The Air Force announced Sept. 7 it will not assume program management and funding responsibility for the NASA X-33 or continue funding beyond September 2002 for the NASA X-37 experimental demonstration programs.

In March, NASA allowed the X-33 cooperative agreement with the contractor to expire and deferred work on the X-37.

Both the X-33 and the X-37 are unmanned aerial vehicles. The X-33 was designed as a technology demonstrator and a possible next step toward a replacement for the aging space shuttle system.

The X-37 is a prototype of a reusable, flexible spacecraft that can be launched into space by another vehicle, maneuver using its own engine, and then re-enter the atmosphere and land. The Air Force, with the assistance of NASA and the National Reconnaissance Office, conducted a 60-day study of the military utility of the X-33 and X-37 programs.

Both programs have made significant contributions toward understanding performance, cost and integration issues, and have provided valuable information on the dynamics of launching space vehicles.

However, the Air Force assessed these programs against desired military space plane performance requirements. Air Force officials determined neither of these programs provide a level of military utility needed to continue development and funding by the Air Force. Responsive spacelift is a critical capability to support future military operations in space.

The Air Force will continue to pursue the integration of space technology assets with NASA, working to define the future for reusable launch vehicles and develop a national approach for our vision of space operations, officials said.