This TRS spacecraft is illustrated being used to re-boost the Skylab space station to a higher orbit. An early Space Shuttle flight would have boosted Skylab to a higher orbit, adding five years of operational life. The TRS (which was on contract with Martin Marietta for $26 million) contained about three tons of propellant, remote-control capabilities with TV cameras and was designed for duties such as space construction and servicing and retrieving satellites the shuttle could not reach. After rescuing Skylab, the TRS would have remained in orbit for future use. Alternatively, it could have been used to de-orbit Skylab for a safe, controlled re-entry and destruction.
However, development of the Shuttle was delayed, and Skylab reentered Earth’s atmosphere and disintegrated in 1979, with debris striking portions of Western Australia.