Secret US spaceplane launches for new mission

It is the second flight for the original X-37B craft, after it circled the planet for seven months in 2010. A second X-37B spent more than a year in orbit.

The mystery machines are about one-quarter the size of Nasa’s old space shuttles, and can land automatically on a runway.

The stated mission of the craft, according to the US Air Force, is “to demonstrate technologies for a reliable, reusable, unmanned space test platform”. The US government has been quiet about its precise purpose, and would not confirm a launch time.

But one scientific observer, Harvard University’s Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics, has speculated that the spaceplane is carrying sensors designed for spying.