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Science & Exploration

N° 21–1993: Spacelab D-2 in orbit

27 April 1993

After a successful lift-off on 26 April 1993 at 14:50 hrs, (UT) the second German Spacelab mission D-2 on board Space shuttle Columbia has reached orbit and operations have started as scheduled. On this occasion, ESA has sent up to space facilities hosting a number of European experiments to further expand the knowledge of basic phenomena in fluid physics and material sciences, and particularly to perform for the first time an integrated medical screening of the human body in the absence of gravity.

From the DLR (the German Research Establishment for Aerospace) control centre in Oberpfaffenhofen, near Munich, almost 200 specialists are directing and controlling the activities taking place on board the Shuttle. At the same time, scientists from all over Europe, the United States and Japan are interacting on a permanent basis with the crew of 7 astronauts, which includes two German Payload Specialists from DLR, as they conduct experiments in the fields of material sciences, life sciences, human physiology, Earth observation and robotics technology.

While already seated in the orbiter waiting for launch, during lift-off and the first hours of their presence in orbit (before activation of Spacelab), the astronauts performed medical experiments in connection with ESA's Anthrorack facility. The change in the gravity pull on the human body from 1g (normal weight conditions on Earth under the influence of gravity) to almost 0g (weightlessness), causes an accumulation of fluids (blood and liquids) in the upper body which leads to an increase in blood filling of the heart and the lungs, gradually leading to a new equilibrium. The experiments in Anthrorack which are being run in the first part of the mission are suited to monitoring all these modifications and analysing how the human body reacts and adapts to the new 'gravity- free' environment.

In the first couple of days in space, during the phase in which the astronauts could still suffer from space-motion sickness, an experiment is being performed to monitor the adaptation process taking place in the blood circulation and in the lungs. On the 4th day of the mission the full set of tests on Anthrorack will start on a daily basis and the astronauts will have to undergo, at regular intervals, a number of tests during exercise and at rest. Blood, urine and saliva samples will also be taken to monitor and collect data on the endocrinological system and the metabolism.

The results of the tests are being transmitted in real time to ground at the NASA Lyndon B. Johnson Space Center (JSC) in Houston, and from there to the DLR Control Centre in Oberpfaffenhofen where the teams of scientists who developed the experiments are immediately able to record and analyse them.
Belgian, Danish, Dutch, French, German, Italian, Swedish, Swiss and American scientists are involved in the Anthrorack experiments.
ESA's Advanced Fluid Physics Module (AFPM) will be switched on in the course of the second day of the mission. The 5 experiments contained in the facility will determine how absence of gravity influences the properties and behaviour of fluids (liquid column dynamics, convection, capillary forces and interfaces between immiscible liquids). The experiments, which are being performed for scientists from the University of Madrid (Spain), the Battelle Institute (Germany), the University of Essen (Germany), the University of Naples (Italy) and the University of Brussels (Belgium), will continue until a few hours before landing.

The Crew Telesupport Experiment (CTE) is to be performed between two portable computers and optical disc player systems linked to a standard modem to allow communications and exchange of graphic information (schematic diagrams, digitised photos, etc) between astronauts on board and scientists on the ground. It will be set up on the 4th day of the mission. After a 10-minute set-up session, two half-hour operational sessions are scheduled for this experiment. The CTE, which was designed mainly to make Spacelab easier to use and thereby make missions more cost-effective, will be and essential aid for future European astronauts on Columbus missions.

The Microgravity Measurement Assembly (MMA) was switched on about five hours after lift-off. During the whole mission the equipment will measure the level of residual accelerations on board Spacelab and the data collected will be used to support the other experiments on board and assess the level of microgravity to which they are submitted. The current MMA concept will help in defining the microgravity measurement systems for the future Space Station laboratories. Nearly a third of the programme of scientific work for the Spacelab D-2 mission concerns the study of physical phenomena occurring in the fluid phases when materials are produced under microgravity conditions and the influence of such phenomena on the quality of materials. Six ESA funded experiments in the field of material sciences will be performed during the mission, mainly for German researchers. On the 5th and 6th days of the mission the HOLOP (Holographic Optics) laboratory on Spacelab D-2 will give European scientists an excellent opportunity to remotely operate from Earth a fluid physics experiment investigating liquid motion (convection). The MARCO (for MARangoni COnvection) experiment, continues the telescience operations initiated by ESA and already tested several times during previous Shuttle missions. The HOLOP/MARCO telescience experiment will be directly controlled by the investigators from a remote centre in Cologne, the DLR Microgravity User Support Centre (MUSC).