Air Force's mystery space plane is back on Earth, ending 2-year mission

The Air Force's mystery space plane is back on Earth, following a record-breaking two-year mission. The X-37B landed at NASA's Kennedy Space Center in Florida early Sunday. The Air Force is mum about what the plane did in orbit after launching aboard a SpaceX rocket in 2017. The 780-day mission sets a new endurance record for the reusable test vehicle.