# Thread: How much quicklime would it take to terraform Venus?

1. ## How much quicklime would it take to terraform Venus?

If you could drop a load of god knows how many teratons of quicklime into Venus's atmosphere, how much would it take before you reduced the CO2 to near Earth levels?

2. With one significant digit accuracy, you need a cube of quicklime 100 km on a side.

3. A large asteroid's worth of the stuff. I don't think that is available.

I think another way of doing it might be preferable; importing hydrogen to convert the CO2 into water and carbon, for example. Even then I think the atmosphere is too massive for it to all be removed by this method, and some of it will need to be physically removed and exported.

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You would need, assuming 100&#37; absorbtion of CO2, about 1.23 tons of quicklime (CaO) for every ton of atmosphere. That would be about 10,000 tons for every square meter of Venus's surface, or a layer about 3 kilometers deep.

Venus has a surface area of about 460,000,000 square kilometers so this would be about 1,380,000,000 square kilometers which would be a cube over 1,000 km across. This is a bit more than Ilya's figure, but I am often wrong about these sorts of things.

5. Stick an orbital tube in it and suck away the atmosphere. It's got a vacuum at one end, after all...

ADDED: And sell the CO2 to new space habitats to add to their ecosystems. Gotta get some use out of it.
Last edited by Noclevername; 2007-May-23 at 10:18 PM. Reason: added

6. Carbon and oxygen separately would be very much in demand around the Solar system.
The Moon needs carbon if it is to support any amount of population. Mars could do with more CO2 as a greenhouse gas. Every orbiting habitat need oxygen; and carbon may become the building material of choice if the promises of nanotechnology bear any fruit.

7. Originally Posted by Ronald Brak
You would need, assuming 100% absorbtion of CO2, about 1.23 tons of quicklime (CaO) for every ton of atmosphere. That would be about 10,000 tons for every square meter of Venus's surface, or a layer about 3 kilometers deep.

Venus has a surface area of about 460,000,000 square kilometers so this would be about 1,380,000,000 square kilometers which would be a cube over 1,000 km across. This is a bit more than Ilya's figure, but I am often wrong about these sorts of things.
You added an extra zero in "10,000 for every square meter of Venus's surface". On Earth every square meter has 10 tons of air over it. On Venus it is 90 times more -- 900 tons of mostly CO2, hence about 1400 tons of quicklime.

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You added an extra zero in "10,000 for every square meter of Venus's surface". On Earth every square meter has 10 tons of air over it. On Venus it is 90 times more -- 900 tons of mostly CO2, hence about 1400 tons of quicklime.
Thanks for that. As you can see, I am often wrong about these sorts of things. 3km does seem sort of excessive, doesn't it?

9. Originally Posted by Noclevername
Stick an orbital tube in it and suck away the atmosphere. It's got a vacuum at one end, after all...

ADDED: And sell the CO2 to new space habitats to add to their ecosystems. Gotta get some use out of it.
For some reason (by no suprise), this picture came to mind.

Anyway; just stick the other end of the tube on Mars. The centrifugal force will move the atmosphere. Two terraforms for the price of one.

(yes, I'm joking)

10. Nah Crash some comets into it to raise the water content then seed it with some engineered photsynthetic micro-organisms - Its alwys best to let biology run a long time project like terra forming - it is also self replicating.

11. You'd need to lower the temperature. Water is fine as liquid, but as vapour it's just another greenhouse gas. Besides, Venus is so hot that the water would break up into hydrogen and oxygen. No; first, get rid of the CO2, then you can start work on the water.

12. Why not use it as rocket fuel*? If CO2 can blow up a soda bottle, it can power a spacecraft.

*D'oh! I meant to say, for reaction mass. It would make a pretty sucky rocket fuel, wouldn't it?
Last edited by Noclevername; 2007-May-24 at 05:11 PM. Reason: d'oh!

13. It's fine as fuel. The tough part is getting someone to shake the rocket vigorously before you launch.

14. What's the mass/thrust ratio for Mentos, anyway?

15. Originally Posted by parallaxicality
You'd need to lower the temperature. Water is fine as liquid, but as vapour it's just another greenhouse gas. Besides, Venus is so hot that the water would break up into hydrogen and oxygen.
No, it is not THAT hot -- water does not break up into hydrogen and oxygen until temperature is in thousands of degrees. But you are right about water vapor being a greeenhouse gas.

16. Oh. I read somewhere that the reason there was no water in Venus's lithosphere is because the water had broken down into H2 and O2; the O2 had combined with HS to form H2SO4, and the hydrogen had escaped into space.

17. Only in the upper atmosphere, where the water molecules are exposed to direct sunlight. The energy breaks the bonds, O2 sinks, H2 rises, and blows away into space.

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You want to get rid of Venus's CO2? Stick it inside diamonds. Get the carbon to make diamonds from CO2. Then you can use the diamonds to fill in all the shallow areas on Venus so you won't need so much water to make oceans. Or if you don't want to reduce the air pressure too much you could build giant platforms that reach up to areas of lower pressure for people to live on. Giant diamond fibre optic cables could carry light to the night side. Diamond disco balls could be make for export to the galaxy's discos and so on.

I tried to explain to my ex-girlfriend that a graphite engagement ring was just as good as a diamond one since it's all carbon, but she just didn't want to listen.

19. That still leaves us with far more oxygen than one planet needs.

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That still leaves us with far more oxygen than one planet needs.
That goes in the diamonds too along with the C. You make a hollow diamond and then you put the atmosphere you don't want inside it under pressure. Provided you don't skimp on the diamond container's construction it should be pretty safe in there. You might have to make them pretty small so kids wouldn't be trying to pop them.

21. Hmmm, eventually even diamonds will wear out (or get crushed back into the crust), and all that gas will go back where it came from. I'd rather go with removing the excess, it's a more long-term solution.

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Hmmm, eventually even diamonds will wear out (or get crushed back into the crust), and all that gas will go back where it came from. I'd rather go with removing the excess, it's a more long-term solution.
Surely covering the entire planet with diamonds would be cheaper?

23. Originally Posted by Ronald Brak
Surely covering the entire planet with diamonds would be cheaper?
It would pay for itself, surely.

24. Originally Posted by Moose
It would pay for itself, surely.
If diamonds could be mass-produced that cheaply, they'd be practically worthless. "Why, that's just a common diamond..."

25. Yup. The trick is to sell them to people who don't follow the news or the market much and have more dollars than sense (cents).

It'd be kind of neat having a full set of diamond bits for my El-Cheapo brand cordless drill.

26. Well, then you're in luck; such people are more common than diamonds!

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This discussion broke down at, about, the diamond production post.

28. If we engineered the photosynthetic organisms as gasbags, they could hover at more equitable atmospheric layers.

29. Originally Posted by ravens_cry
If we engineered the photosynthetic organisms as gasbags, they could hover at more equitable atmospheric layers.
Photosynthesis is still only going to convert CO2 to O2, giving you an extremely high pressure, nearly pure O2 atmosphere and a bunch of flammable organic material.

The only vaguely workable approach I've seen is to import vast amounts of hydrogen (which would be needed for photosynthesis anyway, as the carbon ends up as carbohydrates) to convert the atmosphere almost entirely into water and carbon. You can then work on seeding it with photosynthetic life to turn the rest into oxygen and biomass, and cooling the planet so the water rains down to the surface rather than adding to the greenhouse effect.

Now you've got a high pressure (couple atmospheres) oxy-nitrogen atmosphere with considerably greater depth and solar energy input than Earth's and two month long days and nights. Good luck with agriculture, you'll probably have to live in underground bunkers to survive the storms and temperature extremes.

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Originally Posted by cjameshuff
Now you've got a high pressure (couple atmospheres) oxy-nitrogen atmosphere with considerably greater depth and solar energy input than Earth's and two month long days and nights. Good luck with agriculture, you'll probably have to live in underground bunkers to survive the storms and temperature extremes.
Hmmm, sounds like we need to bleed off some excess atmosphere anyway, so why not put a tap on the magnetotail, or better, a double tap: one big filament to Mars with stuff we'll eventually need there, and another smaller filament that interacts with the Venetian ionosphere to recycle water vapor.

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