NASA has chosen the RS-68 engine to power the core stage of the agency's heavy lift cargo launch vehicle intended to carry large payloads to the moon.

The announcement supersedes NASA's initial decision to use a derivative of the space shuttle main engine as the core stage engine for the heavy lift launch vehicle.

The cargo launch vehicle will serve as NASA's primary vessel for safe, reliable delivery of resources to space. It will carry large-scale hardware and materials for establishing a permanent moon base, as well as food, fresh water and other staples needed to extend a human presence beyond Earth orbit.

Recent studies examining life-cycle cost showed the RS-68 is best suited for NASA's heavy-lift cargo requirements. The decision to change the core stage engine required an increase in the size of the core propulsion stage tank, from a 27.5-foot diameter tank to 33-foot diameter tank, to provide additional propellant required by the five RS-68 engines.

The RS-68 is the most powerful liquid oxygen/liquid hydrogen booster in existence, capable of producing 650,000 pounds of thrust at sea level. In contrast, the space shuttle main engine is capable of producing 420,000 pounds of thrust at sea level. The RS-68, upgraded to meet NASA's requirements, will cost roughly $20 million per engine, a dramatic cost savings over the shuttle main engine.

The prime contractor for the RS-68 engine is Pratt & Whitney Rocketdyne of Canoga Park, Calif. Pratt & Whitney Rocketdyne is the same company that manufactures the shuttle main engine.

The RS-68 is used in the Delta IV launcher, the largest of the Delta rocket family developed in the 1990s by the U.S. Air Force for its evolved expendable launch vehicle program and commercial launch applications.

The cargo launch vehicle effort includes multiple project element teams at NASA centers and contract organizations around the nation and is led by the Exploration Launch Office at NASA's Marshall Space Flight Center in Huntsville, Ala.

The project office is part of the Constellation Program led by NASA's Johnson Space Center in Houston. Constellation is a key program of NASA's Exploration Systems Mission Directorate in Washington.

For information about NASA's exploration efforts, visit:

http://www.nasa.gov/exploration

For information about NASA and agency programs, visit:

http://www.nasa.gov/home

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