A robotic Air Force space plane that has spent 15 months in orbit on a mystery mission came back down to Earth on Saturday.
The X-37B landed at California’s Vandenberg Air Force Base at 5:48 a.m. local time Saturday (8:48 a.m. EDT; 1248 GMT).
There is speculation on the purpose of the mission and ultimately its application in terms of military preparedness.
The X-37B looks like a space shuttle and is 29 feet long and 15 feet wide with a payload bay the size of truck bed.
The X-37B is built by Boeing, though NASA originally used the vehicle as an experimental test bed until funding for the project ran out in 2004. The space plane then passed to the Defense Advanced Research Projects Agency, and it was ultimately turned over to the Air Force in 2006.
Built by Boeing, the X-37B is designed to land itself without a human controller.
The Air Force first launched the X-37B on March 5, 2011, sending the reusable space plane design on its second-ever space mission. The X-37B currently zipping around Earth is known as Orbital Test Vehicle-2, or OTV-2.
Another X-37B, called OTV-1, made the program’s maiden flight back in April 2010. That vehicle stayed aloft for 225 days, well under the spacecraft’s supposed 270-day limit. OTV-2 is already about 200 days above that limit.