This artist's rendering depicts the McDonnell Douglas X-33 proposal for a technology demonstrator of a Single-Stage-To-Orbit (SSTO) Reusable Launch Vehicle (RLV). McDonnell Douglas submitted a vertical landing configuration design which used liquid oxygen/hydrogen bell engines. NASA considered design submissions from Rockwell, Lockheed Martin, and McDonnell Douglas. NASA selected Lockheed Martin's design on 2 July 1996. NASA's Dryden Flight research Center, Edwards, California, expected to play a key role in the development and flight testing of the X-33. The RLV technology program was a cooperative agreement between NASA and industry. The goal of the RLV technology program was to enable significant reductions in the cost of access to space, and to promote the creation and delivery of new space services and other activities that was to have improved U.S. economic competitiveness. The X-33 was a wedged-shaped subscale technology demonstrator prototype of a potential future Reusable Launch Vehicle (RLV) that Lockheed Martin had dubbed VentureStar. The company had hoped to develop VentureStar early this century. Through demonstration flight and ground research, NASA's X-33 program was to have provided the information needed for industry representatives such as Lockheed Martin to decide whether to proceed with the development of a full-scale, commercial RLV program. A full-scale, single-stage-to-orbit RLV was to have dramatically increased reliability and lowered the costs of putting a pound of payload into space, from the current figure of $10,000 to $1,000. Reducing the cost associated with transporting payloads in Low Earth Orbit (LEO) by using a commercial RLV was to have created new opportunities for space access and significantly improved U.S. economic competitiveness in the world-wide launch marketplace. NASA expected to be a customer, not the operator, of the commercial RLV. The X-33 design was based on a lifting body shape with two revolutionary "linear aerospike" rocket engines and a rugged metallic thermal protection system. The vehicle also had lightweight components and fuel tanks built to conform to the vehicle's outer shape. Time between X-33 flights was normally to have been seven days, but the program hoped to demonstrate a two-day turnaround between flights during the flight-test phase of the program. The X-33 was to have been an unpiloted vehicle that took off vertically like a rocket and landed horizontally like an airplane. It was to have reached altitudes of up to 50 miles and high hypersonic speeds. The X-33 program was managed by the Marshall Space Flight Center and was to have been launched at a special launch site on Edwards Air Force Base. Due to technical problems with the liquid hydrogen fuel tanks, and the resulting cost increase and time delay, the X-33 program was cancelled in February 2001.
