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 cost around $450 million. Roger A. Pielke, Jr. has estimated that the Space Shuttle program cost about US$170 billion (2008 dollars) through early 2008; the average cost per flight was about US$1.5 billion. Two missions were paid for by Germany, Spacelab D1 and D2 (D for "Deutschland") with a payload control center in Oberpfaffenhofen. D1 was the first time that control of a manned STS mission payload was not in U.S. hands. At times, the orbiter itself was referred to as the Space Shuttle. This was not technically correct as the "Space Shuttle" was the combination of the orbiter, the