A critical design review of the proposed VentureStar reusable launch vehicle, based on the Lockheed Martin X-33 advanced technology demonstrator, will take place this month.

Work on the X-33 has convinced Lockheed Martin that the VentureStar will use an external payload bay, says Jerry Rising, Lockheed Martin's X-33 and VentureStar Skunk Works chief. The external canister configuration is in windtunnel testing.

By housing the 16m (50ft)-long 5m-diameter payload bay externally, Lockheed Martin can package the lightweight fuel tanks and other internal systems more efficiently. The design of the payload bay, slightly smaller than the Space Shuttle's, could be flexible to accommodate different types of payload. The bay would be protected during re-entry by being on the leeward side of the spacecraft.

The VentureStar will also be able to ferry the X-38 International Space Station (ISS) lifeboat lifting body to the ISS. At a recent Congressional hearing in Washington, NASA future launcher programme chief Gary Payton said that the earliest the Space Shuttle fleet could be complemented by the VentureStar would be 2008, but is more likely to be 2012.

If the VentureStar were developed by Lockheed Martin, NASA would not use it until it had flown at least 17 return trips to orbit and, even then, there would be several years of transition.

Lockheed Martin aims to roll out the first X-33 Advanced Technology Demonstrator vehicle in the first quarter of next year, the company says, adding that preparations for the crucial testing of the vehicle's aerospike engine and liquid hydrogen tank are going well.

Lockheed Martin says 90% of the vehicle software has been integrated and the avionics bay is in place. Oxygen tank tests will start next month.

Payton says, however, that the first flight is likely to be postponed from next July because of delays in delivering other hardware.

Source: Flight International