What's to stop DARPA unveiling the technology that was developed for Aurora, and claiming that it's a product of this current research programme, whilst diverting a good part of the $750 million for the NEXT generation of ultra-secret propulsion systems?

... it's just so secret that even DARPA doesn't know that 'Aurora' has been flying for some time now.

Hat, coat etc

For all we know, they are announcing they are going to build the already built Aurora (and it's going to make it's public debut in a couple of years), and this is really a cover to channel funds into some other blacker than black project!

Of course the Aurora's development is not exactly published like Intel's road map for processors is; what do you want them to say it's for?

Pity that they retired the SR-71/73 really. Rather than go for an expensive leap forward, why not go for an incremental update of the SR-71 with improved tech and materials?

They should never have cancelled the X-20, in my opinion.

Then again, since the USAF apparently have anti-gravity-driven flying saucers, why bother?

Governments are always spending zillions on redevelopment of technology. The things that the NSA did in the 70's and 80's with supercomputers and voice recognition took the business community and the rest of the "white" world another decade to re-engineer. Say what you will, but Darpa is a white organization, although I certainly wouldn't rule out Simon Ball's suggestion.

Pirate icon for some variety.

but decides not to bother.

announcing this program allows daylight testing of the super seekrit Aurora craft and other alien-w@nkership. Just like the only reason the "stealth" programs were outed in the late 80's.

Mine's the bubble helmet moon suit with the antennae. Bleep bleep!

Slowing the intake air with a magnetohydrodynamic system?

1: It needs the intake air to be ionised.

2: OK, you generate electricity, and use it in a second MHD system to accelerate the exhaust gas. That's a lot of energy to be throwing around, and what's the conversion efficiency?

3: This same problem is the critical weakness in the Bussard Ramjet concept. Was Aurora a prototype interstellar probe?

Obviously they have these. The additional budget is for anti-gravity driven flying cups to put on them.