Compared with the interplanetary probes of the last decades, how can the next generation in the next decades be miniaturized? Not really meaning small in size, but low in mass. The purpose would be to allow a larger part of the mass budget for science instruments. And what are the most important developments in this direction which have already happened between for example Voyager and New Horizons?
How do different functions contribute to mass on an interplanetary probe today?
I have some naive imaginations:
A physical structure which can survive launch from Earth. But maybe the individually sturdy components of a probe could be assembled to a fragile structure in microgravity at the ISS? For example, solar panels and radio dish could be folded out manually, without the probe having to carry the unfolding mechanism onboard.
Power system and thermal control. I suppose an RTG is as about slim as it can be. But what about the heat distribution system?
Radiation protection. One necessarily needs mass to stop cosmic rays. But it is only electronics which is sensitive to radiation (right?) So if one has multiple redundancies and can reprogram damaged chips to work around their damages, maybe shielding could be replaced by several almost massless microchips?
Communication with Earth. How thin and light can you make a reflecting radio dish? The rest, I suppose, is electronics which is of negligible mass already.
Orientation. Maybe one could use solar pressure instead of rotating wheels, or fuel for rocket engines?