In the mid-1990s, NASA launched a competition for the design and development of a successor to the Space Shuttle. The competitors were McDonnell-Douglas and Lockheed Martin. The competition phase included concepts and costs for the ground infrastructure for pre-flight and post-flight operations, including launchpads (below left) and maintenance hangars. This project developed concepts to support the McDonnell-Douglas proposal. The company proposed a vertical take-off and landing vehicle named the X-33 based on an experimental predecessor named the Delta Clipper that it had developed and successfully tested in the early-1990s. Shown below are two versions of the X-33 hangar structure in blue. On the left, internal work platforms in red on either side of the vehicle are in the raised positions. On the right they are lowered. Lockheed-Martin won the competition with a vehicle named VENTURESTAR but technical failures led NASA to abandon the project in 2001.