Stats: Delta 4 history and manifest

On its third flight Monday night, SpaceX’s Falcon Heavy rocket will fly to three different orbits with two dozen spacecraft on a mission set to last more than six hours, prompting SpaceX founder Elon Musk to declare it the company’s “most difficult launch ever.”

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.

Replays from cameras at the Baikonur Cosmodrome capture the launch of a Soyuz booster from different angles.