The document summarizes key details about three Space Shuttles - Challenger, Endeavor, and Columbia. It describes how Challenger exploded shortly after launch in 1986 due to an O-ring failure. It details how Endeavor successfully repaired the Hubble Space Telescope in 1993 over five spacewalks. It also outlines how Columbia disintegrated during reentry in 2003 after launch damage to its heat tiles was sustained during liftoff.