Amateur Astronomer Spots US Air Force Space Plane Lurking in Orbit

The US has something very mysterious in orbit.

Top Secret

Dutch astronomer and satellite tracker Ralf Vanderberg just spotted something extraordinary and rare: the U.S. Air Force's top-secret X-37B space plane.

Also known as the Orbital Test Vehicle, the military craft looks like a scaled-down version of NASA's Space Shuttle and measures just 29 feet long with a wingspan of 15 feet. The craft spotted by Vanderberg is the fifth iteration, launched into space atop a SpaceX Falcon 9 in 2017.

"It is really a small object, even at only 300 kilometers [186 miles] altitude, so don't expect the detail level of ground-based images of the real space shuttle," Vandebergh told Space.com. "We can recognize a bit of the nose, payload bay and tail of this mini-shuttle, with even a sign of some smaller detail."

Space-Based Mission

Details surrounding the mission are extremely sparse. The Air Force squadron responsible for the mission oversees space-based demonstration operations, as well as gathering info on objects flying at high altitudes over Earth, according to Space.com.

The X-37 project began in 1999 and was taken over from NASA by the U.S. Department of Defense in 2004. An earlier version, called the X-37A, completed a test flight attached to the underbelly of California Spaceport Scaled Composites' White Knight carrier plane in 2005.

Though we still don't know what the X-37 is doing up there, the episode is a startling reminder of the power of citizen science — even in the age of the militarization of space.

READ MORE: Skywatcher Captures Rare Image of Mysterious X-37B Military Space Plane [Live Science]

More on X-37B: SpaceX Just Launched Its “Secret Mission” for the U.S. Air Force