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Tom Kalbfus

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Re: Venus

I think if we introduced Earth life in the Venusian clouds, it would be like dropping fresh water goldfish in the ocean, I don't think any of the tuna would be threatened by them, the gold fish might make an extra meal for them, as they won't live long in salt water. I don't think we are likely to be able to do anything in the near future that will significantly alter the Venusian climate, by the time we can, we will have and sufficient time to discover and study whatever native life might exist there, and if there is life that is hidden so well that we can't find it even after all that, then too bad. One thing about Venus, is that Geologically it resembles an early Earth before continents began to form. Venus has little water, therefore most of the rock is basaltic, I believe granite can't form without water, so continents as we know them don't exist on Venus, Venus does have highlands though, in the form of pseudo continents Ishtar and Aphrodite, the rest of the globe is dominated by various mountains which would be islands on a terraformed Venus. Venus requires less water than the Earth would to have the same hydro-graphic percentage of its surface covered with water, as its oceans would be less deep than Earths, this probably means blue green algae would flourish in such oceans, and it would probably oxygenate the atmosphere to a greater extent than Earth. There would be a lot of fish in those shallow oceans, plenty of coral reefs eventually too. My sense is it would be easier to do Venus as a tropical planet, shading the area over the equator and some distance to the north and south while letting the poles get a full does of Venusian sunshine, would probably produce a hot steamy planet at the edge of a runaway greenhouse effect. Perhaps this would be what we would want, a global tropic zone, with some relief obtained by climbing the mountains. A 3 bar atmosphere at sea level would probably mean that the tops of the highest mountains would have air that would be quite breathable for us.

robertwalker

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Re: Venus

I think if we introduced Earth life in the Venusian clouds, it would be like dropping fresh water goldfish in the ocean, I don't think any of the tuna would be threatened by them, the gold fish might make an extra meal for them, as they won't live long in salt water. I don't think we are likely to be able to do anything in the near future that will significantly alter the Venusian climate, by the time we can, we will have and sufficient time to discover and study whatever native life might exist there, and if there is life that is hidden so well that we can't find it even after all that, then too bad. One thing about Venus, is that Geologically it resembles an early Earth before continents began to form. Venus has little water, therefore most of the rock is basaltic, I believe granite can't form without water, so continents as we know them don't exist on Venus, Venus does have highlands though, in the form of pseudo continents Ishtar and Aphrodite, the rest of the globe is dominated by various mountains which would be islands on a terraformed Venus. Venus requires less water than the Earth would to have the same hydro-graphic percentage of its surface covered with water, as its oceans would be less deep than Earths, this probably means blue green algae would flourish in such oceans, and it would probably oxygenate the atmosphere to a greater extent than Earth. There would be a lot of fish in those shallow oceans, plenty of coral reefs eventually too. My sense is it would be easier to do Venus as a tropical planet, shading the area over the equator and some distance to the north and south while letting the poles get a full does of Venusian sunshine, would probably produce a hot steamy planet at the edge of a runaway greenhouse effect. Perhaps this would be what we would want, a global tropic zone, with some relief obtained by climbing the mountains. A 3 bar atmosphere at sea level would probably mean that the tops of the highest mountains would have air that would be quite breathable for us.

Certainly true for most life. The thing is though that we have life able to live in environments on Earth that would be just as lethal to nearly all living organisms. For instance well above 100C, well below freezing, very acid, very alkaline, high levels of metals, high levels of ionizing radiation, extremely dry conditions etc. You also get polyextromephiles that can handle several of those extremes at once. See Extremophile Classificiations

And the thing is also, that microbes retain their adaptations when they are in more clement conditions. So a human habitat, and indeed the human body itself, can host extremophiles and polyextremophiles.

So - is not immediately obvious that Earth life would be unable to survive there, might be, but needs study and simulations.

However the 2006 planetary protection report for Venus seems pretty conclusive

A slight possibility exists that terrestrial organisms could grow on airborne particles near to the
cloud tops of Venus. The problem was discussed at the 1970 COSPAR [Committee on Space Research of the International Council for Science] meeting, and some interest was expressed in investigations of airborne life. Life on Venus is no more than a remote contingency, but the
possibility of contamination by terrestrial organisms must be considered.

Regarding the atmosphere, there are some uncertainties on the likely presence of sufficient
nutrients, a high water activity and the convective rate by which water droplets containing
microorganisms are transported downwards and pyrolyzed at the higher temperatures. The
probability of contaminating the Venus atmosphere was treated in the SSB 1970 summer study;*
in that study, a probability of growth for the atmosphere ≤ 10−6 was recommended and approved
by the Space Science Board (a recommendation which superseded the previous value of Pg
≤ 10−4).

So  that means they think the chance that Terrestrial microbes could grow in the Venusian atmosphere is less than one in a million.

In principle, life in the Venus ocean could have been transported to the clouds and then persisted
there after the point at which life on the surface became impossible and even until the present day. While
this hypothesis overcomes the problems inherent in an origin of life within the clouds, it does not
overcome the formidable problems that would face an organism living in this hostile environment, which
include the following:

• The extremely acidic, dehydrating, and oxidizing environment of the cloud droplet environment, which will lead to the destruction of organic matter;
• The very high energetic cost of recruiting water from concentrated sulfuric acid;
• The high temperatures of the droplets at the cloud base, through which all droplets inevitably cycle;
• The lack of persistence of individual droplets, which have a probable life span of months to,
at most, a few years;
• The loss of nonvolatile elements that fall to the surface of Venus; and
• The absence of biogenic elements that do not have volatile forms (e.g., Na, Mg, K, Ca, Mn,
Fe, and most other metals). Although these elements could be introduced into the atmosphere by volcanic
eruptions and by meteoritic infall, there is no obvious mechanism by which they could become widely distributed among all cloud droplets.

Survival of Earth-Life on Venus
The identification of extremophiles on Earth has expanded knowledge of the physicochemical
limits at which life as we know it can exist. Organisms have been shown to grow at temperatures as high
as 121°C,13 in chronic radiation fluxes of 60 gray/hour,14 in extreme pressures at the bottom of oceans,
and in acidities as extreme as pH 0.15 However, none of these extreme but life-supporting environments
approaches the severity of surface and atmospheric conditions present on Venus. In particular, the
ambient surface and atmospheric conditions on Venus render all currently known extremophilic
phenotypes on Earth irrelevant. Concentrated sulfuric acid is sterilizing for all known organisms. Thus,
genetic and other physiologic determinants necessary for life on Earth could not function on Venus, nor
would biological determinants that evolved on Venus be expected to function on Earth.

The cloud layers in the atmosphere of Venus provide an environment in which the temperature
and pressure are similar to surface conditions on Earth. However, the chemical environment in the
clouds, and specifically in the cloud droplets, is extremely hostile. The droplets are composed of
concentrated (82 to 98 percent) sulfuric acid formed by condensation from the vapor phase. As a result,
free water is not available, and organic compounds would rapidly be destroyed by dehydration and
oxidation. Therefore, any terrestrial organisms having survived the trip to Venus on a spacecraft would
be quickly destroyed. It is not possible to demonstrate conclusively that a spacecraft returning to Earth
after collecting samples of Venus’s surface and atmosphere will not come into contact with hypothetical
aerial life forms and inadvertently carry them back to Earth; however, this has to be considered an
extremely unlikely scenario. At any rate, any life forms that had adapted to living in the extremely acidic
environment of Venus’s cloud layer would not be able to survive in the environmental conditions found
on Earth. No special procedures are warranted beyond those required to maintain the sample integrity necessary for scientific studies of the returned samples.

So that seems conclusive. But that is back in 2006, and I wonder if it needs re-assessment. At the time, there was a dissenting voice on the subject, see Planetary Protection Study Group Mulls Life On Venus:

While agreeing with the report on certain points, Dirk Schulze-Makuch, an associate professor in the Department of Geology at Washington State University in Pullman, Washington remains open-minded that the clouds of Venus may be a safe harbor for microbial life.

Not a task force member, Schulze-Makuch has extensively looked into the Venus-life connection, and also briefed the task force on his research.

"I agree with the task force that the risk of forward and backward contamination is very low," Schulze-Makuch told SPACE.com, "because of the very different living conditions in the Venusian clouds compared to basically all known Earth environments."

However, Schulze-Makuch said he was disappointed that the study group did not suggest any scientific investigation for the explicit purpose of reducing uncertainty with respect to planetary protection issues.

"I wonder if they would come to the same conclusion if we would have confirmation that oceans on the surface of Venus existed for billions of years until fairly recently," Schulze-Makuch said, and that life originated there and later found a refuge in the Venusian atmosphere. Even as hostile conditions gradually increased within the atmosphere, life may have been able to hang on and could still be present in the cloud layers, he suggested.

"For me this is an entirely plausible scenario," Schulze-Makuch added.

Rare niches

As the task force explained, there shouldn't be any significant interaction between putative Venusian cloud microbes and Earth organisms, Schulze-Makuch said. However, there is some uncertainty because most Earth microbes are still unknown and there are some known organisms that come close to living in Venus-like conditions, he suggested.

"We do not know [about] and thus obviously cannot estimate capabilities of any alien organism," Schulze-Makuch said. "Perhaps, if they originated in an earlier Venus ocean they may have still retained the capability to quickly adapt to their earlier environment. Thus, they might be capable of competing in selected, rare niches on Earth, such as volcanic vents."

ESA's Venus Express will not resolve the question of possible Venusian life, Schulze-Makuch said. "But its measurements of water, chemical species, and volcanic activity will shed some light on the viability of our hypothesis of possible microbial life in the Venusian atmosphere."

The chances of an indigenous microbial community floating around in the Venusian atmosphere, Schulze-Makuch concluded, "are not remote but are significant in my mind!"

I think part of it is that planetary protection studies usually use similar ideas to biohazard protection on Earth where a 1 in million chance is thought adequate. But if you fail at planetary protection, that could be a hazard for Earth or for the planet being protected for all future time. So potentially trillions of people in the future could be affected if it goes wrong.

So, I think one should use lower probabilities than 1 in a million. I think a closer parallel is the creation of XNA based life in the laboratory - which has potential to out compete DNA in the wild. The required probability of escape for that, if we ever do it - in one study - was set at one in 10^20. I.e. you have to be pretty certain it can't escape, not just 1 in a million sure. They would do it by such techniques as making it so that it requires ingredients you only find in the laboratory and not in the wild to grow - and to make sure it can't adapt to use normal materials available on the Earth.

Those are "Existential Risk" calculations and personally I think that sample returns for the first time from outside of Earth should use probabilities based on existential risk assessment, and also I think same for contamination of other planets by Earth, that is a personal view - I would require all missions to Mars to be sterilized to Viking levels myself or better, because I'd make the probabilities far more stringent. But that wasn't done and there is a chance we have contaminated Mars, perhaps 1 in 1000 or so, hard to estimate - but reasonable chance we haven't. I think, personal view, again, that for places we haven't yet sent missions to such as Europa especially then we should do far better than the 1 in 10,000 and interestingly some of the scientists in the Europa planetary protection assessment put forward that same view that the standard 1 in 10000 risk of contaminating a planet during the exploratory phase is not strong enough for Europa.

I'm not sure if we need to use such a strong standard for not contaminating the Venus cloud decks. But I think we should proceed with care, and take into account the possibility that we might not know enough to properly assess probabilities yet, and that it may need more research.

Our knowledge moves on and there is always the possibility of e.g. finding new acidophiles that could survive on Venus for instance. I don't think that they actually simulated a Venus atmosphere for instance and tried putting Earth microbes into it to see if any were able to reproduce - it was a purely theoretical study. And our knowledge of the Venus atmosphere isn't that great either, I think we need to know more before we can assess the probabilities well - know enough to be able to simulate it on Earth - if we can do that - and try seeding it with Earth microbes, lots of times in long running experiments to simulate e.g. humans visiting Venus, and none of them grow - then can be reasonably confident that we are not going to contaminate it.

Last edited by robertwalker (2014-01-08 07:08:33)

robertwalker

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Re: Venus

As for fully terraforming Venus, the atmosphere is 93 bars, so  to get down to 3 bars is about as hard as to get down to 1 bar. Somehow send it all into space and it will just gather it up again gravitationally. Make it into a layer of carbon and it will ignite in the atmosphere. Carl Sagan thought it was terraformable originally but changed his mind when the results came in about the atmospheric pressure on the surface.

I think might be possible eventually with megaengineering, e.g. build lots of rail guns to fire the atmosphere of Venus as dry ice into space (and perhaps send it to Mars to help terraform Mars at the same time if that is desired - or anywhere else in the solar system where CO2 is useful) - but that's far future sci. fi. at present levels of knowledge and technology.

You also have the issue that the entire surface of Venus is turned over in a big upheaval every few hundred million years ago (doesn't have continental drift - they stick in one place - and then over a short period of time geologically the entire surface gets turned over). I don't know how long it is until the next such upheaval - is an important thing to think about as it would destroy not just any civilization but probably also wipe out most of the life on the terraformed planet. Probably less of an issue for cloud colonies protected from the volcanism by 92 bars of atmosphere though I imagine would be tough times for them too.

Last edited by robertwalker (2014-01-08 07:16:15)

Tom Kalbfus

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Re: Venus

Why would you want to send it into space? Venus needs water does it not? The ingredients for water are hydrogen and oxygen. So how much energy does to take to separate carbon-dioxide into carbon and oxygen? Carbon is a solid and oxygen is a gas, and how much energy does it take to send one fifth the weight of all the water we'd need on the planet in the form of hydrogen from the asteroid belt to Venus, and how much energy would it take to extract hydrogen from the asteroids for transportation to Venus? I think it would be the outer asteroids that would make the most plentiful sources of hydrogen, and at any given moment there is a launch window from one of those asteroids to Venus, since the asteroids are spread all around the Sun, at any given moment there is an asteroid in the asteroid belt that is optimally positioned for a minimum energy transfer orbit to Venus, I think this is much better than Jupiter or Saturn or even any of its icy moons. I think there must be plenty of icy asteroids in the asteroid belt, we just haven't seen too many of those so far as compared to Jovian and Saturnian moons. The transfer time from the asteroid to Venus would also be quicker than from any of the outer planets.

Last edited by Tom Kalbfus (2014-01-08 07:33:04)

Terraformer

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Re: Venus

Still, you're talking about breaking up all that water to produce hydrogen, then forming water out of it again. Why not send methane instead, perhaps clearing Titan in the process (and ideally replacing it with another liquid, perhaps ammonia, to keep the hydrology there going)? Sure, you end up with much more carbon, but it doesn't require splitting loads of water.

For Venus, I don't see why getting to the surface is such a big deal for people. What's wrong with cloud cities among clouds of water, rather than sulfuric acid?

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Use what is abundant and build to last

robertwalker

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Posts: 31

Re: Venus

Yes that was Carl Sagan's idea to split the CO2 and create carbon and oxygen instead. But he didn't realize how dense the atmosphere was or how hot the surface. As Venus is now, then the carbon would just burn and return to the atmosphere. You need some way to get the carbon out of the atmosphere - and also - turn it into some form of rock that will not burn up and return the Carbon to the atmosphere at the surface temperature of 420C.

There is one idea here - to cool down the entire surface with orbital mirrors to below temperature of dry ice, and then cover it with some covering to prevent it from returning to the atmosphere when it warms up, maybe chemically change it? But that is a big mega-engineering project.

Then you still have the long  243 days long day on Venus - so a terraformed Venus wouldn't be that habitable for higher organisms if adapted to and depending on shorter days. (Perhaps if they hibernated every night and woke up in the day?).

While in the cloud tops the super-rotation means that the atmosphere rotates around the surface with a day of about 4 Earth days - which seems reasonable for life to adapt to.

Last edited by robertwalker (2014-01-08 09:52:38)

Tom Kalbfus

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Re: Venus

Still, you're talking about breaking up all that water to produce hydrogen, then forming water out of it again. Why not send methane instead, perhaps clearing Titan in the process (and ideally replacing it with another liquid, perhaps ammonia, to keep the hydrology there going)? Sure, you end up with much more carbon, but it doesn't require splitting loads of water.

For Venus, I don't see why getting to the surface is such a big deal for people. What's wrong with cloud cities among clouds of water, rather than sulfuric acid?

That's a great idea! Methane is CH4, carbon dioxide is CO2. So CH4 + CO2 --> 2C +2H2O So does this chemical reaction produce energy or require energy?
Ammonia has nitrogen in it, I don't think Venus needs any more nitrogen, it has 3 bars of it already. I think some of this nitrogen could be combined with the soil to make nitrates for fertilizer. Carbon is a solid it can be combined with the soil to make top soil as well. There is a lot of carbon beneath out feet on Earth, I think if all of it were combusted, it might make an atmosphere similar to Venus.

robertwalker

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Posts: 31

Re: Venus

Most of our carbon actually is in the form of Calcium Carbonate (limestone). Yes Earth probably has about 90 bars of CO2 as limestone. See Earth's atmosphere before the Dinosaurs

If you could turn the CO2 into limestone - that would work. There would be a risk of the CO2 burning off again - but lime kilns operate at 900C (Lime Kiln - Wikipedia), seems a possibility to me.

Can anyone think of an easy way to turn the CO2 atmosphere into limestone?

You could do it with oceans - but of course no oceans on Venus. Also you still have the problem of the global resurfacing of Venus to think about that happens probably every few hundred million years, no continental drift, is one of those due in the near future? Or should we worry about it if it is a far future thing?

You still also have the problem of the almost year long day. One might decide that it is better to keep the existing atmosphere with the super-rotation for the cloud colonies - to actually rotate Venus faster for shorter days is way beyond the energy levels of human civilization at present.

Last edited by robertwalker (2014-01-08 10:52:27)

Tom Kalbfus

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Registered: 2006-08-16

Posts: 4,401

Re: Venus

Yes that was Carl Sagan's idea to split the CO2 and create carbon and oxygen instead. But he didn't realize how dense the atmosphere was or how hot the surface. As Venus is now, then the carbon would just burn and return to the atmosphere.

Not if the free oxygen is combined with hydrogen to form water. Basically what you do is you create the water at the same time your splitting up the carbon dioxide. You don't do it in steps such as:

Step 1: Split all the carbon dioxide so you get a thick layer of carbon soot and a mostly pure free oxygen atmosphere.

Step 2: Combine the pure oxygen atmosphere with imported hydrogen to produce water oceans

You need some way to get the carbon out of the atmosphere - and also - turn it into some form of rock that will not burn up and return the Carbon to the atmosphere at the surface temperature of 420C.

If you burn the imported hydrogen, that oxygen is then not available to burn carbon with. One way to test this out would be to put a lump of coal into a pot of boiling water, the coal will not burn in that boiling water, it needs exposure to oxygen in order to burn, if we keep the percentage of oxygen low so that there is enough free oxygen to burn hydrogen but not carbon, then as we reduce the carbon dioxide atmosphere, the oceans of Venus get deeper.

There is one idea here - to cool down the entire surface with orbital mirrors to below temperature of dry ice, and then cover it with some covering to prevent it from returning to the atmosphere when it warms up, maybe chemically change it? But that is a big mega-engineering project.

This is comparable to sweeping dirt under a rug, You don't want 90 atmospheres with of dry ice suddenly escaping, it would take a lot of refrigeration to keep the carbon dioxide as dry ice under a temperate surface. I think chemical reactions, even ones requiring energy inputs to occur would be less costly than flinging stuff into space. I'm pretty sure Venus doesn't have more carbon than the Earth, it just has it in different forms that we have it in. The carbon on Earth is mostly in solid form underground. If you rearrange the atoms on Venus, add hydrogen and reduce the temperature, you can get something that resembles Earth.

Then you still have the long  243 days long day on Venus - so a terraformed Venus wouldn't be that habitable for higher organisms if adapted to and depending on shorter days. (Perhaps if they hibernated every night and woke up in the day?).

Its easier to manipulate light through reflecting mirrors than the change the rotation of the planet, we are fortunate that Venus has practically no axial tilt whatsoever. Arrays of mirrors around Venus can make the image of the Sun appear on whatever side of Venus that we desire while at the same time blocking light from coming directly from the Sun. Since Venus gets more light than it needs for this, the reflection process can be allowed to be inefficient.

While in the cloud tops the super-rotation means that the atmosphere rotates around the surface with a day of about 4 Earth days - which seems reasonable for life to adapt to.

The super-rotation will probably change once we thin out the atmosphere, I don't think we can count on that.

Tom Kalbfus

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Registered: 2006-08-16

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Re: Venus

Most of our carbon actually is in the form of Calcium Carbonate (limestone). Yes Earth probably has about 90 bars of CO2 as limestone. See Earth's atmosphere before the Dinosaurs

If you could turn the CO2 into limestone - that would work. There would be a risk of the CO2 burning off again - but lime kilns operate at 900C (Lime Kiln - Wikipedia), seems a possibility to me.

Can anyone think of an easy way to turn the CO2 atmosphere into limestone?

You could do it with oceans - but of course no oceans on Venus. Also you still have the problem of the global resurfacing of Venus to think about that happens probably every few hundred million years, no continental drift, is one of those due in the near future? Or should we worry about it if it is a far future thing?

You still also have the problem of the almost year long day. One might decide that it is better to keep the existing atmosphere with the super-rotation for the cloud colonies - to actually rotate Venus faster for shorter days is way beyond the energy levels of human civilization at present.

Plate tectonics would probably occur if you added oceans and the crust cools. Create an environment similar to Earth and we'll probably get plate tectonics similar to Earth as well. Just a hypothesis, but I feel if we recreate Earth we'll get Earthlike effects on the planet, which if you ignore the atmosphere and its position in the Solar System, is really just a lighter version of Earth. A year long day can be adapted to, as many life forms in the arctic regions will attest. Humans can adapt to it just as they have in the polar regions with artificial lights and shades on their windows where needed.

I think we're going to be blocking some light from reaching Venus anyway, so we'll be adding massive infrastructure around Venus to do this, while were at it we can use mirrors to reflect light to illuminate Venus for a 24-hour day/night cycle. Of course a slow rotation rate will make the prevailing air currents and jet streams around Venus different from Earth. Someday someone has to do a computer simuilation of a terraformed Venus Global whether patterns to get an idea of the climate zones of the various regions, sea currents will also be different.

Last edited by Tom Kalbfus (2014-01-08 11:13:12)

Terraformer

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Re: Venus

Well, I've seen a suggestion to fire metal (such as Magnesium) at it from Mercury, with the metal forming carbonates and carbon. But if we're not going for such projects, I'd say crash comets into it so that aerostat colonies have a much easier time (floating islands!). Perhaps later, it will be shaded enough by them (encouraged by short circuiting the heat to generate power) that the boiling oceans can reform, which might take some of the CO2 out as carbonates. Shade it enough, and you could possibly even get a supercritical ocean of CO2 (and of carbonic acid, which would help to weather the rocks and lock away a lot of the CO2).

There's a terraforming scheme that allows for continuous habitation, and gives benefits along the way - first from being able to grow crops in the open and not having to worry about acid dissolving your ships and homes, then being able to access the surface easier for resources as it gets cooler, eventually having a terraformed surface.

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Use what is abundant and build to last

robertwalker

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Re: Venus

Yes - crashing comets to give the aerostats an easier time sounds a nice idea .

With that approach if you want to encourage shading once we have cloud colonies on Venus, then there is Hall's Weather Machine - seems reasonably likely we would have technology to do that once we have floating cloud colonies on Venus .

Also remember that even without mega-engineering we have the ability to grow trees and plants which have 90% by weight just from the CO2 plus water in the atmosphere - so long as we can find some process to get the water from the sulfuric acid in a form usable by plants.

Perhaps somehow we can also extract the CO2 to use to make the mirrors for the Hall's weather machine.

Though - all of this is still in the realm of kind of hard sci. fi. I think at present. Nobody has done a properly worked out study of it, while have been a few for Mars (I think those are sketchy also in the extreme though). Would be good if someone were to do a proper engineering type study of Venus cloud colonies.

Anyway here is a link to John Hall's Weather Machine

Youtube videos: http://www.youtube.com/watch?v=Fd63OMosnq0, http://www.youtube.com/watch?v=EOPsczPlzzY

Somewhat critical article about it - http://www.nanotech-now.com/columns/?article=486

Last edited by robertwalker (2014-01-08 13:02:26)

Tom Kalbfus

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Re: Venus

Interesting, a kind of artificial smog, probably the method that would have been used in the novel The Sky People by SM Stirling. Basically it leaves Venus looking much like it does today from Space, a featureless white disk, no giant mirrors in spacem but also no 24-hour days unless you could spin up the planet.

robertwalker

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Re: Venus

Just to say, found another article on the cloud cities, 2003 one, by Paul Birch, works out many details, including how to extract water from the sulfuric acid, detailed designs of the cloud colonies - and gradual progression towards terraforming of the Venus surface itself. The cloud colonies section starts on page 163.

http://www.orionsarm.com/fm_store/Terra … uickly.pdf

I found out about it here:
http://nextbigfuture.com/2013/08/cloud- … venus.html

Void

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Re: Venus

I did not find the reference to getting water from H2S04, but I believe you.

Biologically and Thermally processing H2SO4

I recall seeing some type of science program once where they had a fish breathing a very diluted solution of Sulpheric Acid.  I am sure the fish did not benefit long term from it, but apparently it could do it short term and use it as an Oxydizer.  At least that was what was suggested.

H2S04 could be split into S02 and H20 and 0 I would think the "O" being converted to O2.

Where I am going is that if you had a biosphere, and introduced small amounts of Sulpheric Acid into it,  (Perhaps a micro organism soup in a tank), it might might in a natural
way assimilate the H2SO4 and convert it into the biomass and O2.  Of course I am including photosynthesis as a part of the process.

Then to earn it's keep it could feed fish.  From their fish droppings could be distructively distilled to drive off hydrocarbons, and I hope Sulphur Dioxide.

Burn the Hydrocarbons in Oxygen, and you would be likely to get some CO2 to dump overboard, and also some H20.

As for the Sulphur, I would hope you could generate Sulphur Dioxide and dump it overboard, and hope to create high altitude clouds with it.
http://en.wikipedia.org/wiki/Sulfur_dioxide

Sulfur dioxide emissions are also a precursor to particulates in the atmosphere.

As for the 1 out of 4 Oxygen atoms you would capture, I presume that your floating cities would be expanding and the empty spaces could be filled with it.

Curriously SO2 has a reverse process to convert back to H2SO4, so the cities would have to convert H2SO4 to desired chemicals faster than nature could convert it back to unwanted chemicals.

Another possiblity would be to extract the Sulphur and use it for your shade in the vacuum of space, but then you have to get it off of the planet somehow, and to L1.

I recall reading that Sulphur is a strong metal in the vacuum of space.

Last edited by Void (2014-01-09 17:34:41)

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End

robertwalker

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Re: Venus

Okay on extracting water from the sulfuric acid that's the section "Water for Venus". The figures are from 1991 so actual numbers are likely to be wrong. But he says "Sulfuric acid from the clouds will provide water by reactions like H2SO4 + MgSO3 -> MgSO4 + SiO2 + H20 " That's all actually so doesn't say much about it sorry.

Yes the whole thing about the sulfuric acid too concentrated to use wouldn't apply if you are using it within the habitat and diluting it first as you say.

BTW stomach acid has pH 1-2. https://en.wikipedia.org/wiki/Gastric_acid

Acidophiles survive and thrive at PHs below 2. https://en.wikipedia.org/wiki/Acidophile

It says here that the sulfuric acid at the cloud tops would have a pH of 0 and below - similar to battery acid - but that there are some Acidophiles that can live at such low pHs.

http://books.google.co.uk/books?id=b7Xh … ds&f=false

Quite detailed working out of possiblityof life in the Venus Atmosphere by Louis Neal Irwin, and Dirk Schulze-Makuch

I notice says "Buoyancy in air is ultimately a problem for any organism because its density is greater than the air it inhabits. The density of droplets of sulfuric acid, however, is sufficient to keep organisms easily afloat. That means, of course, that organisms are restricted in size to the space available in their airborne aquatic habitat."

Does that mean what it seems to - that sulfuric acid droplets would actually float in 1 bar pressure levels of CO2?? Density of sulfuric acid is 1.84 g/cm³. CO2 has a density of 1.977 g/cm3 at 1 bar and 0C. So yes, seems so, both water and sulfuric acid would float in the Venus atmosphere.

CO2 gas at 1 atm is actually denser than water. If you filled a thin skinned balloon with water it would float in the Venus atmosphere - indeed at the 1 bar cloud colonies level, it would actually float up into the air until it reached the 0.5 bar level.

Void

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Posts: 7,817

Re: Venus

It's a good thing that some type of floation is availible, or Venus might be out of reach.

I might add that by capturing the bulk or all of the H2SO4 and extracting the "Water", and then keeping it in containers, such as floating cities, the process of nature converting Sulphur Dioxide back to H2SO4 would be interupted, and also the greenhouse effects on Venus would be strongly deminished.  Perhaps eventually it would cool down enough for CO2 to liquify in the night side and rain?  If so, then the cold of the upper atmosphere would be quickly delivered to lower layers, and the warmer lower layers would be displaced upward as the "Rain" boiled at

http://en.wikipedia.org/wiki/Carbon_dioxide

−56.6 °C; −69.8 °F; 216.6 K (at 5.185 bar)

Maybe it could happen.

If it did then the atmosphere would turn over, and hot layers would be exposed to space, and radiate off heat perhaps, since the H2SO4 protective greenhouse vapor layer and particulated (Clouds) would be gone.

I am not sure, but I susspect that Sulphur Dioxide clouds would more reflect sunlight than provide a greenhouse effect, but I am not sure about that.

Last edited by Void (2014-01-09 19:12:57)

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robertwalker

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Re: Venus

Sorry got the calc wrong above, and if you stop and give it a moments thought - CO2 gas bubbles of course float in fizzy drinks at normal 1 Atm pressure. The density of CO2 is  0.001977 g/cm3 at 1 bar and 0C. So what does he mean by that quote?

"Buoyancy in air is ultimately a problem for any organism because its density is greater than the air it inhabits. The density of droplets of sulfuric acid, however, is sufficient to keep organisms easily afloat. That means, of course, that organisms are restricted in size to the space available in their airborne aquatic habitat."

Is it just a mistake perhaps? Because sulfuric acid is denser than water, and far denser than CO2.

Last edited by robertwalker (2014-01-09 21:06:38)

Tom Kalbfus

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Re: Venus

As you terraformed the planet the floating habitats would drop lower until they were no longer needed, at which point you might as well settle on the surface. I think as you create oxygen, you turn it into water by combining it with imported hydrogen, as the oceans rise the atmosphere thins out as the carbon becomes a solind and the oxygen becomes incorporated into the water. The pressure at the bottom of Venus' atmosphere is not much different from the pressure deep within our oceans, we are basically talking about exchanging an ocean of carbon-dioxide for an ocean of water, and what's left would be 3 bars of nitrogen, some of that would be absorbed into the soil to form nitrates for fertilizers in top soil I prefer gentle methods pf terraforming, not asteroid collisions, we should treat Venus like a woman.

Void

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Re: Venus

Thats all good, but even without importing Hydrogen, eventually I believe that it can be solved how to mine the Exosphere of Venus.

Not a validated or completed solution to the problem, but I would start by trying to have an atmospheric grazer, where the grazing occured in the planets shadow, and so the cold.  Panels with and adsorption coating cooled rapidly in the shadow of the planet could accumulate atmospheric molecules.  However high speed plasma impacting the adsorption material, such as Carbon would likely splutter some of it, and might chemically react with some of it.  That material may in part be adsorbed into (Carbon Adsorption Material?).

Of course coming out of the shadow, the adsorbed gasses would heat up and be desorbed.  Collection at that point might rely on ionic current flow, and perhaps and electrostatic field (Electrostatic cliing), but a further pumping device to containerize it would be required (I have nothing for that just yet, but a few ideas).

That then requires that the eliptical orbital energy be refreshed by an energy source (Solar photon? Solar wind?) but that is complicated.  I havn't worked out how that can be effectively done to maintain an eliptical orbit where the low point dips into the upper atmosphere.

Finally, the collected gasses have to have ecomonmic value.  This could not be paid for with charity, it would have to be a desirable resource.

If all that is achieved, then it would only be a matter of time before the atmosphere of Venus was deminished to more desirable characteristiics.

As for bringing in Hydrogen, I guess that is an economic decision also.  If it can upgrade the economic value of Venus at a reasonable cost then yes.

Otherwise the water collected in the floating habitats could be distributed to the polar areas where on the surface it might be cool enough to have enclosures to hold the humidity in, where some shading could be employed.  Plants only require 1000 lumens I think, but the surface of Venus unobstructed by atmospheric effects would recieve about 20,000 lumens, so you could reflect 95% of the light off of the habitats, and allow only 5% in to reduce heating.

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robertwalker

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Re: Venus

Okay perhaps ideas like that might work later on - but with present day Venus, even with the long year long night, the night side is almost the same temperature as the day side.

The CO2 near the surface forms a "supercritical fluid" technically, is so dense, is over a tenth of the density of water and transmits heat very efficiently throughout the night side of Venus, same for poles.

https://en.wikipedia.org/wiki/Atmospher … roposphere

In the upper atmosphere above 100 km then you do get a temperature change - the usual thermosphere of Venus on the day side turns into a surprising cryosphere on the night side, extremely low temperatures - but that is well above the cloud habitats level, 50 kms higher.

Another issue with attempts to remove the atmosphere from Venus is that it has so much atmosphere, and the gravity of the planet is strong enough so that unless it is sent into space with enough velocity to leave Venus's orbit and go elsewhere in the solar system, then Venus will just gather all its atmosphere up again, especially heavy gas CO2, over quite short time geologically.

I had the idea - not sure it is original may have read it somewhere else - to freeze the Venus atmosphere and fire it away from Venus and from Venus orbit as dry ice pellets - maybe with some reflective covering added to the pellets to keep the CO2 together as a pellet stop it evaporating - e.g. to Mars if you needed CO2 there or the Moon or wherever in the solar system you needed CO2. Someone else suggested that you could use a Stirling engine, to refrigerate and create dry ice so no need to cool down entire atmosphere and freeze it out. If so that could be a gentle on-going process that gradually removed Venus's atmosphere over thousands of years, lots of these machines, perhaps part of the income of the colony if they can sell the CO2 to other parts of the solar system that need it (at low cost once it is all set up and easy to do).

Last edited by robertwalker (2014-01-10 09:55:21)

Tom Kalbfus

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Re: Venus

Whatever carbon dioxide you throw away is less oxygen for the ocean you'd want to create. Seems to me that it would take more energy to accelerate carbon-dioxide to escape velocity and then bring in an oceans worth of water from the outer Solar System, and all that carbon would be gone, you'd have a silicate basaltic crust to work with, you'd have to import carbon to make soil you can grow stuff in. I think that by throwing away carbon dioxide, you'd be depleting the planet of the carbon it needs to have a living biosphere in the future. My principle is not to throw away stuff you could otherwise use, there is plenty of hydro-carbons in the outer asteroid belt. If you throw out stuff, you would later have to import stuff that you previously threw out. I think it takes less energy to split carbon dioxide into its constituent elements than to accelerate it to escape velocity.

robertwalker

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Re: Venus

Tom - yes your posts are bringing me around to your way of thinking. Given that Venus has the same composition as the Earth, just in different forms with the CO2 all in the atmosphere, then if one can, makes sense to put it back together as it were in an Earth like form again - if it works.

I also think, that this is far future science we are talking about - terraforming is going to be a centuries long / millennia long project most likely - and by then surely we will know a huge amount more about exoplanets and have supercomputers able to simulate the whole thing in great detail - and must be a very stable long lived society to contemplate a project that would need to be sustained for probably well over a thousand years and most likely thousands of years to completion.

So no hurry to start on it, a delay of a century or two would make hardly any difference compared with the time it would take to complete it, even with extreme mega-engineering, and we may find clever shortcuts and neat ways to do things that would save centuries or thousands of years on the process so certainly good to think it through a lot first for that reason also.

Cloud colonies though, we could start on within a few decades, if it was okay for planetary protection reasons - no life there- and would be reasonably low tec. and sustainable - if detailed studies back up the sketchy ideas we have so far that is.

Though I think the most interesting case is where Venus does have life and so interesting that we decide not a good idea to set up colonies there yet - though disappointing for colonization, would be great for science and biology and understanding of primitive cells and evolution and well compensate for the colonization disappointment.

Last edited by robertwalker (2014-01-10 11:05:07)

Tom Kalbfus

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Re: Venus

There is nothing stopping us from building floating habitats while where terraforming Venus, at least so long as we're not hurling comets and asteroids at it! I think the first step in terraforming the planet would be in constructing an orbital mirror and shade array around the planet, this might be a good reason to build O'Neill colonies in orbit around Venus, perhaps some asteroid mining could be done for this.

robertwalker

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Re: Venus

Yes indeed, that's what I meant, we can build the cloud colonies (planetary protection permitting) - and then study to see what is the best way to terraform after that.

The cloud colonies would be fine for the gentler ways of terraforming. And if we did want to export the atmosphere, is plenty of atmosphere to export without disturbing the colonies.

I do feel a bit cautious here, that we don't have any experience at all of anything like it, and so, maybe there might be some "gotcha" we can't anticipate even about seeding a Venus type planet with cloud colonies. I suppose the main things are

1. Is there a risk we could make the planet less habitable for humans - for Venus I think NO (For Mars, YES)

2. Is there a risk that colonization could get in the way of finding out new and valuable science - for Venus - I think - possible but at present seems unlikely - need to explore it first (to check to see if there are any life forms in the clouds). For Mars - again I think, strong YES.

3. Is there a risk that early colonization could cause problems with ideas to terraform the planet in the future. For Venus - yes possibly - if the future terraforming involves impacting asteroids into a planet inhabited by billions of people in cloud colonies. Also could be an issue if the terraforming involves a careful progression introducing photosynthesizing plants that create oxygen first in great quantities and to keep aerobes well away. But I think less of an issue than for Mars for both those things. For Mars I think there is a high risk that early colonization, just landing humans on the surface with all their microbes, if they start to reproduce and transform the planet in an unplanned way, could thoroughly mess it up for terraforming.

So - I think Venus is far better than Mars - but not totally clear that it is okay - I think needs exploration and research, quite a bit of it, before we set up our first cloud colony on Venus if it is feasible and seems a good thing to do. And I think terraforming Venus also - though much less likely to go wrong perhaps - but you have the same issue as for Mars - that we don't really know much yet about how planets naturally terraform. Earth may be a rare exception or may be common. Also we would be attempting to do in a few thousand years something that on Earth took billions of years, which is a huge speed up. So may not be so easy to guide it to the desired end state as one might think.

E.g. may be many different stable states it could end up in and perhaps many of them might have atmospheres poisonous to humans so may not be as easy as it seems to steer it to the desired goal. I don't think we can really be confident about that right now but in future as our understanding progresses we may be able to be.

And is a long term thing also and it might be you have to keep it going keep doing things to keep it on target - so you have to commit to 1000s of years of terraforming once you get started, and we don't yet have enough experience to know if we can maintain a single technological society with a single long term project for thousands of years. It might well be possible, but we only have a century or so of reasonably high technology to guide us and have no other similar projects to compare it to in scale.

Last edited by robertwalker (2014-01-10 11:24:25)