Original URL: http://www.theregister.co.uk/2010/04/23/x37b_launched/

US Airforce secret spaceplane launched successfully

Other countries: Count your satellites

By Lewis Page

Posted in Science, 23rd April 2010 10:28 GMT

The US Air Force successfully launched its pocket-size X-37B robot space plane into orbit last night, on a mission whose nature and duration remain classified. With the imminent departure of the Space Shuttle, the little wingship will soon be the only orbital craft capable of runway landing - and perhaps other things.

The X-37B lifts off from Cape Canaveral. Credit: ULA

The X-37B disappears into the black.

The X-37B took off inside a payload fairing on top of an Atlas V launcher from Space Launch Complex 41, part of the Cape Canaveral Air Force Station rather than NASA's co-located Kennedy Space Centre, at 01:52am UK time this morning. United Launch Alliance, providing the launcher, said the takeoff was successful.

All details of the X-37B's mission are classified, though the air force did say it intends to use the little spaceplane to develop "concepts of operations" for re-usable spacecraft, and that this first mission will be mainly about seeing whether the craft itself works properly. Officials have also suggested that they are as interested in how fast the wingship can turn around between missions as in what it can actually do in space.

Being unmanned and equipped with a deployable solar array - unlike the shuttle which used fuel cells for electric power - the X-37B could spend much longer periods in orbit. The Air Force says it could stay up for 270 days at a time, before making a completely autonomous re-entry and lfying down to a runway landing at Vandenberg airforce base in California.

But as the X-37B, unlike the space shuttle, does nothing much towards getting itself up into space the only reason to use it - as opposed to a normal satellite sent up on an Atlas V - is for its abilities in descending to Earth. This could be handy, perhaps, in bringing back US military space hardware such as spy satellites for re-launch, repairs or upgrades, rather than the usual practice of burning them up in the atmosphere once their supplies of manoeuvring fuel run low.

The X-37B is far too small to retrieve most existing US spy satellites, but it might be merely a prototype aimed at bigger things - or at supporting the trendy new F6* "fractionated" or "swarm" satellite concepts, which would use groups of small spacecraft rather than large single units. The latter idea seems likelier, as a second X-37B has already been ordered.

Even so, a craft with somewhat delta-shaped wings like the X-37B and the Shuttle wouldn't be necessary in this role. Other designs - straight stub wings, or a lifting body - would still be capable of runway landings and thus quick, economical turnarounds; and they would save the weight of heatshielded delta wings.

Why not a lifting-body job this time, then?

NASA says it couldn't use a lifting body on the shuttle as such a large one would be very hard to design - but that wouldn't apply in the case of the little X-37B. Straight stub wings were rejected for the shuttle mainly because the US military wanted to be able to fly it from Vandenberg air force base in California on cunning one-orbit flights that would allow rendezvous with a satellite without anyone being aware that such had taken place. This meant a need for bigger delta wings for "cross range" - the ability to steer sideways during re-entry in order to avoid being left behind by the planet's rotation and coming down in the Pacific.

The X-37B looks very much as though it might be able to perform such a mission, if required. While it is too small to actually capture and bring back another nation's spacecraft in You Only Live Twice style satnappings (except perhaps very small ones) it could easily make a close pass to one without anyone knowing. Most satellites, being focused on their task, have no "situational awareness" of what is happening close by them in space, and a "Mission 3A/3B" X-37B flight on certain spysat style high-angle orbits would be very difficult if not impossible for other nations to monitor from the ground.

Detail on the X-37B's wings. Credit: USAF

Still no lifting body.

Thus the winged X-37B would seem able to get a close visual or electronic look at foreign spacecraft of interest - or perhaps meddle with them using the various new active electronic- and cyber-warfare technologies now coming out - all without flying over any places where it might be tracked by persons not approved of by the US Air Force.

That might offer a clue as to why two such craft have already been ordered when the "fractionated" satellite concept has yet to move out of the design-study stage - and why they have triangular wings rather than straight-stub ones or lifting bodies.

Of course, it's just as plausible that the X-37B looks a bit shuttley simply because it's cheaper to build a mini version of a well-understood machine than do something new. But that doesn't mean the Air Force's original, covert-mission reasons to make the shuttle that shape have gone away. ®

Bootnote

*Future, Fast, Flexible, Fractionated, Free-Flying Spacecraft. The idea is to have the various components of a normal big satellite organised in a wirelessly-linked cluster of small orbiting machines, a so-called virtual satellite. The idea is that this would avoid the expense, limited launch opportunities, inability to upgrade and high risks of critical failure that come with big integrated sats.