A Minotaur IV Lite rocket lifted off with the Falcon Hypersonic Technology Vehicle 2 Thursday morning from Vandenberg Air Force Base in California, successfully released the aircraft and entered the mission's glide phase, the military said.
But the Defense Advanced Research Projects Agency is saying that contact has been lost, without releasing any details.
The Falcon HTV is an unmanned aircraft that can travel at Mach 20 -- 20 times the speed of sound, up to 13,000 miles per hour. The aircraft is fast enough to travel from Los Angeles to New York in just 12 minutes and withstand temperatures hotter than the melting point of steel. It also has the ability to send a missile to an identified target within an hour.
HTV-2 is DARPA's second test flight after a few changes were made when the first attempt failed last year and crashed into the ocean just nine minutes after takeoff. The aircraft was never recovered.
Should the testing of HTV-2 fail this time, DARPA says it will not be building another Falcon HTV.