How can we terraform Venus' atmosphere?

[Everten P.]

So there has been lots of talk of Mars as of late, so I wanted to switch gears and talk about another planet... Venus, Mars' neighbor; So, how could we terraform Venus' atmosphere so that it resembles Earth's?

[rtxoff]

Simply, we can not.

[Xaiier]

Simply, we can not.

QFT

Venus sucks. I mean, terraforming in general is a dumb idea way way way beyond our technology as it is, but Venus takes that bad idea to a whole new low. It's probably one of the most inhospitable places to human life than anything we know of that isn't a star.

[vitekc45c]

It would be more easy and practical to swap "e" for "ol" in Titans oceans than trying to terraform such hellhole as Venus. Its atmosphere´s density and temperature is beyond ridiculous, not to mencion the acid rain and windspeed.

[KerikBalm]

Assuming you were to start splitting the CO2...

Insufficient Hydrogen to ake any reasonable amount of water

Too much Carbon and oxygen, that you'd be asking for an inferno.

The only way to "terraform its atmosphere" is to basically get rid of its atmosphere completely, and bring a new one from somewhere else.

At least it has enough nitrogen (its only 3.5%, but given the atmospheric density, if you could remove the CO2, and keep the N2, you'd have about the amount of N2 you'd want)

[EzinX]

Precursor Tech

A task like this is impossible with today's tech, but conceptually and using tech that is theoretically possible it's actually...pretty damn easy.

We need "just" one piece of technology : something called "atomically precise manufacturing". In short, it's the ability to build factory equipment composed of very small machines that are able to perform automated tasks that manufacture components accurate to the individual atom. Here's a

.

To visualize accurately what this tech really is, it's a box full of billions of nanoscale subcomponents that process feedstock into specific molecular parts. The technology is limited in that a single assembly line is optimized to produce only a single output product. The assembly lines converge onto higher level lines that can combine the parts into subcomponents for machines, and eventually, after enough convergence steps, you get products that can be used. The actual robotic machinery on a given assembly line can be made using this same method.

Ultimately, in the real world, a true nanofactory might be about the size of a shipping container, perhaps a bit larger. The machine would contain 3 main parts : a machine that digests input materials into individual elements (probably using plasma and separation methods similar to how a mass spectrometer works), a feedstock plant that would chemically produce the actual feedstock the APM (nanofactory) can actually accept (it cannot accept individual elements, they have to be bound to other atoms to produce a molecule that is energetically favorable to give up a member of itself to form a covalent bond to a surface), and the factory itself. Physically, the factory itself is probably the smallest part.

The output of this factory would probably be 2 main things : sub-components that can be used to make more factories, and something that can be easily made into a large variety of machines.

One generic product you'd probably build nanofactories to make is a cube-shaped robot, probably about the size of a eukaryotic cell. This cube would have wheels on all faces and little power and data feelers that scrape over other cube robots. Internally, it would have a small battery, small computer of some type, and the motors to drive the wheels. A given cube-bot upon being manufactured would be told a destination coordinate to place itself. It would drive over previously installed cube bots, receiving power from them and sharing data. Eventually it would navigate to where it needs to be (the other cubebots would tell it their coordinates so it knows which way to drive) and set off some kind of chemical reaction to weld itself permanently into place.

There would be other variants on these cube bots, enough to handle the subcomponents needed in any given machine. For instance, some cube bots would have a drive gear and a large motor to drive it on one face of the cube. Others would have a linear gear on one face - the linear gear cubes get installed in a line to make a track, while the motor cubes get installed in a place to drive themselves on that track. This lets a larger machine actually move. Some cubes would have a sensor on one face (like a single photon detector), and would install themselves in big flat arrays on the outside of robots. And so forth.

Doing it this way, you could make an almost infinite variety of robots out of just a few dozen basic cubes.

Plan to Terraform Venus :

So, now you have a factory, that fits into a shipping container. It can make sub modules that can self assemble themselves into other factories. It can also make a constant stream of small cubes that can self assemble themselves into robots.

You load this factory onto a giant rocket. You also load in a few dozen tons of feedstock - especially for elements that might be rare on the crust of venus - and don't forget a nuclear reactor and some seriously heavy duty refrigeration equipment.

Rocket travels to Venus. Reentry vehicle soft lands it on the surface with the help of parachutes.

Factory goes to work. It makes robots that can prospect and shovel element rich crust into the factory's intake hopper. Factory makes the subcomponents for more of itself and more robots. About a month later, you have 2 factories and assorted robots to help them.

Fast forward. Let's say the factory is 5 meters x 5 meters. Then to completely cover venus in factories, we need to wait until we have 1.84 x 10^13 times as many factories as we started with.

That sounds impossible. That's about 10 trillion times as many! But the awesome power of exponential growth means we only need to wait for 44 growth cycles. Living cells can copy themselves in 1 hour, I'm assuming factories are much much slower and take 720 times as long, or 1 month. That means we need to wait about 4 years. Ironically, the actual transit to Venus takes up a big chunk of the time needed.

So ok, 4 years later the surface of Venus is covered in factories. Actually, it's probably covered in towers made of factories or bigger scale factories, and then there are towering mountains of waste everywhere. The surface is now a continuous warren of tunnels dug to find more ore.

Now it's just chemistry. All factories are ordered to build equipment able to process the atmosphere of Venus into other things. Since we have trillions of factories, the equipment is built very quickly.

Venus is 96% CO2. That can't stand. So we rip those carbons loose and convert all the CO2 into diamond. What do we do with the 92 atmospheres worth of oxygen, now? We need to bond it or trap it. Either we pump it all into diamond tanks and store it compressed, or we bond it to something else. If we could find enough hydrogen, we could convert it all into oceans of water.

Now, one other nasty issue : realistic factories aren't going to operate very well at 740 kelvin. Too much of a gradient to overcome all the time to do anything. So a smart move would be to roll back a step and in step 1, conquer another planet with this same technology and use it to build much bigger spacecraft. One obvious way would to conquer the Moon and launch the finished products using superconducting quench guns. In orbit, assemble the mega-spacecraft.

The mega-spacecraft would carry a gigantic set of mirrors. You'd deploy them over Venus to reflect 99% or so of sunlight and IR from reaching the planet. This would allow Venus to cool to a more reasonable temperature. You might have to wait decades for it to cool, unfortunately.

So once Venus has been cooled and all that nasty atmosphere packed away, it's almost habitable. Just gotta plant a whole ecosystem and you're ready to move in!

[Everten P.]

What if we just had to deal with the carbon dioxide? How could we deal with that? Especially since oxygen is really just trace on Venus so no plants!

[AngelLestat]

We did this discussion so many times before, but venus is so interesting that always come back.

What you mean by terraforming the atmosphere? You want terraform all the atmosphere or just a layer?

For example at 50km height venus atmosphere has similar temperature and pressure than earth at ground level. Also is a lot easier to float there and has many other benefics that can not be found in any other place in the solar system.

So with a long process you can live up there and expell oxigen, it will take a lot but you can make the atmosphere at 50km more comfy.

But it will never would be as earth because there is a element missing. "Hydrogen".

Venus has 15000 km3 of water in its atmosphere. That is more than earth, but is 90 times more dense. So is too dry. And that is all the hidrogen that you can find.

About the Von Neumann machines would also face the same problem.. There is not hidrogen.

[Aethon]

Here's an old usenet post about Venus terraforming featuring the great Henry Spencer.

http://yarchive.net/space/science/venus.html

Edited October 31, 2014 by Aethon

[Stargate525]

Presuming you have the technology to make this sort of thing remotely feasible, you could mine the atmosphere of its CO2, compress it into asteroids of dry ice, and send them to Mars, which would need the extra greenhouse gasses.

Water's no problem, as it's one of the most abundant elements in the Oort cloud and Kuiper belt.

your biggest worry, I imagine, wouldn't be the atmosphere; it would be the fact that the geological activity on the surface makes it look like Mordor.

[Bill Phil]

We did this discussion so many times before, but venus is so interesting that always come back.

What you mean by terraforming the atmosphere? You want terraform all the atmosphere or just a layer?

For example at 50km height venus atmosphere has similar temperature and pressure than earth at ground level. Also is a lot easier to float there and has many other benefics that can not be found in any other place in the solar system.

So with a long process you can live up there and expell oxigen, it will take a lot but you can make the atmosphere at 50km more comfy.

But it will never would be as earth because there is a element missing. "Hydrogen".

Venus has 15000 km3 of water in its atmosphere. That is more than earth, but is 90 times more dense. So is too dry. And that is all the hidrogen that you can find.

About the Von Neumann machines would also face the same problem.. There is not hidrogen.

Correct me if I'm wrong, but does't acid have Hydrogen in it? If that's so, the von Neumann machine idea could work quite well...

But feel free to correct me. I'm honestly not sure.

EDIT:

Yep. There's Hydrogen in acid, probably a lot of it. Enough in one sulfuric/carbonic acid molecule for a single molecule of water, and there's plenty of oxygen in the upper areas of the atmosphere in CO2.

Maybe if the von Neumann machines could directly manipulate molecules, so then chemical reactions could be more easily undone. Perhaps beamed power from orbital arrays?

Edited October 31, 2014 by Bill Phil

[Rondon]

Correct me if I'm wrong, but does't acid have Hydrogen in it? If that's so, the von Neumann machine idea could work quite well...

But feel free to correct me. I'm honestly not sure.

EDIT:

Yep. There's Hydrogen in acid, probably a lot of it. Enough in one sulfuric/carbonic acid molecule for a single molecule of water, and there's plenty of oxygen in the upper areas of the atmosphere in CO2.

Maybe if the von Neumann machines could directly manipulate molecules, so then chemical reactions could be more easily undone. Perhaps beamed power from orbital arrays?

SOME acid has hydrogen in it, the acid in the Venusian atmosphere is sulfur di-oxide, there's no hydrogen in it. And barring some magnificent advance the reaction you're talking about to create hydrogen is a nuclear reaction, at best it would be extraordinarily energy intensive and probably several if not hundreds of orders of magnitude harder than just extracting the trace water.

[Bill Phil]

Source?

And I remember reading that there was all kinds of acids in the Venusian atmosphere.

Plus, you kind of missed my point.

My point is that you shouldn't limit what you want (hydrogen) by just talking about water

[AngelLestat]

You are talking of the sulfer cycle.

Which one of its steps is h2so4, but I already take into account that in my estimation.

In fact I said 15000km3, but I was wrong, that number was for earth, Venus has close to 10000 km3 of water. This include the water that is combined with SO2.

Venus atmosphere is 100 times our atmosphere. So earth has almost 10000 ppm, and venus has 40 to 60 ppm (as last studies show).

But a big part of that amount is concentrate in the venus clouds at 50 km height. This make it easier to people live there, but this amount of water is not enoght to transform all the CO2 which Venus has.

Any atmosphere terraformation would need a lot more hydrogen.

[Bill Phil]

Maybe bombard Venus with base-rich asteroids. Ads hydrogen and the acids may react with the bases, making water. Problem is, we then need to keep it that way.

[peadar1987]

It would be more easy and practical to swap "e" for "ol" in Titans oceans than trying to terraform such hellhole as Venus. Its atmosphere´s density and temperature is beyond ridiculous, not to mencion the acid rain and windspeed.

"olthane"?

[cantab]

First up you're probably going to need a sunshade. Venus is a little too close to the Sun to maintain a good climate otherwise.

Then you need to remove something like 99% of the atmosphere. I'm happy to rule out freezing it for obvious reasons. Shipping it into space would work but be a phenomenal amount of stuff to launch.

Preferable would be to lock it up in rocks by silicate weathering, a reaction that is important in controlling atmospheric CO2 on Earth. Water with dissolved CO2 reacts with silicate rocks to produce carbonate and bicarbonate salts which can then precipitate out as limestone.

Of course this requires some water to get running. Said water could be obtained initially by distilling Venusian air; there's not a lot of water vapour but it would suffice to get started. I'm not sure what temperatures the silicate weathering reaction can take place at, but if it will work at Venus surface temperatures then the water could be pumped through boreholes in the rock, and the carbonates subsequently precipitated, freeing up the water for repeated re-use.

It's going to take a long time and a lot of equipment, with the challenge compared to Mars that closed-environment surface settlements are unlikely. But I think this "surface based" approach is viable and will need much less energy overall than "space based" approaches of shipping bulk atmosphere in and out.

[AngelLestat]

But you need a lot of energy to move those asteroids, besides crash asteroids in venus atmosphere would only help to rise its temperature even more.

If you dont want just terraform the atmosphere and you want seas.

The best candidate is Iapetus (Saturns´moon), it has 1400 km diameter, and is 3/4 water (this is a little more than all the water in earth). If you have an imaginary system that gives you a lot of energy, you can use the same water of iapetus as proppelent to move it in a big time lapse (with huge orbit math patchs, gravity assitance from titan plus use saturn as Oberth effect, etc) then you can trasport iapetus with several different gravity assistance from jupiter to Venus.

Once in venus orbit (I know... a lot of miracles needed), you use the same propulsion system to deliver water to the atmosphere at retrograde, so all water particles lose its orbital speed and fall to the planet, this particles would cool down before touch the atmosphere reducings its temperature in the process.

Then you just need a bio organism floating in the atmosphere converting all the co2 into oxygen, then the carbon falls to the surface.

That is how you get rid of the 98% of the atmosphere, what remains is something very similar to earth (amount of carbon, water and all other gasses).

The remaning problem is venus rotation, I dont know if there is a way to use iapetus to change that without producing heat. This will solve the magnetic shield problem that allows the hydrogen to escape.

About Venus - Sun distance is not a problem, depending the amouunt of atmosphere and components which you end it, you can have a low greenhouse effect to mimic the earth temperatures.

The 1/4 of iapetus moon remaning, can help as shadow.

[Rakaydos]

But you need a lot of energy to move those asteroids, besides crash asteroids in venus atmosphere would only help to rise its temperature even more.

Would you? put a robotic ion thruster on Hally's comet, and have it make a course change over a few years at apoapse, and I'm pretty sure you can get it to hit venus at periapse on it's next orbit. With as much eccentricity as we see out of comets, course changes can be pretty cheap, delta V wise.

As for raising the planetary temperature, I believe the effect would be neligable. if we're adding a sunshade anyway, it might delay the drop in tempertures, but that's all.

[cantab]

Well, quick rough-and-ready estimate. Let's guess we need 10 m/s to course correct a comet so it smacks into Venus, and we have a thruster offering a specific impulse of 10,000 s. That means we need a mass ratio of about 1.0001. Seems tiny, right? Well a good sized comet will mass maybe 10¹⁴ kg, so you'll need about 10¹⁰ kg of propellant. That's a lot, any way you cut it.

OK, so you get round that with an ion engine that can use the comet itself as propellant. Much better. Now you want to accelerate 10¹⁴ by 10 m/s in 10⁸ s (about 3 years). That's gonna need about 10 MN of thrust. Ion engines require around 10000-10000 Watts per Newton, so you'll need a power plant delivering 100 GW to 1 TW.

That's on the order of the power consumption of an entire country. I'm not even going to try and calculate how massive the nuclear reactors would be.

And remember, comets are in difficult and time-consuming orbits to reach.

[AngelLestat]

It all depends of the amount of water that you want to sent to venus, just to transform all the co2 there is not need so much water (I guess) but if you want more even if you drop all asteroids in the solar system that is not even close the amount of water that earth has.

And I guess that is more difficult try to locate, visit, and transport each asteroid than just go for a big body and do it all in once.

If you dont have problem rising venus temperature when you deliver water (which can take a lot to cold down, to start the biologic transformation process) , then you can go to Iapetus, and use your proppelent engine to deliver water particles from saturn orbit to venus. Without moving iapetus. Maybe there is a way to slow down those particles before their enter in the atmosphere. Solar wind maybe...

No matter how efficient is our method of choice, something that is clear, this would consume an imaginable amout of energy, something that with still dont know any possible technology or energy source to do it.

For example: What is more efficient? Move the mass of an ocean from one part of the solar system to another, or just move the entire earth popullation to a close star system?

Edited October 31, 2014 by AngelLestat

[cantab]

The thing is that there is something like 10¹⁶ kg of water on Venus already. About as much as Lake Superior. That's nothing compared to Earth, but it's equivalent to several hundred good-sized comets.

I'm not sure what kind of climate you could achieve with such an amount of water, though I assume it would be pretty much a "desert". There'd be a need to keep the water cycling and there wouldn't be significant bodies of water on the surface.

To increase it further, I'd still be minded to consider reactions that might break down rock and release water. Even if they're pretty energy-intensive I suspect it'll require less energy than throwing comets about.

[Lunaran]

Mercury would make a nice moon for Venus.

Its oddly strong magnetic field would help to make up for Venus' total lack of one, and if you put it in a tight orbit with a lot of spin, tidal forces would eventually move it to a more reasonably moony orbit while transferring enough angular momentum to Venus to give it something resembling a day-night cycle.

As long as we're driving Mercury around like a school bus and taking the long view, why not take it a step further and test the Theia hypothesis? Smack it right into Venus at a steep angle. Get that disco ball spinning extra-fast. Throw a debris ring into orbit and let a new moon form. See if an inner-mantle dynamo forms the way we think it would. Liquify its insides to within a few dozen miles of the surface, and fragment the remaining crust to kickstart plate tectonics and a carbon cycle. Then see what the atmosphere is like, and go from there.

I mean, you know, priorities.

[peadar1987]

Well, quick rough-and-ready estimate. Let's guess we need 10 m/s to course correct a comet so it smacks into Venus, and we have a thruster offering a specific impulse of 10,000 s. That means we need a mass ratio of about 1.0001. Seems tiny, right? Well a good sized comet will mass maybe 10¹⁴ kg, so you'll need about 10¹⁰ kg of propellant. That's a lot, any way you cut it.

OK, so you get round that with an ion engine that can use the comet itself as propellant. Much better. Now you want to accelerate 10¹⁴ by 10 m/s in 10⁸ s (about 3 years). That's gonna need about 10 MN of thrust. Ion engines require around 10000-10000 Watts per Newton, so you'll need a power plant delivering 100 GW to 1 TW.

That's on the order of the power consumption of an entire country. I'm not even going to try and calculate how massive the nuclear reactors would be.

And remember, comets are in difficult and time-consuming orbits to reach.

You'd need some sort of super sci-fi technology.

To change the velocity of a 10^14kg object by 10 m/s, you need roughly 5*10^15J of energy. This is roughly the energy you could get from annihilating 0.05kg of antimatter.

If you had a perfectly efficient conversion system and thruster, you'd need 62,000 tonnes of Uranium to run a fission reactor. Seeing as we're talking sci-fi anyway, let's assume we can do nuclear fusion. That's about ten times more efficient in terms of mass, so we only need 6,200 tonnes of fuel. That's still far, far too much to bring with us, but if we're on a comet made primarily of water ice, maybe we can refine deuterium from that. Well, water is about 12.5% hydrogen by mass, and hydrogen is about 0.03% deuterium by mass, so if you're processing water, you're going to get out 0.00375% deuterium, or a thirtieth of a gram for every kg you refine. We need 6,200 tonnes of fuel. If we're being generous, and set a goal of 15,000 tonnes of deuterium total, to account for energy that goes into refining, and losses in our systems, we get 1.65*10^8kg of water we need to refine to get enough energy. To put this into perspective, earth's largest mine takes about a year to process this amount of material, and employs over 2,000 workers.

Seeing as we're dealing with sci fi anyway, we can probably put a fleet of robots on the comet at perihelion, set them to work processing the material over the 40 or so years it takes for it to move to aphelion, once the comet reaches aphelion, our sci-fi ion engine fires up, using water as reaction mass, and a 100GW fusion power plant as its power source. The heat from the power plant is dumped into the area of the comet the fuel is coming from, to melt the water and help ionise it.

Or we put a gigantic solar array on Mercury, use it to produce a couple of kg of antiprotons, put them under the surface of the comet at perihelion, and just let them out of their magnet trap at the right moment, and let the resulting explosion take care of the rest.

In any case we're dealing with very far future tech, which is fun to speculate about, but none of us are ever going to see happen.

[Bill Phil]

Or, we could build a network of solar power arrays kilometers in length in width closer to the sun than mercury. Using some high power lasers we could then propel a solar sail vehicle. Problem is, we can't necessarily provide thrust at apoapsis.