GoKawiilSTS-51-F mission's first launch attempt aborted seconds before ignition
On July 12, 1985, the launch of the Space Shuttle STS-51-F was halted at T−3 seconds due to a coolant valve malfunction in engine number two, leading to an automatic abort. The shuttle successfully launched on its second attempt on July 29, 1985, after a delay caused by uplink issues, but experienced an in-flight engine sensor failure that resulted in a lower-than-planned orbit. This was the only RS-25 engine failure during the shuttle program's operational history.