Super-secret spaceplane the X-37B landed back at Vandenberg Air Force Base on Saturday after 469 days of mysterious missions in space.
The second unmanned reusable Orbital Test Vehicle, which carried out unknown experiments in orbit, launched from Cape Canaveral in March last year.
"With the retirement of the Space Shuttle fleet, the X-37B OTV program brings a singular capability to space technology development," said Lt Col Tom McIntyre, the X-37B's programme manager, in a canned statement.
"The return capability allows the Air Force to test new technologies without the same risk commitment faced by other programs. We're proud of the entire team's successful efforts to bring this mission to an outstanding conclusion."
As is traditional when discussing the X-37Bs, vagueness was key in the US Air Force's comments, since despite its supposedly innocuous job of testing space gear in space, no one ever knows what the wee crafts are carrying or doing.
The US government's secretive attitude has led to all sorts of speculation about the purpose (or purposes) of the mini-spaceplanes, including the theory that they are some sort of space warplane.
The US Air Force is planning another X-37B launch sometime this autumn, sending the first craft back into space aboard an Atlas V rocket. ®