There has been a recent increase in emphasis on small satellites because of their low cost, short development times, relative simplicity, and cost efficiency. However, these satellites do have drawbacks. Their small size results in small surface areas which often translate into thermal and power constraints. A small satellite may not have enough surface area for radiators and/or solar panels. The radiators are used to release internal heat during hot environments, and solar panels create necessary power for the heaters during cold environments. Because of the surface area and power limitations, a passive thermal design was then selected for the <b>F</b>ormation <b>A</b>utonomy <b>S</b>pacecraft with <b>T</b>hrust, <b>R</b>elative Navigation, <b>A</b>ttitude, and <b>C</b>rosslink Program (FASTRAC) twin satellites, built by students at the University of Texas at Austin. Thermal cycling and thermal analysis were performed. The thermal cycling was done in Chamber-N at Johnson Space Center, Texas, using worst case hot and cold scenarios. The thermal analysis was conducted using Finite Elements (FE), and the results were compared to the test data and validated. FASTRAC is planned to be in a LEO orbit which ranges between 300km and 500km in altitude. The orbits were then simulated to determine the characteristics of the LEO orbits in which FASTRAC can survive.