An experimental airplane capable of flying unmanned at 20 times the speed of sound was launched today from Vandenberg Air Force Base in California — and promptly disappeared. The "blistering" fast military aircraft, dubbed the Falcon Hypersonic Test Vehicle 2 (HTV-2), is designed to cover a distance equal to that between New York and Los Angeles in less than 12 minutes. At such a speed, "air doesn't travel around you — you rip it apart," the military boasted on its website. But shortly after the HTV-2's flight began, engineers lost all contact with the craft. Here, a brief guide:

What happened on its flight? The HTV-2 was sent into the upper reaches of the atmosphere on the back of a Minotaur IV rocket. It then successfully disengaged from the rocket and began to nose-dive toward the Pacific Ocean, where it was supposed to level off and reach speeds of about 13,000 miles per hour for about 30 minutes. But all contact with the HTV-2 was lost just a few minutes into the flight — and an "eerily similar" problem occurred during a 2010 test flight of the first HTV-2.

What occurred on that first flight? In April 2010, after just nine minutes of flight time, the first HTV-2 craft was also lost. Both planes were equipped with what the military calls "autonomous flight termination capability," which means the wedge-shaped airplanes are designed to automatically crash into the ocean at the end of their test flights.

Were these flights a total loss? Not exactly, according to the military. Even though the first HTV-2 flight ended after only nine minutes, "the flight yielded valuable data, including 139 seconds of data on extremely high-speed flight, ranging from Mach 17 to Mach 22," or 17 to 22 times the speed of sound.

Sources: LA Times, NY Daily News, Space.com, USA Today, Wall Street Journal