Venus ISRU: What Do We Have to Work With?

In the last mini blog-post, we talked about some of the benefits of atmospheric-feedstock ISRU. But that leads to the question, what materials are there in the Venusian atmosphere, particularly in and around the 50km zone? While chemical engineering may limit your ability to rearrange elements from the atmospheric constituents into an end-product, if that element isn’t available in the atmospheric constituents, you’re probably going to have to bring it from earth.

While I’ll go into more detail about the sulphuric acid and water vapor concentration in a future blog post, here are links to two tables (one from wikipedia, and another from a Purdue planetary science lecture). With atmospheric density at 50km being approximately 1atm, and with CO2 being most of the atmosphere, the bulk density is probably just a little under 2kg/m^3. I could get more precise than that, but that’s a decent rule of thumb. So the key atmospheric constituents at 50km, their relative abundance, and their mass density per cubic meter are (assuming I’m doing my math correctly):

  • Carbon Dioxide (CO2): 96.5% of the Venusian atmosphere is CO2. I’m not positive if this varies much with altitude in the ranges we’re talking about. But this would be approximately 1.93kg/m^3
  • Nitrogen (N2): 3.5% of the Venusian atmosphere is gaseous nitrogen. This works out to about 70g/m^3
  • Sulfur Dioxide (SO2): 130-150ppm in the Venusian atmosphere, which works out to 260-300mg/m^3
  • Argon (Ar): 65-70ppm, or about 130-140mg/m^3
  • Oxygen (O2): 30ppm or about 60mg/m^3 [Note: this one is only listed on the Purdue site]
  • Water Vapor (H2O): 20-30ppm or about 40-60mg/m^3. Compared this to the driest place on earth in the Atacama desert near the ALMA observatory in Chile, which had 200ppm water vapor at 5km altitude (.74kg/m^3 atmospheric density), which assuming I didn’t make math mistakes works out to ~145mg/m^3 [Note: I wasn’t able to find anything on how this varies with altitude, so I’m just going with the raw numbers for now, and assuming they still hold at 50km.]
  • Carbon Monoxide (CO): ~17-20ppm or about 35-40mg/m^3
  • Helium (He): ~12ppm or about 24mg/m^3 [Note: This one was only listed on the Wikipedia site, and I don’t know how much it varies with altitude]
  • Carbonyl Sulfide (OCS): 10ppm or about 20mg/m^3 [Note: only shown on the Purdue site]
  • Neon (Ne): 7-9ppm or about 15-18mg/m^3
  • Sulfuric Acid (H2SO4): I had a hard time finding good numbers for this, but according to Figure 3 on this page, at 50km, the abundance works out to ~14mg/m^3 or about 7ppm. So, between sulfuric acid and water vapor, you have about half as much mass per cubic meter as water vapor in the air near the ALMA observatory in the Atacama desert in Chile. Bone dry by terrestrial standards, but sopping wet compared to say the Moon.
  • Hydrogen Chloride (HCl): 0.1-0.6ppm or between 0.2-1.2mg/m^3
  • Hydroflouric Acid (HF): 1-5ppb or between 2-10µg/m^3

Of these components three of them (water, sulfuric acid, and hydroflouric acid) have liquid phases at room temperature, which means they can likely be condensed out as liquid phases relatively easily before processing the rest of the gas-phase constituents. Also, the HCl vapors dissolve so readily into liquid water (forming a hydrochloric acid), that they may also be effectively “condenseable.”

So elementally, we have lots of Carbon, Oxygen, Nitrogen, and Sulfur, decent amounts of Argon, Helium, Neon, and Hydrogen, and trace amounts of Chlorine and Fluorine. What can you do with these building blocks, assuming you can make the chemical engineering work to take these feedstocks and convert them to the outputs you want?

  • Breathable air
  • Drinkable water (from the water vapor and chemically extracted from the sulphuric acid)
  • Chemical rocket propellants (LOX, Methane, Hydrogen, and with a lot more work maybe some storables like N2O, N2O4, Hydrazines, H2O2, and storable hydrocarbons and alcohols)
  • Most plastics including PE, PP, PC, PET, PVC, Epoxies, Teflon and other flouropolymers (in modest quantities–the Florine’s pretty rare). Just no silicones unless you bring your own Si
  • Carbon and aramid fibers
  • Graphite, Graphene, and Carbon Nanotubes
  • Sulfur “Concrete” (likely using graphite whiskers as the reinforcement)

Anything metal would likely need to be imported, but if the ISRU equipment to get to simple polymers and carbon fibers isn’t prohibitively large, you might actually be able to build most of the structures, the sulfuric-acid resistant outer skin, and the breathable atmosphere, and drinking water all from local materials. Seems promising.

Next Up: Condenseables

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Jonathan Goff

Jonathan Goff

President/CEO at Altius Space Machines
Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and is the founder and CEO of Altius Space Machines, a space robotics startup in Broomfield, CO. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.
Jonathan Goff

About Jonathan Goff

Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and is the founder and CEO of Altius Space Machines, a space robotics startup in Broomfield, CO. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.
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54 Responses to Venus ISRU: What Do We Have to Work With?

  1. Andrew W says:

    I think most of those components are going to be at concentrations too low to be useful, maybe if they were a sideline for a population harvesting some other pot of gold, but as the primary resource on which to build wealth?

    No location on Earth would be as resource poor.

  2. Andrew,
    I wasn’t talking about most of these ISRU components as economical sources for export! I was talking about them in the narrow sense of materials you’d need to bootstrap settlements with the minimal inputs from earth. And since these are atmospheric feedstock sources, even trace compositions can be collected economically in vast quantities.

    I’ll get into this more later, but in one day you have about 85000 seconds in a 24hr period. If you had a way of providing 1m/s of airflow into a harvester (say by having a little bit of a drag anchor that slows you down just slightly relative to the 300km/hr jet stream), and had a 1m^2 processor inlet cross section, that works out to 85000 m^3 of air flowing through your processor in one day. If all you were doing was extracting the four condenseables (H2O, H2SO4, HCl, and HF), and your process was only 10% efficient (ie 90% of the condenseables pass through without condensing out), you’d be getting 20-30kg/day of water, about 7kg of H2SO4, 0.6kg of HCl, and 5g of HF.

    Ok, so so at this scale the HF is pretty negligible–you won’t be making much Teflon at this scale/efficiency/relative-velocity. But for a 1m^2 entry area (something you could easily put on a small ISRU testbed), getting 30-40kg/day of condensable materials per day isn’t bad.


  3. George Turner says:

    As an aside, mining on Venus would actually be pretty easy because at the surface the atmosphere is so dense (69 kg/m^3) that a helium filled craft the size of the Space Shuttle external tank (about 2,000 m^3) could lift 100 tons of rock.

    One very simple method would be to drop a big metal bit (built something like a giant post hole digger) attached to an empty hull with a high pressure helium tank, whose burst disk gets ruptured by impact with the surface. The tool free-falls, impacts, and then the helium is released into the hull, which lifts the load to a moderate altitude where an attached balloon could be inflated, which then lifts the load all the way to 50 km altitude. The tons of rock then drift around until rendezvous with an airship. Then you replace the burst disk, repressurize the helium and put it back in the high pressure tank, repack the balloon, and drop it again.

    Though the method is crude, it doesn’t require any electronics or cooling and could provide any elements missing from the atmosphere.

  4. Andrew Swallow says:

    Plants can extract oxygen and carbon from the Earth’s atmosphere. With the high levels of carbon dioxide it may be possible to harvest them from Venus’s atmosphere using organic methods. The acids will probably need removing first.

    I do not know how much sunlight exists at 50 km.

  5. Brock says:

    I would assume that any settlement of Venus would occur after an asteroid mining industry is established on Earth. This suggests two things to me-

    1. Delivering metals and rocks to Venus shouldn’t be any more difficult than delivering it to Earth, depending on the asteroid’s orbit.

    2. We could steer large, volatile rich asteroids or comets, crashing them into Venus. They’d melt quickly and the vapors would mix with the atmosphere. This could enrich the concentrations of many elements.

  6. gbaikie says:

    “Sulfuric Acid (H2SO4): I had a hard time finding good numbers for this, but according to Figure 3 on this page, at 50km, the abundance works out to ~14mg/m^3 or about 7ppm. So, between sulfuric acid and water vapor, you have about half as much mass per cubic meter as water vapor in the air near the ALMA observatory in the Atacama desert in Chile. Bone dry by terrestrial standards, but sopping wet compared to say the Moon.”

    “The atmosphere exhibits a sulfuric acid cycle. As sulfuric acid rain droplets fall down through the hotter layers of the atmosphere’s temperature gradient, they are heated up and release water vapor, becoming more and more concentrated. When they reach temperatures above 300 °C, sulfuric acid begins to decompose into sulfur trioxide and water, both in the gas phase. Sulfur trioxide is highly reactive and dissociates into sulfur dioxide and atomic oxygen, which oxidizes traces of carbon monoxide to form carbon dioxide. Sulfur dioxide and water vapor rise on convection currents from the mid-level atmospheric layers to higher altitudes, where they will be transformed again into sulfuric acid, and the cycle repeats.”

    So it seems to me you lots droplets of H2SO4 in the massive clouds
    of Venus.
    On Earth our clouds are droplets of H2O, on Venus they are H2SO4,
    but heat the H2SO4 it converts into H20 and Sulfur trioxide [SO
    3]. So if collect H2SO4 and heat it, you get water and Sulfur trioxide.
    Or you can get lots of water on Venus.
    Or a reason Venus is dry is it has lots of Sulfur trioxide which will combine with water below 300 C. Or in cooler conditions Sulfur trioxide sucks up water and makes H2SO4.
    It seems to me the Sulfur trioxide could useful to mine water.
    Sulfur trioxide would a good thing to export to Mars and the Moon.
    But it seems that you recycle it, one would need to ship a lot of it- unless a lot of H2SO4 is wanted.

    “Dilute sulfuric acid reacts with metals via a single displacement reaction as with other typical acids, producing hydrogen gas and salts (the metal sulfate). It attacks reactive metals (metals at positions above copper in the reactivity series) such as iron, aluminium, zinc, manganese, magnesium and nickel.
    However, concentrated sulfuric acid is a strong oxidizing agent and does not react with metals in the same way as other typical acids. Sulfur dioxide, water and SO42− ions are evolved instead of the hydrogen and salts.”
    So it seems SO42 largely corrosive because it’s mixed with some water.
    And it seems to me the concentration of oncentrated sulfuric acid in not as rare as “130-150ppm in the Venusian atmosphere” might indicate. In Venus cloud it would similar to a cloud on earth. Or if measure the amount H20 at same elevation of clouds on Earth which is in the air, it will likewise be a low ppm, but clouds have millions of tons of water in them not as H20 gas but as droplets of water. Plus most of mass of Venus atmosphere has not clouds, they up in less dense and cooler air. So 130-150ppm of entire atmosphere is fairly meaningless.

  7. Andrew W says:

    Jon, I wasn’t talking about exporting either, I was looking at it in terms of the return on investment, and I don’t see anything so far that I believe would give a positive return for the settlement on its investment in the processing effort, which is something it needs to survive – unless it had another source of income.

    If I run through the same exercise with seawater as you have with the Venusian atmosphere, I’m pretty sure I could build a case that I could make billions from extracting the elements in it.

  8. Jonathan Goff Jonathan Goff says:

    But unlike seawater, processing tons of air is not only possible but quite common on earth. It’s how we get most of the Nitrogen, Oxygen, Neon, and Xenon we use industrially on this planet. And “air wells” for recovering water from the air in arid places is also used all the time on earth both in modern times and even going back thousands of years.

    Are you really saying that we’d be better off shipping 100s of thousands of tons of materials all the way from earth rather than gather them in the Venusian atmosphere?

    If so, you’re obviously entitled to your opinion, but I think you’re wrong. Hopefully when I can get to the next few articles I can talk through more of the details.

    If this style of ISRU doesn’t make sense, I don’t get why ISRU would be useful on the Moon or Mars.


  9. gbaikie says:

    “If this style of ISRU doesn’t make sense, I don’t get why ISRU would be useful on the Moon or Mars.

    I don’t think ISRU is useful on the Moon or Mars.
    I think it has to be commercially mined, ISRU suggest something a government would do.
    But anyhow, I think Venus might be commercial mined. Or I think Venus will be commercially mined, the question has always been where in space can anyone be commercially mined first.
    And I have not yet come to conclusion that Venus should one of first place to mine.
    So try find out how thick the Venus clouds are, and here paper roughly about that topic:
    [not new- Vol. 14, No. 1 / January1975, but anyhow]
    I suppose I should repeat their caveat:
    We emphasize once again that the uncertainties stated above should be considered by anyone making use of the tables in the interpretation of planetary or telluric spectra. ”
    A conclusion:
    “On the basis of our present work, along with the assumption
    that the Venus clouds do consist of spherical liquid droplets of sulfuric acid at 250 K, our best estimate is that the H2SO4 solution has a concentration of 70.5%.”
    So droplets have about 30% water. Plus heat them to get more water from the SO42.
    So if you could “put a pan out and catch the rainfall” that could way to collect it.
    It seems the most significant aspect of Venus is you get a lot solar energy and get constantly. So at high elevation in atmosphere can you get solar energy at level of about 2700 watts per square meter 24/ 7.
    And the problem with splitting water to make LH/LOX is the energy requirement, mostly. So if you get a child’s swimming pool of water per day, you doing hundreds hundred per year. And problem with more than 100 ton per year is having enough market. And 100 tons rocket fuel per year require large solar arrays.
    So question how how would someone sell Venus water if the quantity was in the 100 to 1000 ton range per year?
    And it seems that Venus water could be worth a bit more than Lunar water since you would need less solar panels to make the same energy.
    Though there other glaring problem of Venus being in large gravity well, like Earth.

  10. Andrew W says:

    “But unlike seawater, processing tons of air is not only possible but quite common on earth.”
    Processing tons of seawater is common enough, though it’s done for desalination, not for the trace elements, ditto with air, it’s done for the major constituents, not the trace.

    “Are you really saying that we’d be better off shipping 100s of thousands of tons of materials all the way from earth rather than gather them in the Venusian atmosphere?”

    Judging by your pilot plant, which no doubt weighs about a thousand tonnes to produce about 10 tonnes of water a year, yes.

    “If this style of ISRU doesn’t make sense, I don’t get why ISRU would be useful on the Moon or Mars.”

    Again it’ll only be useful if the resource in a high enough concentration to justify mining it, there’s gold in your backyard, but if you want to make a living mining gold, mine somewhere else.

    In the petroleum drilling business they use the term energy return on investment, the return needs substantially to be positive to justify the cost of extraction.

    With dairy cows you can feed them a high value feed (pasture, concentrates) and produce milk, or you can feed them a low value feed (straw) and not only will the cows not produce milk, they’ll actually starve to death with full bellies.

  11. Andrew,
    60,000kg/km^3 of Venusian atmosphere isn’t *that* trace IMO. You honestly think that to process 1/6 of a km^3 of air in a year (that equates to handling ~5m^3/s), that you’ll need something that masses twice the ISS? Do you have any analysis going into this, or do you just not like the idea intuitively?

    For comparison, typical gold ores have 5ppm of gold, and solid-feedstock processing is a lot more hardware intensive than gas processing. Do you really think that once you’ve factored in the delivery cost to Venus that you can’t get a decent ROI with those numbers?

    If so, we’re just going to have to agree to disagree.


  12. I think you need to mine the surface for hydrogen. I know it’s harder, but if you don’t rule it out you’ll find it’s not that much harder.

  13. Trent,
    Thanks, I needed that. I don’t think that the surface will be forever unmineable, but I’m with you in that it’s not really low-hanging fruit.


  14. Andrew W says:

    “typical gold ores have 5ppm of gold”
    Ahh, that’ll be why the price of gold is around $40,000/kg, when you can show how to get the price of extracting water from the Venusian atmosphere down to say $10/kg give me a call.

    Of course, even at that price the cost of living in your castles in the air would be a killer.

  15. Paul D. says:

    Andrew W.: seawater is also used as a source of magnesium. Addition of calcium oxide to seawater will cause magnesium hydroxide to precipitate out.

    Seawater can also be used to produce trace elements, like bromine and uranium, but those processes are not currently competitive with more concentrated terrestrial sources. Uranium from seawater is surprisingly close to economical, at least on paper, even though the concentration of uranium in seawater is only around 3 ppb by mass.

    I have wondered if helium could be extracted on Venus by lowering an evacuated vessel with a helium-permeable structure down into the lower atmosphere. It would be cool if solar wind helium made it into Venus’ atmosphere, so that 3He could be mined this way, but from what I’ve read they don’t think that happens significantly.

    The highlands of Venus may have interesting surface deposits of various volatile metallic compounds, which could evaporate at lower alititude and condense on the peaks (affecting radar reflectivity.)

  16. Paul451 says:

    Andrew Swallow,
    “I do not know how much sunlight exists at 50 km.”

    Insolation is roughly double Earth’s, and the atmosphere should be fairly transparent at that altitude, so “much more than on Earth” would be the simplest answer.

    “We could steer large, volatile rich asteroids or comets, crashing them into Venus. They’d melt quickly and the vapors would mix with the atmosphere. This could enrich the concentrations of many elements.”

    That seems to be a waste of a perfectly good resource. It’s already concentrated, why dilute it in the atmosphere then concentrate it again at even greater expense?

    [Same argument against dropping asteroids/comets onto Mars to thicken the atmosphere or add water. It’s already concentrated at the asteroid/comet, why not use it where it already is. In space. (Besides, Mars clearly has Sarlaccs, who needs that hassle.)]

  17. Karl Hallowell says:

    when you can show how to get the price of extracting water from the Venusian atmosphere down to say $10/kg give me a call.

    Andrew W, you are implying that there is some competing way to get water there at $10/kg.

    There are several things to note here. First, extracting gold from rock is energy intensive because it takes energy to break up the rock into pieces small enough that the usual gold extraction technologies can work. In other words, it takes considerable energy to turn excavated rock into something fluid-like for processing. Atmosphere already comes that way.

    Second, these gold extraction technologies often require a lot of space and time in order to work (for example, cyanide leach ponds covering a number of acres and leaching from a large pile of mine tailings for years at a time). In comparison, you could demonstrate water extraction from the Venusian atmosphere on a tabletop and because gases are easy to handle and move, it probably could handle quite a bit of volume over time.

    Third, water would not be the only thing you extract. It would be a value-add on top of the other things being extracted. It doesn’t need to be $10/kg to extract to meet your threshold. It just needs to be $10/kg more than what you were already willing to spend.

    Fourth, CO2 can be extracted from Earth’s atmosphere for somewhere under $4 per kg (the price it sells for in bulk according to some googling). It has a mass density fraction of about 400 ppm. Since it is a heavier molecule gas than water vapor in a lighter molecule atmosphere, that means we have a molar density about a factor of 4 greater than water in Venus’s atmosphere. So a similar concentration, similar processes to extract (using the phase transition of the gas to liquid or solid), and it ends being cheaper than dirt.

    So to summary, Venusian atmosphere would be easy to handle, fast to process, water is rather easy to extract even at the concentrations mentioned, and we have a similar problem on Earth (extraction of carbon dioxide from air) which is already extremely cheap.

    I’d say the whole list that Jon mentioned would be fair game since it’s just not that hard to separate gases which are chemically and physically different. And the waste from earlier extraction processes would end up with higher concentrations of the remaining desirable molecules.

    For example, if you extract 99% of the carbon dioxide and nitrogen, you end up with a gas mixture which has more than 1% sulfur dioxide with significant concentrations of the other trace gases including oxygen and water (both would be around 0.2-0.3% by mass).

  18. Paul D. says:

    Karl: CO2 is not produced industrially by extraction from air. This isn’t a competitive process — if it were, mitigation of CO2 buildup in the atmosphere would be a much more tractable problem.

  19. David Summers says:

    According to the great Wiki:

    It costs $600/tonne to directly capture CO2 from the air. But everyone really looks at chemical processes that are much less expensive, below $100/ton.

    So you can get a 400 ppm gas out of the atmosphere for less than $0.6/kg. You can say what you want about other ppm gasses, but this doesn’t seem that expensive comparatively.

    Excepting transportation costs, of course.

  20. Andrew W says:

    David, the carbon capture methods are probably not much use as a guide to the capture of trace gases in the Venusian atmosphere, “chemical processes” would I assume require feedstocks of chemicals, we’re probably better off sticking to distillation.
    Because of its low abundance, xenon is much more expensive than the lighter noble gases—approximate prices for the purchase of small quantities in Europe in 1999 were 10 €/L for xenon, 1 €/L for krypton, and 0.20 €/L for neon;[53] the much more plentiful argon costs less than a cent per liter.

    From what I can tell, these figures are for the gases at STP, not the liquid state, but happy to be corrected.

  21. Andrew W says:

    The cloud layer on Venus is at an altitude of 60km, it’s 20km thick, temperature and pressure at this altitude are at -10C and 0.24 bars. Little light penetrates the cloud layer.

  22. gbaikie says:


    Andrew Swallow,
    “I do not know how much sunlight exists at 50 km.”

    Insolation is roughly double Earth’s, and the atmosphere should be fairly transparent at that altitude, so “much more than on Earth” would be the simplest answer.”

    More intensity and longer- we if assume you don’t want to be on night side or need to be near morning or evening.
    “A day on Venus lasts for 243 Earth days or 5,832 hours! A day on Earth is 23.943 hours. ”
    So at equator you went 4 mph you traveling same speed as the day at Venus equator. And more poleward the slower you need to travel.
    If you can go up and down in elevation and if in right locations, the winds could probably be managed so as to keep you in constant sunlight.
    So clouds at at 40 km:

    ” Now, as a rough cross-check, we enter the Venus altitude-versus-atmospheric pressure graph at 1000 millibars (the Earth’s average sea level atmospheric pressure) and go up to intersect the altitude-pressure profile line, and across to the left axis where we find the corresponding altitude of 49.5 kilometers (31 miles). This altitude is only three kilometers (or six percent) different than we found from the temperature graph.

    So, in spite of the surface temperature of Venus being on the order of 864 degrees Fahrenheit, there is a region in the Venusian atmosphere which approximates that of Earth with respect to temperature and pressure. But there may be problems.

    52.5 kilometers above the Venusian surface turns out to be in the middle of the Venusian cloud blanket which is made up largely of sulfuric acid droplets. (The cloud bottoms are estimated to be 30 to 35 km above the surface and the tops are estimated to be from 60 to 75 km above the Venusian surface.) ”

    So you layer clouds about 30 to 40 km thick.
    On Earth your troposphere varies from pole to Equator, but essentially it’s where all our clouds are. In tropics the troposphere is 20 km high, mid-latitudes: 17 km, and polar regions: 7 km.
    We just look at tropics clouds are “6,100 to 18,300 meter”
    If we in tropics and in middle cloud level we at 12 to 13 km or
    39,000 to 42,000- around level airlines fly.
    Or if at 50 km you in middle clouds, but you also have 1/2 the clouds below you in a world which has a lot more clouds than Earth.
    Or if pick areas of Earth which are the most cloudy- say Seattle.
    It’s mid-latitudes clouds at 5,000 to 12,200 meter. And in middle of clouds is 8000 meters [26,000′]. So higher than any mountain in area. In Seattle it’s “It is cloudy 201 days out of the year and partly cloudy 93 days”
    But if at 26,000′ in Seattle you going to far fewer clouds days.
    If go skiing, it can be cloudy and snowing, but many times you are above the clouds. You return home to cloudy weather. And that was like 6000′ elevation. Or same with flying- much of the time you not flying through clouds. Though with weather forecast pilots tend to avoid flying through bad weather. And same goes for Venus, first you aviod being regions which have high clouds and you could avoid them if weather forecast show them developing.
    So mid of clouds could said to have 1/2 as many above you.

    Next part is we have about 10 km worth of clouds [capable single event rainfall of billions of tons of water- or hundreds of square km area getting several centimeters of rain- resulting rivers flooding, etc. Or if we had as much clouds as Venus, we could expect Noah’s flood. But is thick clouds or is a more of miles of haze. There probably both haze and thick clouds, but the question what is it mostly and where mostly.

    So would say Venus isn’t going to have *higher troposphere* at tropics like Earth, because Venus doesn’t spin like Earth, but seems to me the “Tropics” on Venus with different than “Temperate zones”
    but not talking about the surface of Venus, which due to Venus massive atmosphere is fairly uniform globally. Sort like bottom of Earth oceans- darkness and mostly same temperature. Though light does reach the surface of Venus some times and some places- only most of Venus total surface in darkness, though most of surface has a dawn and a long dawn cause it has long day.
    But the atmosphere should quite different in Tropics compared to
    Temperate zone. Or lower angle sunlight is not going to get through much atmospheric depth in region outside tropics, or morning and late afternoon in tropics.
    Though if at 50 Km elevation higher rather 20-30 km it would be as much of a difference.
    And it seems possible to me that away from the tropics you might bigger droplets in the cloud- clouds could be lower and cooler.

    So mining clouds on Venus might be in regions of “Seattle”- enough clouds to mine and around 45 degrees latitude. And we try to be always around noon in such regions- so the sun is higher in the sky and you get lots of sunlight.
    Distance of travel. On Earth each degree latitude is 111 kilometers.
    We call it 100. 45 times 100 is 4500. So need 2-3 mph.
    So seems you generally say in more or less one spot for days or week, and find some wind to travel fairly fast [say, 50 mph] find spot camp out for days.
    So it seems you would want ability to say be at as high 60 km and
    as low as 30 km.
    So according above graph 30 km is 500 K. So about boiling and low
    medium oven temperature. Wiki says:
    “30 km 222 C 9.851 atm”
    So that would like 300 ft under water. Not good.
    “40km 143 C 3.501 atm”
    So limit is probably 40 km.
    And 60 km up? Maybe but probably 55 km:
    “55 km 27 C 0.5314 atm”
    Hmm even though rotation is slow, seems one need a fair amount mobility, going further poleward might be necessary, and need info
    on winds. And of course high wind speed could be exciting.

  23. Karl Hallowell says:

    I should have known that a fossil fuel based society would not need to pull carbon dioxide from the air! Sorry about that.

  24. Jonathan Goff Jonathan Goff says:

    Andrew, Paul,
    Regarding how much sunlight there is at around 50-55km, it turns out we don’t need to wildly speculate or point to wikipedia articles…

    Reference #2 from the Venus Rocket Floaties blog post is a paper by Geoffrey Landis on using a solar-powered aircraft to do Venus exploration. Figure 3 from that paper shows actual data from the Russian Venera 11. Looking at that, at precisely 50km, you’re getting about 20% of the infrared, up to about 55% of the blue wavelengths that you would receive in space. Since Venus’s solar insolation is almost exactly double earth’s, that means you’re getting about the same amount of blue wavelengths as you’d get in earth orbit, and longer wavelengths it drops to about say 1/2 of what you’d get in orbit. And it looks like the chart has an inflection point around 50km, where the amount of available sunlight raises quite quickly. By 55km you’re already getting more sunlight in *all* wavelengths than you would in earth orbit. The ideal altitude is probably somewhere between the two.

    So, based on actual flight data, this doesn’t look like a big concern. Unless I’m missing something.


  25. gbaikie says:

    Jonathan Goff

    In terms solar energy and economics as important as the intensity
    of solar energy is the duration of available solar energy. Or having 1000 watts per square meter more 90% of time is more valuable than
    2000 watts per square meter less than 50% of the time.

    Or the reason solar energy on Earth surface is non-viable is because one get solar energy about 25% of the time. And much worse if the region tends to be cloudy. Plus you have seasonal differences which might 10% of time in winter and perhaps 30% of time in the summer. So if half the year was 10% and half 30% this worse than both winter and summer being 20% though it’s the same total, though getting less than 25% is pretty bad.
    Or it’s better to have available 1 kw hour worth of energy 24 hours a day as compared 75% of the day with no power and 4 kw/hour of energy for 6 hours. Or better to have constant 1 kw hour for a year, then 4 km hour for 3 months and none for 9 months, though it’s same amount of energy available.
    Finally it’s better to have predictable lack of power than random lack of power for same amount of time.

    So if you could get 12 hours per day electrical power this better than 6 hours at twice the amount of energy, major advantage of space based solar [from GEO or elsewhere] is the near constant source of solar power. And it makes quite difference that one could more 80% of the time in Lunar polar region in which one can get solar energy. That fact that is more 30% of solar energy available in best locations on earth and at best times, is nice, but is not as valuable.

  26. Andrew W says:

    The atmosphere at the cloud tops moves at 100m/s relative to the much denser atmosphere at lower altitude, if you dropped tethered turbines down into the slow moving air you get:
    a/ lots of power at a modest weight cost
    b/ the ability to steer and alter the speed of your city though the atmosphere around it
    c/ by using the turbines to slow the city on the sunward side of the planet, but not on the night side, you could have several week long days, with nights only lasting ~60 hrs.

    Like Don McLean I’m a county boy, and also like him, I don’t think highly of Castles In The Air.

    The sooner the Land and Mining barons evict these squatters in the clouds and freeze out the atmosphere so we can really use the planet the better!

  27. Andrew Swallow says:

    Plants and some bacteria are self solar powered. Lots of sunlight means that biological means can be used to mine/farm the atmosphere of Venus.

    The biological entities would have to be engineered specially for the gas mixture and pressure but that may be within our technology.

    The green house would need a powered dirigible to fly on. Two major technological projects.

  28. Karl Hallowell says:

    Hmmm, that’s an interesting idea, Andrew. I think it might be possible to go further than growing engineered organisms in raw atmosphere. Imagine if you will a cyanobacteria colony or perhaps a lichen with a density similar to that of the surrounding atmosphere. Perhaps the colony creates a foam or bubble of mostly nitrogen or uses a crude wind sail or streamer in order to stay aloft indefinitely.

    A huge problem with the scheme is that Venus’s atmosphere is missing phosphorus (required in DNA and RNA) and crucial trace elements like iron. These might be present in windblown dust, but I suspect it would require substantial bioengineering, currently well beyond our capabilities, to remove the dependency on phosphorus (that is, restructure DNA/RNA to a new molecule which didn’t require phosphorus) or perhaps find a way to seed the atmosphere from space with phosphorus-rich asteroid impacts or the like. This looks to rule out such a strategy for a near future Venusian colony.

    However, if it should turn out to be possible without a great deal of effort (say because bioengineering advances much more quickly than I expect over the years prior to any attempt to colonize Venus), then you have a self-replicating resource that you can later hoover up for complex organics and concentrations of desirable trace elements. A consequences, which probably is already obvious to many people here, is that these lifeforms could also be used as platforms for designing future organisms which could start the actual terraforming of Venus.

  29. Andrew W says:

    Imagine if you will a cyanobacteria colony or perhaps a lichen with a density similar to that of the surrounding atmosphere. Perhaps the colony creates a foam or bubble of mostly nitrogen or uses a crude wind sail or streamer in order to stay aloft indefinitely.

    Cyanobacteria have had 2.7 billion years to colonize Earths atmosphere but the sky is still blue.

  30. George Turner says:

    Terraforming Venus is a hard problem. There are several approaches I would take, some bad, some really bad.

    First off, I can’t see getting rid of the excess atmosphere because it weighs too much. You’d have to launch over a trillion tons of CO2 a day into outer space, and do it every day for a thousand years. If you could do that you might as well build a whole new planet. So the atmosphere is there to stay.

    You could build a giant wall to the top of the atmosphere, bisecting the planet, and pump the gas from one side of the wall to the other, giving you half an Earth-like planet with a screwed up day-night cycle, at least until an earthquake cracks the wall and everybody dies in a truly awesome cataclysm. Also, the size and required strength of such a wall is infeasible.

    You could freeze the atmosphere in refrigeration plants, converting it to dry ice that would coat the surface to a depth of 2,200 to 2,400 feet. The pressure of Venus is so high that the CO2 near the bottom of the atmosphere (above 72 bars) is already a supercritical fluid, so this wouldn’t actually be that hard as long as you kept the dry ice in giant, very well insulated containers. If you stacked those to a height of about 24,000 feet you’d only have to cover 10% of the planet’s surface with them before you got close to Earth-like conditions (along with storing two thirds of the existing nitrogen and introducing some oxygen liberated from the CO2).

    Or you could just ignore everything below about 52 km and build an entirely new surface at that altitude, which would floats on a pressure differential of about 100+ lbs per square foot, pumping CO2 beneath the enclosing planetary sphere and leaving most of the nitrogen above it. Cut off from sunlight, the winds in the area below the new surface should slowly calm down. Then you magnetically levitate a second surface just above the first, with a vacuum gap, and spin it so you get a normal day night cycle with the sun rising in the east.

  31. Jim Baerg says:

    I see Andrew W (26) beat me to mentioning a better energy source for a Venus balloon town than solar.
    This image ( ) give some idea of the available wind power. The major advantage is that wind is available all the time to the balloon town rather than just half the time.

    BTW about the discussion of extracting CO2 from earth’s air. There is a better way

  32. Andrew Swallow says:

    A huge problem with the scheme is that Venus’s atmosphere is missing phosphorus (required in DNA and RNA) and crucial trace elements like iron.

    Apply the 80/20 rule. The trace elements can be brought from Earth. They may weigh less that the machines to collect them.

  33. Andrew W says:

    Terraforming Venus is a hard problem. There are several approaches I would take, some bad, some really bad.

    Agree it wouldn’t be easy, the first step would be to cool the planet.

  34. George Turner says:

    Well, one way to speed up cooling would be something almost akin to a heat pipe. The dry adiabatic lapse rate is given by the formula Lapserate = g/cp degrees K per kilometer, where g on Venus is 8.87 and the specific heat at constant pressure for CO2 is 0.844, while helium is 5.19 and hydrogen is 14.32 kJ/kg K, giving the latter very low lapse rates. The actual lapse rate on Venus from 0 to 60 km is 7.87 degrees K/km, whereas hydrogen would be 0.619 degrees K/km. So whereas Venus at 60 km is 263 K, if you could run some deep pipes filled with hydrogen and circulate the gas between the surface and 60 km, the hydrogen would still be at 698K at the higher altitude and radiate heat to space like a banshee, and upon descending back to the surface the hydrogen’s temperature would only be 300 K.

  35. Andrew W says:

    George, that’s an interesting idea I hadn’t thought of, but I don’t know about its practicality, I’ll think on it.

    We probably shouldn’t be thread-jacking Jon’s post like this though.


  36. George Turner says:

    To people who terraform whole planets, hijacking a threat is nothing!!! ^_^

    I don’t know if the heat pipe idea is practical, but perhaps the hydrogen or helium being used for heat transfer could help support the weight of it.


    Yes, as dense as that atmosphere is, you could have balloons along the length of the vertical pipe, so that each section is essentially self-supporting, so that you only really have to worry about wind loads and having enough mechanical strength at low altitudes to handle the pressure differential between the surrounding atmosphere and the column of hydrogen.


    Of course, another aspect of the idea is that even if you just built one, you’d have a constant stream of cool gas coming back to the surface, so you could perhaps run a mine or surface operation in something like a coffer dam that holds back the atmospheric pressure, while the heat pipe return keeps the walls cool. Perhaps it’s even possible to configure the whole thing as a heat engine, as well. But of course if the idea is to freeze the CO2 out of the atmosphere anyway, it would probably make more sense to wait until the atmospheric pressure has dropped to reasonable levels.

    And as another side note, I wonder if it would be possible to take advantage of the existing surface pressure and temperature to bind two thirds of the nitrogen up as ammonia before you freeze out the CO2, since the ammonia reaction is carried out at high temperatures and pressures?

  37. Andrew W says:


    At this stage we won’t be buying your heat pipes, calculations show that the amount of materials required to deliver significant effect to be uneconomic.

    Regarding your offer to reduce the quantity of atmospheric nitrogen of Venus, although the physical environment at ground level on Venus appears near ideal for the manufacture of ammonia via the Haber–Bosch process, the difficulty we see is in the supply of the hydrogen required as a feedstock, quite simply (or not simply) vast quantities would need to be imported as the available supply of hydrogen on the planet is inadequate.

    An area where we do need input is in the design of the soletta, and the space mirror required to illuminate Venus for habitation.
    At present we favor a soletta in an elliptical halo orbit about L1, with the mirror, naturally, at L2, as we intend to freeze out almost all of the CO2 and liquify 2/3rds of the N2 at the North Pole with a planetary surface temperature gradient rising to tropical temperatures at the South Pole, we require a soletta of a design, and in an L1 halo orbit that allows very little solar energy to reach the North Pole, but near permanent daylight (albeit at a low angle in the sky) at the South Pole, the soletta and mirror are required to illuminate the planet in a synchronized manner so as to allow a single planet wide time zone, with steadily increasing insolation from northern to southern latitudes.

    At this stage we intend to anchor the soletta to an asteroid sunward of the L2 point with a long tether connecting the two, this will result in the solar pressure on the soletta of over (I calculate) 8 billion Newton that would be pushing it towards the planet being cancelled by the pull of the Sun on the asteroid.

    Despite having an area of over 400 million sq km, the slow spinning soletta is expected to have a mass of only around 100 million tonnes as a result of its being constructed from a coated carbon nanotube mesh weighing only 0.1gm/m^2.

    Clearly we have our work cut out for us.

    Kind regards
    Andrew W.

  38. Peter says:


    If atmospheric ISRU is viable for Venus then could it be done on Earth? This would be accomplished in the exosphere (~200 km altitude free molecular flow) with an exponential horn. At the back end of the horn the air gets compressed enough you can pump it. A portion of the cooled gas is stored for use in SEP thrusters which are used to overcome drag. Periodically the craft would ascend to higher altitude and dock with a LEO fueling station to deposit collected gasses. If necessary the SEP and solar panels could be separated from the horn by a cable (several km long) to reduce drag.

    More info can be found at

  39. Karl Hallowell says:

    Cyanobacteria have had 2.7 billion years to colonize Earths atmosphere but the sky is still blue.

    I’ll just note several things. First, that the Venus atmosphere has a bit more variety in its atmosphere than Earth does (with the presence of large amounts of carbon along with some sulfur). For example, one can make most of the amino acids out of what is present in Venus’s upper atmosphere. The lower atmosphere may be able to bring up nutritious material from the surface such as wind-blown dust, vaporized solids, or volcanic ash.

    Second, Venus’s atmosphere is a lot denser with about 80 times as much atmosphere by mass. That plus the high concentration of sunlight gives both a lot of material and a lot of energy for lifeforms to use.

    Third, cyanobacteria and other single cell organisms have colonized the upper atmosphere of Earth to some degree (one can find bacteria spores and the like at 100,000 feet, for example). It’s not enough to fill the sky with visible organisms, but life is there.

  40. Andrew W says:

    Vertical movement of gas in the Venusian atmosphere is too great for life to survive, and water too scarce, all spores found at altitude in Earths atmosphere are surface based and dormant when at altitude.

  41. George Turner says:

    Andrew, let me puzzle on it a while.

    Meanwhile, take a look at Maxwell Montes, the highest point on Venus, and thus the best place to set foot. At over 400 by 500 miles wide, that would be all the area of the planet you’d need access to for quite some time, and it’s at about half the pressure of the lower regions.

  42. Karl Hallowell says:

    Vertical movement of gas in the Venusian atmosphere is too great for life to survive, and water too scarce

    Sure, it is. I grant the conditions are probably much as you say, but I don’t see how those rule out life. They just make it a bit more difficult. A reproducing lifeform can compensate for losses from organisms that move into unlivable circumstances. And some terrestrial life is already rather impressive in its ability to extract trace molecules from the environment.

    The absence of phosphorus is far more significant BTW and even it doesn’t rule out sufficiently engineered (or sufficiently fertilized) life in the long run.

    all spores found at altitude in Earths atmosphere are surface based and dormant when at altitude

    Sure, it is. To the contrary, only recently have scientists actually started to look at what is up there, just in Earth’s atmosphere. It may turn out that the copious life in the upper atmosphere all comes from the surface (it’s a small amount of organisms per unit volume, but there is a lot of volume in the atmosphere), but that remains to be seen.

    Since this idea doesn’t even register on any technology development scale, I’m not going to discuss it in the thread. I just thought it was worth mentioning in order to spur further creative thought.

  43. George Turner says:

    I’ve been thinking some more about this, and we just don’t know enough about Venusian geology to form a terraforming plan. Carbonates outgas CO2 at high temperatures, and as the temperature drops due to human intervension, the chemical equilibrium will shift, so it’s possible that the CO2 will recombine with Mg, Tn, Ca, and other elements and drop out of the atmosphere over longer time spans, absent freezing CO2 all the way to dry ice glaciers.

    If the CO2 can be tied up in much more chemically stable forms, it would be a big plus, and to find out if that’s a possibility we need more Venus missions.

  44. Andrew W says:

    As you say: “over longer time spans”, time is money, a return on investment in 10 thousand or 10 million years is no return. I would expect the CO2 icecaps to slowly shrink as carbon is drawn from the atmosphere through biological and chemical activity on a cooler inhabited Venus.

    I’ve been thinking about a source of water, and Ceres is certainly not it, the logical option is to go for Centaur and scattered disk objects, these are already in unstable orbits due to their periodic close encounters with gas giants.
    A slight alteration to the orbits of a few thousand of them to cause swing-bys of a giant planet to bring them into a Sun grazing orbit, distilling their components to separate out solar thermal propellent from the water on the fall Sunwards, then using that propellent at perihelion in an Oberth maneuver to get a slow as possible collision with Venus.

    The energy of the impact with Venus needs to be as low as possible to avoid too long a cooling time, that’s if you want enough water to create a world with seas rather than just lakes.

    Using solar thermal, assuming, amongst other things a lightweight mirror, even at ~10 AU from the Sun, to get that swing-by followed by the Oberth maneuver makes getting even 5 X 10^16kg of water to Venus, maybe in the form of 50,000 objects each of a trillion tons, stunningly simple (in theory).

    If such objects are dropped on the planet at a rate of 5 per 24 hours after the CO2 is frozen out, and with the N2 atmosphere just above liquifying you should (if my math is right) be able to keep that cool climate stable (the water would quickly fall out as snow, and as long as you got rid of other potential greenhouse gases – CO2, CH4, NO, NH3 etc as propellent at the perihelion burn) indefinitely, or at least as long as the 30 years required to drop 100 meters of water over the entire planets surface.

    Because Venus doesn’t have ocean basins her topography is smoother than the Earths, 100 meters over the whole surface, would, I understand, result in an ocean covering half the surface with an average depth of 200 meters.

  45. Re: Venus Terraforming, I’m with Andrew–even if you could do it in 100yrs, the time value of money would make it hard for such an investment to pay off. It’s interesting, sure, but I”m more interested in finding ways to use Venus as it is as a destination for offworld settlement.


  46. George Turner says:

    Well, prior to using Venus as is for a settlement destination, we’ll need to gather lots of weather data on the atmosphere to better understand the lightning and thunderstorm threats, and characterize the operating environment. I’d suggest a solar powered dirigible mounting a weather radar, cameras, and a bevy of other sensors, and expand the program from there, soon aiming for surface sampling/upper altitude rendezvous missions. But that’s pretty obvious to everyone.

    As an aside, it might be possible to put a surface base on Maxwell Montes where the pressure is only about 44 bars. The record for human pressure adaptation is I think about 70 bars, so we could function there as long as we cooled off the working environment, perhaps with some variation of the hydrogen heat pipe I suggested earlier, or just use a massive amount of air conditioning. You could also use the 1 atmosphere hard suits that have been taken to a depth of several thousand feet, but then I think you’ll be created structural problems in maintaining a 1 atmosphere living and manufacturing space, and to build airships on the surface you’re going need a very large manufacturing space. If you can establish such a manufacturing facility, producing steel, aluminum, and other metals using carbo-thermal reduction (the standard method for most ore), then the mass problem of delivering intact airship structures from orbit goes away and settlement becomes much more sustainable and feasible.

    Testing 44 atmosphere suits and whatnot in a heated pressure chamber on Earth might make an interesting NASA prize.

  47. Andrew W says:

    Here’s something by Paul Birch, along similar lines to what I’m advocating:

    The longer terraforming takes, the bigger the prize needs to be, a terraformed Venus is a big prize, two hundred years could be justified if the process could be done at a fraction of the value of the finished product, though “risk” would b problematic.

    The problem I see with the castles in the air smog is what is the value of the finished product, would it be a ghost town?

  48. Andrew W says:

    Geometric progression can be a bummer.

    If you’re after an annual return of only 8% on your investment:
    Years — return on initial investment for an 8% compounded annual return:
    1 —- 1.08
    2 —- 1.17
    5 —- 1.47
    10 — 2.16
    20 — 4.66
    50 — 46.90
    80 — 472
    100 — 2200

    Ok, seems unlikely that a business case can be made for terraforming if it takes more than 50 years unless a major fraction of the costs of the endeavor are made later in the process, and/or initial returns can start coming in long before the terraforming is completed.
    So maybe I’ve dismissed the heat pipes too soon, if they were to cut the time for cooling from 80 to 20 years they could well be justified even if they were 95% of the cost of the process.

  49. George Turner says:

    Well darn. That means someone needs to do a bunch of analysis on the heat transfer, how much heat has to be moved vertically, and what the state of the atmosphere would be with various configurations. You could make an enormous number of smaller (shorter) floating heat pipes which would work to alter their local lapse rate. With enough of them at different altitudes, would they accomplish the same thing as long continuous heat pipes? You could even have millions of balloons that descend, get hot, then rise to radiate the heat away, almost like a slow rolling boil on a planetary scale.

    Yet what the system essentially does is move heat to an altitude where it can radiate to space, so could you open enough optical windows through the clouds, transmitting from the surface to space so the surface could directly radiate? That might be accomplished with a giant pressurized vertical cylinder (a giant balloon), clear at both ends and reflective along the vertical walls, filled with a gas that’s transparent in the IR and devoid of condensing fluids (cloud free). That would basically be a little micro-atmosphere that doesn’t act like the one on Venus. It could probably double as a convective heat pipe.

    For someone so inclined, it would probably be a fun project to analyze.

  50. Andrew W says:

    I think one of my comments has gone astray, it had this link in it:

    Paul Birch looks at heat pipes on page 3, using ammonia/water with a phase change.

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