Live coverage: Atlas 5 countdown and launch journal

The first Falcon 9 flight of 2016 is ready for takeoff Sunday from Vandenberg Air Force Base in California, and these photos show the rocket positioned on its launch mount overlooking the Pacific Ocean.

Blue Origin said Sunday that it lost a set of powerpack hardware for its BE-4 engine during a ground test mishap, dealing at least a minor setback to the development of a powerful U.S.-made propulsion system that United Launch Alliance says is the leading candidate to power the first stage of its next-generation Vulcan rocket.

The 8-million-pound mobile service tower is retracted from around the Atlas 5 rocket, revealing the 19-story-tall vehicle for liftoff from Vandenberg Air Force Base, California, on NROL-55.