The concept behind the Tracking and Data Relay Satellite (TDRS) was born out of NASA's effort to rely less on international ground stations and create long-duration and widely available space communication coverage. Using ground-based communications systems, spacecraft could only connect with antennas on Earth for about 15 minutes per connection, at set times in their orbits. A space-based network provides continuous communications services and increases the amount of data that can be received from NASA's critical low-Earth-orbiting missions.
Established in 1973 at Goddard Space Flight Center, the TDRS project launched its first spacecraft in 1983 on the Space Shuttle Challenger (STS-6), and the remaining first-generation TDRS spacecraft by 1995. The second generation of TDRS satellites (TDRS H, I, and J) were built by Hughes (now Boeing) in El Segundo, California, in the late 1990s through early 2000. The contract to develop the third generation of TDRS was awarded to Boeing in December 2007. The primary difference between the second and third generations is the shift from on-orbit beamforming of the S-band multiple access return services to ground-based beamforming (GBBF) (a return to the first generation architecture). The final spacecraft of the third generation will launch in August 2017, ensuring TDRS’s continued reliability for the future. In total, three generations consisting of 12 spacecraft will have joined the TDRSS constellation.