Experience of passive thermal control of long-term near-Earth small satellite mission

The microsatellite BIRD (Bispectral InfraRed Detection) with mass of 94 kg and overall sizes 0.55 x 0.61 x 0.62 m operates on near-Earth sun-synchronous orbit more than 11 years. The temperature range -10…+30 oC for payload and housekeeping equipment with average power of 35 W and peak power of 200 W in the observation mode (10…20 min) is provided by a passive thermal control system (TCS). The TCS maintains a thermal stability of the payload structure by use of heat transfer elements – grooved heat pipes, thermally jointing the satellite segments. Two radiators, multilayer insulation (MLI) and low-conductive stand-offs provide the required temperature level. An analysis of TCS performance includes the definition of minimal, maximal and average temperatures of satellite units and their comparison with the designed parameters. The elaborated passive TCS successfully keeps the nominal temperature level of satellite components during one-year designed period of exploitation and sequent 10 years.