A total of 41 experiments were conducted in the context of the Euromir 95 mission, in the categories of life sciences, materials science, astrophysics and technology (Table 1). First results were presented recently at a post-flight Investigator Working Group Meeting at the European Astronauts Centre in Cologne, Germany. This article summarises all but those of the life-sciences experiments, which will be published separately at a later date.
Eight materials- science experiments were developed for the Euromir 95 mission. They included investigations into directional solidification, crystal-growth, and undercooling effects in the TITUS furnace. The experiment sample containers (two or three cartridge assemblies per experiment) and the TITUS multi-user facility were developed in parallel and launched with the Russian supply vehicle 'Progress' in October 1995.
After successful installation and testing of the facility, the Euromir crew assisted the automatic sample processing in various respects. In particular, some essential and successful trouble- shooting once again proved the advantages of conducting such experiments in a manned spaceflight environment.
The extended duration of the Euromir 95 mission and the available upload capacities during it contributed to the successful repair of the Russian CSK-1 furnace. This furnace had completely failed during the Euromir 94 mission and the sample containers of the four ESA materials-science experiments for CSK- 1 had been retained aboard Mir. During the Euromir 95 mission extension, all of these samples could finally be processed in CSK-1.
All of the experiment runs took advantage of the single-shift- working scheme operated on board Mir. By starting the runs shortly before the end of the crew's working day, the samples reached critical temperatures only once the crew was asleep. Consequently, sample processing mainly took place in a very calm environment (a few hundred µg's as measured by TITUS's built-in accelerometers). Processing was accomplished at temperatures of up to 950 and 1200°:C for CSK-1 and TITUS, respectively, and the two furnaces were operated for more than 450 h during the mission.
The Euromir 95 mid-mission equipment download (Space Shuttle flight STS-74) allowed the early return of some processed TITUS samples (first runs of three experiments). Together with the available telemetry data from TITUS, their preliminary analysis supplied information with which to improve the temperature profiles of remaining experiment runs. All of these favourable circumstances made Euromir 95 a unique opportunity for materials- science research.
Due to a TITUS failure that is not yet fully understood, runs near this furnace's maximum operating temperature were aborted. Fortunately, however, only one experiment's runs could not be completed because of this anomaly.
The evaluation of the experiment results is not yet complete, with ground-reference runs still to be conducted in some cases. Nevertheless, the initial analysis of flight samples and flight data has already demonstrated the in-orbit success of the experiments and facilities. Moreover, some experimenters have already reported novel and promising scientific results during the post-mission IWG meeting.
Figure 1. The TITUS facility (mounted on the floor) and the CSK-1
furnace (the tube on the right) aboard Mir. The portable Crew
Interface Computer used to control TITUS, to store all flight
data, and to provide a link to Mir's telemetry system can be seen
attached to the left-hand wall
ESEF, the European Science Exposure Facility, is a multi-user, multi-purpose platform mounted on the exterior structure of the 'Spektr' module. Though originally intended for the later 'Priroda' module, it became clear in late 1994 that this would not be launched before the Euromir 95 mission, and the servicing could not then be carried out by the ESA crew member.
The ESEF's design is based on a prototype which was flown aboard Salyut-7. The intention, following that successful flight, was to have the facility mounted permanently on Mir at the earliest opportunity, and to conduct a continuing programme of experiments starting in 1986. Due to upheavals in the relationships between Western and Russian agencies at that time, KMP3 (as it was then known) was not flown. The developer, the Institut d'Astrophysique Spatiale at Orsay (F), then stored the flight and technological hardware, but some other development items, including the Hydrolaboratory Model, used for training, were 'lost' in Moscow.
In February 1994, a group of investigators agreed to utilise KMP3, renaming it ESEF, for the Euromir 95 external payload programme. Thus began the task of resurrecting the facility and modifying it for flight in new circumstances aboard Mir.
The original investigators were:
Once the use of KMP3 had been confirmed, J-P. Bibring, Institut d'Astrophysique Spatiale, Orsay (F), was brought in as Facility Scientist. Subsequently, Dr. d'Hendecourt's team with- drew their experiment when it seemed that the accommodation on Spektr would not allow sufficient solar-ultraviolet exposure for their purposes. C. Maag was joined by ESTEC's M. van Eesbeek.
The final team made use of the unique features of the ESEF in the manner originally intended, in that they launched evacuated, ultraclean cassettes containing surfaces and structures designed to provide information on space impactors and perhaps capture some of them. These cassettes were opened and closed at various times in an attempt to obtain some resolution of time-variant phenomena, specifically meteor streams. In addition, C. Maag designed and built an in-situ measurement package which counted impactors and also sensed contamination, long-wavelength radiation, and the atomic-oxygen flux.
Spektr was launched to rendezvous with Mir in May 1995, carrying the ESEF platform and the control electronics for the cassette mechanisms and the active measurement package. ESA Astronaut Thomas Reiter and Russian Cosmonaut Sergei Avdeev successfully installed the remaining parts, the cassettes, their motor drives and the active package on the outside of the station during an EVA excursion on 20 October 1995. The measurement programme then commenced, with periodic downlinking of the environment data, and occasional cassette operations in response to the passage of meteor streams and potential contamination episodes such as vehicle movements.
The particle-capture period ended on 7 February 1996 when the cassettes were finally closed in readiness for the retrieval EVA the following day. On that occasion, Thomas Reiter was accompanied by Commander Yuri Gidzenko, and together they removed two cassettes and mounted a new one to be operated and retrieved at some later date. Much was learnt by ESA during this first EVA experience, both through the activity itself and about the design issues for astronaut-serviced exposed payload facilities.
The retrieved cassettes were opened back in the laboratory in Orsay on 11 March. Some fragmentation of one of the low-density capture materials was apparent, but with little or no loss of science. The observations that could be made so far on these retrieved surfaces and structures are summarised in the accompanying panel.
In summary, this first mission for the ESEF has already demonstrated the effectiveness of a serviced exposure facility on a space station. Much good science has clearly been obtained and a greater understanding of the near-station environment achieved. These, together with the logistic and crew-intervention aspects, provide a firm basis for a future facility of this kind as part of the International Space Station.
Figure 2. ESA Astronaut Thomas Reiter at work during the second
EVA, making use of the 'Strela' manipulator arm
Secondly, the contamination environment, both volatile (at 80°C) and non-volatile, has been measured for an extended period. This shows episodes of very high deposition separated by relatively quiescent states when slow desorption takes place. Short-term deposition rates can be several hundred Angstroms per day, whereas the specification for the International Space Station is 30 Angstroms per year. Due to the total deposition, atomic-oxygen measurements proved to be impossible, as these depended upon the determination of a carbon-film erosion rate. Erosion was prevented, right from the start, by contamination overlaying the carbon.
The technology-experiment package aboard Mir was characterised by an outstandingly large range of techno-scientific areas of investigation, ranging from new micro-biological monitoring techniques, gas-contaminant bio- filtering and gas-detection systems to space-to-ground multi- media interactive communications, passive magnetic levitation for fluid-dynamics research, Earth radiation-environment monitoring, robotics technology and human-factors engineering. The following brief overview of the preliminary results represents the status six months after landing.
The radiation-environment monitoring experiment
'REM'
The goal of this unmanned external payload was to
monitor the low-Earth-orbit radiation environment at the high
inclinations typical of Mir, in order to enhance and upgrade
currently available models of the charged particles that surround
our planet.
Two main radiation contributions are present: protons in the South Atlantic Anomaly (SAA), and electrons in the polar regions. As expected, the preliminary results from EuroMir show that the radiation dose is mainly accumulated in the SAA and at the times of Mir's closest approach to the Earth's magnetic poles. Large changes are observed in the daily absorbed doses in the polar regions, and a general increase in the SAA dose consistent with the approach of solar-minimum.
The on-going analysis of the REM experiment results is also providing valuable data on the proton- and electron-absorption capabilities of the detection shielding material, based on aluminum and tantalum. A comparison of the REM doses with the current NASA radiation models, which date back to the 1970s, has revealed major differences and confirmed the need to upgrade such models, since they are not yet compatible with contemporary geomagnetic field models and do not reflect well the solar-cycle dependence nor the directionalities that are known to exist.
The REM experiment has proved to be an extremely important one, addressing as it does both concerns affecting future crewed spaceflight in Earth orbit and fundamental environmental concerns for our planet.
The microbial contamination monitoring experiment 'MIRIAM-
T2'
This experiment was aimed at analysing new techniques
for microbial-contamination and fungine-growth monitoring onboard
a long-term orbiting space station, by two simple and rapid
measurement methods (described in more detail in ESA Bulletin No.
87, August 1996).
Twin samples were also taken for a-posteriori analysis back on the ground in order to both assess the above methods and identify the biological species sampled at various points on Mir's surfaces and in its air. A preliminary look at the data confirms that both the air and surfaces in Mir's basic block were reasonably clean, comparable in fact to a normal office environment.
Although the sample processing is still going on, the experiment has already demonstrated the flight crew's ability to use such methods to assess - quickly, simply and safely - the prevailing biomass level on board space stations.
The investigation of human posture and biomechanical
motion: the 'Anbre' and Elite-S experiments
Both of these
experiments, conceived, developed and performed independently
employing totally different technologies (see ESA Bulletin No.
87), were aimed at analysing human-body postures in microgravity.
In a few words, T3 (see Table 1) was based on an ad-hoc- developed stretch garment to be worn as a self-contained measurement system by the crew member, equipped with dozens of elastomeric sensors placed in appropriate key positions, while Elite-S employs a space-qualified version of an infrared-based apparatus used on the ground to analyse motorial disorders and sports performances.
Figure 3. Thomas Reiter preparing to run the 'Anbre' experiment
(T3)
The vast amount of data collected with T4 (see Table 1) turned out to be very precise, recording offsets of just a few millimetres over large body limb movements. T3 also provided valuable data on human kinematics in microgravity.
Such results are going to be used to generate a detailed computerised three-dimensional dynamic model of real working postures in space in order both to verify and possibly upgrade human factors engineering requirements for the Columbus-Space Station Programme and for future crewed space missions.
The kinetics of biodegradation: 'Biokin'
Biokin
allowed the concept of microbial decontamination of confined
atmospheres in space to be validated and the microgravity
kinetics of the process to be verified. It was based on one
selected model bacterium, the Xanthobacter autotrophicus, within
a simplified biofilter employing 1,2-dichloroethane as the target
contaminant. The latter represents the class of organic solvents
that evaporate from plastic hardware (e.g. laptop computers) and
which typically support bacterial growth in a spacecraft.
Further details about the experiment's design and operational performance were provided in ESA Bulletin No. 87. The results show that biomass production is greater in microgravity than on the ground. They have also confirmed the suitability of such a bio-filter concept, which looks very promising not only for space environmental control and life-support systems (e.g. for the International Space Station Programme), but also for a new generation of air-filtration systems for ground-based use.
The smart gas sensor: 'SGS'
The purpose of the 'SGS' experimental equipment was to validate a small and light gas sensor vis-a-vis
the expensive and bulky gas-chromatograph/mass-spectrometer-like
types of equipment that are typically required for gas detection
and analysis. The equipment was operated extensively throughout
the mission, and also at times when interesting gases could be
expected to be released, such as during the extravehicular
activities (EVA) and during the repair of the leak that occurred
in one of the Mir thermal-control system circuits.
The SGS system was also briefly described in ESA Bulletin No. 87.
At this point in time, it can be stated that the SGS is indeed capable of providing complete 'smell-patterns' for a space station. Inter alia, it also provided a cross-confirmation with the T2 experiment's results concerning the quality of the Mir environmental control system, and the ability to purify the on- board air very effectively.
The robotics joint controller: 'RJC'
The nominal
objective in this case was to assess the microgravity
disturbances induced by various velocity and acceleration
profiles of a robotics joint as a part of a robotic arm.
The successful Euromir extension programme in 1996 enabled the science team to gather additional data, currently under analysis, about the possible influence of single-event effects, disturbances in transient phases, Mir back-ground acceleration noise, and possible performance degradation due to long-term functioning.
Although data processing is still in progress, it is already clear that RJC performed properly, gathering important data with which to characterise disturbance sources, to assess the disturbance levels on the Mir station (e.g. the strong disturbance detected at 400 Hz frequency), and to identify design improvements aimed at enhancing robotics technology for the automation of microgravity laboratories, with particular application to the International Space Station.
The Crew Support Computer Assembly: CSCA
The use
of the onboard laptop computer during the mission is summarised
in the companion article titled 'Crew Support Tools for Euromir
95' in this issue of the Bulletin.
The magnetic levitation experiment: 'Maglev'
This
experimental equipment was developed to demonstrate a simple and
inexpensive technology for the generation of passive magnetic
fluid levitation in microgravity, but also provided interesting
data on thermally-induced Marangoni convection generated within
the target levitation cell.
Maglev proved that a levitating central force field can be generated by means of an array of permanent magnets acting on the test cell, the latter being filled with transparent ferro-fluid and a non-magnetic levitation sample, in this case an air bubble.
The trapping system's stability was also demonstrated by analysing how such a passive magnetic field can keep the air bubble in the centre of the test cell, even when the bubble is 'disturbed' by Marangoni convection flows or by mechanical transient forces applied externally to the test cell.
This experiment can certainly be considered a complete success, despite its extremely low development and integration costs.
The video integrated services controller: 'VISC'
The idea of having a remotely controlled video switcher and mixer
to handle real-time visual information in synchronisation with
other main information formats from Space Station experiments
(e.g. audio and alphanumeric data), led to the development of
VISC.
Despite some technical problems with the space-to-ground link, the VISC features available on board functioned well. For instance, Mir-to-ground exchanges of graphical annotations on VISC screens were demonstrated, as well as onboard remote and ground control of Mir's TV cameras.
Although some shortcomings were apparent when operating the touch screen and when linking space and ground modems, VISC was proved to be capable of enhancing both telescience space operations and crew/ ground interactions.
Although final results are not yet available in many cases, it is already evident that the Euromir 95 experiment programme has provided a wealth of valuable data, samples, and findings. With very few exceptions, all experiments were run successfully, much to the credit of ESA Astronaut Thomas Reiter and his Russian colleagues. The first results and conclusions drawn from this novel experiment programme are already influencing the on-going decision processes regarding the future utilisation of the International Space Station.
ESA Bulletin Nr. 88.