Overview:At the end of a nearly flawless 15-day mission in early 2003, the Space Shuttle Columbia disintegrated during reentry into Earth's atmosphere, killing the crew of seven men and women. In this documentary, NOVA probes the accident and the decisions stretching back four decades that made the tragedy almost inevitable. It offers a penetrating look at the history of the shuttle program and the political pressures that made the shuttle a highly complex engineering compromise, which fell short of its ambitious goal to make space travel routine, cheap, and safe.