A test flight of a hypersonic aircraft, which was touted as the world's fastest ever plane, capable of reaching speeds up to 13,000 miles per hour, failed as the Falcon HTV-2 crashed into the Pacific Ocean.

The plane hurtled into the sky at 7:45 a.m. PST Thursday on a Minotaur IV rocket from Vandenberg Air Force Base in California. The unmanned Falcon HTV-2, which was designed to fly at 20 times the speed of sound, successfully separated from the booster and entered the mission's glide phase, but lost contact with control. This is the second time officials have lost contact with a Falcon HTV, following a similar incident in April.

HTV-2 was the last scheduled flight for the Falcon program, which began in 2003 and cost taxpayers about $320 million.

In the latest mission, the Minotaur IV vehicle successfully inserted the aircraft into the desired trajectory, and separation of the vehicle was confirmed by rocket camera.

After that, the aircraft transitioned to Mach 20 aerodynamic flight, which represents a critical knowledge and control point in maneuvering atmospheric hypersonic flight.

More than nine minutes of data was collected before an anomaly caused loss of signal. Initial indications are that the aircraft crashed into the Pacific Ocean along the planned flight path, Defense Advanced Research Projects Agency (DARPA) said in a statement.

"Here's what we know," said Air Force Maj. Chris Schulz, DARPA HTV-2 program manager. "We know how to boost the aircraft to near space. We know how to insert the aircraft into atmospheric hypersonic flight. We don't 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."

DARPA admitted that the sophisticated simulations and extensive wind tunnel tests carried out by the technical team haven't yielded the necessary knowledge.

"Filling the gaps in our understanding of hypersonic flight in this demanding regime requires that we be willing to fly," said DARPA Director Regina Dugan. "In the April 2010 test, we obtained four times the amount of data previously available at these speeds. Today more than 20 air, land, sea and space data collection systems were operational. We'll learn. We'll try again. That's what it takes."

Schulz said the HTV-2 flight regime faced three technical challenges -- aerodynamic; aerothermal; and guidance, navigation and control. DARPA said experts would analyze the flight data collected during the test flight to expand the technical understanding of this incredibly harsh flight regime.

"As today's flight indicates, high-Mach flight in the atmosphere is virtually uncharted territory" Schulz added.

The assembled independent Engineering Review Board is expected to review and analyze the data collected in the coming weeks and will inform policy, acquisition and operational decisions for future Conventional Prompt Global Strike programs.

DARPA's Falcon (Force Application and Launch from Continental U.S.) HTV-2 program was a multiyear research and development effort to increase the technical knowledge base and advance critical technologies to make long-duration hypersonic flight a reality. The ultimate goal is to be able to reach anywhere in the world in less than an hour.

Falcon HTV-2 is an unmanned, rocket-launched, maneuverable aircraft that glides through the Earth's atmosphere at Mach 20. The HTV would take less than 12 minutes to fly between New York City and Los Angeles.

HTV-2 flew its maiden flight on April 22, 2010, collecting nine minutes of unique flight data, including 139 seconds of Mach 22 to Mach 17 aerodynamic data.

The aircraft is part of plans from the U.S. Defense Department to build what it calls a "prompt global strike" capability, enabling it to hit global targets within an hour with conventional or nuclear warheads.

Watch the below video of Falcon HTV-2: