Question

What is the radiation background on Europa?

Charged particles trapped in the magnetosphere of Jupiter create a high radiation environment when they strike the surfaces of the two inner Galilean satellites, Europa and Io, or when they hit a spacecraft operating in these parts of the jovian system. The most extensive study of Europa was carried out by the NASA Galileo spacecraft, which repeatedly approached this moon. However, the spacecraft spent most of its time farther from Jupiter, just plunging briefly into the heavy radiation areas for each flyby of Europa. Near the surface of Europa, the radiation doses are several times higher than in the Van Allen Belts of the Earth’s magnetosphere. Studies carried out a decade ago of a possible Europa orbiter indicated that the spacecraft would survive only about a month once it went into orbit 200 km above the surface. More recent studies, however, suggest that it is possible to use radiation-hardened and shielded electronics to extend the lifetime of an orbiter substantially. For a Europa lander, a few meters of ice provide effective shielding, so if we could get below the surface, the high radiation levels would not be a problem.

David Morrison
NAI Senior Scientist
November 4, 2009