A prototype spaceplane built for the US military has returned to Earth after seven months in orbit. The unpiloted X-37B touched down at Vandenberg Air Force base in California at 0116 PST (0916 GMT).
The project has been shrouded in secrecy, prompting widespread speculation about the craft’s purpose. The Air Force has not said whether it carried anything in its cargo bay, but insists the primary purpose of the mission was to test the craft itself. Officials have said the X-37B could be used to carry out experiments in orbit.
The robotic X-37B was launched atop an Atlas 5 rocket from Florida’s Cape Canaveral Air Force Station on 22 April, with a maximum mission duration of 270 days.
“We are very pleased that the programme completed all the on-orbit objectives for the first mission,” the project’s programme manager Lt Col Troy Giese said in a statement.
Jeremy Eggers, an Air Force spokesman based at Vandenberg said the craft is expected to return to space in Spring 2011.
At 8.9m (29ft 3ins) long and with a 4.5m (14ft 11ins) wingspan, the reusable spaceplane is about one-quarter the size of the space shuttle, with a large engine mounted at the rear of the ship for changing orbit.
While the space shuttle uses a fuel-cell power-system, the military vehicle is powered by a solar array and lithium-ion batteries.