Chilling Venus

[Nightside]

While the humans are hard at work Veneraforming the Earth, I wondered what it would take to cool off Venus to a point that it's atmosphere would start to change.

If we added something reflective to the atmosphere to reduce solar radiation, what would happen as it cooled off? 

Would the sulphur dioxide cool enough to precipitate out of the atmosphere?

Could atmospheric gasses liquefy at lower temps?

[wumpus]

I suspect that Venus' albedo is already pretty high, making it more reflective would be hard.

I'd expect that in nearly all terraforming projects, some sort of genetically engineered life would be designed to thrive in the initial conditions and slowly move things more Earthish.   Kind of like how early life caused Earth's (somewhat) oxygenish atmosphere.  Presumably some floating plant-life, that could exist in the upper clouds and photosynthesize carbon dioxide into oxygen.

[K^2]

Might be easier to build floating structures filled with breathable air, which is lighter than Venusian atmosphere, and put plants or artificial CO2 processing factories there. There's an altitude that should be quite comfy for long stay, and anything you can't get there can be acquired at lower altitudes by autonomous systems. You probably couldn't get any metals, so you'll have to get really good at recycling these. But everything you need for carbon-based life you should be able to get, and you can use most of that for a range of building materials. So long as you get occasional shipments of things you need for electronics, it should be possible to adapt the planet for long term stay. And sure, maybe over a long enough time, that would allow us to bind enough carbon to make surface survivable.

[StrandedonEarth]

It might be easiest to move an asteroid into the L1 point and spin it into a sunshade. 

[Spaceception]

If we really wanted to cool down Venus, a project like that is already on the planetary level, so it makes sense for any proposals to be on that scale. One way to do it are enormous starshades at the L1 point of Venus between the Sun and Venus, I don't know how wide it'd have to be, but it could be pretty thin, and made from the material of some asteroids.

I think it'd take something like a few centuries or so, but it'd cool down to freezing temperatures, and along the way, its atmosphere would condense and fall as snow. We could ship that off and separate it into oxygen and carbon for fuel, air, and graphene, among other things. You can also ship some to Mars to help with its terraforming efforts.

Once most of the air is gone and frozen, you can let the planet start heating up again, letting the rest of the air come back. All that infrastructure at the L1 point can be converted to a magnetic field to protect the atmosphere from solar wind.

Now there's the problem of day/night. And there's 2 solutions, The first, and I don't have the numbers off the top of my head, is using mass drivers to ship the condensed atmosphere off the planet, that momentum transfer can be used to speed up rotation, though I don't know by how much. You can also collide asteroids in such a way that it also helps to speed up rotation as well, though that'll throw a lot of soot up for awhile (which I imagine you should be able to take care of technologically at this point). Since you need to get water to the surface, and most of the atmosphere off the planet, you'll be doing those anyway, so may as well use it to your advantage.
The second way, perhaps as the rotation is still increasing, or if it wasn't enough, is to use a system of sunshades and mirrors to mimic a day/night cycle.

While the planet is warming up, you can introduce life to the planet to begin making the air breathable.

And there you have it, a tropical paradise in our back yard in a few easy steps.

Edited May 6, 2020 by Spaceception

[sevenperforce]

Genetically engineer a photosynthetic, acid-resistant bacteria that can reproduce in aerosol form and loves to split CO2 into diatomic oxygen and carbon-carbon chains it uses to make its own encapsulation (which allows it to float).

Accidentally release it on Earth and wipe out all life.

[magnemoe]

1 hour ago, Spaceception said:

If we really wanted to cool down Venus, a project like that is already on the planetary level, so it makes sense for any proposals to be on that scale. One way to do it are enormous starshades at the L1 point of Venus between the Sun and Venus, I don't know how wide it'd have to be, but it could be pretty thin, and made from the material of some asteroids.

I think it'd take something like a few centuries or so, but it'd cool down to freezing temperatures, and along the way, its atmosphere would condense and fall as snow. We could ship that off and separate it into oxygen and carbon for fuel, air, and graphene, among other things. You can also ship some to Mars to help with its terraforming efforts.

Once most of the air is gone and frozen, you can let the planet start heating up again, letting the rest of the air come back. All that infrastructure at the L1 point can be converted to a magnetic field to protect the atmosphere from solar wind.

Now there's the problem of day/night. And there's 2 solutions, The first, and I don't have the numbers off the top of my head, is using mass drivers to ship the condensed atmosphere off the planet, that momentum transfer can be used to speed up rotation, though I don't know by how much. You can also collide asteroids in such a way that it also helps to speed up rotation as well, though that'll throw a lot of soot up for awhile (which I imagine you should be able to take care of technologically at this point). Since you need to get water to the surface, and most of the atmosphere off the planet, you'll be doing those anyway, so may as well use it to your advantage.
The second way, perhaps as the rotation is still increasing, or if it wasn't enough, is to use a system of sunshades and mirrors to mimic a day/night cycle.

While the planet is warming up, you can introduce life to the planet to begin making the air breathable.

And there you have it, a tropical paradise in our back yard in a few easy steps.

Yes, you need to rotate the thing, you could use Oort cloud objects for this and to add water, Mars could need more co2, earth don't however if you do this you are Kardashev 1 level as an default.

[Nightside]

Some really good ideas here. Thanks everyone!

2 hours ago, Spaceception said:

One way to do it are enormous starshades at the L1 point of Venus between the Sun and Venus, I don't know how wide it'd have to be, but it could be pretty thin, and made from the material of some asteroids.

A Venusian blind, if you will.

[kerbiloid]

I believe, there is no practical need in the whole Venus cooling even to build there.

The Venusian conditions are not as terrible as they sound.
The pressure is just 1 000 m of underwater (submarines are floating there).
The temperature is just < 500°C, way below any construction alloy softening point.

All we need to stay there is an onion-like hull with cooling gas pumped between the layers, a reactor powering the cooling system, and fiery exhaust pipes to throw out hot gas hotter than "air".

We can estimate that a crewed lander/rover-sized thing should stay cool inside for several hours (enough to have a short trip around the flag and gather stones).
A hundred meter large hull could probably survive as long as the reactor is running, and a day if it's stopped, in thermal capacity mode.

So, we can just build bases there, but their building should be large, each building of about a battleship size.

As by that time we'll definitely have some kind of semi-closed food loop with fishtanks for algae and cultured meat, that means we could build a colony there (with limited supplies from the Earth), and the only question is why we need the Venus at all.

P.S.
For those ones who once read about the "Carnot cycle" in a book and tries to apply it everywhere and says it's impossible, a special note: Carnot is happy about this.

The reactor active zone is hotter than the "air", so the exhaust should have a temperature in between.
Say, 1000°C for the active zone, 500°C for the air, 800° for the exhaust.
Then the heat is transferred from the hot to the cool and Carnot applauses, kindly smiling. That's pure fizzix. Fridges and chillers work so.

P.P.S.
It's also easier to warm the building than warm the Antarctica, or cool the building than cool Sahara.

Edited May 6, 2020 by kerbiloid

[magnemoe]

2 hours ago, kerbiloid said:

I believe, there is no practical need in the whole Venus cooling even to build there.

The Venusian conditions are not as terrible as they sound.
The pressure is just 1 000 m of underwater (submarines are floating there).
The temperature is just < 500°C, way below any construction alloy softening point.

All we need to stay there is an onion-like hull with cooling gas pumped between the layers, a reactor powering the cooling system, and fiery exhaust pipes to throw out hot gas hotter than "air".

We can estimate that a crewed lander/rover-sized thing should stay cool inside for several hours (enough to have a short trip around the flag and gather stones).
A hundred meter large hull could probably survive as long as the reactor is running, and a day if it's stopped, in thermal capacity mode.

So, we can just build bases there, but their building should be large, each building of about a battleship size.

As by that time we'll definitely have some kind of semi-closed food loop with fishtanks for algae and cultured meat, that means we could build a colony there (with limited supplies from the Earth), and the only question is why we need the Venus at all.

P.S.
For those ones who once read about the "Carnot cycle" in a book and tries to apply it everywhere and says it's impossible, a special note: Carnot is happy about this.

The reactor active zone is hotter than the "air", so the exhaust should have a temperature in between.
Say, 1000°C for the active zone, 500°C for the air, 800° for the exhaust.
Then the heat is transferred from the hot to the cool and Carnot applauses, kindly smiling. That's pure fizzix. Fridges and chillers work so.

P.P.S.
It's also easier to warm the building than warm the Antarctica, or cool the building than cool Sahara.

The problem is not 80 bar and 500 degree, lots of processes opperate at heven harder conditions. 
its that as an ambient temperature. Its very hard to get rid of heat in that environment and you also need to get rid of all the heat you generate cooling and the energy you produce generating that energy. 
Not doable today. 

[kerbiloid]

13 minutes ago, magnemoe said:

Not doable today. 

Today - of course. Doable - of course, too.

13 minutes ago, magnemoe said:

Its very hard to get rid of heat in that environment and you also need to get rid of all the heat you generate cooling and the energy you produce generating that energy. 

There is no much difference between cooling a 1300 K hot reactor in the 300 K air (Earth) or 750 K (Venus) "air". This works here, this would there.

Just instead of water (an external pool) it should use carbon dioxide in the open external contour. And a multilayer hull of the building with cooling gas pumped inside.

Edited May 6, 2020 by kerbiloid

[Piscator]

5 hours ago, sevenperforce said:

Genetically engineer a photosynthetic, acid-resistant bacteria that can reproduce in aerosol form and loves to split CO2 into diatomic oxygen and carbon-carbon chains it uses to make its own encapsulation (which allows it to float).

I love biological solutions to this kind of problem, but I see one or two problems with it. The biggest one is that the sequestered carbon likely wouldn't stay afloat indefinitely. When the organisms die, their remains would likely loose their buoyancy, sink into the hotter parts of the atmosphere and react with the oxygen they released earlier.

Also, since there's no way to create chains of pure carbon as far as I know (and the biological generation of other modifications of pure carbon seems also somewhat unlikely), you would probably need more hydrogen than the Venusian atmosphere can currently offer to bind a sufficient amount of carbon.

[Nuke]

idk how far we could go with genetic engineering. i imagine an engineered plant with some kind of gas bladder that collects and convects co2 from the atmosphere through solar heating. essentially a living hot air balloon which can carry out its entire life cycle in the upper atmosphere.  the thing would need to be able to aeroponically get all its nutrients from the atmosphere. if it cant get everything it needs then maybe have a few drone blimps that look for clusters of the floating plants and gives them a nutrient mist, water is another problem. but if you could make it work without any further human intervention, they would just multiply until they convert the bulk of the atmo to o2.

another idea, go find an icy kuiper belt object with a very eccentric orbit, attach a lot of nuclear powered ion engines. wait thousands of years and then add ice. hopefully while increasing the planet's water content, also blast off some of the hot gasses into space. maybe just inducing a nuclear winter will help.

Edited May 6, 2020 by Nuke

[magnemoe]

2 minutes ago, kerbiloid said:

Today - of course. Doable - of course, too.

There is no much difference between cooling a 1300 K hot reactor in the 300 K air (Earth) or 750 K (Venus) "air". This works here, this would there.

Just instead of water (an external pool) it should use carbon dioxide. And a multilayer hull of the building with cooling gas pumped inside.

The problem is that cooling something down produces heat. Producing power also produce heat. Assuming you use an nuclear reactor for producing power this has to run at much more than 500 degree as that is the lowest temperature you can get. 
Now you cooling system need to cool room temprature in an 500 degree atmosphere will be much harder than keeping hydrogen liquid. 

[kerbiloid]

53 minutes ago, magnemoe said:

The problem is that cooling something down produces heat. Producing power also produce heat.

Yes, and that's how your fridge and freezer works.
Its engine produces heat. It pumps the cold coolant fluid through the cold pipes, taking away the heat from the frozen food (-15° or so).
Then the warmed coolant adiabatically expands and quickly becomes cold again, then is gets pumped back to the cold pipes.
The energy from the adiabatic cooler heats the external air.

So, the engine stays, say, +60°C hot, the food -15°C, the summer air is +40° C, and the flow of hot air from the fridge is, say, +50°C (between the engine and the room temperature).

Exactly the same with Venus, just the temperatures are greater. Your fridge works at 300..350 K, while the Venusian module at 800..1200 K, but the principle is the same.
Of course you need something heat capable as coolant, maybe (but not necessary) hydrogen.
And while on the Earth a fridge warms and exhausts air, a nuclear plant warms and exhausts water (water pool next to the plant or condensating cooling towers), the Venusian habitat should be exhausting torches of hot carbon dioxide (pumped inside, warmed from 750 K to, say, 900 K, then exhausted).

1 hour ago, magnemoe said:

Now you cooling system need to cool room temprature in an 500 degree atmosphere will be much harder than keeping hydrogen liquid. 

Spoiler

A nuclear plant in Arabian desert. Of course, 330 K outside is less than 750, but still hotter than inside the room, and the room is cooled by the reactor power.

[Hannu2]

5 hours ago, kerbiloid said:

I believe, there is no practical need in the whole Venus cooling even to build there.

The Venusian conditions are not as terrible as they sound.
The pressure is just 1 000 m of underwater (submarines are floating there).
The temperature is just < 500°C, way below any construction alloy softening point.

Actually those are much more terrible as they sound, if I think development of production or scientific devices. There is not any applications for tech in those conditions on Earth. There may be sensors, rotor blades, tubings, valves, tanks etc. but not complex machines or electronics working there.

5 hours ago, kerbiloid said:

So, we can just build bases there, but their building should be large, each building of about a battleship size.

Your "can" means we do not know exact natural laws against it. From my point of view as an engineer it is science fiction. "Can" means that I know how to do or where to order components or can find it out in reasonable time and budget. If my boss ask something operating on Venus, I have to say that it is impossible. He is not interested natural laws and philosophy but when it is ready to work and how much it will cost. Those are questions in which no one can answer. And in my opinion those must be include in word "can".

And my personal feeling is that at the time they can be answered there is no reason to do so. Humans are adapted (with genetic engineering) to zero gravity and live in huge space stations. There is no reasons to live on planets, except maybe some kind of scientific research and primitive cultures on Earth. Asteroids give all resources and space stations have room for billions of humans. All such is probably easy tasks compared to living on Venus or terraforming it. It must be much more practical to change human biology suitable to space than space suitable for current humans.

 

[kerbiloid]

1 minute ago, Hannu2 said:

Actually those are much more terrible as they sound, if I think development of production or scientific devices. There is not any applications for tech in those conditions on Earth. There may be sensors, rotor blades, tubings, valves, tanks etc. but not complex machines or electronics working there.

Unless they inside a cold room.

2 minutes ago, Hannu2 said:

Your "can" means we do not know exact natural laws against it. From my point of view as an engineer it is science fiction. "Can" means that I know how to do or where to order components or can find it out in reasonable time and budget. If my boss ask something operating on Venus, I have to say that it is impossible.

Unless it violates known physical laws, it's possible but requires time, funds, and researches. So, the boss should decide if he really needs it.
Also it's easier and faster than terraform the same Venus.

4 minutes ago, Hannu2 said:

Humans are adapted (with genetic engineering) to zero gravity

For spending 1.5 years with active medical assistance.
And unlike the uncertain "genetic engineering", the active cooling is just pure mechanics implemented in thousands of nuclear reactors.

[Hannu2]

2 minutes ago, kerbiloid said:

Exactly the same with Venus, just the temperatures are greater. Your fridge works at 300..350 K, while the Venusian module at 800..1200 K, but the principle is the same.

Of course you need something heat capable as coolant, maybe (but not necessary) hydrogen.
And while on the Earth a fridge warms and exhausts air, a nuclear plant warms and exhausts water (water pool next to the plant or condensating cooling towers), the Venusian habitat should be exhausting torches of hot carbon dioxide (pumped inside, warmed from 750 K to, say, 900 K, then exhausted)

What are practical amounts of powers and coolant flows?. Efficiency of electric production is very poor in those temperatures. You have to get rid of tens of megawatts excess heat for every produced megawatt. Do you know for example what kind of winds there are? Othervise you heat gas around your powerplant which decreases efficiency and power output and, on the other hand, increases power intake of building cooling. You are in positive feedback loop, which ends to destruction.

Even in cold Finland they have to occasionally decrease the power of nuclear powerplants if we have exceptionally warm weather because they have strict limits how much they are allowed to heat sea water around them. In Earth it is easy to replace them with other means, but in Venus the situation is not so nice if there is no winds and air begins to warm around the base.

[Scotius]

Cloud of solar power stations in Venusian L1 point. Enough to shade the surface and drop temperature down. Also, power as profit

[Hannu2]

 

8 minutes ago, kerbiloid said:

Unless it violates known physical laws, it's possible but requires time, funds, and researches. So, the boss should decide if he really needs it.
Also it's easier and faster than terraform the same Venus.

Humans ask always do we really need or want or can afford it. And unfortunately, but not surprisingly, those who have money and those who think cool space adventures are needed are completely different groups.

 

Quote

For spending 1.5 years with active medical assistance.
And unlike the uncertain "genetic engineering", the active cooling is just pure mechanics implemented in thousands of nuclear reactors.

I wrote about time when operations on Venus are possibly considered severely and not just in small talk on net forums. It must be hundreds or thousands of years in future.

Edited May 6, 2020 by Hannu2

[kerbiloid]

Just now, Hannu2 said:

What are practical amounts of powers and coolant flows?

As the heat flows from outside to inside for the Venus base, the net power should be equal to the heat transmission rate which is defined by the external hull material (carbon plastic or phenol formaldehyde resin, or maybe some carbides), by the temperature difference, and by the hull thickness. This can slow the flow and make the power relatively low.

6 minutes ago, Hannu2 said:

Efficiency of electric production is very poor in those temperatures. You have to get rid of tens of megawatts excess heat for every produced megawatt.

The reactor core is significantly hotter than the Venusian "air", so I can't see a problem here. Definitely not such volcano of power. Probably something of a regular powerplant value.

7 minutes ago, Hannu2 said:

Do you know for example what kind of winds there are?

Yes. In a 900 K hot torch which makes a vertical wind blowing away from the station.

9 minutes ago, Hannu2 said:

Even in cold Finland they have to occasionally decrease the power of nuclear powerplants if we have exceptionally warm weather because they have strict limits how much they are allowed to heat sea water around them.

Exactly a problem not relevant for the Venus. As well as carbon footprint.

5 minutes ago, Hannu2 said:

Humans ask always do we really need or want or can afford it. And unfortunately, but not surprisingly, those who have money and those who think cool space adventures are needed are completely different groups.

If the boss asks if we can build a base on Venus not as a private question not related to the business, I presume he's serious and estimates pros and cons.
So, I would not judge myself if it is possible at all, but I'm sure it will require additional time, funds, and researches. So, if he decides that it's enough interesting idea, this can be calculated.
Otherwise the boss asks strange things and probably it's a time to start searching for another boss.

[Hannu2]

2 minutes ago, kerbiloid said:

As the heat flows from outside to inside for the Venus base, the net power should be equal to the heat transmission rate which is defined by the external hull material (carbon plastic or phenol formaldehyde resin, or maybe some carbides), by the temperature difference, and by the hull thickness. This can slow the flow and make the power relatively low.

Good luck in plastic building on Venus. I would use some low density ceramic insulator.

 

2 minutes ago, kerbiloid said:

The reactor core is significantly hotter than the Venusian "air", so I can't see a problem here. Definitely not such volcano of power. Probably something of a regular powerplant value.

Yes. In a 900 K hot torch which makes a vertical wind blowing away from the station.

Are you sure? It is not trivial problem what kind of flow 900 K gas causes on Venus and is it enough to transport all heat away. Or how much power you need to produce such flow artificially. I meant exactly this kind of questions. Usually in science fiction and overoptimistic techtalk this kind of questions are omitted. Complex things are just assumed to be done "somehow". But I think that if there is not answers operation is impossible for now. It may be possible in future, if it is investigated and solutions are found, but before that it is unsure and I can not say it is possible.

You probably think that what is not proved to be impossible (i.e. against known natural laws), is possible by default and can be done.

[kerbiloid]

20 minutes ago, Hannu2 said:

Good luck in plastic building on Venus.

No problem, the listed materials are reentry vehicles cover. They survive much greater temperatures than poor 450°C.
Though, the mentioned carbides can be the ceramics you mean.

20 minutes ago, Hannu2 said:

It is not trivial problem what kind of flow 900 K gas causes on Venus and is it enough to transport all heat away. Or how much power you need to produce such flow artificially. I meant exactly this kind of questions.

A hot gas tends to raise up even with no pressure. And the cold room should be shaded from it with a firewall anyway.

20 minutes ago, Hannu2 said:

Usually in science fiction and overoptimistic techtalk this kind of questions are omitted. Complex things are just assumed to be done "somehow".

I've counted by fingers, it looked workable. Of course, more accurate answers require additional calculations. Probably will do them but currently no time to dive deep.

20 minutes ago, Hannu2 said:

You probably think that what is not proved to be impossible (i.e. against known natural laws), is possible by default and can be done.

What is not proved to be impossible can't be considered impossible.

Edited May 6, 2020 by kerbiloid

[farmerben]

 

Spoiler

 

 

Water vapor floats like a dream on CO2.  

If there were large blimp like fungus living around 45-60 km in altitude, they could suspend themselves on steam.  A host of extremophile organisms on Earth could survive in a primarily steam environment and use photosynthesis to support the ecosystem functions.  If highly successful, this environment would eventually extinguish itself through climate change.  For a while though, it could be more economical to grow fields of sky-fungus than to build foil factories on Mercury.  

edit: also methane performs almost exactly as well as steam

 

Edited May 6, 2020 by farmerben

[Hannu2]

4 hours ago, kerbiloid said:

No problem, the listed materials are reentry vehicles cover. They survive much greater temperatures than poor 450°C.
Though, the mentioned carbides can be the ceramics you mean.

They are ablative materials. They evaporate and absorb heat during couple of minutes of atmospheric entry. If I remember correctly, entry burns several centimeters of ablative stuff. Any plastic can not handle high temperatures continuously. You must use carbides, ceramics, stone or glass wool etc. if you want long lived thermal insulator. Probably chemical composition of Venus's atmosphere restricts materials. I have no idea how for example gaseous sulfuric acid affects to normal insulator materials.

 

4 hours ago, kerbiloid said:

A hot gas tends to raise up even with no pressure. And the cold room should be shaded from it with a firewall anyway.

I know and use it to cool electronics. But it has limited ability. I would not trust that 150 K temperature difference induce enough mass flow at conditions on Venus. How cooling tower work in high density atmosphere and how to build such massive buildings on extreme hostile environment?

 

4 hours ago, kerbiloid said:

What is not proved to be impossible can't be considered impossible.

Nothing in real world can't be proved impossible. Even if something is against known natural laws there is always possibility that we find new physical phenomena or known natural laws change for some reason (there are speculations on some odd phase transitions of space or quantum fields, which can change natural laws, but I am not familiar with such extreme physics). In my opinion it is much more interesting what is practically possible or impossible in foreseeable future and realistic resources.

Manned operations on Venus is certainly impossible with these rules. But I read somewhere that industry investigates gallium nitride electronics, which can operate at much higher temperatures than silicon. They may be able to operate at Venus temperatures at some day (it is investigated to get smaller and cheaper power electronics, not for Venus operations).