However, it is a good question to ask what this offers over ICBM equipped with conventional weapons. (The speed is about the same.) I'd imagine it's cost.
Both system consist of booster (which need to provide 20 Mach delta-v to its payload) and payload - upper stage which is warhead carrying vehicle. ICBM is cheaper because it follows dumb ballistic trajectory which puts no specific structural requirements on the warheads and their enclosure. The warhead vehicle traveling at 20 Mach in the upper atmosphere would cost enormously more ( and possibly would be much heavier, thus requiring bigger booster). I.e. ICBM is cheaper.
The dumb ballistic trajectory was a weak spot of the ICBM system, and thus modern ICBM warheads perform evasive maneuvers during final atmosphere re-entry.
1. Can't be shot down by any known SA missile technology (which the Russians are pretty good at)
2. Isn't a sitting duck like satellites, can't be shot down with anti-satellite weapons.
3. Can go anywhere anytime, so adversaries can't time their troop movements and other clandestine activities around your spysat flyover schedule.
4. Perfect for keeping tabs on China's opaque military buildup, since the US's sats and humint isn't as effective at that as desired.
This is actually scramjet technology, which has very general applications beyond delivering a bomb.
ICBMs can carry non-nuclear warheads but it's a VERY expensive way to get a payload on target.
Normally I don't care, but I guess I'm just grumpy today.
http://security.blogs.cnn.com/2011/08/11/new-york-to-la-in-l...
"This test flight was their last shot at success before the project is considered for closure."
http://www.guardian.co.uk/world/2011/aug/11/fastest-ever-pla...
"Had the latest test flight gone to plan, the Falcon HTV-2 would have separated from its rocket high above the atmosphere and entered a steep dive before levelling out and performing a series of subtle manoeuvres to test its aerodynamic performance. At the end of the flight the plane would have rolled upside down and steered a graceful arc into the ocean."
The official press release at http://go.usa.gov/KLe says that they confirmed separation and that they achieved high-speed aerodynamic flight, not that they "would have separated". They lost contact 9 minutes into the aerodynamic tests, and the plane (if you can call it that, the CNN article calls it a "triangular wedge of zoom" which seems more appropriate) went down sometime after that.
http://news.ycombinator.com/item?id=2873003 - 4 comments
http://news.ycombinator.com/item?id=2873313 - deleted
This pcmag article is from yesterday, the plane has already taken off. The Twitter feed (https://twitter.com/#!/DARPA_News) points to several updates after launch, and now to this news release (http://go.usa.gov/KLe) which says:
Separation of the vehicle was confirmed by rocket cam and the aircraft
transitioned to Mach 20 aerodynamic flight. This transition 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
impacted the Pacific Ocean along the planned flight path.
Interestingly, Flight 1, which flew in April of last year, also collected 9 minutes of data. Maybe they just have to speed it up so they get where they want to be in less than 9 minutes....