Lets take an Earth mass moon orbiting a Jupiter mass planet with an orbit of say 18 hours and no other moons within 10 million miles with almost 0 eccentricity. Can the moon in question have limited geological activity or does the proximity of the moon to the host planet guarantee activity. I realize Io has intense activity because of the distance to Jupiter, the eccentricity and the other moons flexing Io. Just curious.
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"almost 0 eccentricity"
The key word is "almost"
If you could have the satellite on an orbit of EXACTLY 0 eccentricity
AND
with its rotation "spin locked" (always presenting same face)
THEN
you would have no tidal heating.
But, in practice, this does not happen because the Sun (a 3rd object in the system) will have an effect on the orbit itself -- it will cause an effect similar to a tide on the orbit itself, as if the orbit was a separate object.
Therefore, the 0 eccentricity will not remain exactly 0.
Almost, in this case, will guarantee that the rotation period will not exactly match the orbital movement (the difference is called libration). This difference is the main cause of "tidal" heating in Io.
The key word is "almost"
If you could have the satellite on an orbit of EXACTLY 0 eccentricity
AND
with its rotation "spin locked" (always presenting same face)
THEN
you would have no tidal heating.
But, in practice, this does not happen because the Sun (a 3rd object in the system) will have an effect on the orbit itself -- it will cause an effect similar to a tide on the orbit itself, as if the orbit was a separate object.
Therefore, the 0 eccentricity will not remain exactly 0.
Almost, in this case, will guarantee that the rotation period will not exactly match the orbital movement (the difference is called libration). This difference is the main cause of "tidal" heating in Io.
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The Radiation from the Jupiter mass planet is what worries me. I believe the less mass the moon has and whether or not its interior is already molten may help, also. Since its orbit is stable and secure, the stress on the moon will be very little, since it is in the same position relative to the Jupiter mass planet at all times. Unlike Io, it won't be stretched and pulled. Most of its heat would probably come from radioactive elements in its interior and from the larger planet (in the form of radiation.)