Terraforming Venus

[rhoenix]

Quite a few years ago, I was reading a book about plasuble science advances, and in that book was a section on terraforming Venus to near-Earth standards.

The book used a bit of handwavium to describe the steps, which were:
1. "Genetically modify" blue-green algae to survive, and thrive, in Venus' upper atmosphere, and dump tons of it.
2. Wait about 200+ years for the algae to process enough of the carbon dioxide into oxygen, thus reducing the cloud cover enough for sun to shine again on the surface.

However, doing a bit of further reading about this revealed that (my source for this was Wikipedia) that Carl Sagan put forth a paper in Science magazine in 1971 suggesting this very idea, but it was shot down:

Later discoveries about the conditions on Venus made this particular approach impossible since Venus has too much atmosphere to process and sequester. Even if atmospheric algae could thrive in the hostile and arid environment of Venus's upper atmosphere, any carbon that was fixed in organic form would be liberated as carbon dioxide again as soon as it fell into the hot lower regions.

Do you think that the prospect of learning how to terraform Venus is valuable enough to do so?

[Surlethe]

I'm wondering if it might not be a little more possible to terraform Mars, or at least to render the air breathable and get some sort of ground cover, or try to unlock some of the polar water.

[rhoenix]

I'm wondering if it might not be a little more possible to terraform Mars, or at least to render the air breathable and get some sort of ground cover, or try to unlock some of the polar water.

Actually, this is a pertinent question. To the best of my understanding, to make Mars habitable, we'd effectively need to accellerate the "global warming" process through various means to warm the planet enough for human habitation, and to melt the ice caps enough to create a ready supply of pure water.

Also to the best of my understanding, the problem is the opposite with Venus - we'd need to find a way to thin the cloudcover, and cool down the planet.

Even due to the contrast between Mars and Venus in terms of terraforming with the goal of making either one habitable for human life, is Venus worth further thought, despite the relative ease of terraforming Mars versus terraforming Venus?

[Admiral Johnason]

Is the soil and surface strong enough to support plant life once the terraform is at that stage?

[Surlethe]

Is the soil and surface strong enough to support plant life once the terraform is at that stage?

You don't get soil without plant life -- soil is a combination of sand and decomposing organic matter. So, you'd need to get plant life, or at least lichens and fungi, before you start getting layers of soil. Eventually, if it gets to that stage, the soil plants would strengthen the soil where the environment permits, paving the way for larger lifeforms.

[RedImperator]

Venus has a horrible atmosphere, an extremely slow rotation, no magnetic field, and almost no water (which means the algae idea won't work). Oh, and apparently every half billion years or so, the entire crust breaks open and floods the entire planet with lava, and it's overdue.

If you want to talk about terraforming Venus, you need to think a lot bigger than algae. We're talking glancing blows from outer system ice moons to increase the planet's rotation just to start.

[rhoenix]

Venus has a horrible atmosphere, an extremely slow rotation, no magnetic field, and almost no water (which means the algae idea won't work). Oh, and apparently every half billion years or so, the entire crust breaks open and floods the entire planet with lava, and it's overdue.

This is fascinating, do you have a link handy for this?

If you want to talk about terraforming Venus, you need to think a lot bigger than algae. We're talking glancing blows from outer system ice moons to increase the planet's rotation just to start.

I see what you mean - thank you for your reply. I was also reading that the process of bombarding Venus with big chunks of ice for the purpose of just changing the atmosphere wouldn't be feasable. If the rotation speed of Venus is also a problem, then I do see how Venus wouldn't be immediately feasable for human habitation.

[GrandMasterTerwynn]

Quite a few years ago, I was reading a book about plasuble science advances, and in that book was a section on terraforming Venus to near-Earth standards.

The book used a bit of handwavium to describe the steps, which were:
1. "Genetically modify" blue-green algae to survive, and thrive, in Venus' upper atmosphere, and dump tons of it.
2. Wait about 200+ years for the algae to process enough of the carbon dioxide into oxygen, thus reducing the cloud cover enough for sun to shine again on the surface.

However, doing a bit of further reading about this revealed that (my source for this was Wikipedia) that Carl Sagan put forth a paper in Science magazine in 1971 suggesting this very idea, but it was shot down:

Later discoveries about the conditions on Venus made this particular approach impossible since Venus has too much atmosphere to process and sequester. Even if atmospheric algae could thrive in the hostile and arid environment of Venus's upper atmosphere, any carbon that was fixed in organic form would be liberated as carbon dioxide again as soon as it fell into the hot lower regions.

Do you think that the prospect of learning how to terraform Venus is valuable enough to do so?

No. You'd have to build an enormous sunshade to reduce the planet's insolation. Then you'd have to spam the planet with comets (Venus is very dry) and add genetically engineered algae to begin sequestering carbon as soon as the temperatures dropped enough. Then there's the 243 Earth-day-long Venusian day (that's longer than its fucking year, by the way) to worry about. So either you impart a lot of angular momentum on it, or build a complex network of orbital sunshades and mirrors. And it also has that cataclysmic geology thing that Red mentioned. The whole spamming the planet with water-rich comets thing would possibly trigger such an episode by way of punching holes in the crust. (Unless you were very, very careful about it. Though all that water working its way into the crust may also do lots of fun things, even if you tried to bring it all down as gently as possible.)

After you've expended all that effort, you'll probably conclude that it probably would've been easier and rather more profitable to terraform Callisto or one of the other icy Galilean moons of Jupiter.

[rhoenix]

No. You'd have to build an enormous sunshade to reduce the planet's insolation. Then you'd have to spam the planet with comets (Venus is very dry) and add genetically engineered algae to begin sequestering carbon as soon as the temperatures dropped enough. Then there's the 243 Earth-day-long Venusian day (that's longer than its fucking year, by the way) to worry about. So either you impart a lot of angular momentum on it, or build a complex network of orbital sunshades and mirrors. And it also has that cataclysmic geology thing that Red mentioned. The whole spamming the planet with water-rich comets thing would possibly trigger such an episode by way of punching holes in the crust. (Unless you were very, very careful about it. Though all that water working its way into the crust may also do lots of fun things, even if you tried to bring it all down as gently as possible.)

After you've expended all that effort, you'll probably conclude that it probably would've been easier and rather more profitable to terraform Callisto or one of the other icy Galilean moons of Jupiter.

Thank you for that reply. Given the responses I've been getting so far, it appears that the book I was reading initially forgot to include the third step, which is:

"3. Forget the whole thing, and try something easier - like FTL travel."

Well, as somewhat disappointing as it was to find out this wasn't feasable, I'm still glad to know, and know why. Thanks to everyone for your responses - I'm glad I asked this question here.

[Ariphaos]

My personal sci-fi setting posits an insane control over electromagnetic fields, to the point where speeding up Venus' rotation is done in a matter of a century. Rather wankish, but I wanted shields. I forget how much energy was involved, several times what Earth gets. Naturally, this is doing a number on the atmosphere too, I probably should go find that molecular escape equation to see how much.

Anyway, you absolutely need a solar shade in front of Venus, at least in the short term. In the (very) long term you can use gravity tugs to drag Venus further out. If you didn't mind an extremely long term (several millenia) project, I don't think it's unfeasible. Just, like Terwynn said, we'll be colonizing the Jovian moons first. IMO if Alpha Centauri has reasonably terraformable worlds (it should, looksa vera nice), we'll colonize them first.

[Spin Echo]

Getting Venus rotating would be essential. The lack of a magnetic field would be quite problematic. The earth's magnetosphere deflects a lot of cosmic radiation. Without that, life would recieve a lot more DNA damage and the effects that go along with it. To preempt the question, the belief that the magnetic field disappears during a pole reversal is incorrect. It's just a lot more complicated and twisted, with poles popping up in strange places.

You'd also have problems with equipment as well. Satellites and electronics on the planet's surface would be much more affected whenever there was a sun storm flare up.

[darthkommandant]

My steps to terraforming venus.
One. Siphon off atmosphere. The atmospheric pressure is 90 times Earths and it is highly acidic. So it has to go.
Two. Speed up rotation. I would use rockets/railguns on the equator to do this. Hopefully this jump starts the magnetic field on venus since it is nonesistent now.
Three Move venus further away from the sun. I would use a gravity tug system using a few good size asteriods.
Four Replace new more earthlike atmosphere. 70% nitrogen 15%CO2 13% O2 2% other gases.
Five Seed With primitive blue/green algea.
Six Set up colonies plus ecosystems
These steps assume several thousand years of commitment and no translation errors over time. Also assumes rotation strengthens magnetic field. By the time of completion humans will have probably colonised several other solar systems. In conclusion not practical at all.

[CJvR]

Blocking the sunlight and let the place cool down seems like the best idea before we even start on the rest of the stuff. However a planetary sized shadow will require a very big parasol.

[GrandMasterTerwynn]

Blocking the sunlight and let the place cool down seems like the best idea before we even start on the rest of the stuff. However a planetary sized shadow will require a very big parasol.

Yes. It would be something like twice the diameter of the planet, at least. You might want to make it larger still, so you can locate it further out. You could construct it out of very thin materials, to keep the weight down, but it would have to have a good deal of intelligence to it, since you'll essentiallly be building a giant solar sail, and then demanding that it not actually go anywhere.

[AMX]

Now I'm wondering, why build an actual massive sunshade in space?
Why not "simply" fill the upper atmosphere with highly reflective (but, of course, IR-transparent) dust?

[Lord of the Abyss]

Rather than moving the planet and spinning it up, it might be easier to just leave the sunshade in place. When the planet cools down, add a similar giant mirror farther out. By manipulating the two, you can create a day/night cycle without moving a whole planet.

I recall a short story where they chilled the planet until the atmosphere froze, then covered it with Von Neumann machine mass drivers and threw the frozen air off the planet; that would be less likely to cause a geological disaster than ramming comets into it. ( Relatively ) soft landing the cometary ice for the future oceans might be a good idea as well.

Still, it would be better to terraform Mars or the outer moons first. For that matter, it would be easier to terraform our Moon. It's big enough to hold air for something like 100,000-1,000,000 years, going by memory. That's a long time by human standards, and if IIRC someone came up with the idea for orbiting "shrouds" that would bounce the escaping volatile atoms back towards the Moon, making the air last indefinitely.

[Vehrec]

I once saw a PBS special that explaine d the differances between venus and the earth were due not to wildly different differnaces in composition, but to their differant possitions. If venus had and earth standard atmosphere, it would be only 50 degrees C hotter on average. Saddly, that was enough to shift the water vapor to liquid ratio up. A lot. Water vapor is a greenhouse gass. And CO2 is mostly locked up on earth by disolving it in water and water dwelling creatures. So this 50 degree differance lead to about 500 degrees differance. Until that basic problem is solved, you aren't going to have an inhabitable planet.
And yes, the planet does pave itself over. Last time was 500 million years ago. Since it totaly melts the surface every time it does this, we have no way of knowing how long this process would take. Sufice to say that a lack of plate tectonics is a bad thing.

[Dooey Jo]

The biggest problem with Venus is its atmosphere. If you can get rid of all the CO2 you won't need extremely huge shades. However, if you thin out the atmosphere, the slow rotation is bound to create some really nasty weather on the surface (as it is, the surface recieves virtually no solar radiation at all, making the temperature and weather very uniform over the whole planet), so you'll need to speed it up somehow. The good news is that if you have the energy generation capabilities to speed up a planet of Venus' size, you won't have any problems at all removing the atmosphere

[GrandMasterTerwynn]

Now I'm wondering, why build an actual massive sunshade in space?
Why not "simply" fill the upper atmosphere with highly reflective (but, of course, IR-transparent) dust?

The planet already reflects much (65%) of the sunlight coming to it. And it is very good at retaining heat, so somehow filling the atmosphere with particles that reflect everything but IR will only serve to make Venus even brighter, while providing zero in the way of temperature drop. That, and the insolation (amount of sunlight) at Venus is something like over 2.5x that of Earth's.

So you need to reduce the amount of sunlight striking Venus. Then you need to spin the planet up and get rid of the bulk of its atmosphere. Spinning the planet up is essential for both the generation of a planetary magnetic field, and for the construction of a space-elevator. (Venus is virtually the same size as Earth. As a result, it has a comparably steep gravity well. Getting things on and off Venus would be a losing proposition compared to, say, Mars, which spins fast enough to make the building of a space elevator feasible (not to mention it already comes with two convenient platforms to construct an elevator from, and anchor a space elevator to,) and would even be a losing proposition compared to colonizing, say, Callisto, which has a gravity well comparable to Earth's Moon.

Arguably you wouldn't want to colonize the solar system closer than the orbit of Earth, since you're working against the solar gravity well in order to get things to the outer solar system, and because shielding against the increased insolation gets dramatically more expensive the closer to the Sun you get. The only reason you'd do it is if you were building enormous solar collectors in the inner solar system with the intention of beaming power to other places in the system, or manufacturing antimatter. However, in that case, you'd colonize any Venusian Trojans (asteroids) which exist. Arguably, even maintaining colonies on Mercury would be less of a loss than trying to do so on Venus.

[Patrick Degan]

Seems to me you won't get much of anywhere remaking Venus without first scooping off about 90% of its atmosphere, and that's just stage one of the problem.

[AMX]

Now I'm wondering, why build an actual massive sunshade in space?
Why not "simply" fill the upper atmosphere with highly reflective (but, of course, IR-transparent) dust?

The planet already reflects much (65%) of the sunlight coming to it. And it is very good at retaining heat, so somehow filling the atmosphere with particles that reflect everything but IR will only serve to make Venus even brighter, while providing zero in the way of temperature drop. That, and the insolation (amount of sunlight) at Venus is something like over 2.5x that of Earth's.

So you need to reduce the amount of sunlight striking Venus.

Nonsense.
Reducing the sunlight reaching the planet has exactly the same effect on said planet's temperature as increasing its albedo.

Then you need to spin the planet up and get rid of the bulk of its atmosphere. Spinning the planet up is essential for both the generation of a planetary magnetic field,...

Whatever for? Don't you like bunkers?

... and for the construction of a space-elevator.

If you have the resources to significantly alter a planet's rotation, you don't really need a space elevator any more...

(Venus is virtually the same size as Earth. As a result, it has a comparably steep gravity well. Getting things on and off Venus would be a losing proposition compared to, say, Mars, which spins fast enough to make the building of a space elevator feasible (not to mention it already comes with two convenient platforms to construct an elevator from, and anchor a space elevator to,) and would even be a losing proposition compared to colonizing, say, Callisto, which has a gravity well comparable to Earth's Moon.

Arguably you wouldn't want to colonize the solar system closer than the orbit of Earth, since you're working against the solar gravity well in order to get things to the outer solar system, and because shielding against the increased insolation gets dramatically more expensive the closer to the Sun you get. The only reason you'd do it is if you were building enormous solar collectors in the inner solar system with the intention of beaming power to other places in the system, or manufacturing antimatter.

Or if you simply want to colonize every place you can (for whatever reason).

However, in that case, you'd colonize any Venusian Trojans (asteroids) which exist. Arguably, even maintaining colonies on Mercury would be less of a loss than trying to do so on Venus.

Truth be told, a Mercury colony sounds pretty neat.

[CaptainChewbacca]

One of the prevailing theories for why Venus doesn't have a magnetic field is that because its surface is so hot, its core is unable to cool and differentiate. If you could reduce the surface temperature, ongoing continuing volcanism would start to reduce the temperature of the interior which would lead to earth-style tectonics and possibly the formation of a magnetic field. Of course, it would take at least a hundred-thousand years.

[wolveraptor]

Speaking of Mercury, I seem to recall an Asimov space colony that was situated on a planet much like our closest planet to Sol. Since the diurnal half of this planet (like Mercury) experiences blistering heat and the nocturnal half freezing cold, the colony placed in the twilight area between these two extremes. Is this feasible?

[darthkommandant]

If you put most of the colony underground than yes it might be. There are also several craters that never recieve sunlight on the floor so you woudnt have to deal the heat. These areas might contain water ice so the colonise would most likly be located there for coversion into Hydrogen for fusion rockets and reactors.

[GrandMasterTerwynn]

Now I'm wondering, why build an actual massive sunshade in space?
Why not "simply" fill the upper atmosphere with highly reflective (but, of course, IR-transparent) dust?

The planet already reflects much (65%) of the sunlight coming to it. And it is very good at retaining heat, so somehow filling the atmosphere with particles that reflect everything but IR will only serve to make Venus even brighter, while providing zero in the way of temperature drop. That, and the insolation (amount of sunlight) at Venus is something like over 2.5x that of Earth's.

So you need to reduce the amount of sunlight striking Venus.

Nonsense.
Reducing the sunlight reaching the planet has exactly the same effect on said planet's temperature as increasing its albedo.

The planet already has a high albedo. And you want to cool it down in a hurry. Quickest, most easily controllable, way to do that would be to drop the insolation to zero and let the heat radiate away (though you want to scrub off the atmosphere at the same time, since you only want something like a tenth of the planet's atmosphere.)

Then you need to spin the planet up and get rid of the bulk of its atmosphere. Spinning the planet up is essential for both the generation of a planetary magnetic field,...

Whatever for? Don't you like bunkers?

Bunkers would be necessary to begin with, sure, but if the aim is maximizing habitable surface area, you're going to eventually going to want a cheap way of shielding the planet from the solar wind and other particles a planetary magnetic field normally deflects. This says nothing about dealing with the planet's geology.

... and for the construction of a space-elevator.

If you have the resources to significantly alter a planet's rotation, you don't really need a space elevator any more...

If you could dump that much energy into a system in a controllable manner, it's equally arguable that you're probably also capable of building starships and looking for easier marks than Venus.

However, in that case, you'd colonize any Venusian Trojans (asteroids) which exist. Arguably, even maintaining colonies on Mercury would be less of a loss than trying to do so on Venus.

Truth be told, a Mercury colony sounds pretty neat.

Why? It's uncomfortably close to the Sun, and all your consumables will have to be imported, given that Mercury lacks volatiles. Sure it's got a higher concentration of metals than Earth does, but nickel-iron asteroids are cheaper to get to and exploit than Mercury is . . . so you'd have to have been exploiting the solar system for quite a while before you get to the point where a Mercury colony starts to make sense.