X-37B space plane at rest

A shroud of darkness becomes the X-37B Orbital Test Vehicle, the unmanned space plane design that twice has ventured into orbit on hush-hush missions for the U.S. Air Force. Oh, the Air Force and X-37B maker Boeing don't mind telling you about the launches and landings and the vehicle's remarkable endurance. Just don't bother asking detailed questions about what they're doing with all that time in orbit.

This photo shows the first X-37B, designated OTV-1, on the runway at Vandenberg Air Force Base in California on December 3, 2010, just after it returned from its debut trip into space, which lasted 224 days.

As it turns out, that was just a warmup act. The second X-37B, OTV-2, touched down on Earth at 5:48 a.m. PT on Saturday, June 16, to end its maiden mission, which began with a liftoff on March 5, 2011 -- meaning it was orbit for 469 days, easily doubling the record of its older sibling.

Editors' note: This slideshow was initially published June 14 at 8:42 a.m. PT. It has been updated with details about the landing of OTV-2.