A mysterious robotic ‘space plane’ has now been in orbit for a record 677 days – and America is remaining silent about what it’s doing up there.
Observers have speculated that the Space Shuttle-esque vehicle might be designed to destroy satellites – or work as a ‘movable’ satellite itself.
When it landed from a previous mission, it was greeted by ground crew in biohazard suits – sparking gossip that there was something radioactive on board.
The aircraft has a wingspan of less than 15ft – and is taken into space on a rocket, but glides back to Earth like a space shuttle.
NASA has said that there is a materials experiment on board – but its main payload remains a mystery.
During the aircraft’s previous missions, amateur astronomers were able to detect the orbital pattern of the first X-37B which included flyovers of North Korea, Iraq, Iran, Pakistan and Afghanistan, heightening the suspicion that the vehicle was being used for surveillance.