Criticism of the Space Shuttle program costs through amortization. Development costs were expected to be recouped through frequent access to space. These claims were made in an effort to obtain budgetary funding from the United States Congress. Beginning in 1981, the space shuttle began to be used for space travel. However, by the mid-1980s the concept of flying that many shuttle missions proved unrealistic and scheduled launch expectations were reduced 50%. Following the "Challenger" accident in 1986, missions were halted pending safety review. This hiatus became lengthy and ultimately lasted almost three years as arguments over funding and the safety of the program continued. Eventually 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