modelled the Deursen, L.L.J.M. van, Deursen, D.L. van, of these muscles leads to loss of stability in Running ground studies aim at verification relation between annulus fibrosis stress and Snijders, C.J. & Wilke, H.J. (2004). Spinal the spine and pelvis and hence to pain in on patients with low-back and pelvic-floor intradiscal pressure (Van de Poel, 1995). As a Shrinkage Measured in Different Postures ligamentous structures as the iliolumbar problems such as stress incontinence (Pool- continuation of previous work, the Team and Exercises. Submitted to Euro. Spine J. ligaments inserting on the iliac crest (the site Goudzwaard et al., 2003; 2004). proposes to model the influence of disc Fuchs, H.S. (1980). Man in Weightlessness: of pain described by the astronaut). In order height increase during microgravity on Physiological Problems, Clinical Aspects, to stabilise the spine and pelvis, the intra- Deload model of injury intradiscal pressure, annulus fibrosis stress Prevention and Protection. Related Bio- abdominal pressure can be increased and the The aim of this research is to demonstrate and load increase on iliolumbar, lumbosacral Medical Research in Microgravity during pelvic floor muscles can have a higher level that the body’s natural antigravity protective and iliosacral ligaments.This is the region the Forecoming SPACELAB Missions. Riv. of activity.This higher level of activity can mechanisms are very fragile and sensitive to where most trigger points of the regional Med. Aeronaut. Spaz. 43(3-4), 332-346. lead to constipation, as demonstrated in a disuse, especially in relation to modern low-back pain syndrome is found. Grigor’ev, A.I. & Fedorov, B.M. (1996). Stress population of LBP patients. lifestyles on Earth and, very importantly, for Disc height response to absence of under Normal Conditions, Hypokinesia By stretching the lower vertebrae, the those who live and work in space.With the postural muscle activity and gravity load will Simulating Weightlessness, and During tension in the ligamentous system decreases functional status of these joint-protection most probably involve inverse viscoelastic Flights in Space. Human Physiol. 22(2), 139- and the pain eases, as shown by the mechanisms now able to be quantified, there behaviour with a new steady state value. 147. astronaut’s stretching exercises. is the potential for the deload model of injury Hutchinson, K.J.,Watenpaugh, D.E., Murthy, G., The results of this single case study must to be validated and hence countermeasures 4. Future Studies Convertino,V.A. & Hargens, A.R. (1995). be interpreted with reserve, but they form a prescribed and their relative effectiveness Based on the results of these studies, Back Pain during 6-degrees Head-down strong base for future studies with series of determined. Measurements have been countermeasures can be developed and Tilt Approximates That During Actual astronauts staying in the ISS for several devised and tested at the University of implemented, involving ground studies and Microgravity. Aviation, Space & Environ. months.The results of future studies can Queensland to address predicted differential flight experiments. Future research will Med. 66, 256-259. have a large impact on in-flight changes in individual muscles of the lumbo- involve the selection and development of Kraan, G.A., Snijders, C.J., Delwel, E.J.,

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Stoeckart, R. & Kleinrensink, G.J. (2004). Stoeckart, R. (2003).The Iliolumbar Snijders, C.J., Hermans, P.F.G., Niesing, R. & Extraforaminal Ligament Attachments of Ligament: its Influence on Stability of the Stoeckart, R. (2004).The Influence of Human Lumbar Nerves. Spine;in print. Sacroiliac Joint. Clin. Biomech. 18, 99-105. Slouching and Lumbar Support on LeBlanc, A. (1995). Magnetic Resonance Pool-Goudzwaard, A.L., Slieker ten Hove, Iliolumbar Ligaments, Intervertebral Discs Imaging after Exposure to Microgravity. M.C.P.H.,Vierhout, M.E., Mulder, P.G.H., and Sacroiliac Joints. Clin. Biomech. 19, 323- Research proposal. Project Identification Pool, J.J.M., Snijders, C.J. & Stoeckart, R. 329. 106-130 (E029). (2004). Relation between Low Back and Stapley, P.& Pozzo,T. (1998). Does the Centre Ledsome, J.R. (1997). Spinal Changes in Pelvic Pain. Submitted to Euro. Urology. of Mass Remain Stable during Complex Microgravity. In Second International Richardson, C., Jull, G., Hodges, P.& Hides, J. Human Postural Equilibrium Tasks in Microgravity Laboratory (IML-2) Final (1999). Therapeutic Exercise for Spinal Weightlessness? Acta Astronaut. 43(3-6), Report, (Ed. R.S. Snyder), NASA RP-1405, Segmental Stabilization in Low Back Pain. 163-179. Washington DC, pp182-185. Churchill Livingstone, London. ISBN 0443 Styf, J.R., Ballard, R.E., Fechner, K., Marçal, N., Correia, J. & Marques, A.J. (1999). 058024. Watenpaugh, D.E., Kahan, N.J. & The Piriformis Syndrome. In Proc. Failed Richardson, C.A., Snijders, C.J., Hides, J.A., Hargens, A.R. (1997). Height Increase, Back Surgery Syndrome Conf., Damen, L., Pas, M.S. & Storm, J. (2002).The Neuromuscular Function, and Back Pain 9-12 November 1998, Rotterdam,The Relationship between the Transversely during 6 degrees Head-down Tilt with Netherlands, pp101-102. Oriented Abdominal Muscles, Sacroiliac Traction. Aviation, Space & Environ. Med. 68, Morrissey, M.C., Harman, E.A. & Johnson, M. Joint Mechanics and Low Back Pain. Spine 24-29. (1995). Resistance Training Modes: 27(4), 399-405. Thornton,W.E., Moore,T.P., Pool, S.L. & Specificity and Effectiveness. Med. & Sci. in Richardson, C., Hodges, P.& Hides, J. (2004). Vanderploeg, J. (1987). Clinical Sports & Exercise, 27, 648-660. Therapeutic Exercise for Lumbopelvic Characterization and Etiology of Space Morrissey, M.C., Drechsler,W.I., Morrissey, D., Stabilization: A Motor Control Approach for Motion Sickness. Aviation, Space & Environ. Knight, P.R.,Armstrong, P.W. & the Treatment and Prevention of Low Back Med. 58 (9 Pt 2), A1-A8. McAuliffe, T.B. (2002). Effects of Distally Pain. Elsevier, Churchill Livingstone, Wilke, H.-J., Neef, P.,Caimi, M., Hoogland,T. & Fixated versus Nondistally Fixated Leg Edinburgh. Claes, L.E. (1999). New In Vivo Extensor Resistance Training on Knee Pain Snijders, C.J.,Vleeming, A. & Stoeckart, R. Measurements of Pressures in the in the Early Period after Anterior Cruciate (1993).Transfer of Lumbosacral Load to Iliac Intervertebral Disc in Daily Life. Spine 24, Ligament Reconstruction. Physical Therapy Bones and Legs. Part II: Loading of the 755-762. 82(1), 35-43. Sacroiliac Joints when Lifting in a Stooped Wing, P.C.,Tsnag, I.K., Susak, L., Gagnon, F., Poel, L.P.F.van de. (1995). Biomechanical Posture. Clin. Biomech. 8, 295-301. Gagnon, R. & Potts, J.E. (1991). Back Pain Aspects of the Intervertebral Disc; Analysis Snijders, C.J., Slagter, A.H.E., Strik, R. van, and Spinal Changes in Microgravity. of Annular Wall Strain due to Intradiscal Vleeming,A.,Stoeckart,R.& Stam,H.J. Orthopedic Clinics of North America 22, Pressure and Spinal Deformations.Thesis, (1995).Why Leg-Crossing? The Influence of 255-262. Erasmus Medical Centre, Rotterdam,The Common Postures on Abdominal Muscle Netherlands. Activity. Spine 20(18), 1989-1993. Pool-Goudzwaard, A.L. (2003). Biomechanics Snijders, C.J., Ribbers, M.T.L.M., Bakker, J.V. de, of the Sacroiliac Joints and the Pelvic Stoeckart, R. & Stam, H.J. (1998). EMG Floor.Thesis, Erasmus Medical Centre, Recordings of Abdominal and Back Muscles Rotterdam,The Netherlands. in Various Standing Postures: Validation of a Pool-Goudzwaard, A., Hoek van Dijke, G.A., Biomechanical Model on Sacroiliac Joint Mulder, P.,Spoor, C.W., Snijders, C.J. & Stability. J. Electromyo. & Kinesiol. 8, 205-214.

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Topical Team Members

Prof. Dr. Chris J. Snijders M. de Groot Prof. Dr. Josef Cywinski, ScD., FACC Erasmus MC, University Medical Center Erasmus MC, University Medical Center Rotterdam, Institute of Medical Technology, 64 Avenue Rotterdam, Department of Biomedical Department of Biomedical Physics and Grand-Champsec, CH-1950 Sion, Switzerland. Physics and Technology, Dr. Molewaterplein Technology, Dr. Molewaterplein 50, 3015 GE Tel: +41 27 203 74 75 50, 3015 GE Rotterdam,The Netherlands. Rotterdam,The Netherlands. Fax: +41 27 203 59 70 Tel: +31 10 408 73 68 Tel: +31 10 408 73 75 Email: [email protected] Fax: +31 10 408 94 63 Fax +31 10 408 94 63 Email: [email protected] Email: [email protected] Dr. Jack W.A. van Loon Dutch Experiment Support Center, ACTA, Free Prof. Dr. Carolyn A. Richardson Prof. Dr. Hans-Joachim Wilke University Amsterdam,Van der The University of Queensland, Department of University of Ulm, Institute for Orthopaedic Boechorststraat 7, 1081 BT Amsterdam,The Physiotherapy, Brisbane, Queensland 4072, Research and Biomechanics, Helmholtzstrasse Netherlands. Australia. 14, D89070 Ulm, Germany. Tel: +31 20 444 86 86 Tel: +61 7 336 522 09 Tel: +49 731 502 34 81 Fax: +31 20 444 86 83 Fax +61 7 336 527 75 Fax: +49 731 502 34 98 Email: [email protected] Email: [email protected] Email: [email protected] Dr.P.Brands Dr. Annelies L. Pool-Goudzwaard Dr. Matthew C. Morrissey Pie Medical Equipment B.V., Philipsweg 1, Erasmus MC, University Medical Center King’s College London, GKT School of Biomedical 6227 AJ Maastricht,The Netherlands. Rotterdam, Department of Biomedical Sciences, Physiotherapy Division, Shepherd’s Tel: +31 43 382 42 88 Physics and Technology, Dr. Molewaterplein House, Guy's Campus, London SE1 1UL, UK. Fax: +31 43 382 46 01 50, 3015 GE Rotterdam,The Netherlands. Tel: +44 207 848 63 17 Email: [email protected] Tel: + 31 10 408 73 75 Fax: +44 207 848 66 78 Fax: +31 10 408 94 63 Email: [email protected] Mr. Ruud J. Snackers Email: [email protected] Enraf-Nonius B.V., Röntgenweg 1, 2624 BD Delft, Dr. Nelson Marçal The Netherlands. Dr. Julie A. Hides Hospital de S. João, Department of Anaesthesia Tel: +31 15 269 83 82 The University of Queensland, Department of and Reanimation, Alameda Prof. Hernani Fax: +31 15 262 83 51 Physiotherapy, Brisbane, Queensland 4072, Monteiro, P-4202-451 Oporto, Portugal. Email: [email protected] Australia. Tel: +351 22 550 60 74 Tel: +61 7 336 522 09 Fax +351 22 550 25 59 Fax +61 7 336 527 75 Email: [email protected] Email: [email protected]

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Report of the ESA Topical Team Shielding against Cosmic Radiation in Life & Physical Sciences Shielding from Cosmic Radiation for Interplanetary Missions: on Interplanetary Missions Active & Passive Methods

Contributors: M. Casolino, Rome (I) M. Durante, Naples (I) R. Mueller-Mellin, Kiel (D) P.Nieminen, Noordwijk (NL) G. Reitz, Cologne (D) GCR Trapped Protons L. Rossi, Milan (I) Radiation is one of the crucial factors that cosmic rays (SCR), the outer walls of the V. Shurshakov, Moscow (RUS) 2 need to be addressed when considering spacecraft (about 5 g/cm Al) provide total M. Sorbi, Milan (I) long-duration space missions.The ESA protection from protons up to 50-70 MeV. P.Spillantini, Florence (I) international and interdisciplinary Topical However, some exceptionally intense solar Team was established in 2002, and worked to events eject a great number of protons at provide an overview of current knowledge higher energies. In this case, the dose on the radiation environment, with special released in a few hours can exceed the dose emphasis on radiation directionality, provide limits recommended for astronaut during interplanetary flights. In addition, an up-to-date overview of knowledge on protection, and can lead to acute protection against SPEs is, fortunately, easier passive shielding and the biological effects of deterministic effects, including lethal than against GCR, because of the lower radiation, and investigate aspects of active radiation syndromes. masses and energies of the solar particles. shielding by magnetic fields generated by In October 2002, ESA appointed a Topical The galactic radiation component was also Fig. 1.Dose variation with shielding thickness for different superconducting magnets. From this work, Team (TT) to study these issues and to considered, in order to establish the main materials in the International Space Station orbit for solar recommendations on further research and suggest possible solutions, strategies and a parameters for quasi-hermetic high-intensity minimum conditions (Cucinotta, 2000). technical activities were derived; they are roadmap.The team was interdisciplinary in magnetic systems in different configurations, summarised here.These recommendations order to address the needed technical R&D and to suggest possible lines of future R&D range from specific, detailed analysis of on the basis of a careful analysis of the activities. existing data, to ground-based accelerator physics and the physiological and statistical unit mass is proportional to the cube root of studies and the development of space problems.The Team was proposed to ESA in 2. Passive Shielding and its Influence on the atomic mass. Hence, hydrogen is the prototypes. October 2001, in response to the ESA-RA-LS- Biological Effects most efficient material for shielding against 01-PREP research announcement, and Bulk shielding poses obvious mass problems heavy ions, and materials abundant in loosely established by contract between ESA and for a spacecraft. A heavy load, added purely bonded hydrogen atoms are excellent 1. Introduction the Physics Department of Florence to reduce radiation exposure, imposes a candidates for efficient radiation shielding. Cosmic radiation has been identified as the University. substantial mass penalty and may therefore Having only one shielding material is an main health hazard to crews on long- The main questions addressed were: dramatically increase the mission cost. ideal case, which will in practice be difficult to duration interplanetary missions. For However, a storm shelter – a small volume realise.The final effectiveness therefore also terrestrial radiation workers, protection – what are the characteristics of solar with heavy shielding of 20-30 g/cm2 Al – is depends on the geometry and abundance of against radiation exposure is usually energetic particle events (SPEs), with foreseen for protection against large SPEs. the various other materials in the shielding. provided by increased shielding. emphasis on the energy spectrum, time An immense amount of work has already Ultimately, detailed simulations will always be Unfortunately, shielding in space is evolution and angular distribution? been done on developing passive shielding mandatory in evaluating and designing a problematic, especially when Galactic Cosmic – what are the R&D activities required to strategies for human space exploration realistic vehicle or habitat. Simulations Radiation (GCR) is considered. High-energy achieve optimal passive shielding on missions.This activity has produced suggest that shielding is effective against radiation is very penetrating. Furthermore, interplanetary spacecraft? numerous workshops and publications in trapped protons in LEO, but its efficiency is although thin or moderate shielding is – what R&D activities are needed to this area. All the calculations and poor against GCR penetration.This is generally efficient in reducing the equivalent achieve efficient magnetic shielding on measurements show that hydrogenous demonstrated clearly in Fig. 1. dose, shield effectiveness drops as thickness interplanetary spacecraft? materials are the best candidates on a per Much of the protection inside a spacecraft increases.This is the result of the production unit mass basis. In fact, for a given mass is provided by structural elements and the of a large number of secondary particles, The work focused on the solar thickness and a given incident particle, equipment. For a spacecraft structure, there is including neutrons, from nuclear interactions component of cosmic radiation because ionisation energy loss increases with the a compromise between shielding efficiency of the GCR with the shield. effective protection against these charge-to-mass ratio of the target nucleus, and mechanical stability, with multifunctional For the much softer solar component of potentially lethal events is mandatory while the fragmentation cross-section per materials needed to optimise the process. For

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Skin burns Fig. 2.Risk of three different deterministic effects (skin burns,eye Cataract cataract and lethal bone marrow syndrome) caused by a worst- Haematopoietic syndrome case SPE (4x September 1989) as a function of Al shielding thickness.

a shelter inside the spacecraft, there are no The effect of shielding on the risk of term missions in LEO (Durante et al., 2001). such restrictions (as long as the materials are different deterministic effects can be The increase was close to the values acceptable for space application) because estimated for a worst-case scenario of an SPE predicted by calculation. efficiency per mass is the only important with the same energy spectrum as the Late degenerative tissue effects include endpoint. September 1989 event, but four times the non-cancer mortality, cataracts and CNS Estimates of radiation exposures for intensity. Dose to skin, eye lens and blood- damage. An increased risk of ocular cataracts homogeneous isotropic shields of an average forming organs have been evaluated for this the mounting evidence that in some cases has been proved in astronauts (Cucinotta et thickness can therefore serve only for worst-case scenario (Wilson et al., 1997a). (such as central nervous system damage) the al., 2001); it remains the only disease in space qualitative comparison of different These values can be used to estimate the risk heavy-ion effects cannot be simply scaled directly attributable to cosmic radiation. configurations. For accurate quantitative of eye cataract, skin burns (moist from low-Linear Energy Transfer (LET) data. The uncertainties in the biological effects assessments of radiation exposures, desquamation) and bone marrow lethal Passive shielding will never be able to reduce of radiation have a direct consequence on knowledge of at least the exact distribution syndrome (without medical treatment), the stochastic risk to zero, given the shield planning. How low should a dose be of the surrounding shield matter as a respectively.The calculation of the risk R for a effectiveness of low-dose radiation in for safety? There is no simple answer. In function of representative shield thickness is given effect is based on the Weibull function inducing late effects, and the mass limits in radiation protection, it is generally assumed compulsory. (Edwards & Lloyd, 1998): space. that the risk of late effects is proportional to Shielding against GCR and SPE particles is In its recent Critical Path Roadmap (NASA, dose.This linear-no-threshold (LNT) model limited, but a significant dose reduction can 2004), NASA has classified the different has been challenged by data suggesting a be achieved with optimised shield material hazards related to interplanetary missions, supralinear (owing to bystander effects) or and an optimal inclusion of consumables in with a ranking from 1 to 5 in order of sublinear, and even negative (hormesis) risk the shield design. As a first step, the decreasing seriousness. For radiation effects, at low doses. As shown in Fig. 1, thin shields procurement and characterisation, using where D is the dose, V provides the the following risks are ranked: are efficient in reducing the equivalent dose, computer codes, of candidate flexible steepness of the dose-response curve for a but shield effectiveness drops as the

materials has to be done for future manned given biological endpoint, and D50 the dose 1. carcinogenesis; thickness increases.This results from the missions in LEO and beyond. In order to at which 50% of the exposed persons are 2. central nervous system (CNS) production of a large number of secondary reduce overall uncertainty, the next step is expected to show the effect.The results of damage; particles caused by nuclear interactions of the improvement and validation of the the calculation are shown in Fig. 2.The eye 3. late degenerative tissue effects; the primary energetic HZE nuclei. models and tools for shielding analysis, by cataract is virtually certain if the astronaut is 4. early or acute effects; In addition, the effectiveness of shielding comparison with measurements from exposed to the SPE during an EVA, but can 5. hereditary effects. in reducing health risk depends on the accelerator shielding studies and flights, and be spared by a storm shelter. Shielding biological model or endpoint.This has been by correlation and tuning of models. rapidly eliminates the risk of skin burns, Cancer is the main concern, justified by elegantly demonstrated by Wilson et al. The risk of acute biological effects in deep while the risk of lethal haematopoietic the epidemiological evidence that radiation (1997b) at NASA, who used HZETRN to space or on a planet is limited to a large SPE, syndrome is already below 1% during EVA, exposure increases cancer risk, the grave calculate the GCR dose (in Gy) behind especially if it occurs during an Extra- but it is reduced by shielding more slowly consequences of the disease, and the limited different shielding materials and thickness, Vehicular Activity (EVA). A storm shelter than in skin burns. countermeasures available. Although no and then converted the energy deposited (> 10 g/cm2 Al) can spare the crewmembers For chronic exposure to GCR, the epidemiological evidence of an increased into either equivalent dose (using the from most deterministic effects, albeit with a knowledge of stochastic effects of heavy cancer risk in astronauts has been found so International Commission on Radiological residual risk of late stochastic effects. As most ions is still insufficient to provide accurate far, there is some indirect evidence from Protection (ICRP) model) or cellular neoplastic SPEs are composed of protons < 500 MeV/n, risk estimates for interplanetary missions. biological dosimetry. In fact, a significant transformation frequency (using published bulk shielding should be very effective.Very A major issue is the relative biological increase in the yield of chromosomal experimental data).The attenuation energetic events (> 1 GeV/n) would be much effectiveness of the particles comprising the aberrations in peripheral blood lymphocytes characteristics are qualitatively similar for more difficult to shield efficiently. GCR, which is currently under revision, and was detected in astronauts involved in long- both biological models (Fig. 3), yet there are

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Fig. 3.Attenuation of dose equivalent and cell transformation frequency in 1-year exposure at the solar minimum behind several shield Fig. 4.A defocusing magnetic lens can play the same role as an Fig. 5.Mass of the water absorber and of the toroid system shielding a ‘shelter’volume.The toroid is 10 m materials.GCR transport calculated by HZETRN.(a) equivalent dose, calculation based on ICRP-60 (ICRP,1991); calculations described in absorber in protecting a volume from the directional component long,its inner radius is R1 = 1 m and outer radius R2 = 3 m, and it covers the end caps of the shelter (Wilson et al., 1995a; 1995b); (b) neoplastic cell transformation, calculation based on track-structure Katz’s model (Katz, 1996).Plot courtesy of solar energetic particles. down to R = 0.5 m.Left: the cold mass,the envisaged total mass and the maximum total mass of the of F. Cucinotta. toroidal system are given for the same kinetic energy cut that gives the same dose (in Gy) of the absorber for the MaxSEP event.Right: the same masses as a function of the MaxSEP proton dose.

clearly large quantitative differences. Results of However, technical limitations in the the dangerous high-energy tail of the these simulations suggest that the estimates production of intense magnetic fields in space particles in the most intense solar events. of the shield effectiveness depend on the have been the main hindrance in the Present information mainly concerns the biological endpoint under consideration, and application of magnetic shelters in spacecraft. energy region below 100 MeV, while there on the biophysical model used for the Technological progress in high-temperature are scant data at higher energies. Instead, calculations. Unfortunately, very few biological superconductors may have a large impact in knowledge of the angular distribution of the experiments are available to validate these this field.The Team decided to proceed by most energetic solar rays as a function of models (Schimmerling, 1992; Medvedovsky et adiabatic approximation. energy, and of the characteristics and al., 1994;Yang et al., 1998). Not surprisingly, the As a first step, the simple scheme of a development in time of the solar event are US National Academy of Sciences has particle beam impinging on a magnetic lens very important not only for the active shield recommended investigating the biological protecting a shelter volume behind was solution, but also for the distribution of the effects of heavy ions with shielding. A few assumed.This preliminary exercise (Spillantini, passive shields inside the spacecraft. experiments in this field are now under way 1999; Spillantini et al., 2000; 2001) was The other direction, to be pursued in (Durante, 2000; Durante et al., 2002). suggested by the fact that a portion of the parallel, would provide quasi-hermetic energetic SCR can be considered as a beam, shelters, where astronauts would move Fig. 6.Total envisaged mass of the toroids as a function of the kinetic energy cut given by a water- 3. Active Shielding since it is roughly collinear with the basic during the short time of highest flux. Bulk equivalent absorber.At left,the total mass of the toroid is given for the kinetic energy cut that gives the An attractive alternative to passive, bulk layout of the local solar magnetic field (in an shielding and/or magnetic fields produced same dose (in Gy) as the water absorber for the MaxSEP event.The arrows show the mass of the equivalent water shield given in the two NASA studies.At right,the total mass is reported as a function material shielding is the use of opening of a few tens of degrees). Spacecraft by superconducting coil systems can be of the dose (Gy) inside the shelter. electromagnetic fields to deflect the charged could be oriented in that direction, in order to pursued, the choice depending on the particles. See different concepts in Vogler, protect the astronauts behind a suitable thick masses, reliability, safety, other technical 1964; Levy & James, 1966; Brown, 1962; Bernert absorbing wall. parameters and the spacecraft design. & Stekly, 1965; Levine & Lepper, 1971; Paluszek, A magnetic lens realised with present The second step in the evaluation of active 1978; Townsend, 1983; 1984. A comprehensive techniques provides mass benefits. Fig. 4 shields has been that of providing such a of the whole spacecraft.The MaxSEP event listing of nearly all publications related to shows the case of full protection from protons quasi-hermetic shelter (Spillantini, 2002), and considered in Fig. 5 is the convolution in active shielding of spacecraft can be found in up to 200 MeV; it would require power comparing its mass with that of an energy of the fluences of all the solar events Sussingham et al. (1999). A recent short review consumption of < 1 kW.The rewarding result equivalent water shelter.The result shows a registered so far. was given in Townsend (2001). A systematic of this exercise encourages us to proceed in rewarding mass saving by the active shield However, when the active shield is discussion of active magnetic shielding two parallel directions. (Fig. 5), but perhaps not enough to justify the evaluated for NASA (NASA, 1998),TransHab problems was given in Trukhanov et al. (1970). One is to understand the directionality of technical effort and the increased complexity (Kennedy, 2002), Aurora (ESA, 2004) and

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Only the level of the GCR dose/year at minimum solar activity is indicated in Fig. 10, obtained by multiplying the dose of unshielded protons by 5. However, the total Fig. 7.Dose (Gy/year) from the GCR proton component at solar Fig. 8.Deployable toroidal magnetic system for mitigating the GCR GCR dose should be reduced as much as that Fig. 9.Masses of the water absorber and the toroidal systems minimum inside the shelter as a function of the residual dose from dose inside a crew habitat. for protons.This is because, even if nuclei are (12 m long,4 m external radius) shielding an ISS-like habitat the MaxSEP inside the shelter. twice as rigid as protons in a magnetic field, volume.Left: the cold mass and the total mass of the toroidal system at the kinetic energy cut that yields the same dose (in Gy) of their energy spectrum expressed in kinetic the absorber for the MaxSEP event.Right: the same masses as a energy per nucleon is only half as high. function of the MaxSEP proton dose. There are two directions of development for attenuating GCR in a spacecraft’s living Russian (ISTC, 2000) concepts of manned Mars in the innermost part of the system, where quarters: increase the magnetic field missions, taking into account that the system magnetic forces can be more easily intensity without increasing the outer radius is not standalone and the end-cap regions are supported; the mechanical strength is much of the system, or return the electric current of protected by the spacecraft structures, the smaller in the outermost part of the system. the toroidal system at a larger external mass saving becomes really interesting. Fig. 6 For the ‘habitat’ case, the toroidal radius. compares the active system mass as a function configuration is more compelling than for the As an example of the first route, consider of the energy ‘cut’ with the mass of water ‘shelter’ case because the larger dimensions for R2 = 4 m the field intensity that could required for the different spacecraft concepts would lead to a prohibitive increase in mass if halve the GCR-released energy inside the for protecting the same shelter volume in the the outer part carries an important habitat. It should be B =3T at R1=2m to same angular region. mechanical structure. So the field intensity reduce the level to < 150 mGy/year While the absorber sharply cuts the energy profile with radius for a habitat should be (30 mGy/year from protons) at minimum spectrum of the arriving particles, the typical for the toroidal configuration, solar activity. reduction by the active system is not sharp, produced by a current running longitudinally This choice guarantees that the toroidal Fig. 10.Toroids of different external radii shielding a habitat but it also reduces the flux of particles at along the innermost radius of the system and system is compatible with the outer diameter volume.Energy released by protons in the human body for the higher energies.This makes the active shield returning at an outer radius, as shown in Fig. 8. of launch vehicles, but implies an increase in MaxSEP (continuous lines) and for galactic protons at solar minimum (broken lines) as a function of the magnetic field more effective in mitigating the GCR dose.This For simplicity in our preliminary evaluation, the cold mass at least proportional to the intensity at R = R1.The level of the unshielded GCR total dose is is well illustrated by Fig. 7, where the an International Space Station (ISS)-like increase of the field (from 4 t to 10 t in the shown for comparison. mitigation of the galactic proton dose by module was assumed for the habitat, 4 m in example), and a significant mechanical water and toroidal systems are compared via a diameter and 5 m long. structure to counteract the ponderomotive function of the residual MaxSEP dose inside The masses for the toroidal system and the forces, which increase with the square of the the shelter. equivalent water shield that gives the same field. Note, however, from Fig. 9, that the A third step is therefore worthwhile: reduction in energy of SCR protons are shown equivalent mass of water for a similar GCR space (Fig. 8). However, it is a much more evaluating an active system for protecting a in Fig. 9. For the 200 MeV cut, the ‘cold mass‘ mitigation would be more than 100 t. interesting and promising solution, and it much larger volume, a ‘habitat’ where (i.e. the mass of hardware that needs to be The choice of returning the electric could be worth paying the price. astronauts spend most of their time during a cooled) of the toroidal system would be 4 t; current at a greater external radius avoids It is necessary to stress a very important mission’s cruise phases. the total mass would be 6 t. Mitigation of these problems, but that could be technical aspect. Lower fields work at First consider the advantage of using the galactic protons would be at least 30% (from incompatible with the maximum diameter of relatively higher temperatures (above 10K for toroidal configuration for the magnetic field. 60 mGy/year at minimum solar activity to the launch vehicles.This implies that the the already available NbSn superconductor Given the 1/radius trend of the field intensity, 40 mGy/year). Compare these values with the conductors returning the electric current material), opening the possibility of obtaining the maximum mechanical strength is needed 15 t of water needed for the same protection. would need to be deployed or assembled in such temperatures by relatively simple and

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lightweight cryocoolers.This solution sets us linked to the design of the spacecraft and to and its evolution with time.The analysis of years, NASA has used analytical models such free of supplying liquid helium. Cryogen-Free the mission scenario. Another reason for not their data should be oriented to gathering as HZETRN (Wilson et al., 1991), which are Superconducting Magnets (CFSMs) could be delaying this development is the possible energy and angular distribution on a particle- very fast and fairly accurate. ESA could conceived, cooled at the expense of only the benefits that superconducting techniques by-particle basis and as a function of time. exploit European experience in Monte Carlo electric power required by the cryocoolers. could bring to other fields in space travel. However, none of these instruments is suitable (MC) codes (FLUKA; Hammond et al., 1991; In conclusion, the toroidal magnetic field, for supplying a complete and sufficiently GEANT; GEANT4; PHITS). MC codes are new materials and cooling techniques 4.1 Retrieval of Data Collected by Previous accurate picture continuously or even over a certainly slower than analytical codes, but promise active systems that will afford Interplanetary Probes long period for all the types of solar events. could provide a benchmark for comparison habitable modules total protection from Many probes have been launched into with NASA calculations. In particular, MC SCRs at all energies, and a more than halving interplanetary space and some are still 4.3 A Dedicated Instrument for Surveying codes should analyse shielding and of the GCR flux. returning data. All of them are equipped and Monitoring SEPs secondary radiation production processes, with instruments measuring the flux of The development and testing of prototypes considering geometry, materials and 4. Conclusions and Recommendations cosmic rays in several energy and incidence for a possible interplanetary instrument radiation sources.The codes should be able According to the most recent proposals, angle ranges. Of particular interest here should be pursued in parallel to the retrieval to simulate both protons and heavy ions manned interplanetary flights could start in would be to retrieve from these data the and direction analysis described above.The from a few MeV/n up to several GeV/n, in 2015, and certainly no later than 2020 for distribution of the angles of arrival of the dedicated instrument should be operated in complex 3-D geometry, and taking into lunar missions. Research into particle particles from different solar phenomena, deep space, at 1-1.5 AU or, better, in orbit account the effect of external forces such as radiation shielding must be accelerated over especially for the > 50 MeV (Cane et al., 1988; around Mars or the Moon for a full solar cycle, magnetic fields. A few MC codes are already the next 10-20 years to provide safe Reames, 1999) that are potentially dangerous accepting particles over the whole sphere. It able to perform simulations of protons and exploration of the Solar System. Passive for astronauts.This new interpretation is could be relatively simple, demanding few HZE particles under these conditions, and shielding is already fairly well known, and it is necessary to understand the role of the resources and based on the well-known time- more efforts should be devoted to expected that more research in this field (see possible non-isotropic distribution of of-flight technique for measuring particle improving such codes. the recommendations below) will ensure the energetic SEPs for designing shield systems. energy, identifying the particle by the energy best possible bulk shielding for the next No such data have been found in the losses in scintillation counters and registering 4.5 Material Science: Development and generation of interplanetary spacecraft, as scientific literature. It is assumed that there is the direction via silicon micro-strip devices. It Characterisation of New Shielding well as for habitat modules on other planets. some useful information on the angular must be emphasised that such an instrument Materials While this can be satisfactory for 3-6 month distribution of the most energetic SEPs in the must be positioned in near-Mars space for Material science research should be able to missions on the Moon, the Topical Team raw data, never before extracted.The registering the direction and anisotropy define, characterise and provide materials for argued that passive shielding may be unable ‘direction reanalysis’ of these data is not only evolution of the early-arriving electron accelerator-testing (ground-based) or flight- to solve the radiation problem for exploring worthwhile, but a real duty of the component of solar events, in order to alert testing. New materials specifically designed Mars and perhaps Jupiter’s satellites. community before taking more demanding the human habitats around Mars or on the for radiation shielding or spacecraft and In order to pursue a significant reduction steps. A small scientific team should surface of the imminent arrival of the much planetary habitat modules need to be in the GCR-equivalent dose, a series of collaborate with the original instrument more dangerous proton and nuclei studied. A first task is to define combinations activities in active shielding are teams to retrieve the needed information. components.The alert will provide half an of flexible materials for habitat structures. recommended, aiming at effective magnetic hour or more for taking countermeasures. Candidate materials are multi-layered, shelters by 2025.These activities should 4.2 Analysis of Directional Information including Beta cloth (glass fibre), Mylar, begin now if we want to exploit the novel from Operating Instruments 4.4 Computer Code Development for Active Kevlar, Nextel, Combitherm and techniques fully, even if the objectives can be Several of the instruments now operating and Passive Shielding polyethylene, graphite nanofibres, space suit attained only far in the future. beyond Earth’s magnetosphere can supply The use of fast and accurate computational material and in situ materials (regolith). The configuration adopted for protecting detailed information on energetic solar tools for evaluating cosmic radiation transport Detailed materials data should be provided astronauts from ionising radiation is strongly particles, including their angular distribution and interactions is strongly advised. For many for simulations with MC codes. Reference

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multilayer configurations can be tested in energetic heavy ion exposure, using astronauts from ionising radiation.They should be monitored and if necessary flight experiments, using dedicated facilities in vitro and animal models, with emphasis could control plasmas in space, for stimulated to realise high-power (1 W) and with appropriate radiation detectors, such as on carcinogenesis, CNS and late tissue propulsion and manoeuvring, or for other low-mass cryocoolers suitable to run in space the Matroshka dummy now attached to the damage, acute and hereditary effects; technical and scientific purposes, such as for long periods. It is important that the exterior of the ISS. In addition, the radiation – biophysical measurements of the experiments requiring high-accuracy scientific community exploits the experience response of these materials should be tested effectiveness of shielding, with different magnetic spectroscopy.This wide role of and new developments of industries in this in accelerators. composition and thickness, in modulating High-Temperature Superconductor (HTS) field.The opportunity of collaborating with the biological damage induced by heavy magnets should be taken into account in the institutions that have already realised 4.6 Ground-Based Accelerator Experiments ions; design and development of the cryocooler. powerful magnetic systems for particle beam While shielding materials should be tested – physics experiments to measure nuclear From a technical point of view, limiting the handling, as in particle physics, must be during spaceflight using physical dosimetry, fragmentation cross-sections of heavy mass of the full-coverage superconducting pursued. ground-based accelerator experiments are ions in different shielding materials. magnetic system for a shelter or habitat certainly superior for determining the means avoiding the use of NbTi or NbSn 4.7.2 Deployable Current Elements biological impact of heavy ions and its It would also be important to have an superconductors, mainly because of the As outlined above, a principal limitation in modulation by shielding. Flight tests are accelerator-based SPE-simulator to provide difficulties of working at very low designing active shield systems is the barely reproducible, affected by many in a single experiment a given SPE spectrum. temperatures (Rossi et al., 2004). allowed external dimensions.This is certainly confounding factors and generally provide Similar plans are under way at NSRL, but one HTS can be considered because their true for an active system designed to only very low doses, close to or below the could be established in Europe, especially at reliability for large coils is on the way to mitigate the effect of the galactic component sensitivity of the biological systems. GSI, where there is large experience in active being demonstrated. A high-critical of cosmic rays because the high energy of Accelerator-based biological experiments are beam energy modulation. Microbeams using temperature superconducting system, the particles and their isotropy implies the strongly supported by NASA (through the heavy charged particles would also be very operated at moderately low temperature (20- production of an intense magnetic field over NASA Space Radiation Laboratory (NSRL) in useful for low-flux biological studies. 30K) could be cooled by single-stage huge volumes, of external diameters of 10 m the Brookhaven National Laboratory), but cryocoolers.The key point is the availability or more.This is a bad fit with current and this is insufficient to reduce uncertainty and 4.7 Recommendations for Active Shields of reliable cryocoolers for the thermal loads. next-generation launch vehicles. Solving this develop countermeasures for Mars missions 4.7.1 Cryocooler Development In fact, the convenience of active magnetic requires new ideas, the development of new within the next 20 years. ESA is strongly To guarantee simple and safe operation in shielding in complementing passive materials, and probably more complex recommended to support European space during a long cruise, it is necessary to shielding strongly depends on the integration of a shielding system in future accelerator-based experiments. Several develop cryogen-free superconducting effectiveness, reliability, mass and power spacecraft – and consequently a very long facilities are available in Europe for magnets that operate at the expense of consumption of these subsystems. A serious period of elaboration. For this reason, even if biophysical experiments.The Gesellschaft für electric power and a minimum consumption study of what will be available in the near building an effective shield against the GCR Schwerionenforschung (GSI) in Darmstadt (D) of cryogenic fluids.This implies the choice of future would very useful if coupled with an component is something for the farther is able to cover the whole GCR spectrum the most suitable superconducting materials, evaluation of some key characteristics.This future, the study of the possible solutions both in atomic number and energy. Other dedicated R&D for developing reliable comparison among different types of must be pursued in a timely fashion. facilities include the Grand Accelerateur cryocoolers optimised in mass, efficiency and cryocoolers and cooling schemes will help in For the toroidal configurations, the National d‘Ions Lourds (GANIL) in Caen (F) for power consumption, and the construction making the proper choice. For example, in deployment in space of the conductors that low-energy heavy ions and the Paul Scherrer and validation in space of down-sized addressing if it is better to have one 2-stage return the currents generating the magnetic Institut (PSI) in Villigen (CH) for protons up to systems. cryocooler, cooling both the coils at 4-20K fields is an interesting possibility. An 250 MeV.The experiments to be supported It must be stressed that the development and the thermal shield at 70K, or separate attractive proposal worthy of detailed study include: of superconducting magnetic systems that specialised cryocoolers for different is to use flexible conductors self-expanding do not require consumables for cooling is an functions. under the ‘push’ of the magnetic field they – basic biology experiments to characterise important technical feature for space Low-power cryocoolers are already being produce. A specific R&D effort must assess and estimate the risk associated with magnets, and not only for protecting used in space. For an active shield, the field this problem, both through computer

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simulations and prototypes to test the shielding systems before one is integrated Cataracts in Astronauts. Radiat. Res. 156, Mars Expedition, Project 1172, International principle and reliability of the deployment into a Mars spacecraft.The number of the 460-466. Science and Technology Center, Moscow, mechanism. magnetic configurations and of the models Durante, M. (2000). Italian Space Radiobiology Russia. needed to be validated depends on the Program: Influence of the Shielding on the Katz, R., Cucinotta, F.A.& Zhang, C.X. (1996). 4.7.3 Superconducting Magnet System Model other components of the Mars project. Biological Effects of Heavy Ions. In The Calculation of Radial Dose from Heavy The situation for SEPs is much different than However, the validation in a controlled Exploring Future Research Strategies in Ions: Predictions of Biological Action Cross for the GCR component. Owing to the lower environment of a portion of a Space Radiation Sciences (Eds. H. Majima & Sections. Nucl.Instrum.Meth.B107, 287- energies of SEPs, the active protection can superconducting magnetic shield – for K. Fujitaka), Iryokagakusha,Tokyo, Japan, 291. adapt present techniques to the space example, a slice of a toroid energised with a pp79-85. Kennedy, K.J. (2002). Lessons from TransHab: environment. Some resources should be magnetic mirror that simulates the global Durante, M., Bonassi, S., George, K. & An Architect’s Experience. 1st Space dedicated to the study and the construction of force – is a necessary step in any sensible Cucinotta, F.A.(2001). Risk Estimation Architecture Symposium (SAS 2002), a portion of a superconducting magnetic path to active shielding. Based on Chromosomal Aberrations Houston,Texas, USA, 10-11 October 2002. shield.This model should first be validated on In general, the complexity of the problems Induced by Radiation. Radiat. Res. 156, 662- Levine,S.H.& Lepper,R.(1971).An Active the ground and then submitted to a long test to be solved and the long time required to 667. Radiation Shield for Cylindrical Shaped in space, possibly in a controlled environment, develop the techniques demand that the Durante, M., Gialanella, G., Grossi, G., Vehicles. J. Spacec. & Rkts. 8,773-777. such as the ISS. It should assess: issues outlined in this report are considered Pugliese, M., Scampoli, P., Kawata,T., Levy, R.H. & James, G.S. (1966). Plasma well before detailed plans are formulated. Yasuda, N. & Furusawa, Y. (2002). Influence Radiation Shielding for Deep Space – the functioning of the principle of cooling, of the Shielding on the Induction of Vehicles. Space/Aeronautics 45, 106-120. warming, cooling and subsequent References Chromosomal Aberrations in Human Medvedovsky, C.,Worgul, B.V., Huang, Y., energisation and de-energisation cycle Bernert, R.E. & Stekly, F.J.J.(1965). 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Report of the Preservation of Samples during ESA Topical Team in Life Sciences Preservation of Fixed and Non-Fixed Space Experiments Samples during Space Experimentation Contributors: F.J. Medina, Madrid (E) (Coordination) A. Cogoli, Zurich (CH) C. Dournon,Vandoeuvre-lès-Nancy (F) F.Franks, Cambridge (UK) R. Marco, Madrid (E) H.J. Marthy, Banyuls-sur-Mer (F) C. Martin Pascual, Madrid (E) Life sciences experimentation in space is using telecommand procedures and J. Kraemers, Leiden (NL) seriously constrained by the spacecraft designing the operations to be as simple as M. Pastor, Barcelona (E) environment. In particular, the procedures possible. In general, hardware and used on the ground for preserving living procedures must demand low power. Fig. 1.NASA astronaut Michael Foale (left) and ESA astronaut materials and fixing living specimens are A typical procedure in space biology Pedro Duque (right) in the Russian segment of the International rather difficult, if not impossible, to apply on research comprises multiple steps, several of storage times before and after the Space Station, during the ‘Cervantes’Spanish Soyuz Mission of board, and they need to be adapted or which involve the preservation of living experiment without surveillance by the October 2003.(ESA) modified.This report describes the work specimens and/or fixation of living materials. investigators. carried out by the ESA Topical Team to First of all, the experiment should be The preservation requirements are highly analyse the situation and explore possible prepared in the ground laboratory, which variable, depending on the quality of the solutions. First, the procedures that have often involves keeping a specimen alive in samples and the objectives of the research. If been adapted to space so far are briefly stable and probably constant conditions it is necessary to preserve living samples, reviewed; then, solutions from theoretical until the time of experiment activation in then all vital activities must be suspended as and practical points of view are proposed. orbit. In most cases, this means that a much as possible, so that they can be preservation procedure must be applied to recovered later (‘preservation of viability’). In the specimen, which is stored for launch and, other cases, the investigator needs to keep 1. Space Experimentation: Constraints and once in orbit, for some time that depends on the sample structure unaltered, to allow Requirements the mission schedule. Once the experiment is observation of morphology and in situ Fig. 2.Murine Friend Leukemia Virus transformed cells cultured Performing scientific research in space activated and carried out in space, it must be localisation of components.This is achieved and fixed (1% glutaraldehyde) in space,and observed in a requires the modification of the usual preserved again, until the samples are with fixation. In some cases, the molecular scanning electron microscope.The bar represents 10 µm.(Bechler procedures routinely used on the ground, recovered by the investigator. In many cases, integrity of the samples, mostly affecting et al., 1993; Erasmus Experiment Archive, ESA) because of the constraints imposed by the this preservation procedure consists of nucleic acids and proteins, must be conditions in the spacecraft and its fixation, usually chemical, in order for the preserved in order to allow the further use of environment.These constraints include the specimens to be suitable for microscopic genomic and proteomic methodologies on available volume – a spacecraft is a observation. By definition, fixation is a the specimens (‘molecular preservation’). For satisfactory for preserving cultured cells, at crowded precinct that must accommodate stabilising procedure, although some fixation every case and biological model system, least for 28 days, but it has to be removed many activities.The atmosphere is reactions, such as the interaction of dedicated procedures have to to be after thawing. recirculated in a highly closed loop, with formaldehyde with the amino groups of developed.The following sections review a limited filtering and purification. Another proteins, are reversible. However, in some few examples. 2.2 Preservation of Viability in Embryos of constraint is the manpower: the operators cases, the specimen has to be preserved Aquatic Organisms are restricted to the crewmembers, and alive, in a state as similar as possible to the 2. Techniques in Use The sea urchin is the biological model most they often have limited training in the moment of the completion of the 2.1 Preservation of Viability in Cultured frequently chosen from aquatic organisms for specific scientific field. Finally, the power experiment; this needs dedicated Cells studies into embryo development (Fig. 3). In demand is strictly limited, because it is a procedures.Whatever treatment is applied to Cultured mammalian cells (Fig. 2) are usually this material, sea urchin embryos from the very expensive and technologically limited the samples, they are stored until the end of sent into space in a frozen state and then blastula stage onwards can tolerate low resource (Fig. 1). the space mission, transported and reactivated in orbit. After the experiment, the temperatures of +5-6°C for about 3 weeks. Space experiments should therefore be recovered on the ground for analysis and cells are fixed and stored until recovery on Under these conditions, development is not designed to avoid or minimise the use of evaluation of results by the investigators. the ground.The freezing procedure uses completely blocked but extremely slowed. toxic volatile reagents, which could pollute Preservation is a key factor in all ground either a deep freezer, at –80°C, or liquid This temperature range is therefore suitable the cabin air.The limitation in crew time biological research, but it is critical in space nitrogen. A cryoprotectant, such as 10% for storing samples before or after the space may be overcome by automating processes, research, because of the atypical long DMSO, is added to the culture. It is experiment. Once on the ground, the

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samples in space research remains counter some of them, and to make possible Fig. 4.Hardware used for Arabidopsis seed germination and insufficiently resolved; it is a challenge for investigations using one of the more seedling fixation in flight during the ‘Cervantes’Spanish Soyuz space experiments. important model systems, the possibility of Mission of October 2003.Seeds are placed on a filter paper sheet, Different approaches to this problem were modifying some of the current techniques of which is enclosed in a sealed double-wall plastic bag (a ‘berlingot’),together with breakable glass ampoules filled either discussed by the Topical Team. As a result, a growth, preparation and fixation of with culture medium or fixative solution.Berlingots are laid tentative research project has been Drosophila melanogaster has been explored, within MAMBA biocontainers (Biorack type I/E containers),which elaborated for proposal to researchers and taking into account the requirements and the can selectively break the ampoules by a motorised mechanism. agencies. A summary of this project is given constraints of long-term space missions.The below. results were reported in the preceding references. It was shown that it is possible to 3. A Research Project: Improved Methods simplify the methodology of Drosophila and Techniques for Biological Sample embryo fixation (paraformaldehyde, solutions are extremely volatile, producing Preservation NeofixTM or acetone) and storage to obtain toxic vapours, so that a triple level of 3.1 Fixation successful morphological images and containment is required in most cases.The The objective is to develop a fixation molecular preservation of specimens suitable Fig. 3.Sea urchin eggs fertilised and fixed in space.a: flown virgin process is more complicated in biological procedure in which the risks of toxicity and for nucleic acid hybridisation and protein eggs recovered live, no longer fertilisable.b: flown egg, fertilised materials with hard cuticles (as found in inflammability are minimised, without immunodetection. Among many other and fixed during the µg phase; arrow indicates sperm attached to insects), which hampers fixative penetration. compromising the quality of structural problems, they will us allow to establish how the fertilisation envelope.c: aberrant pluteus larva, differentiated on ground, from an egg fertilised in µg.d: Young pluteus The alternative of deep freezing is not preservation of cells and tissues, or the the different processes taking place during differentiated from a ground control egg, at day 7.(Marthy, 1997) suitable because it results in poor integrity of protein epitopes and nucleic acid development actually proceed in the space ultrastructural preservation unless dedicated sequences for in situ localisation of environment and to monitor the adaptation cryofixation procedures are used.These are macromolecules. and changes the organisms may experience difficult to implement in space laboratories, in long-term multigeneration experiments. owing to the complexities of the hardware 3.1.1 New Methods Investigated Microwave-enhanced fixation has also recovery rate of normal embryos is about and the use of hazardous freezing agents Some methods have already been proved to be useful and promising for the 95% when returned to a culture temperature such as liquid propane and nitrogen. investigated, and their development is under future. It allows a dramatic reduction in around +20°C. Embryos at the blastula stage way or will begin in the near future. For fixation time and aldehyde concentration, and older, cryopreserved and stored in liquid 2.4 Molecular Preservation Drosophila embryos, the use of a non- with excellent structural and antigenic nitrogen at –196°C for 9 months, recover at Protein structure and epitope integrity are aldehyde fixative (NeofixTM) after preservation (Lería et al., 2004).The activities rates higher than 30% and continue usually well preserved in deep freezing permeabilisation, followed by long-term so far have explored microwave fixation with embryonic and larval development (Anthony (–80°C). For RNA, fixation in anhydrous cold storage in methanol, has been explored the objective of achieving quicker fixation et al., 1996). acetone (–20°C) has been successful. For cell (Herranz et al., 2002; 2005).The development regimes, lower concentrations of toxic and cultures, RNA preservation has been of this technique reflects the possibility of volatile reagents, and enhanced antigen 2.3 Fixation (Structural Preservation) achieved by adding lysing buffers based on conducting longer experiments aboard the detection. A modified domestic microwave Fixation in flight is usually performed by guanidine isothiocyanate (GITC), International Space Station. However, there oven (900 W) and a low-power (5 W) injecting or releasing fixative (a solution of centrifugation/filtration, and storage at are several obstacles, some involving the microwave bench were used, working with glutaraldehyde or formaldehyde) within a –80°C. availability of suitable hardware but others plant materials.The oven was supplemented closed chamber, with storage in the fixative However, none of these methods has more technical. Even in the best possible with a cooling device and a stirring system, itself (Fig. 4).The procedure is satisfactory provided a complete solution to the scenario, experiments have to fit around the and the sample temperature and time of only for short storage periods (maximum constraints of life sciences research in space. Shuttle-Station servicing schedule, which is effective irradiation were recorded.The 2 weeks). It is dangerous because aldehyde The problem of preservation of biological longer than a few months.To eliminate or sample, immersed in a fixative solution of 1%

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paraformaldehyde (PFA) in PBS, was buffer. For this purpose, the use of alcoholic within a container, which can be inserted into irradiated for only 10 min.The sample media for storage (NeofixTM, 70% ethanol) is a common facility (this will be a requirement temperature did not exceed 37°C. Under proposed. on the experiment developer).The facility these mild conditions, the quality of the should provide safe handling of hazardous (ultra)structural preservation of the samples, 3.1.2 Dedicated Hardware fluids, equipped with thermal control and morphometrically assessed, was at the same The industrial partners of the Topical Team have the possibility of microwave or UV level as obtained with the same fixative using collected the methodological fixation enhancement (Fig. 5). conventional methods. On the contrary, recommendations proposed by the scientific samples fixed in the same conditions without members and designed a Dedicated Prototype irradiation showed poor structural Automatic Fixation Facility for the The facility (Fig. 5) consists of two units.The preservation.The antigenic preservation of International Space Station. first provides storage for the different fluids, the irradiated samples was excellent: the including waste fluids.Thermal control of the labelling levels of two nucleolar proteins, Concept reservoirs does not need to be active, detected by immunogold, were three times Fixation usually requires a combination of because this part of the facility can be stored higher than in conventionally fixed samples. mechanical operations, fluid handling, in a cooler/incubator until use.The second The path of microwaves is guided in the physical stimulation and temperature body contains pumps and valves to circulate microwave bench, so that low-power control.The simplest fixation procedure fluids through the sample and apply physical microwaves directly hit the sample, without could be envisaged as: stimuli to the sample. It may even be capable dispersion of energy.The temperature of the of taking a sample from the experiment fixative did not increase after microwave – addition of a single fluid (usually container/culture chamber, and guiding the irradiation. Fixation in the bench with either formaldehyde or glutaraldehyde) into the probe into a vial, which then undergoes the 4% PFA or 1% PFA for 20 min resulted in sample; fixation or preservation treatment. Exact structural preservation of samples similar in – before fixation, the fixative agent is stored amounts of chemicals and accurate time quality to conventional fixation and to a at 4°C; control are crucial parameters in maintaining similar or better level of antigen – the fixative is automatically injected into the morphological quality and molecular preservation.Therefore, controlling the sample via a septum in the integrity of samples, important for temperature and effective irradiation is experiment container (EC) using a double- performing further investigations involving crucial in obtaining optimal structural and containment syringe; DNA. antigen preservation with microwave- – the whole EC is later stored under cool or A preliminary experiment protocol could enhanced fixation.The dramatic differences freezing conditions, or, alternatively, the be initiated by subjecting the culture plate or observed between microwave-irradiated sample is automatically retrieved and the vial with the suspension of cells on a samples and samples fixed under the same stored at –20°C. micro-carrier to a continuous flow of a buffer. conditions without irradiation strongly Then, a flushing step replaces the old support the existence of specific effects of However, most of the fixation procedures medium and washes the cells. A second Fig. 5.Concept for a fixation and preservation facility.Different microwaves on fixation, independent of require the use of different fluids and sequence, in which the continuous flow is fluids stored in a container specifically designed for storing merely heating the samples. washing cycles between fluids. stopped, would allow exact trypsinisation of hazardous fluids can be circulated through the sample in a Finally, preserving the quality of The approach suggested for biological the culture. Finally, the cells could be sequence defined by the investigator.The facility can transfer paraformaldehyde fixation after long storage sample fixation, in a dedicated facility, transported by a second washing process to samples, or part of the samples, from one sample container to another (carried by circulating fluids), perform filtration is a third approach to be explored.This would consists of leaving the sample in the EC a different chamber, to be collected on a filter processes,concentration processes,etc., provide thermal control minimise the reversion of the fixation during the initial phase of sample ready for the final treatment (reseeding, and can enhance the fixation process by electromagnetic reaction caused by prolonged storage in a preparation until the sample is confined fixation, staining). radiation.

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3.2 Preservation of Viability and Molecular grasses has raised the possibility of using compounds (PHCs) are the favoured of resisting and surviving extreme Preservation them as ice cream stabilisers. It might not be candidates for this type of stabilisation, conditions, such as low temperatures, The concept requires that chemical reactions impossible therefore to use anti-freeze because they are miscible among themselves freezing, high radiation levels and in the sample should be stopped in such a agents as ice-growth controllers in biological and with water in all proportions. Under desiccation. way that it is possible to restart them under material after exposure to weightless certain conditions of temperature and certain conditions, such as on the ground conditions and after storage for extended composition, such mixtures undergo a glass If we cannot find the perfect organism(s) after landing. If chemicals are added, they periods at subfreezing temperatures. transition under which the viscosity increases in the wide spectrum available on Earth to must be removable when restarting the For freeze tolerance, the cold-shock by a factor of 106 over a very narrow accompany humans on the adventure of biological activities, without producing any proteins are probably involved in temperature interval.This leads to a drastic space exploration, let us engineer them in unwanted reaction linked to their presence. fundamental cellular processes at stress reduction in molecular mobility and chemical our laboratories! Initially, only simple model systems should temperatures.Two genes in Escherichia coli, reaction rates. be used to begin testing assays, such as cspA and groEL, are involved in responses to References isolated biomolecules and their complexes, temperature changes. Protein CspA is rapidly 3.2.2 A Final Long-Term Objective Anthony, P., Ausseil, J., Bechler, B., Benguría, A., bioassemblies like phages, viruses and single and dramatically induced during the cold- Although initially the proposed work would Blackhall, N., Briarty, L. G., Cogoli, A., cells from various origins, such as shock response (up to 200-fold) and focus on the type of simple model systems Davey, M.R., Garesse, R., Hager, R., microorganisms, yeasts, plants and mammals. comprises more than 10% of the total listed above, it is clear that the work should Loddenkemper, R., Marchant, R., protein synthesis in cells experiencing such be expanded in the long-term to extending Marco, R.,Marthy, H.-J., Perry, M., Power, J. B., 3.2.1 The Problem of Water Management shock.The CspA mRNA is found to be the applications to high-multicellular Schiller, P., Ugalde, C.,Volkmann, D. & Water management is perhaps the main unstable at 37°C but is stabilised upon cold organisms (plants and animals).There are at Wardrop, J. (1996). Preservation of Viable problem. Ice is the fiercest enemy of life. It is shock, indicating that CspA expression at low least three complementary approaches to be Biological Samples for Experiments in lethal and its growth in living species needs temperatures may be regulated by post- explored: Space Laboratories. J. Biotechnol. 47, 377- to be managed with care.This will involve the transcription mechanisms. Some homology 393. avoidance of freezing or limited tolerance to between the Drosophila melanogaster – study the reasons why complex Bechler, B., Hunzinger, E., Muller, O. & Cogoli, A. freezing. genome and the sequences of groEL and multicellular organisms do not easily (1993). Culture of Hybridoma and Friend The in vivo occurrence of freeze avoidance cspA genes suggest the possibility of a survive the conditions that allow the Leukemia Virus Transformed Cells in has been intensively studied, particularly in similar homology between these two genes preservation and survival of simpler Microgravity. Spacelab IML-1 Mission. Biol. Antarctic fish species that spend all their lives and genes in other freeze-tolerant insect systems, as established in the previous Cell 79, 45-50. (up to 150 years) at temperatures below the species that may be involved in the freeze- investigations; Herranz, R., Husson, D., Pastor, M., Díaz, C., freezing point of blood. Several antifreeze thaw process.There are specific species that – increase understanding of the Mateos, J.,Villa, A., Medina, F.J. & Marco, R. proteins (AFP) and glycoproteins have also have developed particular dormant mechanisms that allow the preservation (2002).Towards the Establishment of a been identified in other species, such as adaptations for survival under very and survival of particular multicellular Permanent Colony of Drosophila in the insects and grasses. Although the detailed uncommon and extreme conditions. organisms at defined developmental International Space Station. J. Gravit. mechanisms are not yet clear, the AFPs, at There is a tested and proven method for moments when subjected to the same Physiol. 9,357-358. micromolar concentrations, are able to inhibit stabilising biomacromolecules, particularly conditions; Herranz, R., Husson, D.,Villa, A., Díaz, C., the growth, but perhaps not the nucleation, therapeutic proteins, against chemical – apply the potential of the powerful new Ruíz, J.M., Mateos, J., Pastor, M., Medina, F.J. of ice crystals. In the case of Antarctic fish, deterioration: vitrification. It relies on the genetic methods to allow the & Marco, R. (2005). Modifications in Basic they are active at temperatures even below formation of highly supersaturated aqueous incorporation, in selected complex model Handling Techniques to Study the Effects –2°C. Until recently, technological solutions by adding substances that do not systems, of the particular successful of Drosophila melanogaster Exposure to exploitation, perhaps to preserve the texture themselves readily crystallise but are able, adaptations found either in the studies the Space Environment. J. Gravit. Physiol. of frozen foods, was considered to be too like water, to form 3-D hydrogen bonded using simpler model systems, or in Submitted for publication. costly. However, the discovery of AFPs in networks with water. Polyhydroxy phylogenetically-related species capable Lería,F.,Marco,R.& Medina,F.J.(2004).

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Structural and Antigenic Preservation of Plant Samples by Microwave-Enhanced Topical Team Members Fixation, using Dedicated Hardware, Minimizing Heat-Related Effects. Microsc. Francisco Javier Medina Hans Jürg Marthy Res.Tech. 65, 86-100. Centro de Investigaciones Biológicas (CSIC), Observatoire Océanologique, CNRS (UMR 7628), Marthy, H.-J. (1997). Sea Urchin Eggs under Ramiro de Maeztu 9, E-28040 Madrid, Spain. Université P.et M. Curie, F-66650 Banyuls-sur- Microgravity Conditions. In Life Sciences Tel: +34 91 8373112 mer, France. Experiments Performed on Sounding Rockets Email: [email protected] Email: marthy@arago.obs-banyuls.fr (1985-1994), (Eds. D. Mesland & G. Ruyters), ESA SP-1206, ESA Publications Division, Augusto Cogoli Carlos Martín Pascual Noordwijk,The Netherlands. Zero-g Life Tec GmbH,Technoparkstrasse 1, CH- Distcom.Antenas, Cayetano García 24, E-28250 8005 Zurich, Switzerland. Torrelodones, Madrid, Spain. Email: [email protected] Email: [email protected]

Christian Dournon Jutta Kraemer EA 2401 Génétique et Interactions Cellulaires en Dutch Space, P.O. Box 32070, 2303 DB Leiden,The Reproduction, Université Henri Poincaré, Netherlands. F-54506 Vandoeuvre-lès-Nancy cedex, ESTEC, 2200 AG Noordwijk,The Netherlands. France. Email: [email protected] Email: [email protected] Miquel Pastor Felix Franks NTE, Barcelona, Spain. BioUpdate Foundation, 25 The Fountains, ESA Headquarters, 8-10 Mario Nikis, F-75738 229 Ballards Lane, London N3 1NL, UK. Paris Cedex 15, France. Email: [email protected] Email: [email protected]

Roberto Marco Departamento de Bioquímica, Universidad Autónoma de Madrid, Arzobispo Morcillo 4, E-28029 Madrid, Spain. Email: [email protected]

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Report of the Gravity-Sensing and Plant ESA Topical Team in Life Sciences Gravity-Sensing and Plant Development in Space Development in Space Contributors: M. Pagès, Barcelona (E) (Coordination) C. Koncz, Cologne (D) K. Palme, Freiburg (D) G. Perbal, Paris (F) R. Ranjeva, Castanet Tolosan (F) A.F.Tiburcio, Barcelona (E) D.Volkmann, Bonn (D) 1. Gravity and Plant Development done with entire plants (wild type and The Earth‘s gravitational field has played a mutants), because the role of the activated major role in the evolution of plants.Two genes may be studied in the whole organism different actions of gravity on plants can be only, whereas the process of gene expression microscope with a 63x objective.This kind of studied in space: the development and the per se may be studied in isolated cell analysis instrument should be available in mechanisms of gravity-sensing. cultures. orbit. Plant development will be studied for There have been no studies on ESA must provide support for the Fig. 1 (left).The physiology of Arabidopsis is well known. practical reasons. For long-term spaceflights, gravimorphism in microgravity so far, but multidisciplinary research activities, such as Fig. 2 (right).Maize could be another plant model for space it will be necessary to produce food for this would also be an interesting subject for the development of DNA chips for space and research. astronauts and to build life-support systems the DNA chip analysis. Reasons for the lack of other applications. Hyper-g and simulated in space.The study of plant development in experiments in this field may include microgravity research on the ground must be space deals partly with stress physiology unsatisfactory hardware for plant growth supported by ESA; this is now provided because the environment is not optimal for and problems with post-experiment sample under ESA‘s ‘Access to Ground Based plant growth.The lack of convection even in preservation (e.g. freezing facilities). Facilities Programme’. growth chambers with a controlled The development of such DNA chips is a atmosphere could also perturb plant challenge for European industry, but 3.The Future morphogenesis.The analysis of plant growth potentially offers a wide range of Figure 3 shows the principle of the ‘Molecular in space should include the growth of the applications in areas other than plant Plant Growth Response Monitoring System’ different organs, hormone distribution, research. (MOPS) that should be built to study plant photosynthesis, respiration, transpiration and The investigations will concentrate on one development and gravitropism. gene expression. or two plant models in order to promote An important part of MOPS is the Gravity-sensing in plants is responsible for focused research by several groups with Automatic Sampler, equipped with micro- the orientation of the organs in the different backgrounds and different analysis sensors (ethylene, jasmonate) and micro- gravitational field. It involves the perception methods. One model could be Arabidopsis analysis instruments (green fluorescent of gravity and the transduction chain of the (Fig. 1) because its physiology is very well protein (GFP) analysis).These sensors may be Fig. 3.The Molecular Plant Growth Response Monitoring System gravistimulation known (Muller et al., 1998; Galweiler et al., attached to micro-fibres for fluorescence (MOPS). 1998; Bishop & Koncz, 2002; Panicot et al., excitation and observation. 2. The Tools for Analysing Plants in Space 2002) and there are many mutants The Automatic Sampler takes a specimen For these analyses, DNA chips will be (Szabados et al., 2002).The other should be a from the monitored spot without previous necessary.This technique allows a snapshot well-investigated crop plant (Kizis & Pages, touching or wounding the monitored area of performed under 1 g (orbit or ground), with description of a large variety of parameters 2002) with economic potential, such as the leaf or the plant organ.This sampling image analysis on the ground when sufficient that change when a cell is exposed to a maize or rice (Fig. 2). should ideally be done by an operator via data transfer to Earth can be guaranteed. different environment, such as 1 g and The localisation of proteins that play a key remote control. The design of the freezing unit needs to be microgravity. Instead of analysing all the role in plant development (Molendijk et al., For the Analysis Unit, there is assumed to improved for very fast preservation, for metabolic parameters in many different 2001; Borrell et al., 1995; Riera et al., 2004; be an existing Polymerase Chain Reaction example, by cold plates touching the leaf assays, one preparation will be sufficient, Blilou et al., 2005, Lumbreras et al., 2001; (PCR) system for contamination analysis surfaces to simulate the on-ground liquid allowing the study of all activated genes that Baluska et al., 2004; Ottenschlager et al., aboard the International Space Station (ISS), nitrogen technique. Ground freezing also can describe the complete response of the 2003) should be performed. For the and a mass spectrometer (type to be needs improvement because the cell to the environmental change (Centis- detection of proteins fused to reporter defined) for analysing plant proteins (which replacement of the intercellular air space by Aubay et al., 2003; Ranjeva et al., 1999; Perbal genes, a high-resolution microscope is can also be used for specimens of other liquid requires, for example, rapid pressure et al., 2003).This investigation should be needed, such as a general fluorescence organisms). Protein electrophoresis is changes. So far, only three layers below the

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leaf epidermis can be well-preserved for To study these effects, the following Growth and Patterning in Arabidopsis Bhalerao, R.P.,Sandberg, G., Ishikawa, H., cytology by rapid freezing in liquid instruments are required on the ground: Roots. Nature 433(7021), 39-44. Evans, M. & Palme, K. (2003). Gravity- nitrogen, while deeper cell layers are Borrell, A., Culianez-Macia, F.A., Altabella, T., Regulated Differential Auxin Transport destroyed by thawing. – liquid-nitrogen freezer for cytology and Besford, R.T., Flores, D. & Tiburcio, A.F. from Columella to Lateral Root Cap Cells. The gene expression profile could also biochemistry; (1995). Arginine Decarboxylase Is Proc. Natl. Acad. Sci. U.S. 100(5), 2987-2991. indicate if the growth conditions are – fluorescence microscope for GFP Localized in Chloroplasts. Plant Physiol. Panicot, M., Minguet, E.G., Ferrando, A., appropriate in the greenhouse, growth detection (multi-photon laser scanning 109(3), 771-776. Alcazar, R., Blazquez, M.A., Carbonel, J., chamber or plant cuvette.This is also microscope) with micro-fibres for Centis-Aubay, S., Gasset, G., Mazars, C., Altabella, T., Koncz, C. & Tiburcio, A.F. important for ground applications. In excitation and analysis on micro-surfaces; Ranjeva, R. & Graziana, A. (2003). Changes (2002). A Polyamine Metabolon Involving general, the gene chip technology is also – automatic sensor and analysis system; in Gravitational Forces Induce Aminopropyl Transferase Complexes in useful for human health monitoring. – gene chip reader; Modifications of Gene Expression in Arabidopsis. Plant Cell. 14(10), 2539-2551. A system such as MOPS could be used for – standard analysis instruments. A. thaliana Seedlings. Planta. 218(2), 179- Perbal, G., Lefranc, A., Jeune, B. & Driss- ground research (mutants, crop testing), 185. Ecole, D. (2003). Mechanotransduction in space life-support and nutrition, and To study these effects, the following Galweiler, L., Guan, C., Muller, A.,Wisman, E., Gravisensing Cells. Trends Plant Sci. 8(10), fundamental space research. instruments are required in space: Mendgen, K.,Yephremov, A. & Palme, K. 498-504. The following summarise the topics (1998). Regulation of Polar Auxin Transport Ranjeva, R., Graziana, A. & Mazars, C. (1999). relevant to space research on plants. – –80/–180°C freezer or an equivalent to by AtPIN1 in Arabidopsis Vascular Tissue. Plant Graviperception and Gravitropism: ‘hot phenol extraction system’; Science 282(5397), 2226-2230. A Newcomer’s View. FASEB J. 13 Suppl. The Molecular Plant Growth Response – micro-sensors for ethylene, jasmonate; Kizis, D. & Pages, M. (2002). Maize DRE-Binding S135-S141. Monitoring System should allow space – light box for stimulation with red/blue Proteins DBF1 and DBF2 are Involved in Riera, M., Figueras, M., Lopez, C., Goday, A. & biology studies on: light; Rab17 Regulation through the Drought- Pages, M. (2004). Protein Kinase CK2 – fluorescence microscope for GFP Responsive Element in an ABA-Dependent Modulates Developmental Functions of – definition of target genes responding to detection in root cells; Pathway. Plant J. 30(6), 679-689. the Abscisic Acid Responsive Protein microgravity (gravi-genomics); – automatic sensor and analysis system; Lumbreras,V., Alba, M.M., Kleinow,T., Koncz, C. Rab17 from Maize. Proc. Natl. Acad. Sci. U.S. – kinetics of gene regulation; – mass spectrometer; & Pages, M. (2001). Domain Fusion 101(26), 9879-9884. – cytoskeleton monitoring in microgravity, – PCR device; between SNF1-related Kinase Subunits Szabados, L., Kovacs, I., Oberschall, A., e.g. actin polymerisation by GFP – protein electrophoresis (on 1 g during Plant Evolution. EMBO Rep. 2(1), 55- Abraham, E., Kerekes, I., Zsigmond, L., marking; centrifuge). 60. Nagy,R.,Alvarado,M.,Krasovskaja,I., – photosynthetic response to microgravity Molendijk, A.J., Bischoff, F., Gal, M., Berente, A., Redei, G.P., Haim, A.B. & (including phytochrome system); References Rajendrakumar, C.S., Friml, J., Braun, M., Koncz, C. (2002). Distribution of 1000 – changes in protein patterns in Baluska, F.,Volkmann, D. & Barlow, P.W. (2004). Gilroy, S. & Palme, K. (2001). Arabidopsis Sequenced T-DNA Tags in the Arabidopsis microgravity (gravi-proteomics); Cell Bodies in a Cage. Nature 428(6981), thaliana Rop GTPases are Localized to Tips Genome. Plant J. 32(2), 233-242. – transport processes, including a 371. of Root Hairs and Control Polar Growth. metabolic profile (storage) as response Bishop, G.J. & Koncz, C. (2002). EMBO J. 20(11), 2779-2788. to microgravity; Brassinosteroids and Plant Steroid Muller, A., Guan, C., Galweiler, L.,Tanzler, P., – signal transduction and stress responses Hormone Signaling. Plant Cell. 14, Suppl. Huijser, P., Marchant, A., Parry, G., in microgravity; S97-S110. Bennett, M.,Wisman, E. & Palme, K. (1998). – optimisation of growth processes in Blilou, I., Xu, J.,Wildwater, M.,Willemsen, V., AtPIN2 Defines a Locus of Arabidopsis for microgravity (seed-to-seed experiments); Paponov,I.,Friml,J.,Heidstra,R.,Aida,M., Root Gravitropism Control. EMBO J. 17(23), – identification of regulatory processes in Palme, K. & Scheres, B. (2005).The PIN 6903-6911. mutants responding to gravity. Auxin Efflux Facilitator Network Controls Ottenschlager, I.,Wolff, P.,Wolverton, C.,

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plant development

Topical Team Members

Prof. Csaba Koncz Prof. Antonio F.Tiburcio Max-Planck-Institut für Züchtungsforschung, Unitat de Fisiologia Vegetal, Facultat de Carl-von-Linné-Weg 10, D-50829 Köln, Farmacia, Avda. Diagonal 643, E-08028 Germany. Barcelona, Spain. Tel: +49 221 5062-230 Tel: +34 93 402 4493 Fax: +49 221 5062-213 Fax: +34 93 402 1886 Email: [email protected] Email: [email protected]

Prof. Klaus Palme Prof. Dieter Volkmann Institut fur Biologie II, Albert-Ludwigs- Botanisches Institut der Universität Bonn, Plant Universitat Freiburg, Schanzlestrasse 1,D- Cell Biology, Kirschallee 1, D-53115 Bonn, 79104 Freiburg, Germany. Germany. Tel: +49 761 203 2954 Tel: +49 228 73-4747 or 4748 Fax: +49 761 203 2675 Fax: +49 228 73-9004 Email:[email protected] Email: [email protected]

Prof. Gérald Perbal Coordinator Laboratoire CEMV, Bat. N2, Université P.et M. Prof. Montserrat Pagès Curie 4, Place Jussieu, F-75252 Paris Departament de Genetica Molecular, IBMB.CID Cedex 05, France. CSIC., Jorge Girona Salgado 18, E-08034 Tel: +33 144 27-3741 Barcelona, Spain. Fax: +33 144 27-4582 Tel: +34 93 400 6131 or +34 93 4006100 Email: [email protected] Fax: (+34) 93 204 5904 Email: [email protected] Prof. Raoul Ranjeva UMR 5546 CNRS-UPS, Pole de Biotechnologies Contract Communications Vegetales, 24 chemin de Borde Rouge, BP 17 Mrs. Neus Tur Auzeville, F-31326 Castanet Tolosan, France. Associacio per el Desenvolupament de la Ciencia Tel: +33 5 62 19 35 17 I la Tecnologia, Jorge Girona Salgado 18-26, Fax: +33 5 62 19 35 02 E-08034 Barcelona, Spain. Email: [email protected] Tel: +34 93 400 6100 Fax: +34 93 204 5904

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