Photos: Final ULA mission of the year blasts off successfully

The second Falcon Heavy fires its first stage engines as part of a routine pre-flight test for the upcoming launch of the Arabsat 6A communications satellite.

United Launch Alliance technicians raised the first stage of the company’s next Atlas 5 rocket onto a mobile launch platform at Cape Canaveral Thursday, kicking off the launch vehicle’s build-up for a mission scheduled for liftoff May 16 with the U.S. military’s hush-hush X-37B spaceplane.

The mobile service tower retracts from the Atlas 5 rocket, revealing the 197-foot-tall vehicle for liftoff from Vandenberg Air Force Base, California, carrying the classified NROL-42 national security payload for the U.S. government.