TO THE BACK

Development difficulties and laggard component deliveries have sent costs on the X-37 testbed so far out of bounds this year that NASA has directed prime contractor Boeing to "deemphasize" the orbital variant of the reusable space plane, and concentrate instead on drop tests and advanced technology.

As a result, plans to launch the winged vehicle on an Atlas V or Delta IV in 2006 are on hold. A series of drop tests from NASA's B-52H carrier aircraft remains on track to begin in November 2004, according to Dan Dumbacher, NASA's X-37 project manager. Work will also continue on wing leading edges, lithium ion batteries, carbon-carbon and carbon silicon carbide hot structures, and other advanced technology for the orbital vehicle.

THE ACTION COMES as a mismatch grows between X-37 program goals and NASA's evolving space-access requirements. Even before the X-37 program office at Marshall Space Flight Center in Alabama, formally redirected work under Boeing's $301-million contract in a Nov. 24 letter, program officials were shopping in Washington for new missions and trying to drum up extra money to pay for them.

Originally part of NASA's old Space Launch Initiative (SLI), which aimed to develop a fully reusable follow-on to the space shuttle, X-37 was intended to demonstrate the technology needed for a reusable space plane that would carry humans to orbit atop a reusable booster. The booster portion of SLI has already been deemphasized in favor of what is now called the Orbital Space Plane, which in turn is beginning to look less like a reusable plane than a throwaway capsule and has serious long-term funding issues of its own.