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 Mission 2007 Space Shuttle guiding the user through the mission. Extra-vehicular activities are conducted in first-person view allowing the user to experience the same feeling as astronauts do while "space walking". In certain missions, the virtual astronauts will also drive the Manned Maneuvering Unit to capture satellites for maintenance. The latest mission add-on is the STS-47 Spacelab mission. In this mission, the user can visit the Spacelab-J and float inside the lab in Zero-G just like real astronauts. Space Shuttle Mission 2007 Space Shuttle Mission 2007, is a highly realistic Space Shuttle stand-alone mission simulator for Microsoft Windows. The simulator was released