Watch live: Vice President Pence visits Kennedy Space Center

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.

Originally expected to take off Saturday, the launch of SpaceX’s first operational Crew Dragon mission was delayed to Sunday because of expected high winds at the Kennedy Space Center and weather off-shore where the Falcon 9 rocket’s first stage will attempt to land on a SpaceX droneship. The company plans to re-use the booster for the next Crew Dragon flight.

A top secret payload developed in secrecy for the U.S. government is set to ride into orbit from Florida’s Space Coast aboard a SpaceX Falcon 9 rocket Thursday.