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 program contractor for the program was North American Rockwell (later Rockwell International, now Boeing), the same company responsible for building the Apollo Command/Service Module. The contractor for the Space Shuttle Solid Rocket Boosters was Morton Thiokol (now part of Northrop Grumman Innovation Systems), for the external tank, Martin Marietta (now Lockheed Martin), and for the Space Shuttle main engines, Rocketdyne (now Aerojet Rocketdyne). The first orbiter was originally planned to be named "Constitution", but a massive write-in campaign from fans of the "Star Trek" television series convinced the White House to change the name to "Enterprise". Amid great fanfare, "Enterprise" (designated