Top secret US spaceplane touches down, but what has it been up to?

X-37B(OTV-2)

US Air Force's X-37B lands after a 15-month mission amid speculation that it has been spying on the Chinese space station

BY Tim Edwards LAST UPDATED AT 14:58 ON Mon 18 Jun 2012

AMERICA'S 'top secret' spaceplane, the X-37B, ended its second test flight at the weekend, having spent 469 days in orbit around the Earth – nearly double its supposed 270-day mission limit.

The US Air Force released a video (below) of the spaceplane – also known as the Orbital Test Vehicle 2 (OTV-2) – landing at Vandenberg Air Force base on Saturday.

In a statement, a military spokesman said: "With the retirement of the space shuttle fleet, the X-37B OTV programme brings a singular capability to space technology development.

"The return capability allows the Air Force to test new technologies without the same risk commitment faced by other programmes. We're proud of the entire team's successful efforts to bring this mission to an outstanding conclusion."

But the video has prompted inevitable speculation over what the spacecraft – which looks like the stunted child of a space shuttle and a cruise missile and has a cargo capacity roughly akin to that of a pickup truck – was up to for its 15-month mission.

As previously reported in The Week, the X-37B, was first developed by Nasa in 1999 before being transferred to shadowy US military agency Darpa (Defense Advanced Research Projects Agency) and thence to the US Air Force with Boeing as a contractor.

The mission that finished at the weekend began in March 2011 and was the X-37B programme's second. Another test flight is expected to take off in October this year, according to ZDNet.  

Earlier this year, it was claimed that the X-37B had been spying on China's new space station, Tiangong-1, although the suggestion was dismissed by experts who said the American spacecraft's orbit precluded such a mission.

Previously, it was suggested the X-37B was capable of satellite 'kidnap' missions, while Iran's government mouthpiece, Press TV, dubbed the X-37B a "secret space warplane" and a "first generation of US 'space Predator drones'".  

The US Air Force insists the reality is more boring: that it is finessing reusable spacecraft technologies which would allow such operations as repairing satellites in orbit. One technology probably used in the latest mission is an advanced solar array that extends from the cargo bay. This generates power, which is the likely reason the X-37B was able to remain in space for much longer than expected.  

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