Photos: Atlas 5 on the pad awaiting liftoff on NROL-52

Boeing engineers have completed hotfire testing on a flight-like model of the Starliner crew capsule, clearing a major hurdle before a pad abort test and a demonstration flight to the International Space Station later this summer, Boeing announced Friday.

A covert communications relay station to route spy satellite data directly to users was successfully launched by a million-pound Atlas 5 rocket overnight.

The Atlas 5 rocket emerges from the Vertical Integration Facility for rollout to Complex 41 at Cape Canaveral in preparation to launch the Orbital ATK Cygnus resupply ship to the International Space Station. Liftoff is set for Thursday at 5:55 p.m. EST.