GERMAN EXPERIMENTS DEVELOPED FOR REENTRY MISSIONS

For the development of reentry technology it is essential that the kno wledge gained from ground test facilities and numerical methods is tes ted and broadened in real reentry flights. The first of such projects was the space reentry capsule EXPRESS, which was designed as a German- Japanese enterprise for both microgravity research and reentry experim ents. The capsule was built by the Russian company DB Saljut as part o f the Khrunichev State Research and Production Space Center and modifi ed by DASA. The capsule was launched from Kagoshima by a Japanese M-3 SII rocket in January 1995. Due to a failure of the rocket, the nomina l orbital altitude could not be reached, which led to an early reentry of the capsule in Ghana after two and a half orbits. In the stagnatio n region of the reentry module an experiment was planned with a fibre reinforced ceramic tile of 300 mm in diameter integrated in the ablati ve heat shield. This experiment, called ''CETEX'', was designed by the German Aerospace Research Establishment (DLR) in Stuttgart. The aim o f CETEX is to qualify lightweight fibre reinforced ceramics and relate d structural concepts in terms of heat shield applications for space v ehicles as well as to compare the erosion behaviour shown in Eight exp eriments and ground tests. An integral part of the CETEX experiment is the PYREX experiment of the University of Stuttgart. With PYREX a pyr ometer shall be qualified, which is designed for high precision temper ature measurement of heat shield materials made of fibre reinforced ce ramic compounds during the reentry phase of space vehicles and probes. A third German experiment, RAFLEX, projected by Hyperschall Technolog ie Gottingen (HTG), Was also integrated in the CETEX tile. RAFLEX is d esigned for the measurement of dynamic and static pressures and heat t ransfer at various positions on the EXPRESS capsule. Two small SiC tub es are fed through the CETEX tile for the RAFLEX and RTEX experiments. RTEX is a Japanese spectroscopy experiment which uses the same SiC tu be as RAFLEX. Other pressure measurement points and the heat transfer gauges are located in the conical flare of the reentry module. The aim of these pressure measurements is to verify theoretical flow field mo dels for different flight altitudes and to determine the angle of atta ck of the capsule. In addition, the flight qualification of CETEX and the pressure tube integration are important technological experiments for future reentry experiments. In this paper the EXPRESS and the MIRK A missions will be described briefly. The three experiments, CETEX, PY REX and RAFLEX, in particular their qualification in ground tests, wil l be dealt with in detail. Copyright (C) 1996 Elsevier Science Ltd