The U.S. Air Force’s secretive X-37B space plane returned to Earth on Sunday after completing more than two years in orbit.

The uncrewed X-37B Orbital Test Vehicle Mission 5 landed at NASA’s Kennedy Space Center Shuttle Landing Facility at 3:51 a.m. ET Sunday, the Air Force confirmed. The 780-day mission shattered the spaceplane’s own record of almost 718 days in orbit, which was set by Mission 4 when it returned to Earth in May 2017, Space.com reported.

X-37B MILITARY SPACE PLANE'S LATEST MYSTERY MISSION PASSES 600 DAYS

The X-37B Orbital Test Vehicle Mission 5 landed at NASA’s Kennedy Space Center Shuttle Landing Facility on Oct. 27, 2019. (Air Force photo)

Mission 5 launched from Cape Canaveral Air Force Station in Florida aboard a SpaceX Falcon 9 booster on Sept. 7, 2017.

The solar-powered spaceplane was designed to spend 270 days in orbit, according to the Air Force. Space.com noted that most of its payloads remain classified.

MYSTERY MISSION: AIR FORCE'S X-37B SPACE PLANE NEARS 1 YEAR IN ORBIT

The secretive space plane completed more than two years in orbit. (Air Force photo)

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

CLICK HERE TO GET THE FOX NEWS APP

The Air Force is planning to launch a sixth X-37B from Cape Canaveral Air Force Station in 2020.

Follow James Rogers on Twitter @jamesjrogers