Replacing the Space Shuttle

摘要

In the lifetime of the present Space Shuttle there have been few serious attempts to develop a replacement. The first such attempt was Lockheed Martin's VentureStar with its ill-fated X-33 technology demonstrator. The X-33 was cancelled when it proved too difficult to build and the full scale VentureStar never progressed beyond a few pretty computer graphics. A number of advanced technologies were demonstrated on small air-dropped vehicles and the X-38 prototype Crew Return Vehicle made a number of successful landings at Edwards Air force Base, California, before it was cancelled in 2001, along with the Crew Habitation Module, in an attempt to bring the International Space Station (ISS) budget under control.