It was developed to potentially re-boost the Skylab space station to a higher orbit.
[3] A remotely controlled booster rocket was to be carried up in the Space Shuttle's third mission.
Astronaut Jack R. Lousma described the remote booster as "as big as a truck" and requiring a control system able to match the circular motion of the Skylab docking port.
It had a 24 nozzle 6-axis control thruster system to support Space rendezvous, docking, and orienting the spacecraft.
In addition, another reason for its selection was the long-term use for task in general including "payload survey, stabilization, retrieval and delivery missions, recovery and re-use capability.."[2] The TRS project was overseen by the NASA Marshall Spaceflight Center.
[5] Lousma and Haise's mission was canceled when NASA realized that STS-1 would not be early enough before the station's reentry.