The mysterious US Air Force “space plane” returned to earth Sunday after a record-breaking two years in orbit.

The unmanned X-37B Orbital Test Vehicle Mission 5 touched down at the Kennedy Space Center in Florida at 3:51 a.m. — blowing away its own orbital record by 718 days, Fox News reported Monday.

The solar-powered craft, which carried classified cargo, was designed to spend 270 days in space.

It launched from Cape Canaveral Air Force Station in Florida strapped to a SpaceX Falcon 9 booster on Sept. 7, 2017, Fox reported.

“The X-37B continues to demonstrate the importance of a reusable space plane,” Air Force Secretary Barbara Barrett said in a statement. “Each successive mission advances our nation’s space capabilities.”

The ship resembles the space shuttle, but is one-fourth the size, NBC News said.

The program remains largely shrouded in secrecy, but Air Force officials said a sixth flight is expected to take off sometime next year.