The US Army - yes, Army - has announced a successful test flight by a prototype hypersonic missile. The Advanced Hypersonic Weapon (AHW) demonstrator took off from the island of Kauai on a three-stage rocket booster at 1:30 AM local time yesterday, and splashed down close to its target coordinates some 2,400 miles away at the Ronald Reagan Ballistic Missile Defense Test Site on Kwajalein Atoll.
A Pentagon statement announcing the test said:
The vehicle flew a non-ballistic glide trajectory at hypersonic speed to the planned impact location at the Reagan Test Site. Space, air, sea, and ground platforms collected vehicle performance data during all phases of flight. The data collected will be used by the Department of Defense to model and develop future hypersonic boost-glide capabilities.
The AHW program is managed and executed by the US Army Space and Missile Defense Command/Army Forces Strategic Command program office in Huntsville, Ala. The booster system and glide vehicle were developed by Sandia National Laboratories and the thermal protection system by the US Army Aviation and Missile Research Development and Engineering Center.
The Department of Defense is using AHW to develop and demonstrate technologies for Conventional Prompt Global Strike (CPGS). As part of the CPGS effort, the Defense Advanced Research Projects Agency [DARPA] conducted boost-glide flight tests in April 2010 and August 2011, results from which were used in planning the AHW flight test.
The previous DARPA tests were much more ambitious, attempting hypersonic glides at Mach 20+ as opposed to the Army space-and-missile-defence command AHW's more sedate Mach 8. Both of those cracked up in flight, but evidently they managed to transmit back some useful data.
Weapons of this type - so-called "boost glide" projects - have a long history, dating back to Nazi plans for a "Silbervogel" rocket bomber which would circumnavigate the globe by skipping along the top of the atmosphere like a flung stone, dropping a bomb on America as it passed. Down the years other proposals and test efforts have been seen, such as the X-20 Dyna-Soar, the Boost Glide Re-entry Vehicle of 1968, etc.
Apart from the failed Hypersonic Test Vehicle trials, DARPA has also lately stated aspirations towards an "Arc Light" boost-glide weapon capable of fitting into the standard launch tubes of US Navy surface warships and able to do Mach 12.
The idea of Conventional Prompt Global Strike as mentioned by the Pentagon is to strike targets anywhere in the world, very quickly. This can already be done using an ICBM, which could easily be modified to carry a conventional warhead, but the fear is that ICBM launches could lead to panic and nuclear war - so hypersonics are being investigated instead.
This does seem a bit odd as nobody panics when a Tomahawk cruise missile gets fired off, and a Tomahawk can carry a nuke - as can a bomber, as could a boost-glide vehicle. However it means more cash for hypersonic research, and that could lead one day to various excellent things such as better access to space, so one mustn't grumble. ®