The Space Shuttle program or officially the Space Transportation System (STS) is the current US manned space program administered by NASA. The first flight designated STS-1 launched aboard Columbia on April 12, 1981 and landed April 14, 1981. Six operational oribiters have been built (listed in the order of construction): Enterprise, which was the first space shuttle built that was air-worthy, but not space-worthy, Columbia, Challenger, Discovery, Atlantis, and Endeavour. In 1986 the program was suspended, as the Space Shuttle Challenger disintegrated 73 seconds after launch, causing loss of orbiter and crew. The mission was widely covered by the media due to the presence of S. Christa McAuliffe, as part of NASA's Teacher in Space program. A faulty O-Ring seal was determined to be the caus