How would "Fixing" Venus and Mars effect Earths orbit?

[madd0ct0r]

Query - could we use the same carbon dioxide scrubbing tech being developed now for 'cleaning' the venus atmosphere?

[Surlethe]

Setting aside plausibility questions, only if you eject that CO2 out of the planet's gravity well or inject it deep into the crust.

[madd0ct0r]

I was thinking more splitting it, using the oxygen to stabilize other stuff in the atmosphere and the carbon can be stored as oil, or fired at mars to raise the albedo.

[eion]

you could only create oil with the carbon if you had some hydrogen, as in a hydro-carbon chain. Venus lacks hydrogen due to a lack of a magnetic field exposing the atmosphere to the solar wind.

One very easy way to convert the CO2 into something useful would be to introduce water ice to Venus. With the high temperature and large concentration of CO2, the only component of the Bosch reaction missing is the hydrogen. You'd need a lot of hydrogen, 4×1019 kg to be precise. But in the grand scheme of things that isn't much, it's only 1/329 of Pluto's mass, and there's a lot of objects out in the Kuiper belt brimming with water ice.

Use a nice Nuclear Thermal Rocket (Or likely a whole array of them) to slowly deorbit the KBO(s), using the excess volatiles as the rocket fuel. Crash it into Venus, and with a little time the water will break up into its elements, and the hydrogen will bond with the CO2 in the high temperature environment, reforming into water and leaving elemental carbon behind.

Reacting the entire 4×1019 kg of hydrogen will give you enough water to cover 80% of the surface with water, as opposed to Earth's 70%, but with only 10% of the amount of water, and leave you with a 3 bar atmosphere of mostly nitrogen.

Then you'll have thousands and thousands of years before the lack of a magnetic field strips away the hydrogen again. Plenty of time to either bring in more hydrogen or erect a magnetic field in some way.

[madd0ct0r]

you could only create oil with the carbon if you had some hydrogen, as in a hydro-carbon chain. Venus lacks hydrogen due to a lack of a magnetic field exposing the atmosphere to the solar wind.

take the gas, compress it and electrolysis?

i think your method sounds better, especially as I have no clue what i'm talking about.

[eion]

I only know enough to know I don't know very much at all. I'm sure one of our members who didn't struggle with chemistry once stoichiometry (and therefore my longtime foe, mathematics) entered the game will be along soon to point out a flaw in my reasoning.

In my limited reading experience though, the methods of terraforming aren't the hard part, it's the execution. Terraforming Venus is more difficult than Mars or even the Moon due to its larger size, impossibility of locating anything on the surface, high-escape velocity, etc.

With the former, you really just need to do what we humans have been doing to Earth for the last century or so: global warming. Warm up Mars enough and you get a pretty dense atmosphere of CO2, which will continue to warm the planet and melt the water ice, and then you’ll just need fine-tuning. The same can be done on a smaller scale with the Moon, though you'll likely need to introduce far more water to achieve the effect. In either case, once you've built up a dense enough atmosphere it will take some time (thousands of years) for it to fly off into space, and that's assuming you do no maintenance