The return of a robotic space plane to Earth last week marked a milestone for US space capabilities, but did nothing to lift the veil of secrecy surrounding the vehicle's mission.
After spending more than seven months in orbit, the US Air Force's X-37B spacecraft returned safely to Earth on Friday, landing at Vandenberg Air Force Base in California. The vehicle is the first in the history of the US space program to reach orbit and return autonomously to a runway, the BBC reports.
The 9-metre-long plane, which resembles the space shuttle but is roughly a quarter the size, carries a shuttle-like cargo bay that is about the size of the bed of a pickup truck. Its ability to land on a runway means it has the potential to be used to routinely loft instruments to space and bring them back, or even to retrieve objects already in orbit.
In all likelihood, space analysts say, such planes will be used to carry sensors or deploy satellites that can be used to spy on Earth. But little information has been forthcoming about the nature of the X-37B's first mission or the plane's intended purpose. That's raised some concerns that the plane could have a dual use, carrying instruments that could sabotage satellites belonging to other countries.
But Air Force undersecretary for space programs Gary Payton has said the plane program is not pursuing "offensive capabilities". "It's just an updated version of the space shuttle kind of activities in space," quotes the AP. "We, the Air Force, have a suite of military missions in space and this new vehicle could potentially help us do those missions better."
The X-37B isn't the first unmanned spacecraft to land on a runway, FlightGlobal points out.
The Soviet Union's Buran space shuttle accomplished a similar feat in 1988 before the project was abandoned.
Payton has said that the top priority for the program is to demonstrate the cheap and efficient reusability of spacecraft, with planes that can be readied for another flight 10 to 15 days after landing. It is not yet clear when the pioneering plane will be flown again. A second vehicle is set to launch in the first half of 2011.
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