NASA is to stop funding the X-33 and X-34 reusable launch vehicle (RLV) technology demonstration programmes. The efforts will end without either vehicle having flown.

Neither programme has been selected for NASA's $4.5 billion Space Launch Initiative (SLI) to support commercial development of second-generation RLVs to eventually replace the Space Shuttle. The first contracts under SLI are expected to be awarded next month.

NASA says the benefits to be derived from flight testing the X-33 and X-34 did not warrant the heavy investment required. Both the programmes got under way in 1996 and experienced considerable cost overruns and technical delays.

The co-operative agreement between NASA and Lockheed Martin on the X-33 single-stage-to-orbit RLV technology demonstrator expires on 31 March. NASA funding for the project totals $912 million, while industry investment has increased from the original plan costing $212 million to over $350 million.

The ambitious programme to flight test a subscale, suborbital prototype of Lockheed Martin's proposed VentureStar single-stage-to-orbit RLV came unstuck in November 1999, when the X-33's composite liquid hydrogen tank failed during testing. The company proposed completing the X-33 with aluminium fuel tanks, but a first flight was delayed from 2000 to 2003.

NASA has allowed Lockheed Martin to compete for SLI funding to fly the X-33, but says the benefits of flight testing the vehicle did not jusify the cost.

The decision to end the X-34 programme with Orbital Sciences was taken after a review revealed that the cost of completing the project at acceptable risk had risen significantly above the planned budget of $205 million.

Source: Flight International