Heatshield Qualification for the SpaceMail Re-entry Capsule'Fotino' in the VKI Plasmatron

摘要

This paper highlights the plasma chamber testing of an innovative lightweight heatshield. The tests were highly successful and it is believed that the available test data justifies the choice of the new material as heatshield for light-weight capsule re-entry from Low Earth Orbit. Unfortunately there is no evidence (yet) that the material's first orbital demonstrator Fotino, a spherical re-entry capsule weighing only 6 kg at 40 cm diameter, survived its ordeal on the way from space to the ground. Fotino's Thermal Protection System (TPS), is based on soft mats of alumina blanket, surrounded by a shell of vacuum-formed rigidized alumina which is in turn covered by a thin silicon ablator. The low mass allows for a capsule with a uniquely low ballistic coefficient and thus a cooler re-entry. The VKI Plasmatron was able to apply stagnation point enthalpy matching simulation results. Familiarization tests at high and constant enthalpy on a standard sample shape were used to tune silicon layer thickness and composition. Next emissivity, conductivity and catalycity of the heatshield were determined. Finally, survivability was successfully demonstrated using a full reproduction of the expected enthalpy profile on a scaled model of the capsule for both a nominal and a case considered conservative.