Photos: Tuesday’s Atlas 5 rollout

A dramatic automatic abort 7.5 seconds before the planned liftoff of a United Launch Alliance Delta 4-Heavy rocket Saturday night kept the towering launcher on the pad at Vandenberg Air Force Base, California, with a top secret spy payload for the National Reconnaissance Office.

If all goes according to plan, engineers in southern Mississippi later this month will load cryogenic propellants into the core stage of a rocket NASA says will launch astronauts back to the moon, exposing its tankage and internal plumbing to extreme operating conditions hundreds of degrees below zero for the first time. The fueling test — a major milestone in its own right — is a precursor to a high-stakes eight-minute test-firing of the Space Launch System’s four shuttle-era main engines planned as soon as November.

SpaceX’s Falcon 9 rocket is set for liftoff from Cape Canaveral on Tuesday carrying the U.S. Air Force’s next GPS 3-series navigation satellite destined for an orbit more than 12,000 miles above Earth.