 Complete the following phrase:  The Shuttle was originally billed as a space vehicle that would be able to launch once a week and give low launch 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 