WASHINGTON — The U.S. Air Force on April 22 launched a winged spacecraft designed to conduct military experiments on orbit for as long as nine months before re-entering the atmosphere and gliding to a runway landing in California.

The service hopes the unmanned X-37B Orbital Test Vehicle will pave the way for a cost-effective, reusable spacecraft platform that can be reconfigured on the ground and relaunched in just a few weeks, Gary Payton, undersecretary of the Air Force for space programs, said April 20 during a media teleconference. But because the X-37B’s  specific experiments are classified, as is its budget, much about the mission remains unknown.

NASA started the X-37 program as an experimental space-access technology demonstrator  in 1999. The agency made several atmospheric flight tests with a smaller version of the craft dubbed the X-40A before it transferred the program to the Defense Advanced Research Projects Agency in 2004. NASA never built an orbital version of the X-37, but the design was picked up by the Air Force’s Rapid Capabilities Office, which contracted with Boeing Phantom Works of El Segundo, Calif., to build two vehicles.

The first X-37B spacecraft was lifted to low Earth orbit aboard an Atlas 5 rocket with a 5-meter-diameter faring out of Cape Canaveral Air Force Station, Fla. The 8.9-meter-long vehicle has a payload bay similar to the one on the space shuttle that can accommodate a pair of satellites weighing several hundred kilograms each, Payton said. 

This particular model does not have a capture arm like the space shuttle and is not designed to approach or retrieve spacecraft already on orbit, Payton said. Rather, the first flight of the X-37B seeks to demonstrate autonomous on-orbit operations, re-entry and maneuvers through the atmosphere and a controlled landing at Vandenberg Air Force Base, Calif. The other important aspect of this mission is to validate if the spacecraft is robust enough to be reused without too much refurbishment and repair on the ground, he said.

“The top priority is an inexpensive turnaround,” Payton said. “[Does it need] a lot of tile replacement? A lot of servicing? If that’s the case, it makes this sort of vehicle less attractive to us in the future.”

While the X-37B is designed to stay on orbit for as many as 270 days, the Air Force says the length of time needed to complete its missions will determine when commands are sent to the spacecraft to deorbit itself. The military has long used the space shuttle as an experiments platform, but those missions last only about two weeks and the shuttle is set to be retired soon, Payton noted.

Once the X-37B spacecraft returns to Earth, lessons learned from the first flight will be applied for the flight of the second craft, currently scheduled for 2011, Payton said. While no decision has been made to pursue an operational space maneuvering vehicle, Payton said he can envision using such craft in “kind of like an operationally responsive space scenario” where one is launched for one mission, returns to Earth and is quickly redeployed either with a different payload or to a different orbit.

“The Orbital Test Vehicle combines the best of aircraft and spacecraft to enable flexible and responsive missions,” Paul Rusnock, Boeing’s vice president of experimental systems and X-37B program director, said in an April 22 press release. “This first flight will demonstrate the readiness of the X-37B to begin serving the Air Force as it continues to investigate ways to make space access more routine, affordable and responsive.”

Space vehicles designed to re-enter the atmosphere with precision could potentially be used to deliver weapons, but Payton was quick to dismiss the notion.

“I don’t know how this could be called weaponization of space,” Payton said. “Fundamentally it’s just an updated version of the space shuttle kind of activities in space. We, the Air Force, have a suite of military missions in space, and this new vehicle could potentially help us do those missions better.”

The X-37B spacecraft would not be effective as a weapon for a number of reasons, said Brian Weeden, technical advisor at the Secure World Foundation, a group that promotes peaceful uses of space. The U.S. military is seeking to develop a conventional weapons capability known as Prompt Global Strike that can deliver munitions to anywhere on the Earth within an hour. But an orbiting space maneuver vehicle would not pass over likely target areas with sufficient frequency to serve as a quick-strike weapon, unless a dozen or so craft are on orbit at once, Weeden said. And given that, like the space shuttle, it would descend slowly on a very straight path from its orbital trajectory, such a vehicle would be a sitting duck for air defenses, he said.

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