The old space shuttle landing facility at NASA’s Kennedy Space Center received an unusual visitor early Sunday morning when the Air Force’s secretive X-37B space plane autonomously returned from orbit after a record-breaking mission. For the last 780 days, the Air Force Research Laboratory used the space plane as an orbital platform for classified experiments. These experiments tested technologies ranging from avionics to advanced propulsion systems, and deployed a few small satellites.
We’ll probably never know exactly what sorts of experiments were being done up there, but the Air Force called the mission a big success. “The X-37B continues to demonstrate the importance of a reusable space plane,” Secretary of the Air Force Barbara Barrett said in a statement. “Each successive mission advances our nation’s space capabilities.”
The X-37B looks like a small-scale version of NASA’s space shuttle. At just under 29 feet in length and with a 14-foot wingspan, it’s hardly bigger than a school bus, but it provides more than enough room for the Air Force to test new tech in microgravity. Although Boeing floated the idea for an X-37C space plane capable of carrying up to six astronauts to and from orbit back in 2011, there have been no updates on these plans since. The Air Force did not respond to WIRED’s request for comment about the status of the X-37C program.
The X-37B’s return to Earth on Sunday marks the end of the fifth successful mission for the space plane, which first took flight in 2010. The X-37 program was originally developed by NASA in the late ’90s before it transferred the tech to DARPA in the early 2000s. The Air Force made two flight versions of the X-37B and to date they have spent a total of 2,856 days in orbit. The most recent mission was launched on a SpaceX Falcon 9 rocket in 2017 and broke the space plane’s previous record in space by 62 days.
Beyond some vague generalities about the types of experiments being conducted on the X-37B, the Air Force has kept mum on the specifics. This time around, the only details released by the Air Force was that one of the experiments would be testing a highly efficient heat pipe. Exciting stuff.
Secretive as it is, the space plane has become an object of fascination for a global network of amateur spy satellite hunters who have spent years documenting its trajectory. Tracking the space plane proved to be particularly challenging because it has the capability to alter its orbit in space, so space sleuths have to maintain constant vigilance to not lose it.
Although the X-37B remains the only space plane making trips to orbit after the end of the space shuttle program in 2011, it may soon be joined by a commercial variant, the Sierra Nevada Corporation’s Dream Chaser. The Air Force says it plans to launch the X-37B on its next mission in early 2020 sometime between April and June. So if you find yourself stargazing next spring and can’t shake the feeling that something is watching you—it might not be in your head.