Video: Time-lapse of Atlas 5’s rollout for launch of GOES-S (members only)

SpaceX’s first Falcon Heavy launch for the U.S. Air Force took a major step closer to liftoff with a hold-down engine firing Wednesday night at launch pad 39A at NASA’s Kennedy Space Center in Florida. Liftoff with a cluster of experimental satellites and weather monitoring craft is set for June 24.

A United Launch Alliance Atlas 5 rocket blasted off from Vandenberg Air Force Base in California at 5:49 a.m. local time (8:49 a.m. EDT; 1249 GMT) Thursday on the classified National Reconnaissance Office NROL-55 mission.

Scientists eager for answers to long-standing questions about the geology of Mars will get a lift Saturday with the blastoff from California of an Atlas 5 rocket with NASA’s InSight mission, a robotic landing craft that will take the pulse and temperature of the red planet.