Live coverage: SpaceX cargo ship arrives at 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.

Seven astronauts and cosmonauts are gearing up for launches April 9 and April 22 to the International Space Station, replacing seven outgoing crew members set to land in Kazakhstan and off the coast of Florida on April 17 and April 28.

Leaving six crewmates behind in orbit, a Russian commander, his NASA co-pilot and a first-time flier from the United Arab Emirates undocked from the International Space Station early Thursday, executed a fiery plunge back to Earth and landed safely on the steppe of Kazakhstan.