Figure 1: Schematic of the AGHF furnace (courtesy of Dornier GmbH)
ESA's Microgravity Programme, covering both Physical Sciences and Life Sciences, has contributed now for more than ten years, payload equipment and experiments for manned space missions on NASA's Space Shuttle-related Spacelab and Spacehab missions or, as recently, on long-duration missions with the Russian Space Station Mir. These missions were in historical order: D-1 (30 October to 6 November 1985), IML-1 (22 to 30 January 1992), USML- 1 (25 June to 9 July 1992), D-2 (26 April to 6 May 1993), Spacehab-1 (21 June to 1 July 1993), IML-2 (8 to 23 July 1994), Euromir '94 (3 October to 4 November 1994), Euromir '95 (3 September 1995 to 29 February 1996), USML-2 (20 October to 5 November 1995) and S/MM-3 (Spacehab mission to Mir, 22 to 31 March 1996). The next mission with significant ESA microgravity participation will be the 16-day Life and Microgravity Spacelab (LMS) mission, scheduled for launch in the Space Shuttle Columbia on 20 June 1996.
For the near future, ESA experiment instrumentation is firmly scheduled for flights on S/MM-05 (December 1996), S/MM-06 (May 1997), and Neurolab (STS-90 in March 1998).
The Neurolab mission will be the last Spacelab flight which is presently foreseen. However, it is expected that several manned missions with ESA microgravity payloads on board, either in Spacelab, Spacehab or Mir, will be performed before this type of research will be fully transferred to the International Space Station in the next millennium.
The long gap of more than six years between D1 (November 1985) and IML-1 (January1992), during which ESA did not participate in manned microgravity flights, had been caused by the Challenger accident on 28 January 1986, after which Space Shuttle flights were interrupted for two and a half years.
For the first Spacelab mission SL-1, from 28 November to 8 December 1983, ESA and national European space agencies provided 50 % of the First Spacelab Payload (FSLP) under ESA management. However, at that time ESA's Microgravity Programme had only just been introduced and did not yet provide a payload.
After the great success of the IML-2 (International Microgravity Laboratory) mission in mid-1994 with ESA's multi-user facilities APCF (Advanced Protein Crystallisation Facility), CPF (Critical Point Facility), Biorack and BDPU (Bubble, Drop and Particle Unit) as part of an international payload fromthe national space agencies of Canada (CSA), France (CNES), Germany (DARA) and Japan (NASDA), it was hoped that NASA would continue this series of international Spacelab flights. This was not the case, but nevertheless NASA invited its partners in November 1994, to help them to compile a payload for a Spacelab flight in mid-1996. This was very short notice, indeed, compared to the nominal preparation time for a Spacelab mission of three to four years.
The LMS Payload
As a result of a quick survey and proposal
exercise the following payload complement was configured for LMS:
Microgravity Experiment Facilities
Acceleration Measurement Facilities
Life Sciences Experiment Facilities
The LMS Mission Parameters
To perform the experiments on the
payload complement mentioned above, the following LMS mission
parameters were defined:
duration 16 +2 days
altitude 150 nautical miles
inclination: 39 degrees
attitude: gravity gradient
Furthermore, it was decided to operate the mission with a crew of seven astronauts in a one-shift mode. This means on the one hand, limited crew coverage of the overall mission, but on the other hand, it enables very quiet night shifts with few microgravity disturbances. In fact, this resulted in a work planning with the majority of the life sciences experiments being performed during day shifts, with crew members acting as test operators and test subjects, and the majority of the physical sciences experiments being carried out during night shifts under remote control of expert teams from the ground.
The LMS Astronaut Crew
The astronaut crew was assigned by NASA
in two steps. Mission and Payload Specialists were introduced to
the LMS user community at the second Investigators Working Group
(IWG) meeting in Noordwijk (NL) on 9 May 1995. ESA astronaut
Pedro Duque (E) was assigned as Alternate Payload Specialist on
this occasion, Commander and Pilot were announced at the third
IWG meeting at Cocoa Beach (Florida) on 30 November 1995.
The full crew team including back-ups is as follows
Tom Henricks NASA-Commander Kevin Kregel NASA-Pilot Susan Helms NASA-Mission Specialist Charles Brady NASA-Mission Specialist Richard Linnehan NASA-Mission Specialist Jean-Jacques Favier CNES-Payload Specialist Robert Thirsk CSA-Payload Specialist Luca Urbani ASI-Alternate Payload Specialist Pedro Duque ESA-Alternate Payload Specialist
The LMS Management Team
NASA's core management team for the engineering, operations and science coordination is located partly at NASA Headquarters in Washington DC, and partly at the Marshall Space Flight Center in Huntsville, Alabama:
Dave Jarrett Programme Manager, NASA HQ Dr V. Schneider Programme Scientist, NASA HQ Dr B. Carpenter Microgravity Scientist, NASA HQ Mark Boudreaux Mission Manager, NASA MSFC Kim Ibrahim Assistant Mission Manager, NASA MSFC Dr Patton Downey Mission Scientist, NASA MSFC Barbara Cobb Operations Director, NASA MSFC
Key interfaces for external users of NASA missions are through the mission manager for all engineering and operations-related issues, and through the mission scientist for all scientific aspects.
ESA's payload / instruments for the LMS mission have been identified above as part of the overall LMS payload complement. Hereafter, each payload / instrument, with its related experiments, will be briefly described. The flight of all ESA facilities on LMS is the result of a cooperation agreement between ESA and NASA, according to which ESA provides and supports multi-user facilities, and makes 50% of their utilisation available to NASA-selected experiments / investigators. If experiments require the development of dedicated hardware as for AGHF (experiment cartridges) and BDPU (test containers), then this is done by ESA as well. NASA, in return, takes over the installation and testing of all ESA- provided items in Spacelab, the launch of Spacelab within the Space Shuttle payload bay, all ground and flight operations tasks, and the training of the astronaut crew.
The multi-user facility AGHF is a Bridgman-type furnace; this means that the cartridge with the experiment sample is in a fixed position, whereas the heater is moved with variable speeds over the length of the cartridge. This principle is illustrated in Figure 1.
Figure 1: Schematic of the AGHF furnace (courtesy of Dornier
GmbH)
Heater temperatures and temperature profiles are programmable and can reach up to 1400°C. High gradients up to 100 K/cm can be achieved with water fluctuation through a cooling zone and close coupling of the experiment cartridge to this cooling zone by means of a Liquid Metal Ring (LMR). Experiment processing is done in a vacuum better than 10(exp -4) mbar, which is established with a turbo-molecular pump installed between the AGHF process chamber and the Spacelab ventline. After each experiment processing, the process chamber is cooled down and flushed with Argon gas. Processing of the experiment cartridges is sequential and requires the exchange of the experiment cartridges and the related activation and deactivation of the AGHF by an astronaut. The actual experiment run - which can be between hours and days - is automatic and preprogrammed but will be monitored by a ground team, and can exceptionally be modified by telecommands.
Initially foreseen for flight on the IML-2 mission, the AGHF finally had to wait for a long time for its first flight on LMS. AGHF has already been introduced in detail in Microgravity News Vol. 3, No. 1, July 1990. Figure 2 shows its actual design.
Figure 2: The AGHF flight model
Table 1 lists the four European investigators selected by ESA, and the two US investigators selected by NASA with their related experiments.
Table 1: AGHF Experiments for LMS
Exp. Code Investigator Exp. Title (Function) Quantity of Processing
Cartridges Time(h)
---------------------------------------------------------------------------------------------------
ESA-2b D. Camel Equiaxed Solidification of Al Alloy 2 2 x 12
CENG, Grenoble, F
ESA-5 U. Hecht Interactive Response of Advancing Phase 2 20; 17.5
Access e.V. Boundaries to Particles
Aachen, D
ESA-7 H. Nguyen Thi Comparative Study of Cells and Dendrites 2 2 x 17
Univ. d Aix- during Directional Solidification of a
Marseille, F Binary Al Alloy at 1-g and at µg
ESA-8 T. Duffar Effects of Convection on Interface 1+ 41
CENG Curvature during Growth of Concentrated 1 spare
Grenoble, F Ternary Compounds
NASA-1 B. Andrews, UAB, Coupled Growth in Hypermonotectics 3 3 x 39
Birmingham, USA
NASA-2 D.M. Stefanescu Particle Engulfment and Pushing by 3 15.5;15.5;
UAB, Tuscaloosa, Solidifying Interfaces 13
USA
The actual experiment sample material is provided by the investigator. Within a crucible, it is installed in a tantalum tube together with thermocouples and auxiliary equipment. This is then the so-called experiment cartridge. The thermocouples are led through a hermetically sealed feedthrough to the AGHF electronics and enable the measurement of temperatures as near as possible at the actual experiment sample. These data, together with other AGHF parameters, are transmitted to the ground and are made available to the investigator for on-line monitoring of the processing of his cartridge. After the mission, these data are given to the investigator together with the processed experiment cartridge. A typical experiment cartridge is shown in Figure 3.
Figure 3: AGHF typical experiment cartridge
Processing of all cartridges with the duration required by the investigators will require the full 16 days of the LMS mission. This will be just within the boundaries of AGHF's capabilities, which are limited by the size of memory for storage of processing parameters, and by the volume of the Argon gas needed for flushing the AGHF process chamber after each experiment run.
AGHF experiment results will become available only after the mission, when the samples processed in microgravity have been metallurgically analysed on the ground by the investigators. Part of this evaluation process is the comparison of the space- processed samples with ground-processed samples. For this reason it is necessary that experiment samples of the same production lot as the flight samples are processed in the AGHF after the LMS mission on the ground with identical process parameters as in flight.
The APCF is ESA's 'workhorse' for protein crystallisation in space. It has flown already on Spacehab-1 (June 1993), IML-2 (July 1994), and on USML-2 (October 1995). ESA has two identical flight models which can carry 48 individual and different experiment growth reactors each, of which 12 can be observed by a video subsystem. Protein growth temperatures can be chosen between 4°C and 30°C, however, only one temperature per APCF flight model can be set prior to the flight. APCF requires in-orbit activation at the beginning of a mission, and deactivation at the end of a mission by an astronaut, otherwise APCF operates fully automatically to a preprogrammed processing profile which includes the taking and recording of maximum 5000 video stills.
APCF has been designed for accommodation in Shuttle Middeck Lockers (MDL) which enables flights in the actual Shuttle middeck, but also in Spacelab, Spacehab and even in the International Space Station (ISS) Express Racks. Allocation in MDLs furthermore allows late (prior to launch) and early (after landing) access, which is a prerequisite for sensitive proteins, since some of them tend to degrade fast after having been put in their growth reactors.
Figures 4 and 5 give an illustration of the actual APCF design and of its accommodation in an MDL.
Figure 4: APCF Assembly/Middeck Locker
Figure 5: APCF flight model
APCF allows its users to optimise the crystallisation environment for their dedicated experiments by offering a choice of a great variety of crystallisation methods, of chamber volumes in the growth reactors, and of growth parameters. Furthermore, the APCF has been enhanced for the LMS mission by the addition of a Mach-Zehnder-Interferometer which will provide a better insight in the crystal-growth process in microgravity.
APCF is the first facility to offer three different methods of protein crystal growth:
Table 2 lists the eleven European investigator groups selected by ESA, and the US Principal Investigator selected by NASA to coordinate other US experimenters. The same table includes type/volume/temperature of experiments and the allocation of video and Mach-Zehnder Interferometer observations.
Table 2: APCF Experiments on LMS
---------------------------------------------------------------------------------------------------------------
Investigator Institute Experiment Reactors Video MZI
& Country Title
---------------------------------------------------------------------------------------------------------------
Nr. Method Temp Vol.
Note 1 Note 2 °C µl Note3
C. Betzel Institut für Physiologische EGFR-EGF 2 HD 20 6
Chemie, DESY, Hamburg dto. 2 HD 20 80
W. Weber Universitätskrankenhaus dto. 1 DIA 20 15 1
D Eppendorf
N. Chayen Imperial College London Crustacyanin 4 HD 20 80
P. Zagalsky The Blackett Laboratory subunits
UK
V. Erdmann Institut für Biochemie 5S rRNA 7 DIA 20 15
S. Lorenz Freie Universität Berlin
D
R. Giegé Laboratoire de Biochimie AspRS 4 DIA 8 67
J. Ng IBMC-CNRS Strasbourg AspRS 4 DIA 20 67 1
F Thaumatin 2 DIA 20 188 1
J.R.Helliwell Department of Chemistry Monitoring 4 DIA 20 188 4 4
UK University of Manchester Lysozyme
crystallisation
via Mach-
Zehnder
Interferometer
T. Richmond Institut für Molekular- Nucleosome core 4 HD 20 80
CH biologie, ETH Zürich particle
W. Sänger Inst. für Kristallographie Photosystem 1 6 DIA 8 15
D Freie Universität Berlin
G. Wagner Membran- und Bewe- Bacteriorhodopsin 4 DIA 20 188 1
D gungsphysiologie, Justus
Liebig Universität Gießen
L. Wyns Institut voor Moleculaire CcdB 2 HD 20 80
M. Dao-Thi Biologie, Vrije Univ. dto. 2 FID 20 200
B Brussel
A. Zagari Dipartimento di Chimica, Alcohol 4 HD 20 8
I Universita degli Studi Dehydrogenase 1 FID 20 200
di Napoli Federico II
J.Garcia Ruiz Laboratorio de Estudios Lysozyme at low 5 FID 20 200 2 1
E Cristalograficos, nucleation density
Universidad de Granada
McPherson University of California TBD by NASA 24 FID 8 470 12
USA Riverside 12 FID 8 200
2 FID 8 67
Note 1: number of reactors
Note 2: DIA = Dialysis, HD = Hanging Drop, FID = Free Interface Diffusion
Note 3: Mach-Zehnder Interferometer
Experiment results will become available only after the mission when the growth reactors processed in microgravity have been handed over to the investigators for analysis together with the related video images. These images will allow investigators to study the history of crystal development in microgravity which can be compared with crystals grown on the ground in parallel to the LMS mission. Scientists are interested particularly in analysing crystals returned from space by using precision X- ray/synchrotron beams to determine the internal arrangement of the atoms within a crystal.
A summary of first results of APCF experiments performed during the USML-2 mission of October 1995 can be found somewhere else in this issue of Microgravity News.
The BDPU is a multi-user facility for scientific research on fluid physics phenomena under low gravity conditions. The scientific objectives of the BDPU in its present configuration are the investigations
The BDPU provides a variety of stimuli (control of temperatures and mechanisms) and observation/diagnostic means (video and cine cameras, Schlieren and interferometer optics, and temperature sensors) as common services for experiments. The experiments themselves require a dedicated design, typically a transparent test cell surrounded by Peltier elements, heaters, and temperature sensors and injection mechanisms, reservoirs, and volume expansion compensation equipment.
Experiments are accommodated in standardised test containers with
During launch and landing the test containers as well as cameras and film magazines are stowed in Spacelab lockers. On BDPU activation in orbit, astronauts have to insert a test container into BDPU through a sliding door, and have to attach cameras to the outside of BDPU. After this an experiment can be processed for which typically 7 - 40 hours are foreseen. The experiments will be processed sequentially, and the astronauts will have to exchange test containers, and to configure BDPU for the run of a particular experiment. The actual experiment processing will be controlled by a ground team either located in the POCC at NASA-MSFC or in a remote centre in Europe.
The LMS mission provides BDPU with its second flight opportunity. It was already flown earlier on IML-2 in July 1994. BDPU is shown in Figure 6, and typical test containers in Figures 7 and 8. A detailed description of BDPU can be found in Microgravity News Vol. 4, No. 2, December 1991.
Figure 6: BDPU power supply, service and basic experiment module
test set-up at Alenia. (courtesy Alenia Spazio S.p.A.)
Figure 7: BDPU test cell with injection equipment (TC#6, A.
Viviani)
Figure 8: Perpendicular optical windows and heat pipes with heat
exchangers (TC #7A, J.C. Legros)
BDPU Experiments
The BDPU experiments selected by ESA's
Microgravity Programme Board and by NASA are listed in Table 3.
The most critical development was TC #4 (D. Saville) due to the
very high voltages of up to 20 kV involved. This experiment was
described in more detail in Microgravity News Vol. 8, No. 3,
December 1995.
Table 3: BDPU Experiments on LMS
---------------------------------------------------------------------------------------------------------------
TC No. Investigator & Institute Experiment Title Processing
Country Time (hrs)
---------------------------------------------------------------------------------------------------------------
TC #3 J.Straub Technische Universität 1) Nucleation, Bubble Growth,Interfacial 18
D München Microlayer, Evaporation and Condensation Kinetics
H. Merte University of Michigan 2) Efficient Cooling of High Power Small Electronic
USA Devices by Boiling under Microgravity
TC #7A & B J.C.Legros Université Libre de 1) Oscillatory Marangoni Instabibility 16
P. Géoris Bruxelles in a Three-layer System
B 2) Thermocapillary Flow in a Symmetrical 14
Three-layer System
TC #2A & B S. Subramanian Clarkson University 1) Thermocapillary Migration and Interaction of 17
USA Bubbles
2) Thermocapillary Migration and Interaction of Drops 8.5
TC #4A & B D. Saville Princeton University Studies in Electrohydrosynamics - the Stability of 15
USA Liquid Bridges
TC # 8 R. Monti Universitá di Napoli Bubble and Drop Interactions with Solidification 20.5
R. Fortezza-I MARS Center, Napoli Fronts
TC # 6 A. Viviani Seconda Universitá di Non-Linear Surface Tension Driven Bubble 6.5
C. Golia - I Napoli Migration
During experiment runs, BDPU operations require intense interaction with the investigators on the ground who, typically, will observe and evaluate video images and temperature data. As a result of these observations, the investigators may propose changes of temperatures, injection or extraction of bubbles or drops, activation of a high resolution cine camera, etc.
Telemetry and video data recorded during the operation of an experiment on ground will be made available to the investigators for further evaluation after the mission.
The TVD with its torque sensor, motor, gears, and electronics is attached to the floor of the Spacelab centre aisle. Special knee, foot, and arm restraints, called human interfaces, mechanically connect the test subject, an astronaut, to the TVD.
The TVD measures the torque which is produced when an astronaut applies force to the rotational shaft of the TVD with his arm or foot. In addition to torque measurements, the TVD gauges the rate at which an arm or foot moves. The result is the angular velocity of the elbow or ankle. These types of mechanical measurements enable the scientists to calculate levels of muscle performance and function, including strength, energy expenditure, and fatigue.
The TVD has already been described in detail in Microgravity News Vol. 8, No. 1, April 1995. Figure 9 gives an impression of the TVD installed on the Spacelab floor and Figure 10 shows the measurement principle.
Figure 9: TVD installed on the Spacelab floor with test subject
connected to the arm restraint.
Figure 10: Torque-Velocity Dynamometer measurement principle.
TVD Experiments for LMS
ESA and NASA-selected experiments which
make use of the TVD on LMS are listed in Table 4.
Table 4: TVD Experiments on LMS
Investigator Institute Experiment Title Subjects Flight
& Country measurements
-------------------------------------------------------------------------------------------------------
R. Edgerton University of California Motor Control of Joint Muscle in 4 3
J. Hudgson Los Angeles Microgravity (MCIM)
USA
P. Cerretelli Université de Genève Percutaneous Electrical Muscle 4 4
M. Narici Stimulation (PEMS)
B. Kayser
CH
P. Di Prampero Universitá di Udine Eccentric/Concentric Exercise 4 3
C, Capelli
S. Milesi - I
E. Stüssi ETH Zürich
J. Denoth - CH
P.A. Tesch Karolinska Institutet An approach to counteract impairment ground ground only
H.E. Berg Stockholm of the musculoskeletal function in space
S
R. Fitts Marquette University Effect of µg on Single Muscle Fiber 4 3
Milwaukee Function
D. Costill Ball State University
USA Muncie
The experiment of Prof. Paolo Cerretelli aims at assessing changes in muscle contractile properties induced by the microgravity environment. Small and early changes will be measured by means of a Percutaneous Electrical Muscle Stimulator (PEMS) which delivers brief constant current pulses via surface electrodes into the calf muscles. The force evoked by this stimulation will be measured by the TVD. The PEMS which will be used in conjunction with the TVD has been developed with Swiss funding (PRODEX) under ESA guidance.
The MMA was developed for and has flown on the D-2 mission in April/May 1993. It allows to connect decentralised triaxial accelerometer heads to a central electronics unit which transmits the measured data to the ground. On-line analysis of these data enables their display in both, time and frequency domains, to investigators on the ground, who in turn can control their flight experiment according to the actual in-orbit microgravity disturbance status.
For the LMS mission, the MMA has been further developed and a sensor for the quasi-static/low-frequency range has been added. In LMS one triaxial sensor package covering the range down to 10 (exp -9) g in the bandwidth DC to 1 Hz, and four sensor packages with the range 10(exp -6) to 10 (exp -2) g and the bandwidth 0.1 to 100 Hz will be flown. The latter sensors will be directly attached to experiment facilities like the AGHF.
The MMA has been described with full details in Microgravity News Vol. 8, No. 2, August 1995.
Payload equipment in Spacelab can be operated by the crew and/or from the ground, the latter capability being called 'Teleoperations'. Simple equipment is often designed for handling and operation by the crew only, whereas more complex equipment, as e.g. most ESA multi-user facilities, require the crew for initial set-up, exchange of dedicated experiment hardware, and configuration for landing, and ground teams for monitoring (telemetry, video) and modification (telecommands) of experiment processes. This means that teleoperations capabilities are inherent design features of most ESA microgravity facilities.
Up to now, Spacelab payload teleoperations have generally been performed from a central location, namely the Payload Operations and Control Centre (POCC). In preparation for European participation in the International Space Station, several Spacelab missions were used to test and demonstrate a new decentralised user operations concept. Starting with the ATLAS-2 Spacelab mission in 1993, ESA has gradually improved the possibilities for European users to perform payload operations from European user centres during the IML-2 and ATLAS-3 missions.
For the LMS mission, some European investigators have asked ESA to provide them with a similar service as during the IML-2 mission. As a consequence, basic ESA ground operations teams will be located at the central LMS POCC at NASA-MSFC, but selected data will be transmitted to three European support centres, namely CADMOS at CNES, Toulouse (F), MARS in Naples (I), and SROC in Brussels (B), from where AGHF and BDPU investigators will support or even fully control their experiments.
Teleoperations require the installation and operation of a complex infrastructure making use of dedicated NASA and ESA networks for the datalinks from NASA-MSFC in Huntsville to ESOC in Darmstadt (D). For further data distribution from ESOC to the individual centres, standard PTT services such as leased lines and dial-up ISDN connections will be used. The diagram of the overall network and related local services is shown in Figure 11, whilst the related data rates are defined in Table 5.
Figure 11: Links and Services of the Interconnect Ground
Subnetwork
Table 5: Data Rates of Overall Network
------------------------------------------------------------------------------
Site Payload Audio Video low rate high rate Total
data data bandwidth
kbps kbps kbps kbps kbps
------------------------------------------------------------------------------
MARS BDPU 56 (64) 384 64 128 640
SROC BDPU 56 (64) 384 64 -- 512
CADMOS AGHF 56 (64) 384 64 -- 512
ALTEC BDPU 56 (64) 384 64 128
ESOC 56
Transatlantic 280 384 64 128 856
Remore Science Processing Scenario for LMS
At present, the general impression is that the Spacelab era may end within the next few years. This means that it will be difficult to find future flight opportunities for instruments like AGHF and BDPU which have been developed as dedicated Spacelab facilities. However, with the Materials Science Laboratory (MSL) and the Fluid Science Laboratory (FSL), next- generation facilities are already being developed for ESA's Columbus Orbital Facility (COF), a module of the International Space Station (ISS).
APCF with its accommodation in Middeck Lockers will find further flight opportunities, possibly even in the Express Racks of the ISS. Nevertheless, the APCF is currently being developed further. The result will be the Protein Crystallisation Diagnostics Facility (PCDF) which will enable beyond the simple growth of protein crystals a more detailed observation and diagnosis of crystallisation phenomena in microgravity. PCDF may already fly in the early utilisation period of the ISS in the years 2001/2002.
A successor of TVD, the Muscle Atrophy Research and Exercise System (MARES) is in its early development phase. MARES will probably become an instrument of NASA's Human Physiology Research Facility (HRF) presently foreseen for launch to the ISS in 1999.
A MMA reflight is foreseen in NASA's MSL-01 Spacelab mission in March 1997. Since MMA can easily be adapted to changing mission requirements, and since the mapping of the microgravity environment of the ISS will be an essential task of the initial ISS operation, MMA will find future flight opportunities and perhaps even its way into the COF/ISS.
ESA Microgravity News Vol. 9 No. 1