In this undated artist's rendition released by the Defense Advanced Research Projects 

In this undated artist's rendition released by the Defense Advanced Research Projects Agency (DARPA) showing the Falcon Hypersonic Technology Vehicle 2 (HTV-2) separating from the rocket. The Falcon HTV-2 is an unmanned, rocket-launched, maneuverable aircraft that glides through the Earth’s atmosphere at incredibly fast speeds, Mach 20 (approximately 13,000 miles per hour). The hypersonic glider is scheduled for launch atop a Minotaur rocket on Wednesday Aug.10,2011 from Vandenberg Air Force Base, Calif.  The Hypersonic Test Vehicle-2 is an experiment in extremely high speed flight technologies by the U.S. Defense Advanced Research Projects Agency. (AP Photo/DARPA)
Associated Press
In this undated artist's rendition released by the Defense Advanced Research Projects Agency (DARPA) showing the Falcon Hypersonic Technology Vehicle 2 (HTV-2) separating from the rocket. The Falcon HTV-2 is an unmanned, rocket-launched, maneuverable aircraft that glides through the Earth’s atmosphere at incredibly fast speeds, Mach 20 (approximately 13,000 miles per hour). The hypersonic glider is scheduled for launch atop a Minotaur rocket on Wednesday Aug.10,2011 from Vandenberg Air Force Base, Calif. The Hypersonic Test Vehicle-2 is an experiment in extremely high speed flight technologies by the U.S. Defense Advanced Research Projects Agency. (AP Photo/DARPA)
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