An interesting new-to-me proposal is for a space observatory that would observe the Jupiter system for years from the L1 position – sort of a hybrid between a (Earth orbiting) space telescope and a planetary orbiter. This would be "outside" the Jupiter system, but about 15 times closer to it than a mission like HST, observing it from Earth orbit.
It's one of several solar system space telescope missions outlined here.
https://www.lpi.usra.edu/opag/meetings/opag...yanagi_6012.pdf
Roughly speaking, a 50-cm telescope at Jupiter's L1 would provide imagery about 3 times sharper than HST. I imagine that the operations would consist primarily of continuous observations of Jupiter, Io, and Europa. Jupiter and Io, obviously, provide known, constant variation in activity. Europa's plumes would be another phenomenon to monitor if possible. Ganymede and Callisto less obviously provide dynamic phenomena to monitor, but would merit enough observations to determine what can be seen, including aurora. Finally, a telescope located there would provide some opportunistic imaging of the outer satellites. In favorable circumstances, an outer satellite might be located about three times closer to this telescope than Jupiter itself is, providing about 10x the resolving power of HST. That would allow for the imaging of detail on the larger ones.