STS-55 Columbia, Orbiter Vehicle (OV) 102, SSME abort at KSC LC Pad 39A

S93-31601 (March 1993) --- The second Space Shuttle launch attempt of 1993 comes to an abrupt halt when one of the three main engines on the orbiter Columbia shuts down at T -3 seconds, resulting in an on-the-pad abort of Mission STS-55. This was the first time in the post-Challenger era that a main engine shutdown has halted a Shuttle launch countdown, and only the third time in the history of the program. In 1984, STS-41D was scrubbed at T -4 seconds when the orbiter General Purpose Computer detected an anomaly in a main engine, and in 1985, STS-51F was halted at T -3 seconds due to a main engine malfunction that caused shutdown of all three engines. Columbia had been scheduled to lift off from Launch Pad 39B is the Space Shuttle Discovery, undergoing preparations for lift off on Mission STS-56.