Together the five orbiters Columbia, Challenger, Discovery, Atlantis, and Endeavour have flown a total of 133 successful missions, an unequaled accomplishment of engineering, management, and political savvy. But it's the two disasters that people remember, that most shape the shuttle's story. The lovely dream of spaceflight I grew up with is marred by the images of Challenger and Columbia breaking apart in the sky, the lost astronauts smiling on hopefully in their portraits, oblivious. Some people took the disasters to mean the entire space program had been a lie, that the dream itself was tainted with our fallibility. But even as a child, I knew it was more complex than that. If we want to see people take risks, we have to be prepared to sometimes see them fail. The story of American spaceflight is a story with many endings, a story of how we have weighed our achievements against our failures.
~ Margaret Lazarus Dean