A configuration of nine satellites launched into geosynchronous orbit by NASA to track other spacecraft in low Earth orbits and relay their communications. The first generation series was TDRS-A, launched in 1983. The first of the second-generation satellites was TDRS-H launched in 2000. The first of the third generation series was TDRS-K launched in 2013, and TDRS-M launched in August 2017. Once it is accepted into the Space Network in early 2018, the TDRS configuration will grow to include 10 in-orbit satellites.

The current configuration is four first-generation, three second-generation, and two third-generation satellites, distributed to provide near-continuous information relay service to missions such as the Hubble Space Telescope and the International Space Station.

Each TDRS weighs 2 270 kg and measures 17.4 m from the edges of the opposite solar panels. One TDRS was lost in the Challenger space shuttle disaster in 1986. The satellites are part of the Tracking and Data-Relay Satellite System (TDRSS) that includes ground stations. Each TDRS is controlled from the White Sands Test Facility in New Mexico by the Mission Operations and Data Systems Directorate of the Goddard Space Flight Center.