WASHINGTON Range controllers lost contact with an experimental hypersonic vehicle launched Aug. 11 from Vandenberg Air Force Base, Calif., according to the U.S. Defense Advanced Projects Research Agency (DARPA), which is sponsoring the demonstration.

According to Vandenberg’s website, the Hypersonic Test Vehicle-2 (HTV-2) launched at 7:45 a.m. local time atop a Minotaur 4 rocket, a converted ballistic missile. Initial Twitter posts by DARPA said the HTV-2 successfully separated from the rocket and was on track for the glide phase of its mission.

But subsequent posts indicated that controllers had lost contact with the vehicle. “Downrange assets did not reacquire tracking or telemetry,” DARPA said in a note posted about an hour and a half after the liftoff. “HTV-2 has an autonomous flight termination capability. More to follow.”

This was the second test flight of the HTV-2, which is designed to demonstrate the aerodynamic properties, materials and guidance of vehicles traveling through the atmosphere at speeds approaching Mach 20, or 20 times the speed of sound. The unpowered vehicle was driven to its testing velocity by the Minotaur launch vehicle.

The first HTV-2 flight, which occurred in April 2010, was cut short when controllers lost telemetry about nine minutes into the mission. “The vehicle’s onboard system detected a flight anomaly and engaged its onboard safety system — prompting the vehicle to execute a controlled descent into the ocean,” DARPA said in a posting on its website.

Warren Ferster is the Editor-in-Chief of SpaceNews and is responsible for all the news and editorial coverage in the weekly newspaper, the spacenews.com Web site and variety of specialty publications such as show dailies. He manages a staff of seven reporters...