GETTING THROUGH THE ATMOSPHERE Abort modes

By carrying out its Moon programme in the full glare of world publicity, NASA had been bound to do its best to ensure the safety of the crew. This was not to be the world of the test pilot from which most of the astronauts had come – a world where a great many gifted pilots died in obscurity at remote bases, wringing out the problems from capricious new aircraft for the military. The prestige of the Apollo programme. NASA and, indeed, of the United States, could not afford the public loss of a crew whose persona had been built up in the media during the weeks leading up to the launch. NASA’s leaders decided that, as far as could be envisioned, there should be no part of the flight where a single failure was not survivablc.

This policy was aggressively pursued during the incredibly dynamic ascent from Earth when prodigious amounts of carefully directed energy were expended from an assemblage of tanks filled with volatile fuel that pushed through the atmosphere at increasingly high speeds. There were so many things that could go wrong; and in the lower levels of the atmosphere, things could go wrong very quickly. Of particular concern was the possibility that engines might fail, especially during the first few moments of flight vehen the Saturn needed all five F-ls to w’ork just to get off the ground. Lor years, the mission planning team analysed and argued over the details of the ascent and eventually broke it down into sections. For each section, they defined an abort mode’ or appropriate get-out-of-there-quick plan that would whisk the crew away from an errant rocket to safety, to continue the flight into orbit if possible or to splash into the sea if not. To assist in these rescue scenarios, the tip of the command module sprouted the launch escape system (LES) with its powerful rocket, the LET, to pull the crew clear of the Saturn V. For each abort mode, the crew and equipment veere poised to react in a certain way in the event of a launch vehicle failure.