>> One thing you need to keep in mind regarding any ideas of terraforming Venus is that Sagan’s “super greenhouse(TM)” theory is a bunch of bullshit. Venus is basically hot because it’s a fairly new planet which simply hasn’t had time to cool off. There’s likely nothing we could possibly do that would cool it in any sort of a hurry. <<
Venus is hot because of the lack of tectonic plates, the planet builds up so much heat in it’s core that it resurfaces itself every 500 million years or so. There is no tectonic movement to subduct or release carbon. So every 500 million years the planet builds up so much internal heat that it resurfaces itself and resales all of the pent up gasses in the crust. Too much at once and it covers the planet in a big blanket.
The best plan I have seen for colonizing Venus is to make floating cities in which the “lifting gas” in an Oxygen/Nitrogen mix. you build more and more floating cities as you process the atmosphere into something more habitable and even use mass drivers to toss off the excess gasses. Within a few thousand years the cities touch down on the planet and it has a breathable atmosphere.
Venus is very likely no more than about 10K years old, tops. Best book on the topic is still Velikovsky’s “Worlds in Collision”. Venus is the main thing which keeps me from being a young Earth creationist since the Earth and Mars don’t look like Venus at all and have to be significantly older.