Space Shuttle It weighed 3.4 metric tons (7,500 lb) less than the last run of lightweight tanks, allowing the Shuttle to deliver heavy elements to ISS's high inclination orbit. As the Shuttle was always operated with a crew, each of these improvements was first flown on operational mission flights. The solid rocket boosters underwent improvements as well. Design engineers added a third O-ring seal to the joints between the segments after the 1986 Space Shuttle "Challenger" disaster. Several other SRB improvements were planned to improve performance and safety, but never came to be. These culminated in the considerably simpler, lower cost, probably
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