Photos: Gantry rolled back to reveal Orion

A decade in the making, the core stage for NASA’s first Space Launch System heavy-lift rocket rolled into the Vehicle Assembly Building at the Kennedy Space Center Thursday to join up with twin solid rocket boosters and an Orion capsule for an unpiloted test flight around the moon.

NASA’s Orion spacecraft will fly a two-orbit, four-hour mission for Exploration Flight Test No. 1 in Earth orbit to test systems.

On its second flight, SpaceX’s mammoth Falcon Heavy rocket hurled an Arabsat communications satellite the size of a school bus nearly one-quarter the way to the moon Thursday, days after NASA’s administrator identified the privately-developed rocket as a backup to the agency’s behind-schedule Space Launch System for sending astronauts back to the lunar surface.