It is thought to be “increasing the versatility of overhead reconnaissance” and a few other things.
It is 29ft long — about one-fourth the size of a Nasa shuttle. The longest X-37B flight lasted about 675 days; touchdown was last October.
There’s no official word on exactly how long this one will stay up, although report suggest it will return to Earth in mid-to-late 2016.
In an unprecedented disclosure, last month month the Department of Defense did reveal some details about the X-37B’s main mission.
‘[We] are investigating an experimental propulsion system on the X-37B on Mission 4,’ Captain Chris Hoyler, an Air Force spokesman, told Space.com.