Two NASA Space Shuttles were lost during the program: Challenger in 1986 and Columbia in 2003, with a total of 14 astronauts killed in the two disasters.

Quick answer

  • Number of NASA Space Shuttles lost: 2.
  • Names: Challenger (OV‑099) and Columbia (OV‑102).
  • Total astronauts lost: 14 (7 on each mission).

What happened to Challenger?

  • On January 28, 1986, Challenger broke apart 73 seconds after liftoff on mission STS‑51‑L, killing all seven crew members.
  • The immediate cause was a failure of rubber O‑rings in a solid rocket booster joint in unusually cold weather, allowing hot gases to escape and destroy the vehicle.

What happened to Columbia?

  • On February 1, 2003, Columbia disintegrated during reentry at the end of mission STS‑107, again killing all seven astronauts on board.
  • A piece of insulating foam from the external tank had struck and damaged the left wing at launch, letting superheated gases enter the wing on reentry and leading to structural failure.

Context in the Shuttle program

  • Across 135 Space Shuttle missions (1981–2011), these two losses represent the program’s catastrophic failures in flight.
  • The disasters led to lengthy stand‑downs, major design and management changes, and ultimately shaped the decision to retire the Shuttle and move toward newer spacecraft designs.

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