HAPPENING NOW: I don't know what the hell is going on with the Falcon Hypersonic Test Vehicle 2, but the Air Force just lost it again. Last year, the first Falcon vanished over the Pacific Ocean, leaving absolutely no trace.
Now it has happened again. The Falcon HTV-2 launched today from the Vandenberg Air Force Base in California on top of a Minotaur IV Lite rocket.
After successfully separating from the missile, the Falcon reoriented itself for re-entry using the Reaction Control System. During the reentry, it used RCS and its aero controls to fly into Earth's upper atmosphere, passing to the pull-up phase, reaching the correct altitude for the glide phase. In theory, during this phase the Falcon was going to test its aerodynamics and integrity flying at Mach 20, experimenting a temperature of 2000C — enough to melt steel.
DARPA controls at Vandenberg acquired signal from re-entry to some time into the glide phase. At that point, they lost telemetry with the aircraft never to get it back again, only 36 minutes from launch. According to DARPA, the Falcon has automated auto-destruction controls in case something goes wrong, but they still don't know what has happened. Two hours ago at the time of this writing they haven't followed up on their last Tweet.
Back in April 2010, the first Falcon flew for nine minutes before DARPA experienced loss of signal. According to the Air Force, "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."
Why did the Falcon fail again? To me, the answer is clear. In two words: Lex Luthor. [DARPA Twitter]