Space Shuttle Shuttle orbiter fleet. Sources: NASA launch manifest, NASA Space Shuttle archive On January 28, 1986, "Challenger" disintegrated 73 seconds after launch due to the failure of the right SRB, killing all seven astronauts on board. The disaster was caused by low-temperature impairment of an O-ring, a mission critical seal used between segments of the SRB casing. Failure of the O-ring allowed hot combustion gases to escape from between the booster sections and burn through the adjacent external tank, causing it to explode. Repeated warnings from design engineers voicing concerns about the lack of evidence of the O-rings' safety when the
Space Shuttle in a September 1969 report of a Space Task Group headed by Vice President Spiro Agnew to President Richard Nixon. Nixon's post-Apollo NASA budgeting withdrew support of all system components except the Shuttle, to which NASA applied the STS name. The vehicle consisted of a spaceplane for orbit and re-entry, fueled from an expendable External Tank containing liquid hydrogen and liquid oxygen, with two reusable strap-on solid rocket boosters. The first of four orbital test flights occurred in 1981, leading to operational flights beginning in 1982, all launched from the Kennedy Space Center, Florida. The system was retired from service