The Falcon Hypersonic Test Vehicle 2 (HTV-2) is part of a US military initiative to develop technology to respond to threats at 20 times the speed of sound or greater, reaching any part of the globe in an hour.
The craft is shaped like the tip of a spear.
The aircraft took off using a Minotaur IV rocket from Vanderberg Air Force Base in California early on Thursday and was programmed by engineers to launch from the edge of space, separate from its rocket and crash into the ocean.
In a statement, Defense Advanced Research Projects Agency DARPA has said, “More than nine minutes of data was collected before an anomaly caused loss of signal," it said. “Initial indications are that the aircraft impacted the Pacific Ocean along the planned flight path."