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Hi Terraformer
Using all that methane is still a good start in terraforming both worlds though?
Titan needs to store or get rid of its excess of methane if it is ever to have an oxygen atmosphere. If we can get CO2 and methane to react the right way then it's definitely useful on Venus.
My point is: to totally react with all the carbon dioxide, making oceans and soot/diamond, then the equivalent of 28 bars of methane needs to be found on Titan - maybe it's under the crust, but for sheer convenience I would think shifting a methane rich cometoid might be the way to go. An eccentric Scattered Disk object could be easier to perturb inbound to Venus than haulling mass up from Titan.
Hi All
Why are you guys so confident that Ceres can hang on to an atmosphere? I've tried to follow your discussion in the archive, but I've come up with very little insight into the argument. That's assuming you're not talking about covering the place in cold CO2 or SF4 or something heavier.
Hi All
Water Boiling Point with Pressure
0.006112 bar, 0.01 C = Triple Point
0.01 bar, 7 C
0.02 bar, 17.5 C
0.03 bar, 24.1 C
0.04 bar, 29.0 C
0.05 bar, 32.9 C
0.06 bar, 36.2 C
0.07 bar, 39.0 C
0.08 bar, 41.5 C
0.09 bar, 43.8 C
0.1 bar, 45.8 C
0.2 bar, 60.1 C
0.3 bar, 69.1 C
0.4 bar, 75.9 C
0.5 bar, 81.3 C
... as you can see for expected temperature ranges (<15 C) the partial pressure of water over a body of water will be pretty low. Once it evaporates what happens to it? If it's warmer than its surroundings then the vapour will rise, eventually hitting the Lifting Condensation Level, thus forming clouds and, of course, clouds eventually precipitate. If it's as rain, the water will end up back in the body of water it came from, or some new body, but if it falls as non-seasonal snow (say on a high mountain glacier) then we might not see it again.
Vapour pressure over Ice...
0.01 C, 0.006112 bar
-10.0 C, 0.002598 bar
-20.0 C, 0.001038 bar
-30.0 C, 0.0003809 bar
-40.0 C, 0.0001288 bar
...thus why the -40 C air of Everest's summit is so painfully dry. Also why exposed ice is unstable in the open vacuum - things have to get really cold for ice to last over the age of the solar system, or else it needs to be coated in dust and tholins (think asphalt.) It's also why the water isn't coming back from cold glaciers if we don't control the mountain and polar temperatures on Mars.
Just a few more facts to guide discussion. Pressures are a bit lower over salty water too.
Hi All
And who's gonna stop me from just goig to the Sun and extracting matter?
Could there be antiparticles in the Solar Wind?
Answer to the second question is 'No' - but there is antimatter floating around in the magnetospheres of the big planets, made from cosmic rays. Up to a few grams worth or so, apparently. Look up the NIAC study on extracting the stuff for details.
As for mining the Sun, I think the only people stopping you will be space-lawyers with asteroid masses of red-tape headed your way. But seriously decreasing the Sun's mass enough to affect its evolution is probably only going to make it turn into a red giant. You'll collapse the core if you only remove the outer layers.
At the end of the Sun's Main Sequence it will have only burnt about 10% of its total hydrogen supply - the Core will "choke" on helium ash and slowly collapse until helium burning kicks in. The non-Core hydrogen burning during the Red Giant and Asymptotic Red Giant stages will burn up and/or blow away the rest of the hydrogen. What the Sun needs is for the Core to be mixed with the rest of the Sun's hydrogen mass - if we can do that then the Sun will burn ~ 60 billion more years before it only has helium left to burn. That would then last ~ 20 billion years.
Burning carbon is probably pointless as the net energy gain is small - instead convert the Sun into a white dwarf burning WIMPs (if we can create a WIMP Scoop to channel them in), or burning up its own mass via reverse baryogenesis. WIMP burning could last for billions of billions of years, if we can channel WIMPs. If not then the Sun's mass-energy would only last 14 trillion years at present power-levels.
Hi Terraformer
There's plenty of carbon in the carbon dioxide of Venus, but there's evidence for extensive amounts of the stuff on Titan and Triton. Methane is probably more useful as a greenhouse gas than as a hydrogen or carbon source. Venus needs 98 tons of hydrogen per square metre to convert all its carbon dioxide into elemental carbon and water via the Bosch reaction, if that's what you're thinking. If there's about 5 bars mass equivalent of methane/ethane on the surface of Titan (following Ralph Lorenz's estimates) that's only about 17 tons of hydrogen per square metre spread out on Venus.
There's probably a lot more locked up in Titan as clathrate, but you have to get to it first. I wonder if the heat of Venus re-entry is sufficient to trigger the reaction: CO2 + CH4 => 2C + 2(H2O) , and to keep the equilibrium away from changing back? A line of thought worth investigating. Of course it means Venus is buried in an extra ~ 300 tons of carbon per square metre, but then perhaps it would be the perfect export product for a few hundred years? Might not want a lot of oxygen around all that potential fuel either.
Hi All
Neptune, and Uranus, suffer from the problem that they have no solid surface that's not incandescent and under millions of bars of pressure. A solid shell of diamond could be produced, the carbon made via hydrogen fusion, and the shell could then be supported by gas pressure. It would need to be incredibly strong - as diamond is - because of the rotational forces acting on it.
Alternatively we could build floating habitats of sufficiently low density to float in atmospheric conditions that better suit Terran life (say the 300 K level.) Neptune's temperature at its 1 bar level is 72 K, thus at 300 K the pressure should be about 140 bar, assuming an adiabatic atmosphere. The gas density is 14.6 kg/m^3 at that pressure (av. molecular mass is 2.6 inside Neptune, at least at the top of the atmosphere.)
Hi Terraformer
Much too hard to make nitrogen into oxygen via alpha reactions - you're wasting a lot of energy to make oxygen when it could be done by converting some of the ice and binding the hydrogen to something else.
Hi Terraformer
I've always liked Titan, especially in its late 1970s version when people imagined that it had 0.5 bar methane and a greenhouse temperature of ~ 155 K or so. Arthur Clarke's Imperial Earth is the best fictional depiction of that Titan, but I don't know too many later depictions that get it straight - Titan is really cold. Stephen Baxter's Titan is the closest, but he needs serious updating as it's not as dreary as he imagined, nor as coated in tholins.
But his imagined terraformed Titan gets a lot of points for getting the issues right - the atmosphere is escaping, the crust is melting (being mostly water) and to have any decent "land" the place has to be cold. All the silicates, bar 4.5 billion years of meteoritic dust, is under hundreds of kilometres of ice and clathrates. Much of that is probably a high pressure version of "mud" - i.e. highly hydrated silicates, perhaps akin to concrete slurry?
Same problem applies to all the icy Galileans and the like - melt them enough to make them nice for Terran style life and the damn things are ALL ocean. So we have to be smart about what we mean by "terraforming" and flexible in how much we're willing to meet our new World halfway. After all if we have planetary scale power sources adequate for terraforming then we can heat whatever habitat volume we like.
If - and it's a big if - Europa has regions of thin ice over its ocean, then potentially the place is already suitable for some forms of advanced terrestrial life (i.e. marine animals.) According to a recent study of Europa's oxidant supplies the ocean probably contains a similar level of oxygen to Earth's oceans. The other Ocean-Moons of the Solar System probably aren't so blessed with free oxygen, but we could change that.
Perhaps, with so many potential habitats to make like Europa, we should be working on better ways of living underwater?
Hi All
To see what gravity does, according to a venerable Earth model, deep down check this one out...
http://geophysics.ou.edu/solid_earth/prem.html
...which has, interestingly, multiple high points for the gravity at certain depths. Bottom of the Upper Mantle is one peak (radius = 5701 km), and the other is at the top of the Outer Core (radius = 3480 km). Gravity peaks at 10.6823 m/s^2.
The PERM is from 1981 and a new ERM is in the works, but things haven't changed too much in a bulk sense. The PERM is pretty PERManent for an ostensibly "soon to be superseded" model. A lot of our detailed knowledge has changed and the Mantle/Core boundary is known in much greater detail, but for the purposes of our discussions I think we should refer back to the PERM when discussing Earth's insides.
A relevant paper from 2006...
Liquid Water Oceans in Ice Giants
...Ken Croswell gives a nice summary of the paper here...
...so once the Sun chills out Neptune's odds of forming an ocean will improve manifold - and after the Sun's AGB phase it'll probably have less H/He anyway. If the "Voyager" gravity data was correct - there's 19% odds that Neptune has an ocean now.
Of course it does have a rather pesky layer of H/He to dispose of presently - fusing them to carbon would give us a shell of diamond to build on. And 10 bars H/He + 0.4 bar O2 is breathable and non-flammable, plus it'd have a decent greenhouse effect.
Our current ignorance of Neptune's interior means we really don't know if it has an ocean or not, though odds are against it. Imagine the fishing if it did!
Hi All
If we gave Titan an oxygen rich atmosphere the methane would react with it - not necessarily igniting - and turn it into water and carbon dioxide. The presence of methane will become a non-issue in a few decades once oxygen is around.
Also the ignition point of methane in air is 3.6% by volume. Titan has only about 1.5% methane so its current atmosphere won't ignite even if the oxygen appeared magically in an instant. However methane is a very efficient greenhouse gas and warming the planet up will cause all its methane/ethane lakes to add to that greenhouse effect - the temperature rise would be +50 C (~140 K) with a few bars of CH4 added.
So we'd need to do something with it eventually - perhaps draining the lakes into huge gas tanks for future use.
Hi Rick
Thanks for the nice reply. What do you think of Bob Forward's idea, from one of his novels, of a nanotech mask that filters the CO2 out directly?
I do like the artificial sense, but I was thinking more of Kim Robinson's idea of bicarbonate binding like crocodiles when I made my quip about enhanced CO2 tolerance.
Hi All
What we need is wormholes of arbitary size and positioning - park one end at Titan and the other end on Mars to transport nitrogen, one on Venus and the other on Titan to dispose of the carbon dioxide and warm up Titan. Stick one in the Sun and one on Neptune/Uranus to dump the excess hydrogen/helium into the Sun. Orbit some really close to the Sun and use them as "artificial Suns" to warm up Mars-sized objects in the inner Oort Cloud thick disk.
A bit of gravitational physics, but we're a century or two from terraforming on such a large scale...
The end Permian extinction had very few large animal survivors, so perhaps it did select for some kind of protective H2S response.
There was a Japanese man who apparently lay in "suspended animation" on a hillside for 23 days, plus numerous other cases of people living in some kind of torpor awaiting rescue.
Not sure I'd want to experiment on myself with H2S without trying it out on some other mammals than mice. The little buggers can survive carbon monoxide levels that'd knock us dead.
Hi All
It's a bit of a mistake to say 35% O2 auto-ignites, as those studies used paper in over-pressurised containers. Earth in the Carboniferous had ~35% O2 and no global conflagrations are known in the fossil record.
Reality is that low pressure pure O2 can be used without those issues arising. High partial pressures enhance flammability - though still higher levels of inert components, or even fuels will eventually suppress ignition.
As for too much CO2 I reckon somatic cell gene tinkering will let us increase our tolerance levels on a reversible basis. And tricky nanotech masks might scrub the rest, if we have too much.