WASHINGTON, May 12 (UPI) -- The U.S. space agency says it's completed the first tests of the J-2X engine that will power the upper stages of the Ares I and Ares V rockets.

The Ares rockets are key components of the National Aeronautics and Space Administration's Constellation Program. Ares I will launch the Orion spacecraft that will take astronauts to the International Space Station and 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.

"This series of tests is an important step in development of the J-2X engine," said Mike Kynard, manager of the upper stage engine for the Ares Projects at NASA's Marshall Space Flight Center in Huntsville, Ala. "We started with a number of objectives and questions we needed answers to as we work to complete designs of the J-2X engine. The data we have gained will be invaluable as we continue the design process."

The J-2X engine is being designed to produce 294,000 pounds of thrust; the original J-2 produced 230,000 pounds of thrust. The tests were completed at NASA's Stennis Space Center, located near Bay St. Louis, Miss.