BAY ST. LOUIS, Miss. - NASA will test one of the rocket engines it is developing for its new launch vehicles at the Stennis Space Center in Mississippi. The agency will build a new test stand at Stennis for the J-2X engine. The engine will power the upper stages of NASA's Ares I and Ares V rockets.

Stennis already is home to Apollo-era test stands that have served the nation's space program through the shuttle era. The newly proposed structure will be the first large test stand built at the center since the 1960s. Unlike the older structures, the new 300-foot-tall, open-frame design will allow engineers to simulate conditions at different altitudes.

NASA engineers need to simulate various altitudes to test the J-2X's ability to function as a second stage engine for the Ares I crew launch vehicle and the Earth Departure Stage engine for the Ares V cargo launch vehicle. To do that, the test stand will generate approximately 4,620 pounds per second of steam and use it to reduce the engine test cell pressure.

NASA will complete the new stand in time to support the first J-2X engine test in December 2010. An existing test stand at Stennis also is being modified to test the J-2X engine at sea level conditions.

Ares I will launch the Orion spacecraft, taking astronauts to the International Space Station no later than 2015, then to the moon by 2020. The Ares V will carry cargo and components into orbit for trips to the moon and later to Mars. The new spacecraft are key components of NASA's Constellation Program.

"This new test stand will enable the critical testing needed to verify the Ares I upper stage engine performance at altitude conditions," said Stennis Center Director Rick Gilbrech. "The Apollo-era test stands have served us well over the last forty years, and I'm excited that NASA will have a new stand to help us accomplish these new goals."

The test stand, along with its control center, propellant barge docks and access roadways, will be built in Stennis A Complex.