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Comment by miohtama | Hacker News Reader

TIL

> The radiation environment around Europa is punishing; an astronaut standing on the surface would get a fatal dose in about a day

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True for all the Galilean Moons more or less. Their orbits all lie within the Jovian equivalent of the Van Allen belts. And Jupiter's magnetic field is much stronger than earth's.

Not Callisto. Being within Jupiter's magnetosphere but out of reach of Io's shenanigans makes it one of the mildest radiation environments in the solar system.

I'm interested in learning more about "Io's shenanigans". What are you referring to?

Io is in orbital resonance with Europa and Ganymede, which causes its orbit to be slightly elliptical. Due to Jupiter's immense gravitational field strength, Io experiences a very high changing tidal force, which causes a changing stress and strain on the entire structure of Io, which causes tidal heating due to friction. This makes it by far the most volcanically active body in the Solar System. Its surface is regularly completely resurfaced, and is covered in sulfur compounds.

https://science.nasa.gov/jupiter/jupiter-moons/io/facts/#h-m...

Jupiter and Io have a very interesting symbiosis. Jupiter melts Io to form dusty volcanos. It then magnetically sweeps Io clean of dust. The dust forms a plasma ring that enhances the same magnetic field.

Not true at all, the daily dose on Ganymede (which has a magnetic field of its own) is ~70 mSv/day, and Callisto is 0.1 mSv/day.

Io, meanwhile, is 35 Sv/day. Location really matters among the four Galilean moons.

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