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 been canceled. in the 2010s, two major programs for human spaceflight were Commercial Crew Development and the Space Launch System with the Orion capsule. Kennedy Space Center Launch Complex 39 was, for example, used to launch a Falcon Heavy rocket. The Space Shuttle program has been criticized for failing to achieve its promised cost and utility goals, as well as design, cost, management, and safety issues. Others have argued that the Shuttle program was a step backwards from the Apollo Program, which, while extremely dangerous, accomplished far more scientific and space exploration endeavors than the Shuttle ever could. After both