Quote Originally Posted by Leewei View Post
The calculations I put up included the assumption that we'd only need to cool 1% of Venus's mass - the atmosphere and the crust.
I did like the idea of that calculation, but I'm pretty sure that the crust is a lot less than 1% of Venus's mass. Earth's crust is on average something like 20 miles thick, call that 40km to be generous. Earth is 6,300 km in radius, so (approximating wildly) the crust is something like 0.3% of the volume, we don't need Venus's crust to initially be quite that thick, though it would be nice if it dropped to the right sort of temperature reasonably quickly.