Venus terraforming fact checking- Chemistry edition

[Rakaydos]

So, the idea was raised in the Venus Terraforming thread that Sulfuric Acid could be broken down to make hydrogen and oxygen for rocket fuel. It would seem to follow that it could also be used to make water.

Carbon Dioxide is even more plentiful, and being so close to the sun you might even be able to crack a few Nitrogen bonds for chemestry. According to Space.com, Carbon monoxide, argon, sulfur dioxide, and water vapor round out the most common elements.

Given these common elements, and plentiful energy, what alchemy can be reasonably be performed to manufacure chemicals useful to a floating city? (that relies on the buoyancy of oxygen in CO2 to stay far from the lethal pressures of the surface)

[Coldfinger008]

Well dependin how far you wanna go.... if you can get enough pure carbon to make a carbide oven, then you can basically pull the entirety of organic chemistry from the thick air of Venus. Well provided you find some Halogens too, well and obviously stupid amounts of power.

[K^2]

Metals are going to be very hard to come by, and they are required by many processes. Chlorophyll, for example, relies on a trapped magnesium ion. And, of course, there is iron's roll in Hemoglobin. Of course, you don't need much, so you might be able to bring all of this stuff down form orbit.

Also, keep in mind that most of sulfur in atmosphere is going to be in form of sulfur dioxide. There is also some water vapor, so you will have some sulfuric acid, but you might as well just grab water vapor from atmosphere. That seems more efficient.

But yeah, other than getting some necessary metals and halogens, which you can bring with you or get a shipment of every once in a while, you can have a pretty good thing going. You'll have all the carbon you could use. You can trap enough water to get by. So you can maintain an Earth-like environment for human habitation and some farming. And you can use either plant byproducts or synthesize polymers from scratch to use for construction.

[Dispatcher]

Water vapor is only 20 parts per million (in context with the relatively rare noble gas argon, 70 ppm). Nitrogen is 3.5% of the composition (compared to Earth's 78%). Sulfur dioxide is 150 ppm. Sulfuric acid is in the cloud layers. The lion's share of the atmosphere is of course carbon dioxide, about 96.5% (compared to Earth's 397 ppm). Culling carbon from that would be difficult, and the native carbon monoxide (17 ppm) molecule is so tightly bound that its likely to remain the way it is. Entities looking for a larger, earlier return on investment will probably look to the Moon, asteroid belt, Mars and Titan.

[AngelLestat]

Dispatcher: All the info that you are giving its not helping. You make all more confusing.

We are talking about live at 50km of altitude. So we need to speak about concentrations levels at that point. No in the entire atmosphere!

At 50km of altitude, we have a temperature of 20 celcius degrees and 1 bar. Is perfect.

But at this height, we need to forget about the 90 bar atmosphere of most CO2, becouse the CO2 is a heavy gas. Most of the CO2 is down. In fact, I would estimate than half of atmosphere weight its in the first 5 km of height.

So we need to cut like 89 earth atmosphere of Co2 when we estimate other gas concentration at 50Km.

First Nitrogen, it is 3% in the entire atmosphere. But, that 3% means 4 times more nitrogen than earth (and air is 73% nitrogen!)

Nitrogen is a lifting gas in CO2 so we would find it from 45km to 70km. This is mean that we can have a mask to filter co2 and sulfure acid, and we just need a little tank of cryo oxigen to breath.

Sencond.. Water. At earth there is 100000 times more water than at venus. (this takes into account all oceans, all ice and atmosphere) But in venus is all at 45-55km height. So even if we have 100000 times less, that is still a lot of water! And easy access becouse we leave in the clouds!

All that without count the water that we can extract from all the sulfer acid that it is in the same layer.

A time ago I read a comparison of how much water there is in a normal thunderstorm at earth, is 1billons of liters. It would take 10 min of niagara falls to drop the same amount.

And venus has a lot more water in their atmosphere than earth. Becouse when it rains, at the time that reach 30km of altitude become vapor and rise again.

Then we have a lot more of sulfure dioxide that it is from 30km to 55km.

So all these elements are easy to get at that height.

I am not a chemistry, so I dont know what is need to extract water and oxigen from sulfure acid, or other components from the atmosphere.

But when I read the original Landis paper, it does not mention any problem to extract them.

I left some graphics to guide:

Edited March 6, 2014 by AngelLestat

[Rakaydos]

So, it sounds like a large Cloud City setup, with a large living area and a narrow pipe down to lower levels for atmospheric resource processing, would be reasonable givin suficent power?

[Dispatcher]

AngelLestat, I understand your arguments and I have seen most of the charts you provided before. However, the atmospheric gases do not differentiate completely either on Venus or Earth. In other words, the gases are not clearly stratified. As an example, while oxygen is heavier than nitrogen (barely), if you light a match near the ground at sea level, you will not ignite the lower portion of the air at that location. Conversely, you will not suffocate if you go to the rooftop of a skyscraper building. Granted, CO2 molecules are heavier than nitrogen, and that implies an upward drift of nitrogen, but that doesn't mean that there is a nitrogen pocket floating "up there" at Venus. Also, if you go up to about 60 to 70 km (if I recall correctly), CO2 will sublimate into snow, which of course sublimates back into gas lower down.

According to some of these charts, the temperature is more like 0 C or lower at 1 bar pressure/ elevation. You'd need to go down a little to have a non freezing temperature (and the pressure would be a little higher there). The winds at your target elevation range from about 60 to 125 m/s. These are gale force and above winds.

As for the chemistry; what is needed is energy, which is available. However, the equipment needed to process atmospheric components would be heavy. Massive to get there and heavy to keep floating in the clouds.

I'm not saying that Landis is wrong (I actually agree with him), but I am saying that the tasks required for survival at Venus are extremely daunting. In practical terms, it will be more economical to survive on the Moon and on Mars. The costs of an infrastructure at those locations will mean a quicker return on investment at those locations as well. In other words, "follow the money".

[AngelLestat]

I know that they are not full stratified. There are gases... For that reason when I descrive a possible mask filter to take nitrogen right from the atmophere, I said that needs to filter CO2 and sulfure components.

But.. most of the CO2 remains down. That is my heavy point. The vapor water clouds and acid clouds are from 45 to 55km. So is in that frame where we would find most of the water.

So we need to remove the 89Bar of atmosphere that is below.

I did the math and we have 15000 km3 of water in vapor form, plus the water that is inclose in the sulfure acide.

This is my case for Co2:

Oxigen and nitrogen are very mix, becouse storms and winds here had vertical vectors and the atmosphere is not so high.

But for example its know that venus does not have lighting in their clouds, this is due becouse there is not vertical winds. That is something that scientist wants to know why..

And even at earth volcanos ashes can go around the world but at the same height.

All co2 of venus comes from the surfuce and the atmosphere is very high, for that reason is mostly stratify.

But I would love to see accurate values about components concentrations at that height.

About the temperature, you are right, at 52km of altiture we had 20 celcius. The floating city can rise or down depending of the confort temperature they want, but more confort is equal to a little more problems due to lost of air by rips on city envelope.

Here another chart that show the concave density shape of Venus vs Earth.

As for the chemistry; what is needed is energy, which is available. However, the equipment needed to process atmospheric components would be heavy. Massive to get there and heavy to keep floating in the clouds.

We have plenty of energy at venus. like 700w/m2 from all directions.

Heavy is not a very big problem, and everything can be made it lighter in case necesary. I am sure that there is plenty of different methods to separate componenets. We need to choice the best due those conditions.

but I am saying that the tasks required for survival at Venus are extremely daunting. In practical terms, it will be more economical to survive on the Moon and on Mars. The costs of an infrastructure at those locations will mean a quicker return on investment at those locations as well. In other words, "follow the money".

That is the point where I strong disagree. Venus does not have the big problems of mars of moon. We can get all elements that we need and more. Even stephen hawking once said that venus is beter for 3 reasons. Location, Location and Location.

[Kryten]

This is my case for Co2:

[snip]

That's petrochemical smog; it's made up of small solid particles, it's not relevant to discussion of distribution of gases.

[Dispatcher]

We have plenty of energy at venus. like 700w/m2 from all directions. Heavy is not a very big problem, and everything can be made it lighter in case necesary. I am sure that there is plenty of different methods to separate componenets. We need to choice the best due those conditions.

Notice that I wrote that there IS energy available at Venus. I'm not saying that we cannot extract materials from Venus, but I am saying that its is far easier to establish a processing and habitat infrastructure on a solid surface (land) than it is to establish one in sulfuric acid clouds. The largest hurdle is setting the thing up in the first place. The second hurdle is maintaining it. If those first two things ever succeed, then the third hurdle (producing a usable excess) can be pursued.

That is the point where I strong disagree. Venus does not have the big problems of mars of moon. We can get all elements that we need and more. Even stephen hawking once said that venus is beter for 3 reasons. Location, Location and Location.

Hawking is a theoretical cosmologist. He is not an engineer nor is he an economist; even if I like his work. And you are obviously passionate about this topic, which I admire.

[AngelLestat]

That's petrochemical smog; it's made up of small solid particles, it's not relevant to discussion of distribution of gases.

Yeah, maybe you are right. But if you see at smog componts, are the same from venus troposphere. CO, a little of NO, sulfure dioxide. Etc.

Not forget that venus has many volcanos and a lot of carbon on its surfuce in supercritic state. And petrochemichals are mostly carbon and nitrats.

Notice that I wrote that there IS energy available at Venus. I'm not saying that we cannot extract materials from Venus, but I am saying that its is far easier to establish a processing and habitat infrastructure on a solid surface (land) than it is to establish one in sulfuric acid clouds. The largest hurdle is setting the thing up in the first place. The second hurdle is maintaining it. If those first two things ever succeed, then the third hurdle (producing a usable excess) can be pursued.

I was doing a quick read of Venus book on google (some pages are not visible), but it seems that the h2o and acid componts are more scattered over the whole atmosphere of what I thought. Still has mostly of its concentration at 50km range. But there is still some bit a lower and upper layers. Due to the high atmosphere density at lower layers this is still (I guess) a lot of water scattered in those altitutudes. Which makes the cloud layer a lot more dry of what I thought.

With that I am not so sure how much problem sulfure acid can do.. I am not totally sure if you really need some cloth (all the time) to protect you against those levels.

But what is certain, that we need more data. There was a lot of doubts from the author about the oxigen and water concentrations in that height.

Still is enoght to place some cities, but the water extraction is not so easy like I thought.

Hawking is a theoretical cosmologist. He is not an engineer nor is he an economist; even if I like his work.

He was not talking about economics, is clearify later. He said that due to Venus is the closer planet (location), the atmosphere pressure and shield radiation (location) and the fact that we are closer to the sun in w/m2 energy and orbital velocity (location)

[Dispatcher]

We totally agree that more data is needed. I think besides orbiters, we need aerostat and more lander probes there. It would be nice to obtain weather data at multiple locations, spanning a Venusian day (which is longer than its year). Only with more information can it be determined how to deal with further efforts at Venus.

[K^2]

Venusian year is almost two Venusian solar days.

I would also strongly suggest raising the altitude above 50km. 1 bar and 20°C might be perfect, but 0.5 bar and 0°C is better in many regards. You can maintain the same partial pressure of oxygen and use waste heat to keep comfortable temperature inside. (At 50km, you'll need heat pumps to keep interiors comfortable.) You'll also get less corosive atmosphere, and high wind speeds aren't as bad of a problem in lower density. Finally, the most important reason is that you get way more sunlight.

[Dispatcher]

I believe it is about 0C instead of 20C at 50 km, according to the previous chart. Would the lower density of a higher elevation be offset by the stronger winds? I agree that sunlight is more available the higher one goes.

[K^2]

The tables kind of disagree on what the temperature is at a given altitude. The ones in K show about 300K at the same altitude as the other chart shows 0°C. I was going by the chart in Kelvin.

Wind speeds seem to be pretty level across the relevant range of altitudes, so I don't think it will matter. Of course, if the ship is floating, absolute wind-speed is irrelevant. It's the turbulence and shears that are going to damage your structure. And I would expect upper cloud layer to have lower turbulence than lower cloud layer, but that's just going off from flight experience. Flight tends to be most shaky right before you hit cloud ceiling and starts to ease off as you raise higher through the clouds. Usually.

But this might be specific to Earth or even specific climate zones. I don't know enough about weather in general to insist that this is always true. It'd be nice to see Doppler results from different altitude on Venus to make a conclusion.

[Dispatcher]

One source, while providing the 0C graphic, posts a table thus: 55 km, 27C, 0.5314 Earth atmosphere (bar). That's about 81F. This would be warm, but not terribly hot, yet the ambient pressure would be difficult but not impossible in terms of breathing. I'd imagine habitats would need to be pressurized higher than the ambient outside; in part to keep slow leaks outward, otherwise CO2 would kill. If the source is correct (Wikipedia), this would of course not be the ideal 68F and 1 bar pressure which is often presented in discussions of this kind. Going lower would make it dangerously hot for human survival, not just comfort. Going higher would make it cold but require a sturdier pressurized environment. So as I've indicated above: difficult but not impossible; also from a return on investment point of view, the Moon, NEAs and Mars are much more attractive destinations for industry and colonization efforts. Beyond that, some moons of Jupiter and Saturn may be promising.

[K^2]

I can definitely see benefits in building a research statoin like that, but I don't know if it makes sense from colonization perspective. In fact, I'm not entirely sure why people are so inclined towards planetside colonization when there is so much habitable space, well, in space. Artificial gravity and pressure are easy to maintain if you are building something populated by thousands of people. And you can find everything from organic building blocks to heavy metals in asteroids.

[AngelLestat]

But in that case you need to deal with vaccum. Any place vaccum proff would increase construction budgets by a lot.

And the risk of any fail mechanism or hole due to rock/debris remains.

You can get almost all the materials that you need from asteroids, but asteroids of one type of materials are not often close to different kinds of asteroids.

So get diversity of materials it would not be so easy. Also all construction labor at space are a lot more problematic.

[K^2]

Asteroids might be far apart, but resources are really cheap to move around if you don't care how long it takes for you to get them. So as long as you have a steady stream of resources from various asteroids or asteroid groups, you're good.

Vacuum proofing has two parts to it. Pressure - that's actually not so bad. It's much easier to build in vacuum than in high pressure environment. If your station is built as a rotating self-suspended bridge, this is going to take the bulk of structural strength, with pressurization being handled by internal structure without any problems. And then there are leaks. These you'll have to deal with with any hostile environment. So overall, it's not so bad. Same deal with possibility of damage. If one of your modules depressurizes high in the Venusian clouds, anyone inside is going to be just as dead as if this happens in vacuum. (P.S. On asteroid impacts. Micro asteroids can be handled easily enough with shields, and larger ones are just as likely to hit you on world as off-world.)

There are challenges in building in space, and in short term, that might be the more expensive option. But the moment you need to move people between habitats in different parts of the Solar system, the added cost of getting someone off world will make expense of building in space seem like nothing in comparison. Once you are in space, you have the whole of Solar system in your disposal, and that by far outweighs any minor disadvantages that we'll learn to overcome with better techniques and materials.

Edited February 17, 2014 by K^2

[AngelLestat]

I always look like good eyes space cities from the point of view of interstellar travel. But if our reason it is stay in orbit, then utilizing a planet to solve our population and resources issues, it seems more efficient from my perspective.

The KG to orbit price down every year. So the launch cost would stop to be a main issue.

Mostly all people dont need to go to space. So why they should live in a space city? If you tell me that some people jobs is to travel from one planet or asteroid place to another. Then live at space has a lot of sense.

So a orbiting city would be really usefull and it shoud be constructed (also for space turism), but not to solve general problems, just to solve some particular people and companies problems.

About the chance to be hit it by an asteroid, being at venus clouds (terminal fall velocity 130km/h) or being at the asteroid belt.

Chances are a lot higher and danger at asteroid belt I would said.

Any rock that change its curse in that orbit, it would go back to the same orbit point over and over. And that orbiting area never was clean up by any planet influence.

All measurements to avoid this risk, increase the value of the station.

About how safe would be a cloud city, I will continue that discussion at terraforming topic (with a sketch) before derail this topic even more.

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I found this in the last pages of the old venus book that I was reading.

Is not encouraging. But again, all this data was build using chemichals and meteorology theories guide it by different measurements taken by some of the probes who arrive.

New books does not have so much info, but they are a lot more encouraging about concentrations. They also describe the formation of acid droplets 70% concentration at 70km and how they grow in side and fall reaching 35 km to become vapor again and rise.

Then they can be easy harvested.

There is som

[Idobox]

In my opinion, the whole point in colonization is not to move people around, or even to get resources, it is to get people living away from Earth.

Sooner or later, Earth will become inhabitable for us, possibly because of an unexpected catastrophe. We need to get people of this rock, even if they can never come back.

The discussion about Mars, Asteroids, the Moon, Venus or some other bodies is an engineering issue.

Venus provides an almost Earth-like environment and good protection against whatever the universe can throw at us.

Asteroids are not in the bottom of a deep gravity well, but the resources are scattered, have negligible gravity (double edged) and provide little to no protection.

Mars is at the bottom of a gravity well, and doesn't have super exciting resources.

The Moon is very close, and makes perfect sense as the first stepping stone for colonization. Especially for ship building and refueling.

[Dispatcher]

In my opinion ... Mars is at the bottom of a gravity well, and doesn't have super exciting resources.

Really? I think Mars has an abundance of resources, as well as being potentially a place for human habitation.

[Kryten]

In my opinion, the whole point in colonization is not to move people around, or even to get resources, it is to get people living away from Earth.

Sooner or later, Earth will become inhabitable for us, possibly because of an unexpected catastrophe. We need to get people of this rock, even if they can never come back.

The discussion about Mars, Asteroids, the Moon, Venus or some other bodies is an engineering issue.

This doesn't make a lot of sense. If you can make Mars or (especially) Venus habitable, then you can keep the earth habitable pretty much regardless of what happens to it. There's no plausible scenario short of the sun going red giant that could make earth less hospitable than Venus is now.

[AngelLestat]

This doesn't make a lot of sense. If you can make Mars or (especially) Venus habitable, then you can keep the earth habitable pretty much regardless of what happens to it. There's no plausible scenario short of the sun going red giant that could make earth less hospitable than Venus is now.

He is saying (and I dont understand where you going with "especially") that if anything happen at earth (big meteorite collission, super volcano, super war, pandemic, wherever...), we would not be extinct.

For example, try to avoid a big asteroid, even if you know that is comming with a time frame of 10 years, it would not be possible to stop it. All those energy requirements it would be a lot bigger than place a self-sustaining colony in mars or venus.

[Kryten]

What effect would a plausibly-sized asteroid be expected to actually have that would be any harder to deal with than Veusian or Martian conditions? People being unable to cope with, say, impact winter but being able to survive just fine in permanent gloom dozens of kilometresabove any surface in a toxic atmosphere (as in your own Venus proposal) simply isn't a credible scenario.