The Air Force launched the unmanned spacecraft Tuesday aboard an Atlas V rocket with an on-time liftoff at 1:03 p.m. at Launch Complex 41.
The Atlas rocket and its Centaur upper stage performed flawlessly through the first 17 minutes and 34 seconds. The mission then switched into a classified mode, and an information blackout followed.
It's the second flight for this original X-37B spaceplane. It circled the planet for seven months in 2010. A second X-37B spacecraft spent more than a year in orbit. The two previous secret flights were in roughly 200-plus-mile-high orbits. These spacecraft are capable of autonomous atmospheric reentry and landing. The first two missions concluded on a runway at Vandenberg Air Force Base in California.
The military isn't saying much if anything about this new secret mission. But one scientific observer, Harvard University's Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics, speculates the spaceplane is carrying sensors designed for spying and likely is serving as a testbed.