Screw the pooch does, indeed, come from pre-apollo days. But it doesnt have anything
to do with a sexual act. It merely means that by some mistake on the part of an
engineer or a pilot, he has inadvertantly doomed a mission to failure. In the early space race, we sent dogs into space to test suits, environment materials, etc. If one of the
engineers 'screwed the pooch', it meant that his experiment or calculations failed, and
that he has 'doomed the dog to death'. I think the military jumped on it and turned the
expression into something more vulgar. In the end, it does just equate to a FAIL.