Photos: Atlas 5 rolls out for launch

United Launch Alliance will need to lure commercial customers to ensure the economic viability of its new Vulcan rocket, which is set to debut in 2019 just as the rate of U.S. military satellite launches is due to take a dip.

SpaceX’s next Falcon 9 rocket arrived at launch pad 39A Thursday for a customary hold-down engine firing. Liftoff from Florida’s Space Coast is targeted for Sunday, weather permitting.

Attempts to restore the U.S. Air Force’s newest weather satellite to service have ended, a military spokesperson said Wednesday, cutting a planned five-year mission short less than two years after it launched.