Snapshots from Atlas 5 launch

A towering mobile platform for the agency’s Space Launch System arrived at launch pad 39B Friday at the Kennedy Space Center in Florida for a sequence of water and propellant flow tests, swing arm checkouts and other rehearsals that should conclude with managers declaring the spaceport’s ground systems ready to support the first SLS launch campaign by the end of the year.

Mission managers are weighing a motley mix of weather models, safety criteria and astronaut workload considerations as they decide when SpaceX’s Crew Dragon spacecraft might have the best chance to launch from the Kennedy Space Center.

The head of NASA’s human spaceflight programs has abruptly resigned, announcing his departure from the space agency two days before before he was to chair a crucial readiness review ahead of the launch of the first crewed U.S. space mission in nearly a decade.