Which of America's Space Shuttles have met tragic endings?

Columbia and Challenger

The Space Shuttle Challenger broke apart 73 seconds into its tenth mission on January 28, 1986. All seven crew members on board were killed including American school teacher Christa McAuliffe.

The Space Shuttle Columbia was destroyed on February 1, 2003. The shuttle broke apart while re-entering the Earth's atmosphere after a 16-day mission, killing all seven crew members aboard.