A STEPPING STONE TO LOW THE BREMEN DROP TOWER EARTH ORBIT
Dezember 08, 2015 NANORACKS ISS WORKSHOP, LEIDEN, NL
Dr. Thorben Könemann ZARM Drop Tower Operation and Service Company WWW.ZARM.UNI-BREMEN.DE founded ZARM‘s Organization Structure in 1985
ZARM%&%Center%of%Applied%Space%Technology%and%Microgravity c/o$University$of$Bremen$ Am$Fallturm,$28359$Bremen,$Germany$ [email protected]
ZARM%&% ZARM%FAB%mbH ZARM%Technik%AG University%of%Bremen
Research%Ins>tute%&%Faculty%04% ZARM%Drop%Tower%Opera>on% Supplier%of%AMtude%Control% Produc>on%Engineering and%Service%Company Equipment%for%Satellites
Prof.$Dr.$Claus$Lämmerzahl$ Prof.$Dr.$Claus$Lämmerzahl$ Holger$W.$Oelze$ (ExecuLve$Director) Peter$von$Kampen$ (Chief$ExecuLve$Officer) (ExecuLve$Board) Peter$von$Kampen$ Prof.$Dr.$Claus$Lämmerzahl$ (Chief$Financial$Officer) (Director$Space$Science) ChrisLan$Eigenbrod$ Prof.$Dr.$Claus$Braxmaier$ Dr.@Ing.$Thorben$Könemann$ Marco$R.$Fuchs$ (Director$Space$Technology) Ulrich$Kaczmarczik$ (Chairman$of$Supervisory$Board) (ScienLfic$/$Technical$Management) @$to$be$announced$@$ (Director$Fluid$Dynamics)
! Research / Teaching ! Technical Support ! Space Hardware
2 founded ZARM‘s Organization Structure in 1985
ZARM%&%Center%of%Applied%Space%Technology%and%Microgravity c/o$University$of$Bremen$ Am$Fallturm,$28359$Bremen,$Germany$ [email protected]
! technical support for ZARM%&% microgravity ZARM%FAB%mbH ZARM%Technik%AG University%of%Bremen experiments
Research%Ins>tute%&%Faculty%04% ZARM%Drop%Tower%Opera>on% Supplier%of%AMtude%Control%! payload Produc>on%Engineering and%Service%Company Equipment%for%Satellitesintegration Prof.$Dr.$Claus$Lämmerzahl$ Prof.$Dr.$Claus$Lämmerzahl$ Holger$W.$Oelze$ (ExecuLve$Director) Peter$von$Kampen$ (Chief$ExecuLve$Officer)service since 1990 (ExecuLve$Board) Peter$von$Kampen$ Prof.$Dr.$Claus$Lämmerzahl$ (Chief$Financial$Officer)! qualification and (Director$Space$Science) ChrisLan$Eigenbrod$ testing Prof.$Dr.$Claus$Braxmaier$ Dr.@Ing.$Thorben$Könemann$ Marco$R.$Fuchs$ (Director$Space$Technology) Ulrich$Kaczmarczik$ (Chairman$of$Supervisory$Board) (ScienLfic$/$Technical$Management) ! competent and @$to$be$announced$@$ (Director$Fluid$Dynamics) well-experienced
! Research / Teaching ! Technical Support ! Space Hardwareengineers
3 Support of ZARM‘s Student Programs Young
ZARM%&%Center%of%Applied%Space%Technology%and%Microgravity c/o$University$of$Bremen$ Am$Fallturm,$28359$Bremen,$Germany$ [email protected]
ZARM%&% DropTES ZARM%FAB%mbHDrop Your Thesis! ZARM%REXUS / BEXUS Technik%AG DropPS University%of%- UNOOSA -Bremen - ESA Education Office - - DLR / SNSB - - ZARM -
Research%Ins>tute%&%Faculty%04%Drop Tower Experiment ZARM%Drop%Tower%Opera>on%Drop Tower Experiment Supplier%of%AMtude%Control%Sounding Rocket and Ballon Produc>on%EngineeringSeries and%Service%CompanySeries Equipment%for%SatellitesExperiment Series
Prof.$Dr.$Claus$Lämmerzahl$ Prof.$Dr.$Claus$Lämmerzahl$ Holger$W.$Oelze$ for School Students Drop Tower Project (ExecuLve$Director) Peter$von$Kampen$ (Chief$ExecuLve$Officer) - DLR_School_Lab (ExecuLve$Board) Peter$von$Kampen$ Prof.$Dr.$Claus$Lämmerzahl$ (Chief$Financial$Officer) (Director$Space$Science) ChrisLan$Eigenbrod$ Prof.$Dr.$Claus$Braxmaier$ Dr.@Ing.$Thorben$Könemann$ Marco$R.$Fuchs$ (Director$Space$Technology) Ulrich$Kaczmarczik$ (Chairman$of$Supervisory$Board) (ScienLfic$/$Technical$Management)
@$to$be$announced$@$ -
(Director$Fluid$Dynamics) ! ! ! Bremen Drop Tower ! Bremen Drop Tower Esrange Space Center Kiruna, Sweden
4 know- how, reliability, ZARM TEST CENTER - we.know.how.flexibility, customer- focused !Convenient Combination of ZARM’s Test Labs ! Aerospace Qualification and Test Services under one roof ! VIBRATION TEST LAB - LONG STROKE SHAKER
! THERMAL VACUUM CHAMBER / THERMAL CYCLING CHAMBER
5 know- how, reliability, ZARM TEST CENTER - we.know.how.flexibility, customer- focused !Convenient Combination of ZARM’s Test Labs ! Aerospace Qualification and Test Services under one roof ! 30g CENTRIFUGE - EUROPE’s LARGEST HYPER-GRAVITY FACILITY
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6 Content !The Bremen Drop Tower !Introduction !Operation !Facts and Figures !Examples: Drop Tower Experiments !Scientific Pathfinder Flights !XCOR Aerospace: Lynx Mark I !End-to-End Service
7 operation The Bremen Drop Tower - Introductionstarted ! drop mode: 120 m ! 4.74 s in weightlessness ! highest quality - 10-6 g
146 m (µg) ! decelerations of up to 50 g ! catapult mode: ! worldwide unique facility ! 9.3 s in weightlessness -6 8 ! highest quality - 10 g (µg) ! accelerations of up to 30 g ! decelerations of up to The Bremen Drop Tower - Introduction
! Drop Tower Capsules payload areas 2560 mm
1718 mm
payload masses
mm 265 kg 165 kg 225 kg 200 kg 953
! power supply: ! 24 / 28 V DC
9 The Bremen Drop Tower - Operation
10 The Bremen Drop Tower - Facts and !Since the Start of Operation in 1990 ! over 7500 drops / catapult launches have been conducted ! more than 200 different experiment types have been integrated ! within Combus oninternational collaborations from over 40 Astrophysics / Planetology countriesFundamental Physics !Research Fields of Drop Tower ExperimentsFluid Dynamics Biology ! fundamental research / mission preparations Materials Sciences Chemistry / Technological Tests
11 The Bremen Drop Tower - Facts and !Scientific Access to the Bremen Drop Tower ! National Research Program ! supported by German Aerospace Center (DLR) ! via DLR Space Administration -> Microgravity Research and Life Sciences Program ! European Research Program ! supported by European Space Agency (ESA) ! via ESA Human Spaceflight and Exploration -> Continuously Open Research Announcement (CORA) ! International Research Cooperations / Bilateral Collaborations 12 Content !The Bremen Drop Tower !Introduction !Operation !Facts and Figures !Examples: Drop Tower Experiments !Scientific Pathfinder Flights !XCOR Aerospace: Lynx Mark I !End-to-End Service
13 Fundamental Physics - QUANTUS I / II
!Ultracold Macroscopic Quantum Systems in Related Publica ons: - T. van Zoest et al., Science 328 (2010) Weightlessness - Drop Tower Experiments - H. Mün nga et al., Phys. Rev. Le . 110 (2013) ! supported by DLR Space Administration - J. Rudolph et al., New J. Phys. 17 (2015) ! QUANTUS - Collaboration / U Hanover, Berlin, Bremen, week ending PRL 110, 093602 (2013) PHYSICAL REVIEW LETTERS 1 MARCH 2013
magnitude. By applying delta-kick cooling (DKC) [28–30] the fringe spacing in our expanding cloud, being the distance we have been able to reduce the expansion and to enhance between two local maxima of the density, increases with the Hamburg, etc. the signal at longer interferometry times. We study the total expansion time T of the BEC and is inversely propor- ex coherent evolution of the BEC for increasing temporal tional to the displacementNew J. Phys.d 17of the(2015) two 065001 clouds. J Rudolph et al and spatial separation of the wave packets inside the inter- Figure 2 illustrates our experiments in microgravity ferometer by monitoring the single-shot contrast and shape performed at the drop tower. We show the complete tem- of the fringes [31]. poral sequence [Fig. 2(a)], which differs from the previous week ending Our experimentsPRL 110, are performed093602 (2013) with an asymmetricPHYSICALexperimentsREVIEW with the apparatus LETTERS [15] in three important 1 MARCH 2013 ! Mach-Zehnder interferometer (AMZI) [20,32] shown in features: (i) We employ DKC to reduce the expansion Realization of first Bose-Einstein Condensates, Atom Fig. 1. Here we(a) display the temporal evolution (b) of the during the free fall by briefly (2 ms) switching on the combined with the nonlinear evolution of the BEC occurs atomic density distribution of the BEC interferometer for trap with frequenciesonly of (10, at very22, 27) short Hz generated times (< by30 the ms). The linear scaling of an experiment on ground [Fig. 1(a)] and the corresponding atom chip 30 ms afterthe the fringe release. pattern (ii) In confirms order to eliminate the unperturbed evolution of the experimental sequence for forming the interferometer detrimental effects ofBEC residual during magnetic extended fields free we fall.transfer [Fig. 1(b)]. A macroscopic wave packet is coherently split, the BEC into the nonmagneticThe expansion state F rate2;m ofF the0 BECby due to the mean-field redirected, and brought to a partial overlap by successive coupling the Zeeman levels with a chirpedj ¼ radio-frequency¼ i Interferometers (QUANTUS I), Dual-Spezies Atom energy is a limiting factor for extending the interferometer Bragg scattering at moving light crystals [26,33,34]. They pulse (adiabatic rapid passage) [35]. (iii) At the time T0 are generated by pulses of two counter-propagating laser after the release of theto BEC, even we longer implement time the scales. sequence It can of be reduced by DKC, beams separated by the two-photon recoil energy of the AMZI outlined inwhich Fig. 1 actsand on detect the the BEC interference like a three-dimensional lens. 15 kHz and detuned from the F 2 F 3 transition pattern at Tex after theIndeed, release in using our experiments absorption imaging DKC realized with the atom 87 ¼ ! ¼ (c) of the D2 line of Rb by 800 MHz to reduce spontaneous with a single laser pulsechip as illustrated eliminates in Fig. a substantial2(b). In Fig. part2(c) of the kinetic energy of Interferometersscattering. There exists a close analogy to the Young double- (QUANTUS II) in µg we show typical imagesthe BEC, of the giving interfering rise BECs to an and effective the temperature of about slit experiment [Fig. 1(c)], where one pair of overlapping corresponding column1 nK. density The profiles method for allows two differentus to extend the observation of BECs plays the role of a pair of coherent light waves ema- values of Tex. the free evolution of the BEC and was tested with our nating from two slits separated by a distance d. Similar to the Figure 3 summarizesAMZI. the Thecentral experimental results of our observations Letter (red squares) of the resulting interference pattern in the far field of the double slit, on probing the coherentfringe evolution spacing agree of a BEC well with thean theoretical predictions (solid red line) for a double-slit experiment with delta-kick ! transportable high-precision quantum sensors(a) (b)cooled (c) atoms. In order to reach even longer times (black FIG. 2 (color). Mach-Zehnder interferometry of a BEC in triangles), we have adjusted the detection time such that microgravity as realized in the ZARM drop tower in Bremen the patterns of the two exit ports overlap, thus increasing (a) where absorption imaging (b) brings out the interference the absorption signal. fringes (c). The preparatory experimental sequence (a) includes As shown in Fig. 3(b), we observe a contrast of more capturing cold atoms in a magneto-optical trap (MOT), loading than 40%, even at times 2T T as large as half a second. an Ioffe-Pritchard trap, creating a BEC, and applying the DKC However, then the contrastÀ decreases with the time over followed by the adiabatic rapid passage (ARP). The remaining which the wave packets are separated, and generally with time before the capture of the capsule at the bottom of the the expansion time of the BEC. The observed reduction is tower is used for AI and imaging of the atoms. The AMZI below Figurenonexponential 1. CAD model in of time the and experimental uniform over setup. theQUANTUS II The cloud. assembly In this consists of four platforms, each with a diameter of approximately the atom chip [top plane of (b)] is formed by scattering the 65 cm. From top to bottom, they are used for the laser system, vacuum pumps, computer control system and electronics, and the BEC off moving Bragg gratings generated by two counter- respect the asymmetric interferometer puts more severe vacuum chambers. propagating laser beams (red arrows directed along the y axis), constraints on the setup than the symmetric one. resulting in two pairs of interfering BECs. A resonant laser beam However, it allows us to analyze- Catapult Experiment - various effects perturbing propagating along the x axis projects the shadow of the the interferometer. A preliminary analysis shows that the BEC onto a CCD camera. Typical interference patterns and reduction may be due to an imperfect alignment of the the corresponding column densities (c) are shown for Tex of beam splitters, inhomogeneous wave fronts or disturbances 180 and 260 ms with corresponding fringe spacing of 75 and resulting from a slight capsule rotation. A more detailed 107 m. discussion is subject to future investigations. QUANTUS I FIG. 1 (color). Temporal AMZI for a BEC based on Bragg scattering at a light grating: experimental images on ground (a), schematic sequence (b), and analogy to the Young double-slit experiment! (c). The evolution of theIn BEC conclusion, and the AMZI our device is visualized represents by a unique test bed for a series of absorptioninterferometer images (a) of in the extended atomic densities free fall. separated It shows by 1 ms. theMAIUS - Sounding Rocket The spatial incompleteexploring transfer is atom a consequence interferometry of the larger with novel states of matter mean-field energyperiod of theBEC of the necessary observed for the fringe ground pattern experiment. [Fig. The3(a) interferometer] as a startsin extendedat the time freeT0 after fall. the In release particular, of the it allows us to test tools 14 BEC, when a =2 pulse (b) made out of two counter-propagating light beams of frequency ! and ! creates a coherent function of the expansion time Tex, and the contrast of atom optics,þ such as the precise mode control of a BEC superposition of two[Fig. wave3(b) packets] observed that drift at apart the withexit the ports two-photon of the AI recoil for velocity increas-vrec 11with:8 mm DKC=s. After at energyT they are scales redirected approaching by pK temperatures. a pulse and partially recombined after T T by a second =2 pulse.Experiment, 2016 A nonzero¼ value of T leads to a spatial interference pattern, which weing record values after 2 T-53T msofin theÀ free time fall. Similar the BEC to the spends far-field patternin the observedThese in the concepts Young double-slit are essential experiment for high-resolution measure- ¼ (c), the fringe spacinginterferometer.l scales linearly Moreover, with the in time Fig. of3(a) expansionwe confrontTex T0 the2T mentsT and both is in inversely fountains proportional and in microgravity. to the separation dexperimentalv T of the results wave packets. (blue circles, The scaling red factor squares, is the black¼ ratioþ of tri- Planck’sÀ þMoreover, constant h and in theour mass experimentm of the we could follow the evo- ¼ rec Rb Rubidium atoms.angles) with the corresponding theoretical predictions lution of the temporal coherence of an asymmetric (solid blue and red lines). The solid blue line originates Mach-Zehnder interferometer with a BEC in microgravity, from a model based on the scaling approach093602-2 [36–39] and which is analogous to Young’s double-slit experiment with describes the interference pattern of two condensates ini- a gigantic matter-wave packet being in free fall for nearly a tially separated by a distance d, which start to expand and second. All preparatory steps necessary for high-precision eventually overlap. Their initial shape is derived from a interferometry are implemented with the help of a robust detailed numerical model of our magnetic chip trap. For chip-based BEC source. large time scales the observed fringe spacing (blue dots) Employing our present setup with a stabilized phase as shows a linear increase with Tex in full accordance with our an accelerometer, the number of condensed atoms would model and with the linear far-field prediction (dash-dotted compromise the gain in resolution due to the extended time blue curve) of the double slit. We emphasize that our in the interferometer. We expect that the next generation of microgravity experiments operate deep in the linear regime our setup will provide us with a BEC consisting of 106 Figure 2. CAD models of the vacuum setup (left) and the atom chip setup (right). The vacuum setup consists of two chambers. In the and the nonlinear behavior typical for the near field 2Dparticles, chamber a improved high rubidium DKC background and techniques pressure to is correct created tofor form a 2D+MOT [23], which generates a beam of pre-cooled atoms. This beam is injected into the 3D chamber, where an ultra-high vacuum is maintained. Here, the atoms are collected by a 3D-Chip- 093602-3MOT and transferred to pure magnetic traps, formed by the atom chip setup and external bias coils. Atom interferometry as well as detection of the atoms are carried out in the 3D chamber. On the right hand side the three layers of the atom chip setup, consisting of the science chip, the base chip and the mesoscopic structures, are shown in an exploded view.
available for 2D+MOT operation is 120 mW, while the 3D-MOT is operated with a total power of 92 mW. A small part of about 2 mW of the cooling light is split off and used for optical state preparation via the F = 22→′F = transition as well as for fluorescence and absorption imaging via the cooling transition.
2.2. Vacuum chambers The vacuum setup consists of two chambers separated by a differential pumping stage (see figure 2), allowing for a pressure difference of up to three orders of magnitude. A high vacuum (HV) area (2D chamber) is used for the − atomic source and is operated slightly below the room temperature vapor pressure of rubidium at 10 7 mbar. It generates a pre-cooled beam of atoms towards an ultra-high vacuum (UHV) chamber. The UHV region (3D chamber) is used to capture the atoms, cool them to degeneracy and perform atom interferometry. Its pressure
3 NATURE PHYSICS DOI: 10.1038/NPHYS2821 LETTERS Astrophysics - EULE Solar insola tion !Experimental Investigation of Light-Induced
Rock/boulder Eruptions in Microgravity - Drop Tower With shadow Gas flow
Martian soil
Figure 4 The natural soil pump on Mars. Owing to solar insolation thermal creep leads to a gas flow from the cool deeper layers up to the surface. The | Experiments resulting pressure difference in the dust bed soaks up atmospheric gas from shadowed surfaces into the soil and pumps it underneath the surface towards insolated (heated) surface regions.
l 2 cm (depth of the dust bed) and basaltic powder with a thermal = 1 1 Laser Dust sample conductivity of 0.01 W K m (ref. 18), we get 1T 300 K (ref. 15). In a simple model of hexagonally packed spheres,= the ! supported by DLR Space Administration radius of a capillary is about 20% of the sphere radius; therefore, we assume r 0.2rparticle with rparticle 50 µm. The molecular mass Moveable lid = = 23 1 of the air is m 28.96 amu and kB 1.37 10 JK . The mean free path of air= in the experiments is=⌦ 17⇥.5 µm. This results in a Knudsen number Kn (⌦/2r) 0.875.= For this Knudsen number, ! we take the Q-value from= ref. 11= of Q 0.36. This leads to a gas mass Experimental Astrophysics Group, University of 14 1 = flow of 10 kg s . Divided by the cross-section of one capillary 10 2 A 10 m and the density of air at 4 mbar ambient pressure = 3 3 1 ⇢ 4.8 10 kg m , we get a mean gas velocity of 9 cm s , which is= consistent⇥ with the velocities measured in the experiment. Duisburg-Essen Scaling this to martian conditions we have to consider CO2 instead of air, which has a molecular mass of mCO2 44 amu. With Cameras NATURENATURE PHYSICS PHYSICSDOI:DOI: 10.1038/NPHYS2821 10.1038/NPHYS2821 10 = NATURE PHYSICS DOI: 10.1038/NPHYS2821 LETTERSLETTERSLETTERS a geometric radius of 4.63 10 m (ref. 19) the molecule has a ⇥ 19 2 cross-section of 1.6 10 m . At p 6 mbar, T 218 K and a particle density =n p⇥/k T, the mean= free path of= CO is ⌦ abab B 2 Figure 5 Schematic diagram of the drop tower experiment. The small (1/p2n ) 21 µm. According= to this mean free path, the Knudsen= Solar insola! | = Natural Transport Mechanism of Dust on Mars container for basalt powder has a diameter of 3 cm and is 2 cm deep. A red number is 1.05 and hence Q 0.31 (ref. 11). Owing to the lower =2 tion laser with 655 nm is focused on a spot diameter of 8 mm on the dust bed. insolation of about 700 W m , a smaller temperature difference Two cameras observe the movement of the dust particles at an than in the experiment is obtained. As a first estimate, we assume angle of 90 . the typical diurnal surface temperature variation as 1T 50 K. 1 = 1 Assuming the same thermal conductivity of 0.01 W K m ,a ! The Martian Soil as a Planetary Gas PumpAs the experimental conditions compare well to the martian length of 2 cm and an average particle radius of 50 µm, the CO2 environment (detailed below), the results can readily be applied to gas mass flow is the same as the air mass flow in the experiments 14 1 10 2 Mars and reveal the following picture: if the martian soil is heated with 10 kg s . Divided by the cross-section A 10 m and the ⇠ 3 3 by solar insolation, gas will be pumped from the colder soil layers density of CO2 at 6 mbar ambient pressure ⇢ 14.6 10 kg m , 1 = ⇥ beneath the heated layers towards the surface. the result is a mean gas velocity of 1.6 cm s on Mars. C. de Beule et al., Nature Physics, 10 (2014At shadowed places) on the surface, gas will efficiently be soaked The details of the martian gas pump will depend on the local light up into the soil, traverse the underground and will be pumped up flux, which varies with daytime and shadow-casting landmarks. It again to the heated (insolated) surface as shown in Fig. 4. Therefore, also depends on the detailed soil characteristics such as pore size, Rock/boulder the resulting gas flow below the surface is a mixture of a vertical albedo and thermal inertia. and a horizontal flow. In this simple picture, shadowed regions are Mars is known to have buried ice within its subsurface20 and With shadow Gas flow needed as a continuous (atmospheric) reservoir of gas. As pores in water vapour can be transported by diffusion to the surface12. soil act like micro-channels and as dust particles and pores exist Ref. 21 estimated the diffusion constant of water vapour in a in the micrometre range, the low atmospheric pressure on Mars is martian simulant (JSC Mars-1 Dust) at 6 mbar ambient pressure to 2 1 1 ideally suited to provide its soil with the ability for natural thermal 1.5 cm s . Diffusive flow might roughly be estimated to 0.3 cm s Martian soil creep pumping. The capability of gas flowing through heated or for a 5 cm layer then. This is below the pump velocity found in 1 cm1 cm 1 cm 1 cm insolated dust layers can also lead to a significant pressure increase. the experiments scaled to martian conditions. The thermal creep It can even be sufficient to levitate large dust aggregates or to gas flow hitherto unconsidered might therefore be a dominant Figure 4 The natural soil pump on Mars. Owing to solar insolation thermal creep leads to a gas flow from the cool deeper layers up toFigure theFigure 1surface.Particle 1 Particle Thetrajectories trajectories above above an illuminated an illuminated dust dust bed bed consisting consisting of basalt of basalt particles. particles.a,b, Thea,b, Thetrajectories trajectories seen seen in the in experiments the experiments (a) are (a) consistent are consistent | EULE eruptively eject particles from the surface, which has been shown in transport mechanism for water vapour in large parts of the martian | withwith a simulation a simulation| of the of thegas gas flow flow (b) (assumingb) assuming a volume a volume force force in the in dustthe dust bed bed due dueto thermal to thermal creep. creep. The Thelight light red bar red10,14–17 marks bar marks the diameter the diameter (8 mm) (8 mm) of the of the resulting pressure difference in the dust bed soaks up atmospheric gas from shadowed surfaces into the soil and pumps it underneath the surface towards 2 ground-based laboratory experiments . soil as it is dragged along with the CO2. lightlight source source (laser, (laser, 655 655 nm, nm, 13 kW 13 kW m m). The2). The direction direction of the of particlethe particle motion motion is represented is represented by the by black the black arrows arrows on image on imageb. Owingb. Owing to the to illumination, the illumination, dust dust insolated (heated) surface regions. To evaluate the gas mass flow in the drop tower experiments we Basalt dust beds were studied here, which we regard as a suitable particlesparticles leave leave the- Catapult Experiment - the surface surface within within the thelaser laser beam. beam. The The lines lines outside outside the laserthe laser (red (red bar) bar) mark mark the downwardly the downwardly directed directed particle particle and gas and flow. gas flow. These These particles particles 22 use equation (1), with pavg 4 mbar and Tavg 300 K. For a length of analogue to martian dust . However, essentially all light-absorbing areare not not illuminated illuminated and and trace trace only only the thestreamlines. streamlines. Streamlines Streamlines enter enter the dustthe dust bed’s bed’s surface surface outside outside the= illuminated the illuminated area. area. The= illuminationThe illumination of the of dust the dustbed bed leads to a convective flow through the soil. l 2 cm (depth of the dust bed) and basaltic powderleads with to a a convective thermal flow through the soil. NATURE PHYSICS VOL 10 JANUARY 2014 www.nature.com/naturephysics 19 15 = 1 1 | | | Laser Dust sample conductivity of 0.01 W K m (ref. 18), we get 1T 300 K 1 cm= s¬1 ¬1 (ref. 15). In a simple model of hexagonally packed spheres,1 cm s the 3.5 3.5 2.0 2.0 radius of a capillary is about 20% of the sphere radius; therefore, 3.0 ¬0.5 3.0 10 10¬0.5 we assume r 0.2rparticle with rparticle 50 µm. The molecular mass Moveable lid = = 23 1 2.5 of the air is m 28.96 amu and k 1.37 10 JK . The mean 2.5 = B = ⇥ free path of air in the experiments is ⌦ 17.5 µm. This1.5 results in a 10¬1.0 ¬1.0 1.5 2.0 2.0 10 Knudsen number Kn (⌦/2r) 0.875.= For this Knudsen number, we take the Q-value from= ref. 11= of Q 0.36. This leads to a gas mass 1.5 1.5 ¬1.5 14 1 = 10 10¬1.5 flow of 10 kg s . Divided by the cross-section of one capillary 1.0 1.0 Velocity (m s Velocity
10 2 1.0 (m s Velocity A 10 m and the density of air at 4 mbar ambient1.0 pressure = 3 3 1 0.5 0.5
⇢ 4.8 10 kg m , we get a mean gas velocity of surfaceHeight over (cm) 9 cm s , which ¬2.0 = ⇥ surfaceHeight over (cm) 10 10¬2.0 is consistent with the velocities measured in the experiment. 0.0 0.0 ¬1 ¬1 ) )
Scaling this to martian conditions we have to0.5 consider CO2 surfaceHeight over (cm) 0.5 ¬0.5 surfaceHeight over (cm) ¬0.5 ¬2.5 10 ¬2.5 instead of air, which has a molecular mass of mCO2 44 amu. With 10 Cameras 10 = a geometric radius of 4.63 10 m (ref. 19) the molecule has a ¬1.0 ¬1.0 ⇥ 19 2 cross-section of 1.6 10 m . At p 6 mbar, T 218 K and ¬1.5 ¬3.0 = ⇥ = = ¬1.4 ¬1.2 ¬1.0 ¬0.8 ¬0.6 ¬1.5 10 10¬3.0 a particle density n p/kBT, the mean free path of CO2 is ¬1.4⌦ ¬1.2 ¬1.0 ¬0.8 ¬0.6 = =DistanceDistance from from laser laser spot spot centre centre (cm) (cm) Figure 5 Schematic diagram of the drop tower experiment. The small (1/p2n ) 21 µm. According to this mean free path, the Knudsen ¬2.5 | = ¬2.5 container for basalt powder has a diameter of 3 cm and is 2 cm deep. A red number is 1.05 and hence Q 0.31 (ref. 11). OwingFigure 2 toVelocities the lower of a sample of tracer particles along their ¬3.5 Figure 2 Velocities of a sample of tracer particles along their ¬3.0 10 10¬3.5 =2 streamlines.| |The x axis shows the distance from the centre of the laser spot ¬3.0 laser with 655 nm is focused on a spot diameter of 8 mm on the dust bed. insolation of about 700 W m , a smaller temperaturestreamlines. differenceThe x axis shows the distance from the centre of the laser spot and the y axis the height over the dust bed. Two cameras observe the movement of the dust particles at an than in the experiment is obtained. As a first estimate,and the wey axis assume the height over the dust bed. ¬1.5¬1.5 ¬1.0 ¬1.0 ¬0.5 ¬0.5 0.0 0.00.50.5 1.0 1.0 1.5 1.5 DistanceDistance from fromlaser laserspot centrespot centre (cm) (cm) angle of 90 . the typical diurnal surface temperature variationconvectionconvection as 1T is not is not50 a thermal aK. thermal convection. convection. The The tracer tracer particles particles follow follow the gas streamlines1 = 1 and enter the dust bed in the non-illuminated Figure 3 Simulation of particle velocities along their streamlines below Assuming the same thermal conductivity of 0.01the W gas K streamlines m ,a and enter the dust bed in the non-illuminated Figure| 3 Simulation of particle velocities along their streamlines below partpart tracing tracing a gas a gas flow flow into into the the soil soil (Fig. (Fig. 1). 1). andand above above the| surface the surface of the of dust the dust sample. sample.The heightThe height 0 marks 0 marks the surface the surface As the experimental conditions compare well to the martian length of 2 cm and an average particle radius of 50 µm, the CO 2 At a radiation flux of2 13 kW m the2 upward velocity is about of the dust bed. The coloured scale gives the velocities, ranging from At a radiation flux of 13 kW m the upward velocity is about of the dust bed. The coloured scale gives the velocities, ranging from 1 0.0687 11.237 1 environment (detailed below), the results can readily be applied to gas mass flow is the same as the air mass flow in10 thecm s experimentswithin1 the illuminated spot and downward velocities 10 10 0.0687to 10to 10 11ms.237 ms. 1. 10 cm s within the illuminated spot and1 downward velocities 14 1 outside10 the illuminated2 spot are about 1 cm s (Fig.1 2). The inflow Mars and reveal the following picture: if the martian soil is heated with 10 kg s . Divided by the cross-section A 10outside m theand illuminated the spot are about 1 cm s (Fig. 2). The inflow ⇢ ⇠of.of gas gas extends extends3 to tothe3 the outer outer end end of theof the dust dust bed. bed. The The fact fact that thatto theto the bottom bottom of the of the dust dust bed bed 2 cm 2 cm below below the thesurface. surface. This This is is by solar insolation, gas will be pumped from the colder soil layers density of CO2 at 6 mbar ambient pressure 14gas6 also10 enters kg the m soil , at the outer extension 1.5 cm away from consistent with a model of forced flow through the porous medium . 1 = gas⇥ also enters the soil at the outer extension 1.5 cm away from consistent with a model of forced flow through the porous medium beneath the heated layers towards the surface. the result is a mean gas velocity of 1 6 cm s on Mars.thethe spot spot indicates indicates that that the the flow flow within within the the soil soil is reaching is reaching down downas seenas seen in Figs in Figs 1b and 1b and 3. 3. At shadowed places on the surface, gas will efficiently be soaked The details of the martian gas pump will depend on the local light 18 NATURE PHYSICS VOL 10 JANUARY 2014 www.nature.com/naturephysics up into the soil, traverse the underground and will be pumped up flux, which varies with daytime and shadow-casting18 landmarks. It NATURE PHYSICS| VOL| 10 JANUARY 2014| www.nature.com/naturephysics | | | again to the heated (insolated) surface as shown in Fig. 4. Therefore, also depends on the detailed soil characteristics such as pore size, the resulting gas flow below the surface is a mixture of a vertical albedo and thermal inertia. and a horizontal flow. In this simple picture, shadowed regions are Mars is known to have buried ice within its subsurface20 and needed as a continuous (atmospheric) reservoir of gas. As pores in water vapour can be transported by diffusion to the surface12. soil act like micro-channels and as dust particles and pores exist Ref. 21 estimated the diffusion constant of water vapour in a in the micrometre range, the low atmospheric pressure on Mars is martian simulant (JSC Mars-1 Dust) at 6 mbar ambient pressure to 2 1 1 ideally suited to provide its soil with the ability for natural thermal 1.5 cm s . Diffusive flow might roughly be estimated to 0.3 cm s creep pumping. The capability of gas flowing through heated or for a 5 cm layer then. This is below the pump velocity found in insolated dust layers can also lead to a significant pressure increase. the experiments scaled to martian conditions. The thermal creep It can even be sufficient to levitate large dust aggregates or to gas flow hitherto unconsidered might therefore be a dominant eruptively eject particles from the surface, which has been shown in transport mechanism for water vapour in large parts of the martian 10,14–17 ground-based laboratory experiments . soil as it is dragged along with the CO2. To evaluate the gas mass flow in the drop tower experiments we Basalt dust beds were studied here, which we regard as a suitable use equation (1), with p 4 mbar and T 300 K. For a length of analogue to martian dust22. However, essentially all light-absorbing avg = avg =
NATURE PHYSICS VOL 10 JANUARY 2014 www.nature.com/naturephysics 19 | | | Combustion - DDI-ADL !Investigation of Droplet-Droplet Interaction utilizing the Advanced Disc Laser - Drop Tower Experiments ! supported by DLR Space Administration Ultra-Long Drop Capsule ! Combustion Engineering Group, ZARM - University of Bremen ! Lowering the Emissivity of harmful Nitric Oxides ! for future gas-turbines of the aero-propulsion type and electric power generators ! experimental data for numerical simulations
!Laser-Induced Fluorescence Spectroscopy (ADL)1,2,3 more - TEXUS Sounding Rocket Mission
16 Fluid Dynamics - CCF (Mission Preparation) Sounding Rocket !Capillary Channel Flow - Experiment onboard Parabolic Flight MissionsMissions: - CCF on TEXUS 37 (2000) ISS - CCF on TEXUS 41 (2004) ! US - German Partnership ISS Mission by NASA / DLR - CCF on TEXUS 42 (2005) ! ZARM - University of Bremen / Portland State University ! Mission Overview (launched in April 2010 / installed Drop Tower Experiments in Dec. 2010 / re-installed in Sep. 2011 - EU#1 and EU#2 with different geometries) ! investigation of capillary flows in the absence of e.g. Microgravity Tests gravity of Channel Geometries
! finding new ways to move liquids in spaceNASA 17 Preparation of Space MissionsPeregrine F - alcon !Asteroid Explorer Mission (Target: Asteroid first return of asteroidal Ryugu) material back ! Japanese Satellite Mission by JAXA ! in Cooperation with DLR and CNES (MASCOT - Lander) ! Mission Overview (Successor of Hayabusa - launched in May 2003 / landed on Asteroid Itokawa in Nov. 2005 / returned in June 2010) ! studying the origin and evolution of the solar system as well as materials for life (launched Dec. 2014 / landing 2018 / return 2020)
JAXA
18 Preparation of Space MissionsPeregrine F - alcon !Asteroid Explorer Mission (Target: Asteroid first return of asteroidal Ryugu) material back ! Japanese Satellite Mission by JAXA ! in Cooperation with DLR and CNES (MASCOT - Lander) ! Mission Overview (Successor of Hayabusa - launched Sampler Horn Testsin May 2003 / landed on Asteroid Itokawa in Nov. Deployment Tests Separa on Tests 2005 / returned in June 2010)(JAXA - Rovers) (DLR - Lander) ! studying the origin and evolution of the solar system as well as materials for life (launched Dec. 2014 / landing 2018 / return 2020)
JAXA
19 Preparation of Space Missions - !Gravity Recovery and Climate Experiment Follow-On ! US - German Partnership Satellite Mission by ! NASA/JPL and the German Research Center for Geosciences (GFZ) (Center for Space Research (CSR) / University of Texas, DLR, …) planned launch ! Mission Overviewin August (Successor of GRACE - launched in March 2002) ! measuring variations in gravity over Earth's surface ! generating a new map of the gravity field every 30 NASA GRACE, Jet Propulsion Laboratory daysGFZ
20 Preparation of Space Missions - !Gravity Recovery and Climate Experiment Follow-On ! Mission Preparation at the Bremen Drop Tower ! GRACE-FO - scientific instrument: accelerometers by ONERA (Office national d'études et de recherches aérospatiales) ! performance tests of the accelerometers (EM, FM, SM) in µg with ZARM’s catapult system as part of the
qualification process turning point of catapult capsule ! ! determining bias values for the test mass positioning! v = 0 / a = 0
21 Preparation of Space Missions - !Gravity-Research Micro-Satellite Mission (Micro-Satellite à traînée Compensée pour l’Observation du Principe d’Equivalence) ! French Satellite Mission by CNES / in Cooperation with ESA ! in Cooperation with ONERA, the Observatoire de la Côte d’Azur (OCA), ZARM, and the National Metrology
Institute of Germany (PTB) Measurement Axis ! Mission Overview (planned launch in April 2016) ! testing the Weak Equivalence Principle down to an accuracy of 10-15
CNES (the major principle of Albert Einstein's general theory Material 1 (Pt) Material 2 (Ti) of relativity) 22 Content !The Bremen Drop Tower !Introduction !Operation !Facts and Figures !Examples: Drop Tower Experiments !Scientific Pathfinder Flights !XCOR Aerospace: Lynx Mark I !End-to-End Service
23 XCOR Lynx Payload User’s Guide Date: November 22, 2013 -- v.5 Page 19 of 52
Scientific Pathfinder Flights
These payload integration locations are shown in Figures 3-1 and 3-2. NOTE: payload 2x suborbital flights XCOR Lynx Payload User’s Guide Date:XCOR Lynx November Payload User’s Guide 22, 2013Date: -- v.5November 22, 2013 -- Pagev.5 13Page of 35 of52 52 !dimensionsSPF - Payloads - provided are subject to change duringLynx Mark I Lynx development. < 1 min under µg then a 90 degree roll that puts the pilot’s window down and gives the vehicle an edge-on attitude for lowest drag.
These graphs illustrate the best estimate at this time for the Lynx micro-g envelope. ELAPSED TIME LYNX MARK IThe FLIGHTse results are subject M ILEto changeSTONES once the vehicle is flying and has demonstrated capabilities. (SECONDS) 0:00 Engine start on runway 17 Take off from ground 169 All engines shut down. Vehicle maintains upward trajectory. 182 Begin low-acceleration period at or below 10-1 g 236 Apogee at 58 km (190,000 ft). Begins free fall downwards. 287 Acceleration exceeds 10-1 g ! 306 Onset of pullout acceleration of 1g EUPHORIE1300 (approx.) Touchdown on runway Table 2-3: Typical Lynx Mark I mission flight sequence, time in seconds
Figure 3-14: Lynx Mark I –Payload B estimated micro-g level vs. time (mission profile) (U Duisburg-Essen) ! Service Module (Payload A) ! Exp. (Payload B)
©2013, XCOR Aerospace, Inc. Approved for Public Release. All Rights Reserved Cleared for Open Publication by Office of Security Review. 12-S-1840
!EQUIPAGE (OVGU Magdeburg)
!Daphnia (U Bayreuth) Figure 3-1: Lynx payload integration location overview Figure 2-2: Typical Lynx Mark I flight profile illustration
24 ©2013, XCOR Aerospace, Inc. Approved for Public Release. All Rights Reserved Cleared for Open Publication by Office of Security Review. 12-S-1840
©2013, XCOR Aerospace, Inc. Approved for Public Release. All Rights Reserved Cleared for Open Publication by Office of Security Review. 12-S-1840 Scientific Pathfinder Flights Payload B !Drop Tower Campaigns - Lynx Mark I
!EQUIPAGE (OVGU Magdeburg) !Daphnia (U Bayreuth)
25 ! Equipartition of Kinetic Energy in Granular Anisotropic Gases Scientific Pathfinder Flights Payload B !Drop Tower Campaigns - Lynx Mark I
!EQUIPAGE (OVGU Magdeburg) !Daphnia (U Bayreuth)
in Geweben oder ganzen Organismen nicht relevant. Die längere Expositionszeit im Vergleich zum Parabelflug wird hier wichtige Hinweise liefern.
c) Verhaltensanalysen von Räuber-Beute-Interaktionen Im Parabelflug, sowie auch im Fallturm wurden bisher Untersuchungen des Schwimmverhaltens von Daphnien durchgeführt. Durch die Länge des suborbitalen Testfluges können nun auch erstmals Interaktionen verschiedener trophischer Ebenen in Mikrogravitation untersucht werden. Bei den hierbei verwendeten Modellorganismen handelt es sich um die Alge Scenedesmus (photoautotropher Organismus), den Wasserfloh Daphnia (Primärkonsument), den räuberischen Urzeitkrebs Triops (Sekundärkonsument) und die räuberische Büschelmüchenlarve Chaoborus (Abbildung 9)
Abbildung 9 Chaoboruslarve (links), Wasserfloh (mitte) und Triops (rechts)
Mehrere Highspeed Kamerasysteme (Abbildung 10) sollen das Schwimm- und Nahrungsaufnahmeverhalten 26 von Daphnien und zwei! unterschiedlichenInvestigation of Model Organism „Daphnia“ (Water F Räubern, welche eine lea) unterschiedliche Jagdstrategie zeigen, in mehreren Küvetten filmen. Triops sind Streifjäger und detektieren mit Hilfe von Mechaorezeptoren ihre Beute. Chaoborus-Larven detektieren ihre Beute ebenfalls mittels über den ganzen Körper verteilter Mechanorezeptoren. Diese nehmen die durch die Schwimmbewegung der Beute generierten Mikroturbulenzen wahr. Chaoborus-Larven sind im Gegensatz zu Triops allerdings Lauerjäger, welche durch ihre im Körper befindlichen Gasblasen regungslos im Wasser stehen können. Bei der 20. DLR-Parabelflugkampagne konnte bereits gezeigt werden, dass sowohl Triops, als auch Chaoborus keine abnormen Verhaltensweisen in µg zeigen und grundsätzlich für den Einsatz bei den „Scientific Pathfinder Flights“ geeignet sind. Die Daphnien sollen dabei erst kurz vor der Schwerelosigkeit mit den Prädatoren in Kontakt treten, um die Wahrscheinlichkeit von Angriffen während der µg-Phase zu erhöhen. Durch den Einsatz von genau definierten Mengen an Mikroalgen (Scenedesmus), die sich im Wasserreservoir der Prädatoren befinden, soll auch die Filtrationsrate der Daphnien während der Schwerelosigkeit bestimmt werden (mittels photometrischer Bestimmung der Algenkonzentration). Dieselben Mikroalgen können auch verwendet werden, um die Fluiddynamik des Schwimmverhaltens in Mikrogravitation sichtbar zu machen. In Mikrogravitation ist zu erwarten, dass die durch die Tiere verursachten Mikroturbulenzen verändert sind, da sich auch ihr Schwimmverhalten ändert. Durch den Einsatz eines mechanorezeptor- orientierten Lauerjägers wie Chaoborus soll deshalb festgestellt werden, ob veränderte Scientific Pathfinder Flights Payload A !Drop Tower Campaigns - Lynx Mark I
!EQUIPAGE (OVGU Magdeburg) !Daphnia (U Bayreuth) ! Service Module (Payload A)
27 Scientific Pathfinder Flights Payload CP / CS !Drop Tower Campaigns - Lynx Mark I
!EQUIPAGE (OVGU Magdeburg) !Daphnia (U Bayreuth) !EUPHORIE (U Duisburg-Essen)
!Drop Tower Tests - done Experimen(dee+ Experimen(dee+ VenJl%
Experimentvolumen% !Thermal Vacuum Test - April 2016 Stromversorgung%für%Laser% Fenster%für% Beobachtung% Lasermodul% Chondren?% Kamera% behälter%
Vakuumkammer% Kollimator% Shuner%
Äußeres%Gehäuse%
! Experimental Investigation of Photophoretic Motion 28 of Chondrules Scientific Pathfinder Flights
Doc. no.: FAB-QTR-666 Vibration Test Lab Issue: 1 Date: 02-Jun-14 Revision: - Date: ZARM Drop Tower Operation and Service Company Ltd. Page: 35 of 79 ! End-to-End Service (Flight Ticket4.1.3 Tests) Setup Y-Axis
! Development of a Service Module / Hardware R3
! Experiment Integration / Technical Support " " YMAxis'(3'g)' " XMAxis'(4.5'g)' " R1 Here," we" have"! a" total" displacementMission Preparation (Drop Tower / Qualification " of" a" maximum" level" of" 3.16" mm." As" described" above"this"is"again"our"FE!model"with"a"conservative"and"less"stable"structure."" P1
" Tests) ZMAxis'(+12'g'/'M9'g)' maximum&Stress&(MPa)&
Here," the" marked" point" has" a" maximum" stress" of" 607" MPa" and" is" inside" bolt." We" ! assumed,"that"all"bolts"Suborbital Flights (Shipment / On-site Assistance - are"able"to"withstand"up"to"1000"MPa."The"displacement"in"Y!axis"is"
displayed"in"the"next"picture." "
R2 " USA)
The" total" stress" level" is" also" under" the" critical" level" of" 1000" MPa." Here," we" have" a" As"marked"on"the"picture,"there"is"a"maximum"Level"of"stress"of"1640"MPa."This"is"due" P2
maximum"level"ofthe"fact"that"the"FE"860"MPa"in"a"bolt!method"of".""Inventor"is"hardly"able"to"simulate"frictional"connections."In" order"to"assume"a"level"of"12"g"with"maximum"payload"mass"we"have"an"overall"force"of"15" kN." Further" we" have" 16" bolts," each" of" them" provides" a" axial" force" of" 17" kN." With" a" coefficient" of" friction" of" 0.1" there" is" a" force" of" 27.2" kN." At" the" end" we" have" a" frictional" 140527_ZARMFAB_LYNX_SM_QTR01.docx ZARM FAB mbH - All rights reserved – Copyright per DIN 34 connection"with"an"additional"safety"margin"of"approx."1.5"!"in"total"approx."2.25"(12"g)." The"total"movement"in"this"axis"is"displayed"in"the"next"picture."
" The"total"displacement"has"a"maximum"level"of"1.63"mm."As"described"above"this"is" our"FE!model"with"a"conservative"and"less"stable"structure.' '
- 6 -
"
- 4 - 29
- 8 - Content !The Bremen Drop Tower !Introduction !Operation !Facts and Figures !Examples: Drop Tower Experiments !Scientific Pathfinder Flights !XCOR Aerospace: Lynx Mark I !End-to-End Service
30 Conclusion I !The Bremen Drop Tower is an excellent platform for conducting short-term experiments underQUANTUS I QUANTUS II DDI-ADL high-quality microgravity conditions !fundamental research / dedicated experiments
! science at the Bremen Drop Tower
31 Conclusion II !The Bremen Drop Tower is an excellent platform for preparing a variety of space µg-ESLm - DLR MPissions CCF - ZARM DLR - Scien fic Pathfinder Flights Blue Origin NEXT ? !scientific and technological experiments on existing and new suborbital / orbital microgravity platforms
MAPHEUS - Sounding Rocket ISS - Low Earth Orbit Lynx - Suborbital Flights New Shepard - Suborbital Flights Experiment Prepara on Experiment Prepara on Experiment Prepara on Experiment Prepara on ??? ! parameter definitions / evaluations, hardware / technology tests
32 THANK YOU VERY MUCH FOR YOUR ATTENTION ACKNOWLEDGEMENTS
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