It stands 9.5 feet tall and 29 feet long. Its wings measure 15 feet from tip to tip. It is not dinosaur, not a leviathan, but the top-secret X-37B.

The Boeing X-37B is a homegrown UFO, an unmanned and reusable spacecraft, the smallest of its kind. For the past two years the fun-sized space shuttle has been exploring earth orbits on a classified mission. On October 25, 2012, it launched from Cape Canaveral, Florida. Its travels through time and space ended 9:24 a.m., October 17, 2014, when it safely touched down at the Vandenberg Air Force Base in Southern California, breaking the record for longest orbital duration of a reusable spacecraft.

“The 30th Space Wing and our mission partners, Air Force Rapid Capabilities Office, Boeing, and our base support contractors, have put countless hours of hard work into preparing for this landing,” said base commander Colonel Keith Balts, “and today we were able to see the culmination of that dedication.”

Such marked the end of the X-37B’s third space mission. The United States Air Force has only revealed that the spacecraft was conducting “on-orbit experiments,” a generic proclamation of which any politician would be proud. Its mission remains a mystery, but theories run rampant. Some suspect the X-37B was an espionage plane, a spycraft sent to seek out the satellites of other nations. The Pentagon has formerly denied allegations that the spacecraft was being used to research development for space-based weapons. A U.S. Air Force orbital analyst also denied claims that the mini-shuttle was used to spy on China’s Tiangong-1 space station module.

A fourth mission is planned for the X-37B in 2015. It will again launch from the Kennedy Space Center in Florida.

Where – and why – it will go, nobody knows.