re: Let's kick up the debate here on more ambitious projects. How about a Venus Sample Return Mission?
You have some interesting ideas.
How about using Thermocouple or (Magnetohydrodynamics, using the flow of hot gasses in a magnetic field to generate electricity.) The subsurface might provide a temperature differential.
It has always intrigued me that there are temperate zones on Mercury Ie the polar regions. Temperate zones on Venus?
Why not take advantage of those temperate zones?
Why not auger under the surface?
Could a round balloon type probe survive by slowly descending to the surface?
How about gliding down?