One of the interesting things revealed by the probes Cassini and New Horizons was the very high radiation encountered around Jupiter and Saturn. Gravity and internal pressures was also considerably higher with an incredibly high gravitational field being generated.
Quote : The subsequent and far more technologically advanced
Voyager spacecraft had to be redesigned to cope with the radiation levels. Over the eight years the
Galileo spacecraft orbited the planet, the probe's radiation dose far exceeded its design specifications, and its systems failed on several occasions. The spacecraft's
gyroscopes often exhibited increased errors, and
electrical arcs sometimes occurred between its rotating and non-rotating parts, causing it to enter
safe mode, which led to total loss of the data from the 16th, 18th and 33rd orbits. The radiation also caused phase shifts in
Galileo's ultra-stable
quartz oscillator.
https://en.wikipedia.org/wiki/Exploration_of_Jupiter
The other interesting aspect is the moons like Europa have their own heat source caused by a slightly elliptical orbit around Jupiter which in turn creates varying pulls, resulting in friction.