europhysics BULLETIN OF THE EUROPEAN PHYSICAL SOCIETY news J.A. Volume 11 Number 10 October 1980 First Spacelab Mission C. Nicollier, ESA/SPICE, Cologne (one of three European Payload Specialists from amongst whom one will be selected for flying on the Mission)

From the year 1983, Spacelab will exist Spacelab is presently built in Europe, able to prove the suitability of this concept as a versatile tool available to scientists to under the control and management of the of an experimental platform for a range of perform space experiments from low earth European Space Agency (ESA), by a con­ disciplines. orbit in such disciplines as Life Sciences, sortium of European aerospace and elec­ The configuration chosen for the mission Materials Science, Atmospheric Physics, tronics firms led by ERNO Raumfahrt- will comprise the long module and one Space Plasma Physics, Astrophysics, Solar technik in Bremen, West Germany. The pallet. The module will be equipped with a Physics and Earth Observation. engineering model of Spacelab has already scientific airlock permitting temporary ex­ The laboratory, consisting of one or been completed and is presently undergo­ posure of instruments from the module in­ several pallets — experiment supporting ing acceptance testing at Bremen. The first terior to the space environment, and a high structures — and, normally, of a pressuriz­ flight unit will be delivered to ESA in the quality optical window that will be used for ed module, will be built into the cargo bay middle of next year. A second Spacelab Earth photography. of the Space Shuttle Orbiter and will be has recently been ordered by NASA. The launch of Spacelab 1 is presently carried into orbit for missions of seven to Figure 1 is an artist's impression of foreseen for May 1983 on the tenth Shuttle 30 days. During the whole mission, it will Spacelab in the Space Shuttle Orbiter. The flight. Originally scheduled for December remain attached to the Orbiter and will use configuration shown, one of many possi­ 1980, it has experienced successive slips a number of resources provided by the Or­ ble, consists of the long module and two due, mainly, to difficulties that were en­ biter, such as electrical power, heat pallets. The open cargo bay doors and part countered in the development, production disposal, attitude control and crew living of Spacelab and the Orbiter's fuselage quarters. panels have been omitted for clarity. Among the unique features of Spacelab Contents as a science and technology laboratory in First Spacelab Mission 1 space, is the possibility of human interven­ The Mission Optical Bistability, Towards the tion, the recoverability of samples and ex­ The main objective of Spacelab's first All-optical Computer 3 perimental hardware, relatively massive mission will be to test the laboratory itself. ASDEX, a Step Towards Impurity equipment and adequate power supplies, Consequently, a substantial fraction of the Control in Fusion Experiments 4 permitting a variety of inter-related or in­ time in orbit will be devoted to testing, in­ Europhysics Conferences dependent experiments to be performed cluding a study of the response of the 12th EGAS Conference 6 simultaneously. For these reasons, laboratory and its subsystems to various Computing in High Energy Spacelab offers a considerable attraction to thermal stresses, and the investigation of and Nuclear Physics 6 experimenters in various scientific environmental parameters. Although scien­ ESSDERC '80 7 disciplines, especially to those who have tific objectives will be given second priority ESCAMPIG 8 not yet been involved extensively in space for this mission, every effort will be made Laser Doppler Anemometry 9 experimentation such as the life and to maximize the scientific data output of A Breadth of Vision 11 materials scientists. the payload and we hope that we shall be Surfaces and Interfaces Section 12 Europhysics News is published monthly by the European Physical Society. © 1980. Reproduction rights reserved. ISSN 0531-7479 1 and testing of the first Orbiter “Columbia", They will allow a detailed study of the of the front section of the Orbiter (see essentially with the tiles used to provide plasma-physical processes operating in the Fig. 1). thermal protection and with the main ionosphere and magnetosphere by recor­ Two other crew members, the Mission engines. Launched from the Kennedy ding the effects (neutralisation, triggered Specialists, have already been chosen by Space Center in Florida, Spacelab 1 will be waves, instabilities and interactions with NASA for this mission. Owen Garriott and put into a circular orbit with an altitude of the local atmosphere) induced by 10 keV Robert Parker, also Astronauts from 250 km and an inclination of 57°. The mis­ ion and electron beams injected into space Johnson Space Center, will spend most of sion will last seven days. of maximum current 3 m A and 100 m A their time performing payload operations, respectively. Detectors include receivers but will also be responsible for the manage­ (up to 100 MHz), an RF plasma probe, an ment of the Orbiter resources for Spacelab, Selected Experiments electron temperature probe and two parti­ and for the operation of the Spacelab sub­ Proposals for experiments in various cle energy analysers. systems supporting the payload. scientific and technical fields were invited The first Spacelab mission is not ideally Finally, two out of five Payload Specia­ for this flight, and from the replies a total of suited to studies in Astrophysics because lists will fly on this mission, one of the two 76 were chosen by ESA and NASA in the of the relatively short flight duration and Americans, Mike Lampton and Byron beginning of 1977. They cover all the the lack of accurate pointing capability of Lichtenberg, and one of the three Euro­ disciplines mentioned earlier, and they the Orbiter in the absence of the "Instru­ peans Ulf Merbold (German Fed. Rep.), share about equally the Orbiter and crew ment Pointing System" that will be avai­ Wubbo Ockels (The Netherlands) and the resources for the ESA and the NASA parts. lable only on later flights. Nevertheless, author (Switzerland). The responsibility of In the field of Life Sciences, several ex­ two wide-field UV instruments have been the Payload Specialists on board will be en­ periments will permit the gravitational in­ selected, the Far Ultraviolet Space Tele­ tirely in the area of payload operations. fluence on biological systems to be studied scope (FAUST), and the Very Wide Field They will also, like the Mission Specialists and, in particular, the adaptability of these Camera, for which the 0.1° pointing stabili­ and occasionally the flight crew members systems to the zero-g environment. A ty of the Orbiter will be sufficient. The very (Commander and Pilot), serve as subjects number will focus on man's vestibular and Wide Field Camera is a particularly remar­ for a number of biomedical experiments. cardiovascular systems. The effect of kable instrument with its field of 60° The choice of the "flight” Payload weightlessness on the human immune which will allow a determination of the Specialists (as opposed to the "ground" response will also be observed. On the distribution of the diffuse UV emitted light Payload Specialists, who will not fly) will pallet, a biostack will allow investigations in our galaxy as well as of other large scale be made only a few months before the mis­ of the influence of hard particle radiation radiation sources. sion. on biological samples, sandwiched bet­ There will also be one X-ray spec­ The Mission and Payload Specialists on ween track detectors, and another experi­ troscopy instrument on board, as well as a board will form the "Center of Control" for ment will observe the effect of vacuum and cosmic ray particle detector, the "Isotopic the execution of the Payload Flight solar UV radiation on micro-organisms and Stack". prepared prior to the mission, although biomolecules. Three instruments will, for part of the possible modifications may be dermanded Most of the proposed Materials Science mission, be looking at the Sun as a set of from the ground during flight. A large experiments will be performed in the Solar Physics experiments. Two absolute number of experiments will be controlled facilities mounted in the "Material Science solar radiometers will measure the total ra­ from one of the two terminals of the on­ Double Rack". These facilities will include diant energy from the Sun from the far UV board Experiment Computer, comprising a a Fluid Physics Module and various fur­ to the far IR, with an accuracy of 0.1%, CRT data display unit and a keyboard. By naces, plus some special purpose ins­ and another instrument will simultaneously means of experiment dedicated displays, a truments. The Fluid Physics Module is record the solar spectrum from 1900 A to 4 crew member will be able to monitor the designed to investigate some properties of pm for identification of the spectral status of a substantial fraction of the rotating and non-rotating fluid zones bet­ elements responsible for any change in the payload and will also get, from some ex­ ween two plates, as well as capillary forces solar constant determined from the periments, scientific data to which he will and the dynamics of the spreading of a li­ measurements with the radiometers. hopefully be able to react in real time. The quid on a solid surface. The results will be Finally, two instruments will be Earth- keyboard will provide the means for the recorded on film for later evaluation on the oriented. As part of the Earth Observation crew to change experimental parameters, ground. The furnaces will be used to study programme, a Metric Camera will take high as well as perform a number of other crystallization and metallurgical processes, resolution pictures of the Earth for mapp­ payload related commands. the processed samples being returned to ing purposes, and a large Microwave Facili­ Payload operations support will also be earth for analysis. ty will be used to monitor the wave struc­ provided from the ground during the mis­ Studies in Atmospheric Physics take ad­ ture of the ocean surfaces. A synthetic sion. This will be one of the roles of the vantage of the low orbit of Spacelab and its aperture radar mode will also be used for Payload Operations Control Center (POCC) high carrying capability to use complex in­ the same facility for surface mapping of the at the Johnson Space Center. The POCC strumentation with high spectral resolution Earth. will be manned by the Spacelab 1 In­ and high sensitivity. The Grille Spec­ vestigators and the back-up (or ground) trometer, for instance, is an instrument for Payload Specialists, among others. Digital high-resolution line spectroscopy. It will command and data, as well as voice link track the sun at sunrise and sunset and will be available between Spacelab and the record absorption spectra of the at­ The Crew POCC via a set of two relay satellites per­ mosphere in various wavelength intervals There will be six crew members on board mitting a coverage of about 60% of the or­ and at various elevations above the the Space Shuttle Orbiter during the bit i me, depending on mission profile. horizon. Other instruments will study the Spacelab 1 flight. Two of these will be the The whole crew on board will work on Lyman-alpha emission of H and D, and Commander and the Pilot, both Pilot alternating 12 hours shifts. Spacelab will be monitor OH emission features in the high Astronauts from the Astronaut Corps at occupied 24 hours a (terrestrial) day. At atmosphere. Johnson Space Center, Houston, Texas. any given time during the mission, at least Interesting results are expected from the The duty station of the Commander and either the Commander or Pilot will be on group of Plasma Physics experiments. Pilot will be the Flight Deck, or upper part the Flight Deck, taking care of the attitude 2 control of the vehicle and the health of the Orbiter subsystems, and two payload crew Optical Bistability members (one Mission Specialist and one Payload Specialist) in the Spacelab module. Towards the All-optical Computer Payload Crew Training S.D. Smith, Edinburgh Our training started right after selection in the middle of 1978. In an early phase, the (Heriot-Watt University) crew travelled to a number of research laboratories in Europe and the United States, and was briefed by the Investiga­ tors of nearly every experiment on their scientific objectives. General lectures were An optical bistable device is one which amplifiers, AND and OR gates, pulse clip­ also given, at the request of the crew, to has two states of transmission for one in­ pers and power limiters so that, in princi­ provide a general understanding of the put intensity. With increasing incident in­ ple, the all-optical computer circuit various disciplines involved. tensity it can, at a given value "switch up" elements needed to construct an all-optical This phase was followed, from mid-1979, to a state of high transmission and stay in computer have been demonstrated in the by what I would call an operational phase, this condition, even if the incident intensity laboratory. in which the crew had the opportunity to is significantly reduced. On further reduc­ Historically the idea of optical bistability visit, a limited number of the same research tion, however, a specific point is reached was advanced by Abraham Szöke and col­ laboratories where the Investigators and when it "switches down" to a lower leagues from M.I.T. They attempted to their teams had, in the meantime, assembl­ transmission level and output intensity is demonstrate absorptive bistability but it ed models, prototypes or training versions dramatically cut. The transmission state of was not until 1975 that Sam McCall and of their experiments. The crew had then the light beam providing the "holding Hyatt Gibbs at Bell Laboratories establish­ the opportunity of learning to handle power" can thus be read out from the ed dispersive bistability in a sodium vapour- equipment that was, for the most part, very ouput intensity of a pulsed beam addressed filled interferometer. Devices based on this similar to the Flight Units that will soon be to this "all-optical memory". principle are large and slow and recent pro­ delivered by the Investigators to ESA and The basic element is a parallel sided gress dates from the discovery in 1978 of NASA. These training sessions were very Fabry-Perot resonator filled with a medium giant non-linear effects in the semiconduc­ fruitful, and operational concepts and pro­ whose refractive index depends on the ap­ tor InSb by David Miller and colleagues at cedures evolved substantially as as result of plied light intensity. It operates as shown in Heriot-Watt University, Edinburgh. This the knowledge and experience gained. the Figure. At low incident intensity, the was applied to bistability in 1979 The operational phase is not ended yet, resonator pass frequency is detuned up­ simultaneously with the Bell group's obser­ but due to the postponement of the mis­ wards in respect to the frequency of the in­ vations in GaAs. sion, a slippage has also occurred in the cident laser beam. As the laser intensity / is The use of semiconductor materials has development and preparation of experi­ increased, the optical thickness increases : brought a considerable breakthrough with ments, to such a point that a hiatus of one nL = (n1 + n2I)L. many new experiments now possible utilis­ year has now been inserted in the training The result is that the resonator pass fre­ ing a third order non-linear susceptibility : plan of the payload crew, from July 1980 to quency is pulled towards the laser frequen­ July 1981. There has been, and will be no cy. Then as interferometer resonance is ap­ or very little payload-related training for our proached, the intensity within the reso­ mission during this period. nator also increases which in turn changes Following negotiations between ESA the refractive index and hence optical and NASA, the latter has accepted to train thickness ever more rapidly. At first the during this year, two European Payload output/input curve becomes supra-linear Specialists (including the author) as Mis­ and then eventually acquires a negative sion Specialists at the Johnson Space slope. At this point the device becomes Center. This training includes academic- unstable and the transmission jumps type courses on manned spaceflight related discontinuously to a value near the max­ subjects, technical courses on the Space imum possible. On reducing the power of Shuttle, technical assignments, and exten­ the incident beam, the internal field is sive flight training on NASA's T-38 jet air­ already established and remains high down craft as part of operational and environ­ to a level that is less than that at which mental training. "switch-up" occurred. This produces the On July 1981, our payload-related train­ hysterisis effect required for the optical ing will be resumed and will concentrate on memory. the use of an off-line crew training facility Using two input beams, with a slight de­ at the Marshall Space Flight Center, Hunts- tuning of the laser frequency in respect to ville, Alabama. We shall also be involved in the resonator frequency, allows the the on-line experiment integration phases output-input characteristic to become the in Europe and at the Kennedy Space Cen­ direct analogue of the transistor and so ter. As in the past, our interaction with the give signal gain. This "three terminal op­ Investigators will remain active to ensure tical circuit element", which operates by an optimization of the payload operating transference of optical phase thickness, is procedures that are likely to evolve until a known as a "transphasor". few months before flight. The mission itself Based on the principles outlined above, will be the ultimate test of the the range of devices which have already thoroughness and quality of our training. been produced includes memories, 3