The thermal environment in space has challenging conditions in which include vacuum, low pressure, atomic oxygen, extremely hot and cold. Satellites consist of electronic equipments and these equipments should be maintained at a certain temperature range during the operation period. Therefore, thermal design and control of observation satellites at Low Earth Orbit in space are considerably important. In our study, we studied thermal design and analysis of a Low Earth Orbit (LEO) observation satellites. A satellite was designed and modeled with Systema-Thermica v.4.8.P1 using Monte-Carlo Ray Tracing Method. The analyses were performed for two extreme scenarios: i) the worst hot, and ii) the worst cold situations. The areas, temperatures, and locations of the radiators on the satellite panels were analyzed by the considered extreme scenarios. The powers and operating conditions of the heaters were evaluated according to the worst cold scenario. It was seen that the temperatures of the electronic equipments on the satellite are to be in the optimum temperature range during the observation process.