|EXPRESS capsule during integration at DASA-RI in Bremen|
In the course of a co-operation between Germany and Japan the project EXPRESS was operated under the direction and financing of the former DARA and under the system responsibility of the DASA. A Russian Salyut capsule was equipped with five re-entry experiments. After the start in January 1995 in Japan the capsule ought to perform a ballistic re-entry after an orbital phase of five days and land in Australia.
Due to earlier successful co-flights of fibre-ceramic samples on Russian FOTON capsules a hot structure made of fibre-ceramics as kind of a small nose cap should have been tested for the first time with the EXPRESS mission during the ballistic re-entry. The Ceramic Tile experiment CETEX is a fibre-reinforced ceramic-component from C/C-SiC, which was developed at the institute and manufactured with the inhouse liquid silicon infiltration process. CETEX was attached to the stagnation area of the ablative heat shield of the EXPRESS capsule.
At a diameter of 300mm and a typical thickness of 5mm, CETEX had a total mass of approx. 4kg, 1kg thereof for the ceramic part itself. For the first time newly developed ceramic load introductions were used for CETEX. The insulation was accomplished with ZrO2 based material. Due to extreme temperatures there were no alternative solutions. The temperature measuring technique was developed in co-operation with Kayser-Threde. Additionally CETEX served to a certain extent as carrier platform for the experiments PYREX (IRS, University of Stuttgart) and RAFLEX (HTG, Goettingen).
During the development of CETEX qualification tests with material and component samples were accomplished in different plasma wind tunnels. In doing so temperatures of up to 2700°C were reached in PWK 2 of the Institut für Raumfahrtsysteme (IRS, University of Stuttgart), a number exceeding by far what was regarded at the time as limitation of use of these materials. C/C-SiC behaves like an excellent ablator at these temperatures.
Despite technical problems with the Japanese launcher a successful re-entry of the capsule occurred, though not in Australia but in Ghana. CETEX bore the temperatures of approx. 2200°C without problems and the middle erosion of approx. 0.9mm correlates very well with the expectations from measured data from plasma wind tunnel tests. For this reason CETEX was the first hot structure made of fibre-ceramics in Europe, which was successfully tested during a ballistic re-entry flight. Results from the EXPRESS mission formed the technical and political basis for the next stage of development namely the development of the nose cap system of the experimental vehicle X-38 for the later CRV (Crew Return Vehicle) of NASA for the International Space Station ISS.