Reporting from the recent American Geophysical Union fall meeting in San Francisco, Astrobiology Magazine writes Friday the mission's development follows NASA's Galileo spacecraft, orbiting Jupiter since 1995, finding evidence for subsurface oceans on the moons Callisto, Ganymede and Europa.

The Jupiter Icy Moons Orbiter (JIMO) would spend month-long stints circling the three moons, which are believed to have vast oceans tucked beneath thick covers of ice.

Scientists are keen to study the Jovian system because of its complexity. The planet and its stable of moons represent, in many ways, a miniature solar system.

"These are worlds in their own right," said Ron Greeley, of Arizona State University, Tempe.

Jimo won't launch until at least 2011. At the Dec. 8 meeting of the American Geophysical Union, scientists prepared a briefing on the mission's progress.