Posts by samy

samy · Terraformation

I hope Venus Express will get us more hard data on Venusian water vapor, among other things!

samy · Terraformation

the partial pressure of water increases with temperature

So most of the water on Venus can be found at the lowest altitudes, since that's where the temperature is highest? That's too bad, I would've hoped for more humidity at the cloudtop levels.

samy · Terraformation

"Should be". I hope you're right, as that would indeed make things much easier.

I'm hoping Venus Express will be able to shed some more light on the Venusian atmosphere composition. When the hell do we get some actual results out of it anyway? It's been there half a year dammit!

Thanks nickname, for a great rundown on the comparisons. I'd hoped to focus on comparing and contrasting the broad strokes of the top three choices, rather than get bogged down on the details of any one in specific -- not too much, anyway: some discussion must of course be conducted.

samy · Terraformation

Why have you come to visit the NewMars site and to pose such an interesting topic for discusion? What do you expect to contribute and or how will NewMars contribute to your needs?

Hello SpaceNut! I hope this tangent won't take up much of this thread as I (and I suspect others) come here to talk about space, not about myself.

I come here because I am interested in off-Earth colonization and would like to learn all I can about the difficulties inherent therein. It is only through knowing those difficulties and understanding them that we can hope to overcome them. It is my hope that before I die, I will get to see (by video transmission) humans living and working on aerostats on Venus. Though I understand of course with the current pace of space exploration I'll likely die before that happens. I hope to contribute by asking questions where I don't know things and providing information where I do know things. NewMars serves my needs by allowing me to get in touch with other people who are interested in the same kinds of things as I am. You can't just go around discussing terraforming with one's office mates whose main interests are beer and sports.

I hope that satisfies your curiosity about me. Now, on to the topic here!

From the Air2Water Dolphin:
It’ll produce 20 liters of water a day in 70% humidity
Even in the parched Mesopotamian desert, the air holds plenty of water. The trick is getting it out.

Venus is much less than 70% humidity, of course. So will Air2Water be of any use there?

What is the approximate humidity of the Mesopotamian desert? I suspect it is on the order of 1-5%, though that is merely a guess. In any case I suspect (though I'll gladly be proven wrong) that even the driest Earth deserts are orders of magnitude different from Venusian humidity (or rather, dryness) levels. In absolute amounts, of course, Venus has a lot of hydrogen as karov calculated, but as noted in that quote, "the trick is getting it out" and I am honestly skeptical about squeezing water out of 0.02% humidity air, at least at any kind of reasonable speed. Let's not forget that to get the amount of water that karov projected, we will need to process *the entire Venusian atmosphere*, which is a long-term project if ever I saw one.

samy · Terraformation

I couldn't find anything on the Air2Water page regarding how much moisture the air must have for the tech to work. It speaks of "humid air", which suggests to me there must be significant (more than 0.02%) amount of water vapor in the air.

samy · Terraformation

I'm a little skeptical about the prospects of extracting water from the atmosphere when it's such a small percentage -- can you tell me more about these US military efforts of water extraction that you referred to?

Also, if we *can* extract 100% of the water vapor and put it to use as liquid water, that would also prevent the H2SO4 from forming, thus preventing any acid problems too, right?

Your ideas for continent-sized colonies aren't feasible in the near future. Maybe 500-1000 years from now, but for the moment, if we're going to go there in the next 100-200 years, I think we will have to do with these "flimsy aerostats", so don't be so dismissive of them. Everything must have a beginning.

samy · Terraformation

All the hard data I've managed to find says H2SO4 is only to be found in trace amounts. If you can find a source that says there's actual substantial amounts of H2SO4, I'd like you to point me to that source.

I imagine the amount of H2SO4 might be barely enough for a couple of manned stations, with a lot of collecting work, but not much more than that. Can you cite any actual amounts?

Here's Wikipedia's atmospheric composition:

Atmospheric characteristics
Atmospheric pressure 	9.2 MPa
Carbon dioxide 	~96.5%
Nitrogen 	~3.5%
Sulfur dioxide 	.015%
Argon 	.007%
Water vapor 	.002%
Carbon monoxide 	.0017%
Helium 	.0012%
Neon 	.0007%
Carbonyl sulfide
Hydrogen chloride
Hydrogen fluoride 	trace

Doesn't even mention H2SO4, so it's presumably less than all the above elements. That's not very much now is it? Sure, there's *some* hydrogen present, but I'm skeptical about there being useful amounts.

Let's note that there is even more actual *water vapor* H2O than there is H2SO4. If we need water, it would make sense to me to go to the water vapor first because it is more plentiful. You don't try to squeeze water from a stone while you're standing next to a lake.

Anybody want to do the math for how many liters of water is 0.002% of Venus' atmosphere?

samy · Human missions

After a lot of thinking, I have come to believe that the realistic (as opposed to idealistic) model will have to feature at least one self-sufficient biosphere space station before Earth will consider colonizing any other celestial body. ISS was a baby step, now it's time for a bigger project, a Stanford torus or an O'Neill cylinder for hundreds or (unlikely) thousands of people, and I do believe this intermediate step is practically mandatory before we can realistically push for Mars colonies or any other colonies.

And even prior to that step, we really do need to get 100% biosphere recycling right. I'm honestly quite astonished that we don't have *dozens* of Biosphere 2 -type projects going on right now (and if we do, that they aren't being publicized enough). The most important concern in colonizing off-Earth (whether space or planetary bodies) is being able to recycle the biosphere indefinitely. We can practice that here, on Earth, in closed systems, but I'm seeing very little progress in that direction. ISS requires resupplying. We will be forever limited to Earth until we actually do the first closed environment that *doesn't* require resupplying like ISS does. Even Biosphere 2 needed resupplying 1 year into the mission. What are we going to do if a Mars colony requires resupplying 1 year into the mission and our next launch window is a year away? Let them suffocate there?

No, we need to solidly, conclusively estabilish that we *can* build a fully closed, 100% recycling biosphere, indefinitely. We, humans, *have not accomplished this yet*. Until we do, our dreams of colonization are ashes.

samy · Science, Technology, and Astronomy

Because they're all we can detect so far?

Once we're able to detect small, rocky planets, I'm sure they'll be more numerous than the brown dwarfs we're limited to finding at the moment.

samy · Terraformation

It seems to me that there are three primary destinations being considered for colonization in the long term: Venus cloudtops, Mars and Titan. Each of these has lengthy threads about each one *individually*, but I couldn't find a thread for comparing and contrasting the three options. So I thought I'd try one. I'm by no means a specialist, so I'm sure there'll be lots of correcting for you guys to do.

I decided to count out any possibilities of significant matter transfer between planets. In other words, "living off the land". Shipping bars of nitrogen between planets might be realistic 200 years in the future, but it's science fiction now. I picked the following criteria to compare by.

Pressure
Temperature
Energy
Hydrogen (needed for water)
Carbon (needed for organic life)
Oxygen (needed for water and breathing)
Nitrogen (needed for buffer gas)

Going from low to high AU

VENUS CLOUDTOPS

Pressure: Good (1 bar - Earth level)
Temperature: Good (0-50 Celsius - Earth level)
Energy: Good (solar and geothermal prospects good)
Hydrogen: Bad (None)
Carbon: Good (more than enough!)
Oxygen: Good (more than enough!)
Nitrogen: Good (more than enough)

MARS

Pressure: Bad (~1 kPa = 1% of Earth = near vacuum for human purposes)
Temperature: Good to bad (up to 20C in ideal situations, down to -140C in worst case scenario)
Energy: Bad (low on chemical and geothermal, mostly solar energy)
Hydrogen: Bad (some in polar water ice but is that sufficient amounts for colonization?)
Carbon: Bad (some in atmosphere, but insufficient for long-term?)
Oxygen: Bad (some in atmosphere, but insufficient?)
Nitrogen: Bad (none?)

TITAN

Pressure: Good (1.5 bar = Earth 5m underwater pressure = adaptable to humans)
Temperature: Bad (-180C = coldest of these three options)
Energy: Good (chemical-based)
Hydrogen: Good (expected to be plentiful in the form of hydrocarbons and water ice)
Carbon: Good (hydrocarbons)
Oxygen: Unknown (water ice expected but unconfirmed, amounts are big question mark)
Nitrogen: Good (98.4% of atmosphere is N)

Based on these quick and dirty reviews, I'm collating what would be needed as survival measures on each planet.

VENUS CLOUDTOPS

Needed: Hydrogen

MARS

Needed: Pressure regulation, temperature regulation, hydrogen, carbon, oxygen, nitrogen

TITAN

Needed: Temperature regulation, perhaps oxygen?

----

Conclusion:

Most places will require imported materials. Titan is the closest to importation independence, especially if water ice is found in large amounts to allow full-scale oxygen production. Venus is also close, but the lack of hydrogen severely hurts survival prospects. Mars is the worst off; it does have carbon, oxygen and hydrogen, but the amounts of all three are much lower than on our other two candidates.

As for active stationkeeping measures, Venus is the best off, as it requires neither pressure or temperature regulation as long as altitude is kept relatively steady. Titan is next best off, only requiring temperature regulation, but pressure is not an issue on Titan. On Mars, again, the worst of the three, both pressure and temperature regulation is critical.

Comments on where I'm wrong?

samy · Terraformation

Then the pumps could be at the bottom pushing instead of on top sucking!

samy · Terraformation

You could still use solar powered pumps to suck harder on the air!

samy · Terraformation

Anyway the planet does not rotate fast enough, my idea with the ocean was to give it a surface that does. You see water reduces the friction between the upper surface and the bottom. Each layer of water would move slowly in relation to the layer below it, but with a deep enough ocean, all these velocity additions add up.

Wouldn't that take immense amounts of energy and huge infrastructure to impart velocity onto the water? You'd need turbines at regular intervals throughout the planet, different powered turbines at different depths...sounds unfeasible to me?

What are the problems with: constructing a long tube with one end in the atmosphere, and one end in the vacuum of space. With a lower pressure at one end, it should automatically start sucking gas out of the atmosphere and vent it into space. If the power/speed is insufficient, we could install additional solar powered compressors at the venting end of the tube that would add to the sucking power. This would seem like a long-term project that would be fairly self-sustaining.

samy · Terraformation

While it might require less energy to go from Venus to Mars, we can't readily access the surface, making construction of any large atmospheric structure a difficult floating import operation.

While yes, it would be a floating import operation, I am not convinced it would be significantly more difficult than any Titanian environmental challenges.

samy · Terraformation

It would take considearbly less energy to transport

samy · Terraformation

I think his point was that construction and maintenance will be much easier on Titan due to easy access to solids, nitrogen and oxygen, and because those are much easier to get, that offsets some (or all) of the delta v requirement. Venus is cheaper to ship things from but solids, nitrogen and oxygen are more difficult to mine (though all are certainly present on Venus in great quantities).

I'm still a little on Venus' side, but he does make good points for Titan.

samy · Terraformation

These aerostats are going to require some sort of large scale air-tight system that an outpost on Titan would require.

Yes, both would need an airtight system; only the Venusian one would not be subject to as much mechanical stress as the Titanian. (The Venusian one would be subject to more acidic stress though, and the Titanian to more cryogenic stress.)

And while we may have some experience building blimps and zepplins, these are a far cry from the mega-aerostats that are going to be necessary in the Venutian atmosphere.

The principles at work are the same. The point is, this is tested and well understood tech, while scientists are even still struggling with biospheres in deserts and Antarctica on Earth. Sure, there are additional complexities in adapting the balloon tech to Venus - I'm not saying it's as simple as taking the exact blueprints for Hindenburg and building it on Venus. But the tech being long-tested, long-used, and well-understood is a significant bonus.

In Titan's favor, the only disaster they have to worry about is an puncture, which isn't necessarily deadly considering the atmosphere isn't poisionus, just nearly cryogenic.

Try breathing Titanian air and then tell me it isn't poisonous. "Nearly" cryogenic? I daresay your lungs would be pretty dead after taking one whiff.

But yes, both the Venusian and the Titanian scenarios will have to worry about punctures. The difference is, a Titanian puncture will result in explosive compression because the air pressure is less on the inside of the dome. A Venusian puncture is less dramatic because the pressure is same on the outside and inside, and thus the atmosphere will not blast in or out. It may leak out slowly, but not blast in or out like the Titanian interior atmosphere would. This means the Venusian puncture is less severe and more easily repairable than the Titanian.

A Venutian aerostat would have to worry about leaks and failure of there blimps, which would lead to terrible plumet of doom to the planet surface.

A Titanian dome will be just as "terrible" and "doomed" if it fails - the difference being that the Venusian scenario has more available repair time.

The atmosphere is still full of toxic CO2, it's not like you can go out without a mask.

No, you can't go out without a breathing mask on Venus, but then, I don't think any of us were arguing that you can do that anywhere in the solar system except on Earth. You'd have to have a breathing mask on Titan, too. However, you'd have to have more than that, as well. A naked human can survive with a breathing mask in 50C carbon dioxide (like on Venus). A naked human cannot survive with only a breatihng mask in -180C nitrogen (like on Titan). The demands on Titan are therefore harsher. In any case, colonists would spend the bulk of their time inside their domes anyway, in breathable air, so this is not much of an issue - although expeditions to the outside (for example, for repair purposes) would be easier on Venus.

Titan's atmosphere is slightly thicker than Earths (1.5atm), but not to a troublesome degree.

Thanks for making me check. I hadn't realized Titan's atmosphere was that thick! Nice.

The outpost could be be run at either overpressure (to prevent atmosphere incursion) or normal Earth pressures, which ever proves more benifical. People can stand either. It is cold, but protection from the cold and and an oxygen supply are all that would be required.

Kind of like on Venus, except on Venus no protection from cold would be required. Resisting -180C colds requires more than just a thick parka. You'd have to wear some pretty heavy suits to go outside the habitat on Titan. As long as you stay at cloudtop altitudes on Venus, you can almost shirtsleeve it (as long as you have the same breathing apparatus that would be needed on Titan). Thicker clothing against the trace amounts of H2SO4 in the atmosphere would be nice - the acid is a minor problem, but nowhere near as crucial as the cold you'd instantly be exposed to on Titan outside the habitat.

Heck, you could use your oxygen supply to burn some of the methane in the atmosphere to give you the heat you needed.

Of course, on Venus, heat and solar energy are plentiful and easily accessible as-is.

And while Nitrogen and Oxygen are present on Venus, the Nitrogen is fairly rare, and you have to break down the CO2 to get O2, which isn't that easy. Titan has plenty of Nitrogen, and O2 is easy to get from water electrolisis.

I agree that the necessary elements *are* easier to obtain on Titan. They are obtainable on both spheres, though. I do concede it'd be easier on Titan, but it wouldn't be impossible on Venus either.

Furthermore, the surface of Titan is as bad as it gets. Plunge deeper into the Venutian atmosphere, and you are into some bad trouble.

Point taken. On Venus, it is possible to end up in more hazardous zones than the habitat's natural area. It should be noted however that we're talking about habitat destruction level events here, and habitats can be destroyed on Titan too.

Aerostats should also be possible on Titan, hot air-ballons would work realy well there.

Though I'm not sure what the point would be, since aerial areas on Titan are not more attractive than the surface. (Unlike Venus, where the aerial areas are much more attractive than the surface.)

Even at high altitudes Venus still has signifigant gravity, much higher than Titans. So in fact the structures would have to be stronger than they are on Titan.

Point taken.

Also, the Aerostats are going to require some HUGE mega-structures. CO2 does allow for more boyancy than our atmospher, but not by alot. To support any amount of weight you are going to need some large gas bags.

This is true. The exact figures are in the vicinity of (quoting here) "A one-kilometer diameter spherical envelope will lift 700,000 tons (two Empire state buildings). A
two-kilometer diameter envelope would lift 6 million tons."

Size would certainly be necessary.

And as I pointed out earlier, the pressure diffrence on Titan is not realy a big deal. People can easily function at much higher atmospheric pressures, but even if they couldn't, resisting half an atmosphere of pressure is chump change.

I suppose so. I guess the cold is really what will do it for Titan; you'll still have to wear some comparatively heavy suits while outside habitats.

Also, Titan habitats can be constructed out of native material, which will not be so easy on Venus. Which brings on my last, most critical point. An outpost on Titan has access to all the material it needs for construction and expansion. Getting minerals on Venus is going to be VERY difficult, as people and equipment simply can't function for long periods of time on the surface. Furthermore, Titan has easy access to huge amounts of water for drinking and rocketfuel. Venus is very hydrogen poor, and so getting a large enough supply of water just for the colonists needs will be difficult. Fueling rockets will be just about impossible.

Excellent points. You've certainly managed to sway me a little towards Titan, though I certainly don't think Venus is implausible either. Both certainly have their pros and cons, and I suppose I could live with either choice.

samy · Terraformation

A common myth. Space is actually pretty darn empty. The odds of hitting a signifigant chunk of matter in transit bettwen Venus and Mars is pretty much nill. And there is no reason a self-sealing gasbag could not be developed.

You don't need to hit a 'significant chunk'. At interplanetary speeds, a grain of sand less than a millimeter across will puncture a gasbag. You're *not* going to get a gasbag from planet to planet without it hitting any cosmic dust on the way.

A self-sealing gasbag is an interesting idea; can you point me to any developments giving us hope that such a technology is possible? Of course, it would need to self-repair almost instantaneously, because any puncture would powerfully blast the air out of the small hole, very rapidly ripping the hole open wider and wider with the force of the escaping air.

Not a terrible idea, but there are problems. Space quite frankly isn't cold enough for liquid nitrogen, especialy as close in to the sun as Venus is. The nitrogen will melt/sublime away into the vacume. Now, the rate of this will be fairly slow, but it signifigant losses will happen enroute.

I'd be interested in any figures and numbers on how fast sublimation would occur. I was wondering about the rate myself, and we can't really determine the feasibility of this method without crunching the numbers.

samy · Terraformation

Makes sense to me. I, also, suspect that H2SO4 will be present in trace quantities only.

I think it's totally awesome that we have a probe only two months away from Venus. In just a few months, we'll have lots and lots of data on Venus atmosphere!!

samy · Terraformation

Venus aerostats are going to be difficult and expensive to construct, while a colony on Titain is probably going to be much simpler.

What makes you say that?

* Venus is more easily accessible than Titan. Distance: Venus wins.

* Venus aerostats are based on hot air balloon/zeppelin design, with which mankind has centuries of experience. Titan airtight domes are basically untested, undeveloped tech. Simplicity of tech: Venus wins.

* Venus 50km altitude is the most Earthlike environment in the solar system. No pressure differential = no explosive decompression if punctured. Habitable temperature, easy access to oxygen and nitrogen for breathing air. Environment: Venus wins.

* No pressure differential = much less mechanical stress for envelope to resist. Venusian aerostats can be constructed of more lightweight material, as long as we pick a suitably acid-resistant one. Actually building on Titan will require metal/rock style heavy construction in order to withstand the pressure differential. Venus will do with acid-resistant cloth bags. Lighter, cheaper materials. Weight and price: Venus wins.

Why do you think Titan would be cheaper or easier? It seems to me to be further away, and environmentally much more demanding.

samy · Terraformation

Here's an image of the sulfur cycle on Earth:

Now it would seem to me that the sulfur cycle on Venus mostly results in sulfur dioxide and sulfuric acid. I would imagine that ideally, we would want the sulfur, instead of those two, to be bound in sulfate salts (SO4) and elemental sulfur (S8). If we could bind the sulfur up in those, the atmospheric acidity could be significantly reduced, no? Would either of those forms be storageable in mass quantities on Venus? I'm thinking if we dump huge amounts of elemental sulfur down to the planet's surface, it'll just boil back into the air due to the high temperatures. Are there any sulfate salts which would have high enough temperature resistance that they could stay solids or liquids on the Venusian surface, without re-entering the atmosphere?

samy · Terraformation

Yeah I'm imagining these huge yellow mountains of leftover sulfur.

Like this:

Except Himalaya-sized.

Too much sulfur and nothing to do with it.

samy · Terraformation

If we get to a point where we can transport significant amounts of gases from planet to planet, basically all our problems will be solved. But *until* we have the ability to transport a zillion tons of nitrogen to Mars, a zillion tons of hydrogen to Venus - until then, we'll have to figure out a way to eke at least minimal amounts of water for any prospective colonists. The prospects for hydrogen on Venus don't look good as things stand right now.

What use would pyrite be to us? I assume you're referring to (http://en.wikipedia.org/wiki/Pyrite) FeS2. I may be wrong about that. We have plenty of sulfur already, though. What we need on Venus is hydrogen.

samy · Terraformation

As I understand it, volcanoes exhale sulfur dioxide, not fully formed sulfuric acid. This then goes on to combine with water to produce sulfuric acid. The distinction is important because if volcanoes exhale fully formed sulfuric acid, that means there's hydrogen in the crust. If volcanoes just exhale sulfur dioxide, then we'll have to deal with only the atmospheric (very minute amounts of) hydrogen.

One of the key issues with colonizing Venus is the availability of water, which is directly related to the availability of hydrogen. The only sources of hydrogen would seem to be atmospheric water vapor (.002%), atmospheric hydrogen chloride and atmospheric hydrogen fluoride (both in trace amounts), and the unclear amounts of atmospheric sulfuric acid. If indeed volcanoes exhaled ready-made sulfuric acid, that would give us a new source of hydrogen (the crust) which would be nifty.

samy · Terraformation

From Wikipedia:

Carbon dioxide 	~96.5%
Nitrogen 	~3.5%
Sulfur dioxide 	.015%
Argon 	.007%
Water vapor 	.002%
Carbon monoxide 	.0017%
Helium 	.0012%
Neon 	.0007%
Carbonyl sulfide
Hydrogen chloride	trace
Hydrogen fluoride 	trace

No mention of sulfuric acid.

From Wikipedia:

The clouds are mainly composed of sulfur dioxide and sulfuric acid droplets and cover the planet completely

The latter seems to imply there are significant amounts of sulfuric acid but the former seems to imply any H2SO4 would be at trace levels at best. How much sulfuric acid is there really in the clouds of Venus?

However much there is, though, there's just no way the water we could extract from sulfuric acid would be sufficient to, in any way, create a hydrosphere. If it is plentiful, however, it could maybe be used to produce drinking water for (small amounts of) colonists?

Problem with that is, I believe it requires a great deal of energy to break down H2SO4 into SO3+H2O. Then again, supposedly we will have a great deal of solar energy available, so maybe that won't be a problem.

I tried looking into methods for decomposing sulfuric acid into sulfur trioxide and water, but couldn't find any existing methods. Is it impossible?

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