The JIMO mission is in its early planning stage and liftoff is not to be expected before 2012, probably later.
JIMO will have a large number of revolutionary features. It will be propelled by ion propulsion and powered by a small nuclear reactor.
Thermo-electric couples will convert reactor heat into electricity. A thousand times conventional spaceprobe electricity output will open up opportunities like flying a full scale ice-penetrating radar system and a strong high-bandwidth data transmitter.
Electric propulsion using ion drives will also make it possible to go into and leave orbits around Jupiter moons, whereby more thorough observation and mapping will be possible than during short time fly-by maneuvers.
The reactor will be positioned in the tip of the spacecraft behind a strong radiation shield protecting sensitive probe equipment. The reactor will only be powered up once the probe is well out of Earth orbit, so that the amount of radionuclides that must be launched into orbit is minimized. This configuration is thought to be less risky than the radioisotope thermoelectric generators (RTGs) used on previous missions to the outer solar system. RTGs contain large amounts of highly radioactive material generating heat for the thermoelectric couples.The JIMO spacecraft