On February 1, 2003, the Space Shuttle Columbia disintegrated upon reentering Earth's atmosphere, killing all seven crew members. The disaster was the second fatal accident in the Space Shuttle program after Space Shuttle Challenger, which broke apart and killed the seven-member crew 73 seconds after liftoff in 1986.
During the launch of STS-107, Columbia's 28th mission, a piece of foam insulation broke off from the Space Shuttle external tank and struck the left wing of the orbiter. A few previous shuttle launches had seen damage ranging from minor to major from foam shedding, but some engineers suspected that the damage to Columbia was more serious. NASA managers limited the investigation, reasoning that the crew could not have fixed the problem if it had been confirmed. When Columbia re-entered the atmosphere of Earth, the damage allowed hot atmospheric gases to penetrate the heat shield and destroy the internal wing structure, which caused the spacecraft 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 put on hold; the station relied entirely on the Russian Roscosmos State Corporation for resupply for 29 months until Shuttle flights resumed with STS-114 and 41 months for crew rotation until STS-121.
Several technical and organizational changes were made, including adding a thorough on-orbit inspection to determine how well the shuttle's thermal protection system had endured the ascent, and keeping a designated rescue mission ready in case irreparable damage was found. Except for one final mission to repair the Hubble Space Telescope, subsequent shuttle missions were flown only to the ISS so that the crew could use it as a haven in case damage to the orbiter prevented safe reentry.