Photos: Atlas 5 rocket aims for International Space Station

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.

Virgin Orbit completed a captive carry flight of its liquid-fueled air-launched rocket Sunday over the Pacific Ocean in what the company described as its final development test before the small satellite launcher’s first mission to space.

The United Launch Alliance Atlas 5 rocket stands poised for flight with the Air Force’s X-37B spaceplane and a batch of CubeSats including the LightSail. The rocket was rolled to Complex 41 on Tuesday in preparation for launch on Wednesday.