For the fourth top secret mission, the US military launched the robotic X-37B space plane into Earth’s orbit on May 20, 2015. Now after more than 500 days, this solar powered, unmanned drone is still roaming in the Earth’s orbit, but we still have no clue why it is there, what it can do, or how long it will stay there.
The X-37B Orbital Space Vehicle (OTV) is a quarter the size of the Endeavour Space Shuttle and was built for the U.S. Air Force as a test vehicle. It can land as it has heat-shield protection for re-entry to Earth’s atmosphere, but no one knows when it will land.
All these unexplained things lead to various conspiracy theories like is it a part of deploying spy satellites in the sky, or is it regarding some Pentagon’s research into drone weaponry, or is it spying on China’s space station?
The Air Force’s first OTV mission was launched on April 22, 2010, and it concluded after 224 days in orbit. The second OTV mission was launched March 5, 2011, and concluded on June 16, 2012, after 468 days on orbit. The successive OTV-3 spent nearly 675 days in orbit.
All three X-37B flights ended at Vandenberg Air Force Base in California. However, the U.S. military has not stated yet where the OTV-4 mission’s craft will ultimately land once its current flight ends.