Study On Thermal Control Of Star Sensor Assemblies And A Fast Responding Space Camera Integrated With Satellite

With the development of satellites, spaceborne integration and rapid attitude adjusting turn to be more important than before. For optical loads, spaceborne integration would make the increase in the number of interfaces and rapid attitude adjusting would lead to sharp variety of heat flux. Both these two trends bring on new challenge for thermal control of the optical loads.The fast responding space camera integrated with satellite is the first camera designed with spaceborne integration method. Light weight, low power, rapid attitude adjusting and taking photographs are its characters. Star sensors, sun sensors,GPS antennas, data transfer antenna and solar panel are all mounted on the main frame of the space camera. All these apparatus could work in a wide temperature range but the temperature of camera need to be maintained in a narrow range, how to reduce the effects caused by them turns to be necessary and important. By the limitation of low power, the usual attitude of the space camera in orbit is oriented to the sun by sun panel. Only when the earth observation is needed, the space camera adjusts its attitude and then takes photographs, attitude adjusting and photographing should be finished in ten minutes. The huge variety of heat flux caused by rapid attitude adjusting would affect the temperatures of the optical components near by optical entrance. The effect needs be reduced to as small as possible by thermalcontrol measurements.Star sensors are commonly used on spacecrafts for its high precision. Currently,attitude precision, slew rate and temperature stability of any star sensor can completely meet the requirement of the satellites. But the error caused by deformation of the support of star sensor is often ignored. With the development of optical loads, the resolution of space cameras turns to be less than 1m and the error caused by deformation of the support of star sensor becomes significant. For some optical observation satellites, the temperature stabilities of star sensor assemblies are even more strictly than space cameras.For star sensors based on CCD mode, two problems should be resolved to maintain the temperature stabilities in orbit. One is the dissipation of interior heat generated by CCD and its thermal electrical cooler and the other is the decrease of the temperature variety caused by the periodical change of heat flux.In this paper, the characters of the fast responding space camera integrated with satellite and the star sensor assembly were analyzed. Then the difficulties and key points of thermal control were discussed. After simulation analyses and thermal balance tests, thermal designs adapted to them were both accomplished. Data in orbit show that the temperatures are in control and the temperature stabilities are better than requirements. The main work and innovation points are as below.1. Discussion, analysis and design about thermal control of the fast spacecamera integrated with satellite were systemically accomplished. Some newtechnical measures were carried out in heat insulation of boundaries and inthermal processing of the baffle.2. Thermal stability of the star sensors in orbit was effectively guaranteedthrough structure-thermal analysis and design for the support of star sensors.