The Jupiter Icy Moons Orbiter (JIMO) mission which was to have launched as early as 2015 will be delayed. Details will be announced Monday, February 7th during the roll out of the NASA 2006 fiscal year budget submission.
The JIMO mission is scheduled to orbit three planet-sized moons of Jupiter, Callisto, Ganymede and Europa, which might harbor vast oceans beneath their icy surfaces. The mission would orbit each of these moons for extensive investigations of their makeup, their history, and their potential for sustaining life.
The orbiter would make use of a new electric propulsion system powered by a nuclear fission reactor which would enable a realistic mission for orbiting these three moons one after the other and would also pave the way for the rest of the outer solar system to explored in later missions.