A hypersonic glider launched by the U.S. military was lost in flight, the second straight mishap crippling the Pentagon's desire to develop a strategic weapon to deliver conventional munitions anywhere in the world in less than an hour, Spaceflight Now reported Thursday.

After a successful launch aboard a Minotaur 4 rocket, the arrowhead-shaped Hypersonic Test Vehicle 2 separated and transitioned to aerodynamic flight at a speed of Mach 20, according to the Defense Advanced Research Projects Agency, or DARPA.

The military said they collected more than nine minutes of data before an anomaly caused a loss of signal from the hypersonic glider. Ships, aircraft and other tracking assets were in place to receive communications from the high-speed vehicle.

Liftoff occurred at 7:45 a.m. Pacific time (10:45 a.m. EDT; 1445 GMT) from Vandenberg Air Force Base, Calif. It used a three-stage version of the Minotaur 4 rocket, which is powered by retired Peacekeeper missile motors.

The flight should have lasted more than a half-hour before impacting the Pacific Ocean near the U.S. Army's Reagan Test Site at Kwajalein Atoll in the Marshall Islands. Initial indications are the aircraft struck the Pacific Ocean along the planned flight path, according to DARPA.

A nearly identical test vehicle launched in April 2010 also ended prematurely after the craft lost control. Engineers adjusted the second HTV's center of gravity, modifed its angle of attack, and designed it to use thruster jets to help the vehicle control itself.

"We know how to boost the aircraft to near space. We know how to insert the aircraft into atmospheric hypersonic flight," said Air Force Maj. Chris Schulz, DARPA's HTV 2 program manager. "We do not yet know how to achieve the desired control during the aerodynamic phase of flight. It's vexing; I'm confident there is a solution. We have to find it."

After being released from the Minotaur's third stage, the glider was supposed to orient itself for entry back into Earth's atmosphere, then pull up to begin a long-distance glide toward an impact site in the Pacific Ocean.