Back to Earth

The Air Force's mysterious robotic space plane returned to the earth over the weekend, renewing speculation about its mission and capabilities.

For the record, the 29-foot craft, better known as the X-37B, spent 469 days orbiting the earth, far exceeding the 270-day mark set by its sister ship in 2010.  The spacecraft landed safely at Vandenburg AFB, California early Saturday, but the service remains mum on what it accomplished during 15 months in space.

However, there is no shortage of theories about the X-37B and what it might be up to.

Popular Science speculated earlier this year that the mini-shuttle was being used to spy on China's new space station:

We know that Tiangong-1--which was launched back in September and is slated to host a manned crew sometime later this year--is in an orbit with an inclination of 42.78 degrees at an altitude of roughly 186 miles. And we know--not from the Pentagon but from a group of vigilant amateur space trackers--that the X-37B is orbiting at about the same altitude and at an inclination of 42.79 degrees. Not only is that orbit strange for a military recon satellite--they usually have polar orbits that offer better access to the entire globe--but it would periodically bring the two orbiters very close together.

Of course, the leap that’s being made--that the reason X-37B and Tiangong are on such similar paths is because the former is spying on the latter--is speculation entirely. The 30-foot X-37B has a cargo bay roughly akin to the interior space of a van, and there’s no telling what kind of sensors or other equipment might be stowed in there. And though China has been somewhat forthcoming about Tiangong-1’s mission, we can’t really be sure about that either. Putting them on the same orbital path is practically a recipe for rampant speculation.

But others note that the "geometry" of these fly-bys was less-than-optimum for surveillance of the Tiangong-1.  Still, the twin space planes (dubbed Orbit Test Vehicle-1 and 2) can carry a variety of payloads in their cargo bays, which are roughly the size of a pick-up truck.  One of the more intriguing possibilities we've heard is that OTV-2--the one that landed on Saturday--had some sort of optical package attached to its robotic arm.  In theory, that could provide some sort of covert collection capability against high-value targets, ranging from mobile ICBMs in Russia, China (and elsewhere), to Iranian nuclear facilities.   

With a reported orbit altitude of 186 miles, the X-37 flies closer to the earth than optical spy satellites and its more maneuverable.  One of the problems with imagery satellites is that they're very predictable; flying orbits known to us and our adversaries.  Maneuvering these platforms can improve the view, but it also burns up precious fuel, reducing the service life of a billion-dollar platform.  Making matters worse, our enemies automatically assume that a satellite is collecting when it passes overhead, so sensitive activities are concealed during suspected collection windows.  

Not only is the X-37 less predictable, it's also refuel-able, and we're guessing that sensors on that robotic arm can be deployed (and concealed) in a matter of minutes.  So, it may be more difficult for our foes to guard against a potential collection threat from the space plane.  And, that task becomes more complex when you have to account for the space plane and known spy platforms.  At some point, as the X-37 fleet grows in numbers, it will be more difficult to accomplish sensitive operations "in the open," for fears that some American platform is passing overhead.    

We're guessing--and it's pure speculation--that low earth orbit (LEO) surveillance is one of many missions that can be performed by the X-37B.  With the end of the shuttle program--and NASA still in disarray--the Air Force clearly wants to maintain a reusable space platform that can perform a variety of tasks, such as putting smaller payloads into orbit and conducting scientific experiments--in addition to possible reconnaissance work.  There's also talk that Boeing's Phantom Works (which developed the X-37B) is at work on a much larger version, one that could carry six astronauts into space.  

Meanwhile, USAF personnel and contractor reps are preparing OTV-1 for another mission later this year.  And quite predictably, the service isn't saying when it go aloft, and what it will do during its extended stay in space.  
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ADDENDUM:  While the X-37B shows great promise, there are still a few tasks beyond its capabilities.  For example, the nation's newest spy satellite was launched into orbit on Wednesday from Cape Canaveral, using an Atlas 5 rocket.  Exact details of the payload are classified, but many surveillance satellites are the size of city buses, far too larger for the space plane's smaller cargo bay.  However, the X-37B would be quite useful in deploying the new, miniature spy satellites currently in development.  Some are so small they could fit into the palm of your hand, so a single space plane mission could carry scores of the small satellites aloft.