WASHINGTON -- Northrop Grumman beat out Boeing and Lockheed Martin to win a $400 million contract to help NASA design the proposed multibillion dollar Jupiter Icy Moons Orbiter (JIMO) mission.

The U.S. space agency hopes to launch the nuclear-powered JIMO around 2015 on an ambitious mission to orbit three of Jupiter's planet sized moons.

Under the contract, which runs through 2008, Northrop Grumman will work with a government team led by the Jet Propulsion Laboratory to complete preliminary design of what would be NASA's first nuclear electric propulsion spacecraft.

"We have assembled an exceptional team of professionals to take us into the next phase of the mission," John Casani, the JIMO project manager at JPL, said in a Sept. 20 statement announcing the awards. "To see the mission evolve is rewarding, and I am confident a good team is in place  to move us forward."

NASA intends to select the scientific instruments for the mission at a later date through a competitive process.