Last week, DARPA carried out the second test of an unmanned hypersonic vehicle that can travel at Mach 20. The test ended when controllers prematurely lost contact with the vehicle, but data now shows that the vehicle flew stably for three minutes, and then made a controlled descent into the ocean. In other words, it worked. Mostly.
The initial results of last week's test were pretty disappointing: DARPA said that some unspecified anomaly caused a loss of signal shortly after the Falcon HTV-2 test vehicle separated from its launch rocket, and they assumed that the vehicle just went out of control and plowed into the Pacific. Air Force Maj. Chris Schulz, DARPA's HTV-2 program manager, tried to put a positive spin on things immediately after the flight, but it was hard to get around the fact that it looked a lot like the thing had simply failed to work and crashed:
"We know how to boost the aircraft to near space. We know how to insert the aircraft into atmospheric hypersonic flight. We do not 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."
As it turns out, a preliminary review of the test data now suggests that maybe DARPA does know how to achieve controlled hypersonic flight after all. Apparently, the Falcon flew for a solid 3 minutes in a completely stable manner, which would have been enough time for it to get from San Francisco to Seattle at its top speed of 13,000 miles per hour. Sometime after the third minute, the Falcon encountered some kind of anomaly (they're not yet sure what) which caused the vehicle to decide that it was probably time to end the test, so it steered itself into the ocean, on purpose and under control up until impact.
So this is definitely good news, but what does it mean? Hopefully, now that two tests in a row have not ended in failure (and data suggest that the issue that ended the first flight was solved for this most recent test), it means that we'll see another hypersonic test vehicle at some point down the line. That's going to depend partially on what the second flight anomaly turns out to be, but the point is that the Falcon flew at Mach 20 under complete control for three minutes. It can be done.