Space Shuttle Challenger disaster cause to the accident. After the accident, NASA attempted to aim at a more realistic shuttle flight rate: it added another orbiter, "Endeavour", to the space shuttle fleet to replace "Challenger", and it worked with the Department of Defense to put more satellites in orbit using expendable launch vehicles rather than the shuttle. In August 1986, President Reagan also announced that the shuttle would no longer carry commercial satellite payloads. After a 32-month hiatus, the next shuttle mission, STS-26, was launched on September 29, 1988. Although changes were made by NASA after the "Challenger" accident, many commentators have argued that
Space Shuttle retirement and then be replaced by a new vehicle. When the concept of the U.S. space station evolved into that of the International Space Station, which suffered from long delays and design changes before it could be completed, the service life of the Space Shuttle was extended several times until 2011 when it was finally retired. In 2010 the Shuttle was formally scheduled for retirement with "Atlantis" being taken out of service first after STS-132 in May of that year, but the program was once again extended when the two final planned missions were delayed until 2011. Later, one additional mission