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Spacecraft which are designed for Mars exploration are exposed to different severe thermal environments. The Thermal Control Design for small Mars landers which are being developed for the MARSNET mission is described. During transfer from Earth to Mars they experience large variations of the incident solar radiation, caused by solar aspect angle variations and the decreasing solar radiation intensity. The entry phase into the Martian atmosphere is characterized by a short aerothermodynamic heating, requiring a dedicated Thermal Protection System. Arrived on the Mars surface, the landers are exposed to an extreme thermal environment with large diurnal and seasonal variations of the atmospheric temperature and the incident solar radiation. The main emphasis is put on the description of the Martian thermal environment and the Thermal Control design for the Mars operation phase.

Thermal design features of the ESA European Polar Platform are described. Due to the low conductivity of the CFRP/aluminium honeycomb sandwich panels of the Payload Equipment Bay, carbon/carbon thermal doublers are used as heat spreaders for high dissipating units. The main challenge for the thermal design of the Data Relay Satellite Terminal Outboard Assembly are the motor gears and the rotary joints. High RF dissipation combined with low thermal capacitances result in extreme orbital temperature variations. The temperature limits are met by a proper selection of thermooptical properties and thermostatically controlled heaters.