Delta IV Common Booster Core (CBC) rocket

The Delta IV is a family of Delta rockets designed by Boeing's Integrated Defense Systems division and built in United Launch Alliance's facility in Decatur, Alabama with final assembly at the launch site by United Launch Alliance. The rockets were designed for the United States Air Force Evolved Expendable Launch Vehicle (EELV) program and commercial satellite business, and are intended to reduce the cost and effort needed to launch payloads into orbit.

The first stage of a Delta IV consists of one, or in the Heavy variety three, Common Booster Cores (CBC) powered by a Rocketdyne RS-68 engine. Unlike most first-stage rocket engines, which use solid fuel or kerosene, the RS-68 engines burn liquid hydrogen and liquid oxygen.