Photos: Atlas 5 rocket aims for International Space Station

SpaceX is gearing up for the first commercial launch of its powerful Falcon Heavy rocket as soon as early April with a communications satellite for Arabsat, and the U.S. Air Force hopes the two side boosters from the Arabsat mission can be safely landed and reused for the military’s first Falcon Heavy mission this summer, an exercise officials said will help certify previously-flown hardware for future national security launches.

NASA astronaut Nick Hague and Roscosmos cosmonaut Alexandr Gorbunov arrived in Florida on Saturday afternoon ahead of their final launch preparations. A flight readiness review occurred on Monday, Sept. 23.

The Atlas 5 countdown leading up to Friday’s early morning liftoff from Cape Canaveral with Boeing’s Starliner crew capsule will be several hours longer than usual.