As the Space Shuttle ascends to orbit it traverses various intact abort regions evaluated and planned before the flight to assure that in the event of ascent failure, the Space Shuttle Orbiter, along with its crew, are safely returned. The primary Space Shuttle intact abort modes are Return to Launch Site (RTLS), Trans-Atlantic Landing (TAL), and Abort to Orbit (ATO). Different intact abort options are available and chosen depending on the time of failure. The most likely failure to initiate an abort is the shutdown of a single Space Shuttle Main Engine (SSME).

It is possible that during an intact...