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22 Flexible External Insulation (FEI) Blankets of various types were subjected to a plasma aging in simulated reentry conditions in TsAGI’s VAT-104 windtunnel in the frame of 4 test campaigns on FEI characterization. Blankets were tested at top side temperature Tw =800…1200°C during 60 min each. Widespread numerical simulation of the test conditions and the model heating was performed using full Navier-Stokes equations. FEI catalyticity obtained from correlation between measured and calculated heat fluxes is Kw=1…10m/s.

The thermo-optical properties of thermal protection systems for spaceplanes or capsules mainly govern the temperature of the aerothermally heated outer surface during ascent and re-entry. High emissivities are favourable to achieve significant surface temperature reduction. Adding of filler materials to a coating is a potential method to improve the emissivity at higher temperatures. When the refraction index of the coating material varies only slightly with temperature, it is demonstrated that overlapping of the spectral emissivities determined at RT with the Planckian spectrum at temperatures T predicts the temperature behaviour of the coating emissivity within a technically acceptable uncertainly bandwidth.

In the frame of the ESA “Manned Space Transportation Programme” (MSTP) the applicability of flexible insulation blankets as thermal protection system of the conical surface of capsules is investigated. The blankets have to withstand the severe ascent and re-entry aerothermal and aerodynamical environment at temperatures of up to 1200 °C. For this temperature regime ceramic components are to be applied due to their excellent temperature stability and strength properties. In the frame of a comprehensive thermal and structural characterization of these materials thermal conductance measurements are performed on a ceramic fibrous core material and a blanket in this operational temperature range at gas pressures ranging from near vacuum up to ambient conditions.

When gas conductance/natural convection plays a major role as heat transfer path, microporous insulations reveal distinct advantages compared to Multi-Layer Insulations (MLI). For re-entry vehicles as e. g. HERMES or capsules silica and ceramic microfiber insulations have been investigated by DASA/ERNO in a temperature range up to 650 °C or, respectively, up to 1200 °C. In the frame of an ESTEC funded study three types of microporous insulations - microfiber, microsphere and polyimide foam - have been analytically and experimentally investigated as candidates for the internal insulation of a MARS-lander in a carbon-dioxide atmosphere for temperatures ranging from - 110 °C to 50 °C. This paper compares the test results with analytical heat transfer calculations and describes methods to improve the thermal insulation performance.

The future deployment of a network of measurement stations on the surface of MARS is presently prepared. The MARS environment is characterised by large daily and seasonal temperature fluctuations in low density atmosphere with carbondioxide as its main constituent. Typical environmental conditions for some locations are presented. Due to geometrical and mass constraints highly efficient and reliable thermal insulations are required for the thermal control of MARS stations which are powered by solar energy. ERNO has investigated the thermal performance of two candidate porous insulations in the frame of an ESTEC technology contract. The paper presents methods to predict the heat transfer modes of both insulations in a Martian environment analytically. Experimental measurements have been performed and evaluated in order to validate the analytical predictions. Based on these results the insulation design concept is reviewed.