A US Air Force space plane has returned to Earthafter a record-breaking secret mission.

The X-37B landed at Nasa’s Kennedy Space Center in Florida early on Sunday. The Air Force is keeping quiet about what the plane did in orbit for the 780 days after it was launched on a SpaceX rocket in 2017.

The mission sets a new endurance record for the reusable test vehicle, which looks like a space shuttle but is a quarter the size, at 9 metres (29ft).

Officials said only that the mission successfully completed its objectives. Experiments from the Air Force Research Laboratory were on board.

It was the fifth spaceflight by a plane of this sort. A sixth is planned to launch next year from Cape Canaveral.

The Air Force secretary Barbara Barrett, said: “Each successive mission advances our nation’s space capabilities.”