TDRS-B was an American communications satellite, of first generation, which was to have formed part of the Tracking and Data Relay Satellite System. It was destroyed in 1986 when the disintegrated 73 seconds after launch.
Launch
TDRS-B was launched in the payload bay of Challenger, attached to an Inertial Upper Stage (IUS). It was to have been deployed from the Shuttle in low Earth orbit. The IUS would have then performed two burns to raise the satellite into a geosynchronous orbit. On the previous TDRS launch, TDRS-1, the IUS second-stage motor malfunctioned following the first-stage burn, resulting in a loss of control, and delivery of the satellite into an incorrect orbit.
Launch failed
TDRS-B was originally scheduled for launch on STS-12 in March 1984; however, it was delayed and the flight cancelled following the IUS failure on TDRS-1.[2] It was later re-manifested on STS-51-E; however, this too was cancelled due to concerns over the reliability of the IUS. It was eventually assigned to