Two space shuttles were lost in missions: Challenger (STS-51-L) in 1986 and Columbia (STS-107) in 2003, with 14 astronauts total lost across the two disasters. Challenger exploded 73 seconds after liftoff, and Columbia disintegrated during re-entry after damage from foam insulation on the left wing. NASA suspended shuttle flights after both events and the fleet was retired after completing the International Space Station program.