Terraformed Venus

[Solauren]

What about hitting it with some comets post KBO collision? Those things would melt and suck up heat.

I'm still in favor of some kind of mechnical atmospheric removal system, if only to speed the process up, and to control where the excess atmosphere goes.

[GrandMasterTerwynn]

What about hitting it with some comets post KBO collision? Those things would melt and suck up heat.

Umm. No. You would be adding heat when those cometary masses impact the planet and convert all that kinetic energy into heat. Sure you could probably magick up some way of getting them down slowly, but then what you're suggesting would not actually remove any heat. The total heat quantity of Venus would not change, only how it's distributed. This is because of thermodynamics.

I'm still in favor of some kind of mechnical atmospheric removal system, if only to speed the process up, and to control where the excess atmosphere goes.

Xeriar's method is a mechanical atmospheric removal system. There are only two ways to reduce a planet's atmosphere. The first is to chemically lock it up in the rocks which comprise the planet. The second is to accelerate it to a mean velocity higher than the planet's escape velocity, causing it to go screaming off into space. To increase the velocity of all those gas molecules involves increasing their kinetic energy. As their mean velocity is a very tiny fraction of the planet's escape velocity, that means adding a lot of energy.

The only other plausible mechanical methods of removing Venus' atmosphere involves moving the entire planet out to the orbit of Jupiter, waiting for the atmosphere to freeze out, and then lofting it all into orbit with mass drivers. Or else, construct a gigantic space-going laser and heat the planet to the point where the atmosphere expands to the point where most of it gets carried off by the solar wind. Of course, that would leave a glowing ball of molten, dry rock, requiring the importation of water via comets. Xeriar's method is the most efficient one, as it combines the blast the atmosphere off step with the infuse Venus with volatiles step without the giant laser, or the hassle of playing interplanetary pool with Venus.

[Surlethe]

Dropping comets onto Venus would only work if you could somehow lower them through the atmosphere in such a manner that you siphon off their GPE and KE with a non-frictional force.

[Ariphaos]

I'm pretty sure my method is more interplanetary pool than just lobbing small comets at it is, since the idea of dropping a KBO or two onto it is, in part, born out of a desire to shift the planet's orbit up, which makes greenhouse management easier in the long term.

[Guardsman Bass]

Or else, construct a gigantic space-going laser and heat the planet to the point where the atmosphere expands to the point where most of it gets carried off by the solar wind. Of course, that would leave a glowing ball of molten, dry rock,

I like this idea, not the least of which would be that it would provide quite an amazing site from Earth. I'd definitely take the "molten, dry rock" ball route; it'd certainly be easier to add an atmosphere to the planet rather than trying another way to get rid of 90 bars' worth of atmosphere.