Pratt & Whitney Rocketdyne Inc. received a $1.2 billion contract from NASA to develop the upper stage engine for the Ares 1 and Ares 5 launch vehicles, the agency announced July 16.

The contract to design, develop, testing and evaluate the J-2X engine includes ground and test flight engines. Ares 1 will transport the Orion crew exploration vehicle to low-Earth orbit, while Ares 5 will be used to launch science and exploration payloads as well as components needed to go to the moon and to Mars.

Work under the new contract will run through 2012, and engines for operational missions will be purchased through a separate contract.

NASA awarded the contract on a sole-source basis, determining that no other existing capability meets its architecture requirements.