Photos: Predawn launch of Atlas 5

When the next Delta 4 rocket flies in July, as well as all future ones to come, the enhanced RS-68A main engine will power the boosters off the launch pad.

A hydrogen-fueled main engine and four solid rocket boosters combined to propel a United Launch Alliance Delta 4 rocket off its launch pad at Cape Canaveral on March 15, successfully sending a U.S. Air Force communications satellite into orbit.

Cape Canaveral was the point of origination for the United Launch Alliance Atlas 5 rocket and the classified NROL-52 payload.