by Tristan Rayner in New Trends on Monday 19 May 2014

The X-37B is a kind of robotic space plane, built by the US. It’s been in Earth’s orbit for more than 500 days. And its real purpose is a complete mystery. Intrigued? [read the full story at Techly]

Here’s what we do know about X-37B

Constructed in California, the Boeing-built X-37B Orbital Space Vehicle was built for the US Air Force as a test vehicle; not intended to reach production. It is a quarter the size of the Endeavour Space Shuttle. It is equipped with heat-shield protection for re-entry to Earth’s atmosphere.

Currently the X-37B is orbiting at 28,044km/h, at a distance of around 350km in the sky. It can land, but no one will say when that will be.

It’s been in the sky before, after being launched on April 22, 2010, on a rocket. It then landed on December 3, 2010 – blowing a tire and suffering minor damage to its underbelly.

It took off again from Cape Canaveral on December 11, 2012 – now reaching 500 days in orbit.

The Air Force also launched a second model of X-37B on March 5, 2011. Described by the U.S. military as an “effort to test new space technologies”, it landed safely at Vandenberg Air Force Base on June 16, 2012, after 469 days in space. This third mission has now smashed this previous record.

X-37B’s actual functions are still heavily classified.

As you’d imagine, conspiracy theorists are having a field day, and here’s why:

Powered by a solar panel that unfurls once in orbit, X-37B can open with small, shuttle-like payload bay in its middle – think of a clamshell opening from underneath. There’s room for more than just a solar panel too. Exactly what items it carries, and why they need to be in space so long, has proved elusive for analysts, the space community, and the media.

To add further intrigue, the plane is classified as a secret project, yet maker Boeing has released pictures and more than two pages of details on the X-37B. That’s not how secrets are usually dealt with. By contrast, the secret Lockheed SR-71 Blackbird was not declassified until decades after it had been flown in the Vietnam War.

Read the best guess that we can make, and some of the crazy conspiracies out there, via Techly

The X-37B Orbital Test Vehicle

The X-37B Orbital Test Vehicle in the encapsulation cell at the Astrotech facility April 13, 2010 (via US Air Force).