Mysterious American ‘space plane’ has been in orbit for 700 days - and no one knows why

Rob Waugh
The U.S. Airforce's X-37B Orbital Test Vehicle (Reuters)

A mysterious robotic ‘space plane’ has stayed in orbit for nearly two years - and few people know what it’s really up to.

The Boeing X-37B craft - also known as Orbital Test Vehicle 4 - has now been in orbit for 700 days.

It launched on its latest mission on September 7, 2017, reports, and is now just a few days short of its all-time record for remaining in space.

Observers have speculated that the Space Shuttle-esque vehicle might be designed to destroy satellites - or work as a ‘movable’ satellite itself.

The X-37B Orbital Test Vehicle (Getty)

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.

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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.

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