High Quality Content by WIKIPEDIA articles! Atlas V is an active expendable launch system in the Atlas rocket family. Atlas V was formerly operated by Lockheed Martin, and is now operated by the Lockheed Martin-Boeing joint venture United Launch Alliance. Each Atlas V rocket uses a Russian-built RD-180 engine burning kerosene and liquid oxygen to power its first stage and an American-built RL10 engine burning liquid hydrogen and liquid oxygen to power its Centaur upper stage. The RD-180 engines are provided by RD AMROSS and the RL10 engines by Pratt Whitney Rocketdyne. Some configurations also use strap-on booster rockets made by Aerojet. The payload fairings, which can be 4 or 5 meters in diameter and three lengths, are made by RUAG Space. The rocket is assembled in Decatur, Alabama; Harlingen, Texas; San Diego, California; and at United Launch Alliance`s headquarters near Denver, Colorado.