The Tracking and Data Relay Satellite System (TDRSS) is a network of communications satellites (each called a Tracking and Data Relay Satellite or TDRS) used by NASA and other United States government agencies. Initial satellites were built by TRW, later versions have been put together by Boeing's Satellite Systems division. 10 satellites have been launched.The first TDRS was launched in 1983 on the Space Shuttle Challenger's first flight, STS-6. The second was lost on the Challenger's 10th mission when it was destroyed with the Challenger shortly after liftoff on STS-51-L in 1986. The next five were launched on other shuttles. Three Boeing-built successors were launched on Atlas rockets in 2000 and 2002.
Communications satellites
