STS-33R & (USA-48)

During the mission, Discovery deployed a single satellite, USA-48 (NSSDC ID 1989-090B). Experts believe that this was a secret Magnum ELINT (ELectronic INTtelligence) satellite headed for geosynchronous orbit, similar to that launched by STS-51-C in 1985, making this mission essentially a duplicate of that earlier mission.

The Magnum / Orion satellites are geostationary signals intelligence satellites, which replaced the Rhyolite / Aquacade series. Their purpose was to intercept missile telemetry from the Soviet Union and China. Originally developed under the codename Magnum, their name was replaced by Orion (RIO) before the first launch.