Khoshnam - Satellite thermal control researcher, ITRC,Kargar ST,Tehran
Shahryari - Satellite thermal control senior researcher, ITRC,Kargar ST,Tehran
Khoddam - Associate professor, ITRC,Kargar ST,Tehran

Satellite Thermal Control is responsible for keeping all the elements in a safe temperature range. Orbit altitude is one of the most important parameters on orbital heat rate received by the external surfaces of a satellite. Also the altitude of a satellite orbit has an effect on determining the orbit period (the time spent for one revolution of the satellite around the earth). By increasing the orbit altitude, satellite period increases too. For a given beta angle, the time of satellite remaining in eclipse depends on the orbit altitude and decreases as the altitude increases. The model includes a small communication satellite with fast spine. Only components and elements that from thermal control point of view are important have been included in the model and analysis. Geometrical and thermal mathematical models of satellite have been built by the use of Thermal Desktop and SINDA/FLUINT soft ware. In this paper transient heat transfer and temperature distributions respectively of a small satellite model in four different LEO (low earth orbits) orbits in with altitudes of 700, 900, 1000, 1500 kilometers respectively analyzed and presented. The effects of orbit altitude variations on absorbed orbital heating rates (earth infrared radiation, Albedo, solar radiation) by external surfaces of satellite are analyzed. The temperature distribution of elements and surfaces are calculated. According to the results obtained, increasing the satellite altitude decreases the absorbed orbital heating rates by the satellite bottom plate so its temperature decreases. There aren’t any considerable changes in absorbed orbital heating rates for satellite top plate and as a result temperature will not change with increasing the altitude. Satellite lateral plates experience different temperature changes due to increasing the altitude (depending on beta angel). The temperature of all internal components will change accordingly.

Satellite- orbital heating rate-altitude-Temperature