- The Washington Times - Thursday, May 12, 2011

Pentagon scientists say they have discovered what went wrong with last year’s test flight of an experimental unmanned space plane, which self-destructed after the autopilot lost control.

“They think they’ve got a solution,” said Mark J. Lewis, a professor at the University of Maryland and a member of the Air Force Scientific Advisory Board.

The board was recently briefed on the $308 million space-plane program by officials from the Defense Advanced Research Projects Agency (DARPA), the Pentagon’s cutting-edge, high-tech development office.

“The good news is, they can fix the problem by changing the trajectory, not the vehicle,” Mr. Lewis told The Washington Times, explaining that DARPA scientists concluded that they could avoid problems on future tests by changing the angle of flight.


“They’ve done a very thorough analysis,” he said.

The news means that the space plane, known as the Falcon Hypersonic Test Vehicle-2 (HTV-2), is cleared for a second test flight this year, Mr. Lewis said.

The Falcon is launched atop a Minotour rocket - adapted from a ballistic missile. In the outer reaches of the atmosphere, the vehicle is released and then glides back to earth at a speed of more than 13,000 miles an hour - more than 20 times the speed of sound.

The space plane is a key element of a Pentagon program to build non-nuclear strategic weapons that can strike anywhere in the world in less than an hour.

Supporters say the program will address novel threats - like terrorists with nuclear weapons - and help reduce U.S. reliance on nuclear weapons as a strategic option in more conventional conflicts.

Arms-control advocates fret about the impact of the new generation of such weapons. Congressional opposition killed a previous proposal to achieve a similar result by fitting conventional warheads to U.S. submarine-launched ballistic missiles.

Opponents feared that other nuclear-armed nations might mistake the launch of such a weapon for the onset of a nuclear war.

An independent engineering review board found that the Falcon’s first test flight last year ended when the computer autopilot flying the futuristic superweapon “commanded flight termination.”

The system is designed to crash the Falcon into the ocean if it loses control, which it did last year after the vehicle began to roll so violently that it “exceeded the available control capability” of the autopilot, according to a Pentagon statement at the time.

Mr. Lewis said “there is much we still don’t understand about the physics” of how vehicles behave at such very high speeds. The Falcon team had made some assumptions about the way the vehicle would fly that “in retrospect turned out to be reasonable but wrong.”