"Carsten Nielsen" wrote in message
om...
"Mike Dworetsky" wrote in message
...
(b) far enough from the primary not to be badly affected by
magnetic fields of the primary (in the case of Jupiter this could be a
problem unless the atmosphere is protective),

Or its own magnetic field, one of the Jupiter moons has its own.

Would Earth's present magnetic field protect us if Earth was to
replace Ganymede or Callisto, or Europa for that matter ?


Earth's magnetic field undergoes reversals, and during these the
"protective" effect is much reduced. Jupiter's magnetic field is much
stronger than Earth's, even at large distances from the planet. The main
thing that has to be protected against is charged particles and solar wind.
Jupiter has a lot of charged particles in its field.


(c) not affected by internal
tidal heating effects such as those that cause Io to be volcanic. The
last
of these could be avoided if the large moon is the only large natural
satellite and has a circular orbit, or is orbiting a long way out, like
Callisto. Maybe one would want just enough internal tidal heating to
generate volcanic activity leading to outgassing of CO2, SO2, S2, NO2,
NO,
and H2O, so that a breathable atmosphere could eventually evolve.

So, perhaps better be in Europa's orbit than Callisto's ?


Possibly. If the body is large enough and made of the right materials, like
Earth, it will have volcanism all by itself, so it could be at a much larger
distance.

--
Mike Dworetsky

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