Vision and Voyages for Planetary Science in the - Solar System ...

FIGURE 8.12 Galileo color image of Europa, showing the disruption of the ubiquitous ridged plains by
chaos, associated with dark hydrated material which may be derived from the subsurface ocean. Smallscale
patches of brighter color are artifacts resulting from noise in the original data. The image is about
150 km across. SOURCE: NASA/JPL.
After the jovian tour phase, JEO would enter orbit around Europa and spend the first month in a
200 kilometer circular orbit before descending to a 100 kilometer circular orbit for another 8 months. The
mission would end with impact onto Europa.
Flagship-class missions historically have a greatly enhanced science return compared to smaller
missions—the whole is greater than the sum of the parts—so the higher cost of a flagship mission
compared to a New Frontiers-class mission is well justified. Europa remains the highest priority for
satellite exploration, and a Europa mission deserves sufficient resources to realize its phenomenal
scientific potential. Therefore, a Europa mission should take precedence over smaller missions to outer
solar system targets during the next decade. If ESA’s Jupiter Ganymede Orbiter also flies, then the
science return will be even higher.
The intense jovian radiation environment remains the largest challenge for the JEO spacecraft and
its instruments, though thanks to extensive study of the issue in the past decade, the risks and mitigation
strategies are now well understood. This work has included characterization of the radiation hardness of
key electronic components (including development of an “approved parts and materials list” for use by
instrument developers), improved modeling of expected radiation fluxes, and detailed consideration of
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