In high-speed-approach landings on distant planets having an atmosphere, space probes are usually protected by rigid heat shields, while their descent is slowed down by parachutes to reduce the impact. In recent years, new technologies have been developed to replace these bulky heat shield and parachute systems.
The Russian spacecraft Mars'96 for instance, which was launched in November 1996 but failed to reach its nominal orbit, carried two modules designed to land on that planet's surface. For the last part of the mission, an Inflatable Re-Entry and Descent Technology (IRDT) had been deployed. The main components of this system were an aerobraking and thermally protective shell, a densely packed inflating material and a pressurisation system.
This technology is now considered applicable to other re-entry scenarios such as payload recovery from the International Space Station, planetary landers for science missions and atmospheric research.
A demonstration mission on 9/10 February 2000 will evaluate the performance of this new technology before it is offered to potential users. A Russian Soyuz/Fregat launcher, lifting off from the Kazakh steppe near Baikonur, will provide a low-cost flight opportunity for the test vehicle, which is equipped with the inflatable heat shield and a sensor package developed by DaimlerChrysler Aerospace (DASA). After four orbits around the Earth, the test vehicle will be powered by the launcher's upper stage to re-enter the atmosphere for a landing the next day about 1800 km north-west of the launch site.
During the mission, a number of technical parameters such as pressure, temperature and deceleration will be monitored and the inflation of the re-entry/descent structure observed. "From this novel technology, we are expecting a major breakthrough, to make re-entry of small payloads more and more reliable, simpler and less costly than traditional systems", explains Dieter Kassing, ESA's IRDT project manager.
One of the main instruments on board the test vehicle is a sensor device developed by the University of Stuttgart for the determination of oxygen partial pressure in low Earth orbit and during re-entry. The scientific/technical investigations will be led by Dr. Ulrich Schoettle (Stuttgart University). Lionel Marraffa (ESA) will lead the evaluation of the IRDT's aerothermodynamic behaviour. DASA was responsible for integration of the sensor package and is ESA's co-investigator for evaluation of the application aspects of this new technology.
In addition to the sensor package, the mission will accommodate a collection of special stones to study the physical and chemical modifications in sedimentary rocks, i.e. simulated meteorites, during atmospheric infall. Co-investors of this experiment are Dr. André Brack (CNRS, Orleans) and Dr. Gero Kurat (Vienna University). This experiment is being co-sponsored by ESA.
The Russian/European Starsem launch company and NPO Lavochkin, the Russian company that developed the original IRDT technology, will be responsible for launch, orbit control, re-entry and recovery of the sensor package under contract with the International Science & Technology Centre (Moscow). ESA, the European Commission and DASA are co-funding this contract, contributing $600K each.
For further information:
Dieter Kassing, IRDT Project Manager,
ESA/ESTEC, Noordwijk, the Netherlands
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