There have been several comments in the other Venus posts about terraforming. I don’t have a lot of personal opinions or ideas on the topic, but would like to provide this open thread for people to comment to their hearts’ content about Venus terraforming, how to do it, and if it’ll ever make sense.
In the meantime, I’ll get back to work on the rest of the Venus ISRU series.
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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 the founder and CEO of Altius Space Machines, a space robotics startup that he sold to Voyager Space in 2019. Jonathan is currently the Product Strategy Lead for the space station startup Gravitics. 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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Just one thought – if there is really 20 ppm of water integrated throughout the Venusian atmosphere, that is about 2 millibars, or a global ocean of 2 cm depth. Not much compared to the Earth’s 2.5 km global ocean depth (ignoring topography), but about the volume of Lake Superior, so enough to start with, at least.
As far as how to do it, a Sunshade to cool it off, heat pipes to accelerate the process, and biology to get all the blasted carbon back down into the ground.
So to terraform Venus, you put a million tonnes of dust in L-point 1.
Next, to cause Venus to cool quicker. Because if stopped all sunlight from reaching venus it would still take century or so to cool.
You drop lot of water in the atmosphere.
So a kg of water to vaporize requires:
2,270 kJ/kg.
And raise temperature of water
At -100 C it’s 1.389 and ice at O C is 2.05 kJ/kg
So from -100 C to 0 C totals something 160 kJ/kg
Ice to liquid: 334 kJ/kg
And water 0 C to 100 C, about 410 KJ/kg
http://www.engineeringtoolbox.com/water-thermal-properties-d_162.html
And orbital velocity of 8km/sec has 8000 times 8000 times 1/2:
32,000 KJ/kg
So 1 kg of ice at -100 C in orbit add energy [heat] to atmosphere if deorbits
But where in the Venus atmosphere does it add this heat.
So if we have 100 meter diameter rock, which hits earth it wouldn’t slow down much by the atmosphere and would slam into the Earth surface. It would be mostly stopped the ocean or land surface and therefore heat at surface. This assuming rock more or less stays intact- not a rubble pile. And if instead of 100 meter rock, it was a 10 meter rock then it blows up in Earth atmosphere- perhaps 20 to 30 km up.
And with Venus one gets earth 1 atm of atmosphere at about 49.5 km elevation. So 10 meter which blows up at 20 km on Earth, blows up higher than 50 km on Venus.
So take a 10 meter diameter sphere of ice drop into Venus atmosphere, it explodes before 50 km elevation. And chucks of ice would fall to surface [and vaporize from the heat of atmosphere before falling to surface- water wouldn’t make it to surface.
So an efficient way to heat Venus would be to set off nukes at the surface- a small nuke might have most of the heat remaining below say, 30 km. Where setting of nukes at 50 Km elevation would very inefficient way to heat Venus- most of it immediately radiates into space and any part of atmosphere warmed also fairly quickly radiates into space.
Therefore despite the high energy/heat one would get from space impactor hitting Venus, it’s possible to cool Venus with dropping stuff into it’s atmosphere from orbit. It momentary tremendously heats upper atmosphere and fragments of explosion can be warmed by the hot atmosphere as fall to surface.
So sun shade of dust will reduce sunlight but Venus would take forever to cool from merely reducing sunlight.
Let’s do rough math:
“Total mass of atmosphere: ~4.8 x 10^20 kg
Average temperature: 737 K (464 C)”
http://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html
Half the mass of Venus is roughly at elevation of 1/2 pressure, +15 km elevation, which is about 100 C cooler than sea level of 464 C.
So all of Venus atmosphere might around 250 C [or cooler].
So total joules of 4.8 x 10^20 kg at 250 C to cool to
50 C is:
At 325 K is 0.871 kJ/kgK and at 550 k it’s 1.046 kJ/kgK
http://www.engineeringtoolbox.com/carbon-dioxide-d_974.html
So 200 times say .9 kJ/kgK. So is 180 kJ times 4.8 x 10^20 kg.
[We will ignore cooling the land.]
So, 864 x 10^20 KJ. Or 8.64 x 10^22 KJ.
Venus currently radiate: 163 watts per square meter:
http://bartonpaullevenson.com/Albedos.html
And global area of 4.6 x 10^14 square meters
So loses 749.8 x 10^14 joules per second
8.64 x 10^22 KJ is 8.64 x 10^25 joules
So divide 8.64 x 10^25 joules by 7.498 x 10^16 joules to get total
seconds. Or roughly longer than 1 x 10^9 seconds.
Year having 3.15569 x 10^7.
So with solar solar only reducing the amount of sunlight and assuming as Venus cools it will emit less than 163 watts per square meter, we could looking at over a century of time.
So how much water is needed?
So if assume we starting cold ice and or hydrated water
and we going to have it evaporated in atmosphere. As said
2,270 kJ/kg to evaporate, changing it from ice or removing it
from hydrated rock will require more energy. Let’s pick round
number of 2500 kJ/kg. So
8.64 x 10^25 joules divided by 2.5 x 10^6.
So 3.456 x 10^19 kg.
Earth has: “Total mass of hydrosphere: 1.4 x 10^21 kg”
http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html
So 1/40th of Earth’s water. So Earth was perfect sphere:
“the seawater would cover the entire earth to a depth of 2440 meters ”
http://eesc.columbia.edu/courses/ees/climate/lectures/o_strat.html
And if 1/40th of water: 61 meter average depth.
And essential until Venus cools enough, this 61 meter average depth of global water will be in the hot atmosphere. And even when it’s only 100 C at surface it’s still mostly going to have the water in atmosphere, and when lakes of liquid CO2 form water will
be mixed in with the liquid CO2. And dry rocks will such up the water and there will be much water on surface. But in the very dry
Venus atmosphere there some water. So it might increasing this existing water by factor 10 or so.
So how do you get this enormous amount water to Venus:
3.456 x 10^19 kg of H20- more than 30 thousand trillion tonnes.
So 1 km diameter rock with density of 2, has volume of 523.3 million
cubic meters- mass of 1 billion tons. So there is not mass [not to mention water] in all Earth’s NEOs. The really big ones, like, 1036 Ganymed have: Mass (1.67 ± 3.18) × 10^17 kg
http://en.wikipedia.org/wiki/1036_Ganymed
So that is about 200 trillion tonnes and largest one are most of mass of NEOs. And as say said not enough.
So to find this much water, need to look at Main Asteroid Belt or
beyond.
If pick a larger rock in Asteriod belt, say Vesta:
“Mass 2.59076±0.00001×10^20 kg”
http://en.wikipedia.org/wiki/4_Vesta
That is 2.5 ×10^20 kg vs need of water of 3.456 x 10^19 kg
So if had more than 10% of it’s mass water that would be in ballpark, though we need it in smaller chunks so doesn’t
impact Venus surface.
So say you look for rocks which are about 10 km in diameter.
So in terms of volume: 533,333 million tons. Or if pure water
1/2 trillion tons- “only need” 60 of them :).
So the scale is hundreds of large space rocks and more than 25% water.
And need to break up the rocks before impacting Venus so they don’t reach deep into atmosphere.
So that is rough scale of doing this. And this requires the use of nuclear bombs. Thousands of nuclear bombs.
So use nuclear bombs to change the rocks trajectories to a hohmann transfer to that intersects Venus. So somewhere around 2 km/sec. And bombs cause the rock to go into smaller pieces.
Hmm, breaking them into smaller piece going require a lot bombs, so makes more sense finding smaller ones. So not hundreds but
tens of thousands of rocks much smaller than 10 km in diameter- and would still make them into smaller pieces before they impacted Venus. So then say 100,000 to 50,000 miles from planet or hours from impacting, you controlled detonations with a few small nukes.
Hmm, one could also have rocks hit other rocks.
So take two similar size rocks, have them intersect at different inclination near Venus and the result of impacting near Venus is
they impact Venus.
So one has to find the right rocks and enough rocks being in right location to meet up at Venus distance.
So this going to be simliar to two people firing a bullet at the wall, but going hit each other bullet before the bullets hits the wall, so they crossing the path of the bullets, and if the bullets miss each other than they still hit the wall. Or the collision occurs near the planet.
But anyhow, massive project, not doable near term. And large part is finding all the rocks. But could use NEOs and other rocks in addition to Main Asteroid belt rocks. But sheer amount of water needed requires Main Asteroid belt or asteroid beyond main belt.
Well, Venus is certainly interesting. Removing the atmosphere seems to be a big problem though, given how much energy it would take.
There are however ways to mine atmospheres in a reasonably low-cost fashion. One of the them is scooping the upper atmosphere at low planetary orbit, sth along the lines of a solar powered PROFAC (I found a nice concept here: http://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods/Resource_Extraction#Scoop_Mining ). A bunch of such vehicle could slowly scoop the CO2 and send it using ion-driven crafts along low-energy transfer trajectories to Mars. We are achieving two things here – reducing the atmo on Venus, and building it up on Mars. The mined Venusian CO2 could be also used as a feedstock to make carbon fiber in plants orbiting around Venus.
Now, I believe that we have all technologies needed to perform such a feat. We have ion drives to power the PROFAC mining scoops, solar panels are a well known technology, we can control vehicles in low planetary orbits, we know how to dock and transfer fluids between vehicles, vacuum pumps are also a well know technology. What remains is integration. Now, would a Kickstarter campaign be a reasonable way to finance a demon mission in LEO? The same vehicle could later dock with a Venus transfer stage and show that it can work in Venusian orbit.
One could imagine blowing the atmosphere into space with large numbers of nukes (the deuterium in the atmosphere, if collected and fabricated into millions of very large bombs, would about do it), but the problem is that it’s so massive the solar wind would not blow it out of the solar system quickly enough. Most would fall back onto Venus or, worse, onto Earth!
How about instead imagining Venus being used as a giant radiator? Conduct industrial operations, like bomb-driven nuclear transmutation on a massive scale, and radiate the waste heat into space from the top of the atmosphere.
Gbaikie, I have a thought on the water. Instead of transporting water, just transport hydrogen because there’s already plenty of oxygen locked up in the CO2.
If you run a Bosch reaction, which takes place at 800K to 1000K (just slightly above the current surface temperature), you can convert carbon dioxide to graphite and water.
CO2 + 2H2 to C(s) + 2H2O
44g + 4g -> 12g(s) + 36g
This reduces the amount of mass you have to transport to Venus to provide water by a factor of 9 (2 grams vs 18 grams), and if you can unlock enough existing hydrogen from the surface you don’t have to transport anything at all. Some of the graphite can be used to build structures, but the bulk of it would just be sealed to prevent oxidation and left on the surface. As an added benefit, unlike dry ice, the graphite doesn’t present a risk of reverting back to a gas when something goes slightly awry.
This is perhaps faster than making carbonates, and would produce oceans of water as a side benefit.
George, where are you getting the hydrogen from?
On another angle, if you look at the absorption spectrum of CO2, you can see it only covers about half the IR spectrum, IR emission from deep in the Venus atmosphere is inhibited at other wavelengths by the clouds and other greenhouse gases. Unfortunately even minute quantities of other GH gases can be pretty effective at blocking radiation (methane on Earth at 1.7 ppm), but it is a tempting idea, at 700 K a surface emits around 13,600 W/m^2, compared to the current outgoing radiation from Venus of around 165W/m^2, and those other GH gases are all on Jon’s list of condenseables.
Well, there’s a whole planet full of elements, so hopefully some resourceful method is found to produce some hydrogen. According to Dr. Freund at NASA Ames in this article, there’s hydrogen trapped in igneous rocks which is released when they’re fractured. By my calculations, each cubic meter of rock should produce enough hydrogen to convert 10 grams of CO2 to water. Unfortunately, that’s a lot of rock. There are possibly some accessible hydroxides and other minerals that might offer up a little.
If that fails, we can get hydrogen from Uranus, or from any body containing ice by splitting the water, which brings up a mass ratio question. If your destination has plenty of available oxygen, is it more efficient to split your water into hydrogen and oxygen and only ship the hydrogen?
*makes a little spreadsheet*
Yes, for all positive mass ratios, you have to split less total water if you only ship the hydrogen as payload and leave the heavier oxygen atoms behind.
And I agree. If we can clean the atmosphere of some other greenhouse gases we could probably open up a piece of spectrum where the heat will radiate out much faster.
As for the sense part: Once you’ve converted (most of) the sulfuric acid into lifting gas for the dirigibles, and (most of) the sulfur dioxide into a cache of elemental sulfur, locked away so it doesn’t reenter the sulfur cycle, why not stop there?
At that point, you’ll have an environment where it’s possible to go outside in shirt sleeves, and oxygen. You’ll have a freaking flying city… Experience and advancements in technology will have made it about as safe as ships on Earth.
If you want to go outside without a breathing mask, it might be possible to continue to lock away the carbon, so you eventually come up with an O2/CO2/N2 air mix that might be breathable (with the necessary adaptations to the organisms that need to breathe it), rather than completely converting it to 78%N2/21%O2 like on Earth. Let alone removing the excess atmosphere to get atmospheric pressure down to what it is on Earth.
I consider terraforming a waste of money no matter where you do it. But on Venus it’s more than a waste, it’s a crime. The entire idea about a colony on Venus is to make it a flying city. That will be the main attraction to potential colonists. Take that away, and you take away everything that would make a Venus colony unique. You want everything to be just another copy of what you’re used to? Go live in a space station. Those should be pretty much the same wherever you put them.
These arguments for the habitability of the upper atmosphere of venus are pretty persuasive. So persuasive in fact that I would be unsurprised if we find that biological niche occupied, meaning that colonists would need to plan for it. http://www.astrobio.net/news-exclusive/venusian-cloud-colonies/ Potentially, seeding invasive, but ‘human friendly’ bacteria that can live in that environment to push out potentially hazardous venusian life from that niche would be a logical solution, and solving invasive species and genetic engineering problems on earth would give us the tools to implement it.
Hydrogen sulfide is also a pretty substantial hazard, I suspect that it is probably common enough that the safety precautions used on oil rigs would be necessary, and that there would be a few accidents. This is especially problematic if it’s used or produced by indigenous life.
I think the oil rig analogy is probably the best, if there’s useful material on the surface (heavy metals/rare earths), then there will evenetually be an economic incentive to extract it, provided an economically viable method of moving it to orbit can be developed, but by the time this is being seriously considered, a space elevator (with a multi-week transit time) would probably be within the realm of possibility.
So, life for colonials would be multi-year ‘hitches’. Humans are needed to monitor and control robotic extraction machines on the surface in real time, and they would ship in and out with the shipments of material in orbit being moved either towards the sun for the beginnings of dyson solar orbiter construction, or outsystem towards mars, jupiter, and the asteroid belt for construction of space habitats and eventually interstellar craft.
Anonymous,
Honestly I’m not sure how much material extraction for export there’ll be from the Venusian surface. I can see material extraction potentially for local use, but I’d be surprised if it was price competitive for say metals with Near Earth Asteroids or the moon. That said, unless you have an arbitrary awesome propulsion system (see my previous blog post), Venus may still be a trading hub with the NEOs. The delta-V to get there is higher, but the synodic period issues tend to be better because of Venus’s shorter solar year…
~Jon
I suspect that much of the primordial hydrogen on Venus is still there, but subducted into the mantle. In silicate melts, small amounts of H2O increase the density. I suspect that on Venus early plate tectonics subducted hydrous minerals into the mantle because the denser H2O containing melts sank.
I think that on Earth, the early presence of life generated reduced carbon in sediments and that carbon formed methane with the subducted water. Methane is insoluble in silicate melts so it percolated up to the surface.
There was a recent article about a “hydrosphere” of water-rich minerals in the Earth’s mantle.
http://www.livescience.com/44057-diamond-inclusions-mantle-water-earth.html
It might be possible to recover that hydrogen on Venus by dropping graphite (weighted with iron) into volcanoes. If the carbon (or iron/carbon/silicon alloys) survive transit to where the H2O is, they could liberate CH4 bubbles that would transport hydrogen to the surface.
This thread is awesome. I’m going to read it through in detail before commenting much so as not to repeat. But I did want to briefly mention that certain algae are hyper-CO2-tolerators, meaning they grow well in conditions of anywhere from 10-60% carbon dioxide. There is even a species called Cyanidum caldarium that is believed to tolerate concentrations of up to 100%! I wrote a blog on this a while back:
http://lonelyspore.com/2013/11/28/little-green-microbes-may-turn-our-carbon-dioxide-into-gold/
Give the composition of Venus’s atmosphere, seems to me that we should start thinking about engineering some of these guys on an industrial scale, growing them in big vats in the atmosphere, and using them for food (algae are a great source of protein, vitamins and unsaturated fats) and biofuels.
Any mention of the Venus-colonization stories of Henry Kuttner or David Drake?
What a nice blog for some far out thoughts! Good job. 🙂
Lots of great details and comments. I have popped in here and there in the past, but it really has grown a lot since the last time over. And the Venus threads are rather epic.
Since I had thought about ‘balloons’ across Venus before, I had some thoughts I figure I would pop out. I figured on a tall hanging ‘string of bubbles’ or maybe a ‘Portuguese man-o-war’ type arrangement. 2-3 main areas vertically along a line. There would be some wind shear issues I suspect, so it might be smart to have it more like the ‘Man-o-war’.
Some balloons (hollow spheres, metal or plastic compatible with the local clouds) at the very top, heated or filled with a LTA mix. They could be thin and contained in a protective net that diminishes effects of the sulfur acids and related. Food could be grown at this level, the color spectrum seems to be good. At this set you could have a ‘launcher’ to get back out to orbit. This could be used as a shield for lower balloons also if needed by having a thin material (porous, 50% fill maybe?) that could be used for power also, or maybe part of a large thin balloon.
The mid set would be ‘living’ quarters. And whatever else. 🙂
Then a lower set that could be two part, one dipping down a mile or so. A dipping string or ‘dipline’?
Power could be from ‘diplines’ that drop a few miles down. The temperature runs above boiling within a mile or two. So using water or another mix you could use the temperature differential to power your habitat. This could also be a place to berth a ‘ship’ that can go down to lower levels to explore/mine.
I really liked the idea somebody had here of an automated ‘drop claw’ that would impact mine the surface, then after it has settled/closes it inflates a balloon and returns to the ‘human space’. That is just brilliant. It could be picked up in the ‘dip lines’ area, and refined there also? It also might give you some really interesting materials – what materials are produced on a 500 degree surface that doesn’t oxidize? There has to be some curious and maybe valuable compounds somewhere there. If nothing else, the right material for more balloon colonies.
The outside surface of the balloons could be covered with some single celled life that can handle/digest the sulfur in the acids and also the CO2. It might even be a food stock, but I figure if the right type is found/engineered just having it as a coating would be good enough. Then the area right around the balloon might have its own micro environment (maybe just a few inches off the surface, but that might be all you would need in some cases) and if the right organism is found it could supply oxygen readily.
Nuclear Thermal Rockets (NTR) and turbines, of whichever type, make a lot of sense. While CO2 is not the best propellant, you can still use it. A setup for either pushing the ‘Venus Man-o-War’ or ‘VMoW’ to ‘VMoW’ travel in a dirigible of sorts, and also for escaping Venus’s gravity well all could use the same technology. NTR could also be part of the processing part to strip chemicals out of the atmosphere. If you did have them on the ‘VMoW’ you wouldn’t need the dip lines for power I suspect.
Maybe the entire purpose of the VMoW is to produce more VMow’s. Build them initially with the purpose of just building more. The only thing I think you might need after that is if they can’t find some of the trace minerals they need they would need more dropped in.
That is about where I left off my thoughts. What do you guys think?
Maybe 20 years ago I read about an elegant way to change the atmosphere of Venus. You just inject a special sort of bacterium into the atmosphere, an organism that loves this environment and even thrives on it. It should ‘eat’ the CO2 and transform it on the long run.
With todays level of bioengenering it should be possible. And maybe you wouldn’t have to wait very long to witness the result. If designed properly these bacteria could multiply explosively and then die out when they have done their job.
Given that much of what makes Earth habitable is the result of being hit by a large planetoid early in our career, colliding a decent sized object into Venus to provide spin and a moon seems important.
And of course, would need to be done before pretty much anything else; but would be harder than anything else.
The only way I can think of achieving this is by using Io. Here’s a suggestion that it will one day break free (http://www.universetoday.com/32639/jupiters-fiery-moon-io-could-one-day-break-free-go-dormant/) encouraging that to occur earlier, and aiming it at Venus, should be within comparatively practical: asteroids using gravity assists to shift the velocity of any and all of the interacting moons – tiny shifts to be granted, but hopefully sufficient.
Granted that it would takes centuries for Venus to recover from the collision, but terraforming a planet isn’t likely to be done quickly.