Inhabitable Planets Too Close Together?

I've read about an experiment with making oxygen from oxide rocks by heating them up enough for the oxygen to be broken loose ("vacuum pyrolysis"). Temperatures seem to be 2000+ K.

http://science.nasa.gov/science-news/sc ... moonrocks/

http://www.uapress.arizona.edu/onlinebk ... rces08.pdf

I wonder what would happen if you did this on a REALLY large scale (eg giant solar mirrors/sails concentrating light to get a continent-sized area of crust hot enough to pyrolyze it).

You might actually be able to give the Moon a breathable atmosphere this way given sufficient (enormous) amounts of solar mirrors ... not the nitrogen though, it'd have to be like the pure oxygen low pressure atmosphere inside spacesuits.

So, we are trying to use solar sails to heat up enough CO2 to produce a breathable oxygen atmosphere.

We have determined that we need to produce 1,200,000,000 kg of oxygen per second for our atmosphere. That is 37,500,000,000 moles per second of O2. According to the research Namelessfly has pointed out, we need 2 moles of CO2 for every mole of O2 produced. So we need to convert 75,000,000,000 moles of CO2 per second. The tables show that the optimal conversion temperature is 3500 C, and the lower the pressure the better. To dissociate 95% of the CO2, we need a pressure of 0.001 atmosphere. If you use a higher pressure, you will have too much leftover CO2 for a breathable atmosphere. Since we are not converting all of the CO2, we actually need to process 79,000,000,000 moles of CO2 per second to get the right amount of oxygen production.

79,000,000,000 moles of CO2 at 3500 C and a pressure of 0.001 atmosphere has a volume of 25,000,000,000,000 cubic meters. For handwaving purposes, if you have one million processors, each processor needs a vacuum chamber 180 meters in radius, which can heat up the low-pressure gas to 3500 C in one second, then load the next batch.

The heat capacity of CO2 in this temperature range is over 50 J/(mol K). So you need more than 1.4e16 Watts, running for 30 years, to process the atmosphere. Not impossible, but more than Namelessfly thought.

This process produces 2 moles of carbon monoxide for every mole of oxygen that is produced. You will somehow have to get rid of the carbon monoxide. Namelessfly’s proposal to simply heat the atmosphere and use differential escape of lighter molecules will not work. Carbon monoxide is too close to the weight of molecular oxygen. If you heat it enough to get rid of the carbon monoxide, you will also get rid of too much oxygen. Also, it will take too long. The plan was to have a breathable atmosphere in less than 30 years.

You will also have a problem as you cool the oxygen atmosphere back down. That hot oxygen will rapidly oxidize anything which can be oxidized. Between that and the loss of oxygen escaping the atmosphere entirely, you will have to produce a whole lot more oxygen to end up with the breathable atmosphere that you want.

If you are going to build a million processors, that will take time. The construction time will have to be taken off the 30 year time-frame, so you will have less time for processing, which means the processing rate will have to be even higher, with larger converters and larger power input. Add in the carbon monoxide elimination process. Add in the cooling process. Namelessfly, I’m afraid you have still not convinced me that this is practical in a thirty year timeframe.

All very relevant criticisms except you persist in presuming that some type of "physical processor" will be employed. I am assuming that you process the atmosphere in situ, perhaps by injecting dust at high altitude to act as a light absorber.

This all presumes a rather radical terraforming of a non terrestrial planet with a CO2 atmosphere into an Earth likeworldwith an Oxygen atmosphere. A far more likely scenario is that you will find a planet that is nearly terrestrial but needs modification involving perhaps 1/10 the energy budget and volume.

The possibility of exploiting synergistic effects of biological and industrial processes should not be ignored. Seed the oceans with algea then use orbiting lightsails to increase ambient light (burn through clouds?) and OTEC systems to enhance nutrients.

SWM wrote:So, we are trying to use solar sails to heat up enough CO2 to produce a breathable oxygen atmosphere.

We have determined that we need to produce 1,200,000,000 kg of oxygen per second for our atmosphere. That is 37,500,000,000 moles per second of O2. According to the research Namelessfly has pointed out, we need 2 moles of CO2 for every mole of O2 produced. So we need to convert 75,000,000,000 moles of CO2 per second. The tables show that the optimal conversion temperature is 3500 C, and the lower the pressure the better. To dissociate 95% of the CO2, we need a pressure of 0.001 atmosphere. If you use a higher pressure, you will have too much leftover CO2 for a breathable atmosphere. Since we are not converting all of the CO2, we actually need to process 79,000,000,000 moles of CO2 per second to get the right amount of oxygen production.

79,000,000,000 moles of CO2 at 3500 C and a pressure of 0.001 atmosphere has a volume of 25,000,000,000,000 cubic meters. For handwaving purposes, if you have one million processors, each processor needs a vacuum chamber 180 meters in radius, which can heat up the low-pressure gas to 3500 C in one second, then load the next batch.

The heat capacity of CO2 in this temperature range is over 50 J/(mol K). So you need more than 1.4e16 Watts, running for 30 years, to process the atmosphere. Not impossible, but more than Namelessfly thought.

This process produces 2 moles of carbon monoxide for every mole of oxygen that is produced. You will somehow have to get rid of the carbon monoxide. Namelessfly’s proposal to simply heat the atmosphere and use differential escape of lighter molecules will not work. Carbon monoxide is too close to the weight of molecular oxygen. If you heat it enough to get rid of the carbon monoxide, you will also get rid of too much oxygen. Also, it will take too long. The plan was to have a breathable atmosphere in less than 30 years.

You will also have a problem as you cool the oxygen atmosphere back down. That hot oxygen will rapidly oxidize anything which can be oxidized. Between that and the loss of oxygen escaping the atmosphere entirely, you will have to produce a whole lot more oxygen to end up with the breathable atmosphere that you want.

If you are going to build a million processors, that will take time. The construction time will have to be taken off the 30 year time-frame, so you will have less time for processing, which means the processing rate will have to be even higher, with larger converters and larger power input. Add in the carbon monoxide elimination process. Add in the cooling process. Namelessfly, I’m afraid you have still not convinced me that this is practical in a thirty year timeframe.

namelessfly wrote:All very relevant criticisms except you persist in presuming that some type of "physical processor" will be employed. I am assuming that you process the atmosphere in situ, perhaps by injecting dust at high altitude to act as a light absorber.

This all presumes a rather radical terraforming of a non terrestrial planet with a CO2 atmosphere into an Earth likeworldwith an Oxygen atmosphere. A far more likely scenario is that you will find a planet that is nearly terrestrial but needs modification involving perhaps 1/10 the energy budget and volume.

The possibility of exploiting synergistic effects of biological and industrial processes should not be ignored. Seed the oceans with algea then use orbiting lightsails to increase ambient light (burn through clouds?) and OTEC systems to enhance nutrients.

Simply heating up the entire atmosphere will not produce a breathable atmosphere. Check those articles again.

The dissociation process is a simple chemical equilibrium. At standard atmospheric temperature and pressure, the equilibrium is almost entirely CO2. Raising it to the optimal temperature of 3500 C and keeping standard pressure, you can dissociate 46% of the CO2. If the pressure is higher than that, you dissociate less. To dissociate a high percentage of the CO2, you have to have very low pressure. That's why I was using 0.001 atmosphere pressure. You should re-read the articles you pointed out.

You must process the atmosphere at low pressure, and remove the carbon monoxide before raising the pressure or lowering the temperature. If you raise the pressur or lower the temperature before removing the carbon monoxide, the equilibrium will shift back again. The carbon monoxide will combine with oxygen to reform CO2.

[edit]If you don't use low pressure converters, and try to do the entire atmosphere at the same time, you only convert 46% of the CO2. So you have to get rid of both the excess CO2 and the carbon monoxide before lowering the temperature. And you will still have the problem that, as the temperature drops, the oxygen will try to oxidize everything exposed on the surface of the planet.

As for finding a nearly terrestrial planet that requires little terraforming, my entire point is that the planet will not have enough free oxygen and low concentrations of CO2 and CO unless there is already life on the planet. It's all about chemical equilibrium. Oxygen is extremely reactive. It will naturally combine with almost any element. Life is one of the few natural processes that will produce an excess of free oxygen. Without life, an oxygen atmosphere is extremely unstable, and the oxygen will combine with other materials on timescales quite short on the geological scale.

In order to produce a breathable atmosphere on a planet without life, you have to produce essentially all of the molecular oxygen, one way or another. Absolutely huge quantities of it.

crewdude48 wrote:And if they were von Neumann type machines, they could leave only one or two on each planet, and still have it much more livable than before the next wave arrived.

I immediately thought of the Frankenstein scenario von Neuman machines always seem to be the source of: Imagine a planet like Grayson with a high percentage of radioactives and a couple of centuries for your machines to evolve.

Finding your new home grabbed by FTL claim jumpers would be bad enough, falling into the clutches of intelligent machines might well be worse. <shudder>

Most of the discussion seems to center on the breakdown of CO2 to C2 and O2. The point nobody seems to account for in the mechanical processes is "carbon sequestration" -- unless the carbon is locked away in some manner it's just going to recombine with O2 (aka burn) and turn all of your energy inputs into heat.

It seems to me that electrolysis or some other method to break water into H2 and O2 would work better for O2 production -- especially if the hydrogen is used as fusion fuel to power the separation process to keep it from recombining with the O2. Helium would serve as well (or better in some cases) as Nitrogen -- both being Noble Gases that don't react with O2 to dilute it to breathable levels.

If a planet doesn't have enough water, bring in a few comets.

Algae -- especially a gene-engineered variety for maximum carbon sequestration -- would seem the simplest and most cost efficient way of dealing with any CO2. Genie-Corals would work, too.

I don't think I would expect a 30 year turn around, but 60-100 years should be in reach by late Diaspora tech. Until then, Domes and space habitats are going to have to be the norm -- or just leave the majority of colonists asleep for another century or so.

All VERY, VERY good points. The key concept here is that an Oxygen atmosphere is unstable on a geological time scale, but not on a human time scale.

While the chemical equilibrium considerations that you focus on are valid, the temporary effectiveness of brute force thermal dissociation suggests possibilities. When combined with other chemical steps such as injecting Ammonia extracted from cometary ices we might be able exploit the properties of free oxygen to transform at atmosphere in place. Alternatively; we can use solar reflectors to simply cook off a problematic atmosphere then chemically process cometary ices in orbit to get the right combination of nitrogen, Oxygen and CO2. Such an atmosphere will be unstable over geological time until beget the planet seeded with life, but we are talking geological time.

SWM wrote:As for finding a nearly terrestrial planet that requires little terraforming, my entire point is that the planet will not have enough free oxygen and low concentrations of CO2 and CO unless there is already life on the planet. It's all about chemical equilibrium. Oxygen is extremely reactive. It will naturally combine with almost any element. Life is one of the few natural processes that will produce an excess of free oxygen. Without life, an oxygen atmosphere is extremely unstable, and the oxygen will combine with other materials on timescales quite short on the geological scale.

In order to produce a breathable atmosphere on a planet without life, you have to produce essentially all of the molecular oxygen, one way or another. Absolutely huge quantities of it.

Use solar collectors to thermal dissociate atmospheric CO2 while simultaneously using solar collectors to process cometary ices to extract free hydrogen and Oxygen. Dump the hydrogen into the atmosphere to combine with freeOxygen and CO to form water and methane, then cook off the methane.

Weird Harold wrote:

crewdude48 wrote:And if they were von Neumann type machines, they could leave only one or two on each planet, and still have it much more livable than before the next wave arrived.

I immediately thought of the Frankenstein scenario von Neuman machines always seem to be the source of: Imagine a planet like Grayson with a high percentage of radioactives and a couple of centuries for your machines to evolve.

Finding your new home grabbed by FTL claim jumpers would be bad enough, falling into the clutches of intelligent machines might well be worse. <shudder>

Most of the discussion seems to center on the breakdown of CO2 to C2 and O2. The point nobody seems to account for in the mechanical processes is "carbon sequestration" -- unless the carbon is locked away in some manner it's just going to recombine with O2 (aka burn) and turn all of your energy inputs into heat.

It seems to me that electrolysis or some other method to break water into H2 and O2 would work better for O2 production -- especially if the hydrogen is used as fusion fuel to power the separation process to keep it from recombining with the O2. Helium would serve as well (or better in some cases) as Nitrogen -- both being Noble Gases that don't react with O2 to dilute it to breathable levels.

If a planet doesn't have enough water, bring in a few comets.

Algae -- especially a gene-engineered variety for maximum carbon sequestration -- would seem the simplest and most cost efficient way of dealing with any CO2. Genie-Corals would work, too.

I don't think I would expect a 30 year turn around, but 60-100 years should be in reach by late Diaspora tech. Until then, Domes and space habitats are going to have to be the norm -- or just leave the majority of colonists asleep for another century or so.

Weird Harold wrote:Most of the discussion seems to center on the breakdown of CO2 to C2 and O2. The point nobody seems to account for in the mechanical processes is "carbon sequestration" -- unless the carbon is locked away in some manner it's just going to recombine with O2 (aka burn) and turn all of your energy inputs into heat.

Actually, I've brought that up several times, but it has mostly been ignored.

It seems to me that electrolysis or some other method to break water into H2 and O2 would work better for O2 production -- especially if the hydrogen is used as fusion fuel to power the separation process to keep it from recombining with the O2. Helium would serve as well (or better in some cases) as Nitrogen -- both being Noble Gases that don't react with O2 to dilute it to breathable levels.

If a planet doesn't have enough water, bring in a few comets.

Sure. Or it could be done by grinding up the surface oxides on a planet like Mars and extracting the oxygen. It all boils down to the same problem, though. You have to produce on the order of 1e18 kilograms of oxygen for the atmosphere, either biologically, chemically, or mechanically.

Algae -- especially a gene-engineered variety for maximum carbon sequestration -- would seem the simplest and most cost efficient way of dealing with any CO2. Genie-Corals would work, too.

I don't think I would expect a 30 year turn around, but 60-100 years should be in reach by late Diaspora tech. Until then, Domes and space habitats are going to have to be the norm -- or just leave the majority of colonists asleep for another century or so.

There have been plenty of studies on using algae for this. Even with extreme genetic modification, it would take many centuries or even millennia to create a breathable atmosphere. Algae simply don't work fast enough.

namelessfly wrote:All VERY, VERY good points. The key concept here is that an Oxygen atmosphere is unstable on a geological time scale, but not on a human time scale.

While the chemical equilibrium considerations that you focus on are valid, the temporary effectiveness of brute force thermal dissociation suggests possibilities. When combined with other chemical steps such as injecting Ammonia extracted from cometary ices we might be able exploit the properties of free oxygen to transform at atmosphere in place. Alternatively; we can use solar reflectors to simply cook off a problematic atmosphere then chemically process cometary ices in orbit to get the right combination of nitrogen, Oxygen and CO2. Such an atmosphere will be unstable over geological time until beget the planet seeded with life, but we are talking geological time.

I certainly agree that this is all possible. And that is certainly a fine way to do it. The only point that I disagree on is that it could possibly be done in just a couple decades, which is what Tenshinai had claimed way back when started on this. That simply is not possible.