On February 1, 2003, the Space Shuttle Columbia disintegrated as it reentered the atmosphere over Texas and Louisiana, killing all seven astronauts on board. The disaster occurred because during the launch, a piece of insulating foam broke off from the external propellant tank and hit the left wing of the shuttle, causing damage that allowed hot atmospheric gases to penetrate the heat shield and destroy the internal wing structure. When Columbia reentered the atmosphere of Earth, the damage allowed hot atmospheric gases to penetrate the heat shield and destroy the internal wing structure, which caused the orbiter to become unstable and break apart. After the disaster, Space Shuttle flight operations were suspended for more than two years, as they had been after the Challenger disaster. Construction of the International Space Station (ISS) was paused until flights resumed in July 2005 with STS-114. The Columbia disaster directly led to the retirement of the space shuttle fleet in 2011.