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Inhabitable Planets Too Close Together?

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Re: Inhabitable Planets Too Close Together?
Post by SWM   » Wed Apr 30, 2014 7:48 pm

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Weird Harold wrote:
SWM wrote:It's still the same problem. It can't sequester carbon any faster than it can generate oxygen from CO2, because it is the same process doing both.


The algae can't, but genie-coral can -- as calcium carbonate. The coral can't generate oxygen, but it can sequester carbon.

You didn't read what I said. It is still the same problem. The very same process that extracts the carbon is the process that produces the oxygen. The genie-coral can't do it fast enough to produce enough oxygen and remove enough carbon in a mere 30 years. It just doesn't work fast enough.
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Re: Inhabitable Planets Too Close Together?
Post by Relax   » Wed Apr 30, 2014 7:56 pm

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Weird Harold wrote:
SWM wrote:It's still the same problem. It can't sequester carbon any faster than it can generate oxygen from CO2, because it is the same process doing both.


The algae can't, but genie-coral can -- as calcium carbonate. The coral can't generate oxygen, but it can sequester carbon.


Basic Chemistry here.

Calcium Carbonate is CaCO3

Turning C02 to CaCO3 would STRIP the world of oxygen. All carbonates either the O3 or the O4 variety will STRIP the atmosphere of oxygen. You do NOT want to make ANY carbonate forms.

If you can come up with some kind of plant that creates calcium carbide or other carbides, then you might have a point. Minor problem: There is no known plant that creates a carbide. ;)

What you want is what currently COVERS the ocean floor today. Methane hydrates. Today, if we could use these methyle hydrates(sequestered CO2 and CH4) via the ocean itself(plankton), we would have an unlimited energy source. Well, not unlimited, but limited to the sequester rate of the ocean surface area on the planet.
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Re: Inhabitable Planets Too Close Together?
Post by namelessfly   » Wed Apr 30, 2014 8:16 pm

namelessfly

Relax wrote:



What you want is what currently COVERS the ocean floor today. Methane hydrates. Today, if we could use these methyle hydrates(sequestered CO2 and CH4) via the ocean itself(plankton), we would have an unlimited energy source. Well, not unlimited, but limited to the sequester rate of the ocean surface area on the planet.



Use solar sails to shade the planet and cill it while dumping frozen methane into the atmosphere. The CO2 and CH4 precipitate into the ocean and ate sequestered as gas hydrates.
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Re: Inhabitable Planets Too Close Together?
Post by kzt   » Wed Apr 30, 2014 8:17 pm

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Relax wrote:If you can come up with some kind of plant that creates calcium carbide or other carbides, then you might have a point. Minor problem: There is no known plant that creates a carbide. ;)

IIRC, they are pretty fiercely toxic.
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Re: Inhabitable Planets Too Close Together?
Post by SWM   » Wed Apr 30, 2014 8:56 pm

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namelessfly wrote:I agree that simply using thermalisis to separate CO2 in an atmosphere in situ is not going to work unless you have something else to bond with the free Oxygen and Carbon. Perhaps hydrogen extracted from Methane from comet could be injected to bond with the free Oxygen to form water that would precipitate out might be a solution. However; it is more plausible to just boil off a CO2 atmosphere from a planet then replace the atmosphere with the proper mix of Nitrogen and Oxygen as well as water if needed for a hydrosphere. Yes, the volumes seem daunting but given the energy budget that an interstellar colony ship should have it should not be that big of a problem. Pick a comet, grab it and bag it, then apply controlled heat to distillation separate the gases that you want, then use your colony ship's fusion rocket as a tug to boost it to the proper orbit. Alternatively; you might thermolisis to extract Oxygen from an orbiting moon to drop on planet.

We can scream about how huge the volumes and masses are but if humans have the technology to build a fusion rocket powered colony ship then this terraforming is within their energy budget. Perhaps no one has realized this because I am the first to crunch the numbers?

Think about it from a philosophical perspective. We worry about our current industrial civilization's 1eex13 Watt energy budget screwing up Earth's environment but our interstellar colony ship will have an energy budget of 1eex15 to 1eex18 Watts. Finding the energy to process and move the relevant masses would probably be less problematic than properely understanding the Macro chemistry to create a viable ecosystem.

Why do you keep harping on the energy budget? No one has suggested that energy budget is a problem!

How long do you think it would take to "boil off" the existing atmosphere? This is called Jeans Escape. Unless you raise the temperature high enough, it will take millennia. At the temperatures we will be dealing with, all the gasses will be dissociated and probably ionized. If the mean velocity of atomic oxygen is equal to escape velocity, the temperature would be around 64,000 degrees Celsius. Let's say we raise the temperature of the atmosphere to 100,000 C to get rid of it. (Note--at this temperature, a lot of heavier elements on the surface will be volatizing into the atmosphere. But presumably they will condense again once it cools off.)

The heat capacity of the atmosphere is on the order of 1 J/(g K). For simplicity, let's assume that stays true at all temperatures and pressures, even though we know it is more than an order of magnitude more at higher temperatures. The mass of Earth's atmosphere is 5e18 kilograms. So to raise the temperature of the atmosphere to 100,000 C, we need to apply 5e26 Joules. You suggest that a slowship can generate 1e18 Watts. If you had 1,000,000 slowships, it would take 100 years to raise the temperature of the atmosphere to that temperature.

Of course, it would actually take much longer, because the planet would be radiating heat at a tremendous rate. In fact, that is 20 times the surface temperature of the sun. At 100,000 C, the planet will be radiating 3e27 Watts! Even if we go with 64,000 C, it will be radiating 5e26 Watts. In 1 second, the atmosphere would radiate away its entire latent heat, unless it were refreshed constantly!

Conclusion--you can't boil the atmosphere away in less than geological time. At the temperatures that will be practical (far less than stellar temperature), Jeans Escape will give an atmospheric half-life of millennia.
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Re: Inhabitable Planets Too Close Together?
Post by Relax   » Wed Apr 30, 2014 9:00 pm

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kzt wrote:
Relax wrote:If you can come up with some kind of plant that creates calcium carbide or other carbides, then you might have a point. Minor problem: There is no known plant that creates a carbide. ;)

IIRC, they are pretty fiercely toxic.


Huh? Carbides are inert.

Now there could be a rare exception like everything else in science, but...
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Re: Inhabitable Planets Too Close Together?
Post by SWM   » Wed Apr 30, 2014 9:24 pm

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Now let's discuss getting oxygen from comets.

Taking Halley's comet as typical, we can expect over 35% by mass will be oxygen. The density of a comet is around 0.6 g/cc. We will assume, for argument's sake, that sufficient nitrogen or other innocuous gasses will be available from some source; the ratio of nitrogen to oxygen in a comet is far lower than the ratio in the Earth's atmosphere.

Namelessfly suggested using comets around 15 km in diameter. Such a comet would have a mass of 1e12 kg, of which 3.7e11 kg will be oxygen. To get sufficient oxygen for the new atmosphere, you will need more than 3,000,000 comets! [edit]Sorry, miscalculated. The comet would be 1e15 kg, and you would need 3000 comets[/edit] And, of course, you will actually have to process all those comets, because the oxygen will be in the form of H2O and CO.
Last edited by SWM on Wed Apr 30, 2014 9:43 pm, edited 1 time in total.
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Re: Inhabitable Planets Too Close Together?
Post by cralkhi   » Wed Apr 30, 2014 9:31 pm

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kzt wrote:
Tenshinai wrote:For one thing, pure oxygen is highly explosive... Low pressure mitigates, but it´s still a dangerous thing to use.

Not so much explosive as inducing everything to burn. "Fireproof" things will burn merrily in 100% oxygen.


100% oxygen at normal pressure, or 100% oxygen at spacesuit (4.something psi) or Apollo capsule (5 psi) pressures?

I mean, I agree things will be more flammable than in Earth atmosphere, but I thought they moved the Apollo capsule down from 16 psi pure oxygen to 5 psi pure oxygen because it was way less flammable? I think the partial pressure matters as well as the %.
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Re: Inhabitable Planets Too Close Together?
Post by Weird Harold   » Thu May 01, 2014 12:06 am

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SWM wrote:
Weird Harold wrote:[The coral can't generate oxygen, but it can sequester carbon.

...The genie-coral can't do it fast enough to produce enough oxygen and remove enough carbon in a mere 30 years. It just doesn't work fast enough.


1) I said genie-coral wouldn't do anything about the free O2 levels, because it cannot generate oxygen. All it can do is sequester Carbon (and calcium) by building coral reefs.

2) I explicitly said I thought it would take at least sixty and as much as one-hundred years. Thirty years isn't a realistic target.
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Re: Inhabitable Planets Too Close Together?
Post by Weird Harold   » Thu May 01, 2014 12:21 am

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Relax wrote:Basic Chemistry here.

Calcium Carbonate is CaCO3

Turning C02 to CaCO3 would STRIP the world of oxygen. All carbonates either the O3 or the O4 variety will STRIP the atmosphere of oxygen. You do NOT want to make ANY carbonate forms.


Yep. Almost any biology based system is going to use some Oxygen. The question then becomes, "are the mechanical O2 generation processes gaining or losing ground on the sequestration process(es)?"

Eventually genie-grass and genie-trees will sequester as much carbon as genie-coral as well as maintain the oxygen cycle, but I don't see land-based bio-processes entering the picture until late in the terraforming process.
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Answers! I got lots of answers!

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