Inhabitable Planets Too Close Together?

1eex24 Joules is the energy equivalent of 1eex10Kg of Deuterium undergoing fusion or about ten million tons of fuel. That seems to be rather trivial compared to the bunker age consumed by the RMN much less the MMM in a typical year.

namelessfly wrote:However; the concept of an atmospheric processing station as seen in ALIENS seems extremely plausible to me with a terraforming time measured in decades.

Quite, but a biologically based processing(using algae, fungi, protoplants or such) is potentially much easier and faster.

Based on paleontology evidence, it is estimated that biological processes required 100s of megayears to transform Earth's atmosphere. This is to be expected when photosynthesis from earth's current, very advanced plants utilize a trivial fraction of Global insolation. A network of fusion reactors comparable in power to a starship fusion rocket would have a power output exceeding global insolation. My money is on the atmospheric processor.

namelessfly wrote:Based on paleontology evidence, it is estimated that biological processes required 100s of megayears to transform Earth's atmosphere. This is to be expected when photosynthesis from earth's current, very advanced plants utilize a trivial fraction of Global insolation. A network of fusion reactors comparable in power to a starship fusion rocket would have a power output exceeding global insolation. My money is on the atmospheric processor.

A fairly large part of the time seems to have been spent filling oxygen sinks in the environment. Simply overpowering the problem to create a lot of atmospheric oxygen won't help long term - it's just going to go into those oxygen sinks and will have to be repeated. Again and again.

Tenshinai wrote:

SWM wrote:I was not using Venus as a typical example. I am curious where you have seen research suggesting that a breathable atmosphere could be produced in decades; I'd like to read that. I find it a bit hard to believe.

Just try searching for terraforming, i have absolutely no idea how much is online since i got it "through the grapevine" so to speak, but nowadays there´s no reason it shouldn´t be online(hmm, a quick look tells me there´s more likely too much online).

And i only used Venus as an example of a really really BAD planet to try to terraform.

I have searched. I don't see anything plausible that suggests terraforming can produce a human-breathable atmosphere on any planet on timescale less than hundreds of years. I found one person who suggested that Mars could be made habitable by the end of the 21st century, but he gave no procedure for doing it, and all the other references I found said it would take hundreds or more likely thousands of years. I think your grapevine was mistaken.

Most suggested procedures for terraforiming are predicated on rather minimal energy inputs at the Terrawatt level that are smaller than the energy flow from photosynthesis. If you are envisioning using the same fusion technology that would be needed for an interstellar colony ship, then your energy input can be in the multiple Exawatt range. The amount of free Oxygen that can be liberated with that much energy flow would probable exceed the reaction rate of the various reducing agents in the biosphere. Itprobablywouldnot be stable over centuries, but given enough energy you can maintain a habitable planet.

I would expect that early colonist live in polar regions until the energy nputscan be reduced.

Terraforming Mars should be no big deal. You need an atmosphere andoceanswould be nice.

Surface area is on the order of 25eex12 square meters.

Atmospheric mass is then 250eex15 Kg or 250eex12 tons or about 1eex3 Km^3 or ~12 Km diameter comet.

Assuming thatnthe Delta Vee to nudge such a comet into an impact trajectory is about 1 Km/s, then we need about one megajoule per Kg.

You need only 250eex18 Joules or 50,000 Megatons.

BFD

SWM wrote:
I have searched. I don't see anything plausible that suggests terraforming can produce a human-breathable atmosphere on any planet on timescale less than hundreds of years. I found one person who suggested that Mars could be made habitable by the end of the 21st century, but he gave no procedure for doing it, and all the other references I found said it would take hundreds or more likely thousands of years. I think your grapevine was mistaken.

Most certainly not "mistaken". They may be right or wrong when shifted to planetary scale, but it´s based on empirical testing in smallscale closed environments.

I´ll see if i can find the stuff, at least one of the papers should still be in my library. But no promises given.

namelessfly wrote:Based on paleontology evidence, it is estimated that biological processes required 100s of megayears to transform Earth's atmosphere. This is to be expected when photosynthesis from earth's current, very advanced plants utilize a trivial fraction of Global insolation. A network of fusion reactors comparable in power to a starship fusion rocket would have a power output exceeding global insolation. My money is on the atmospheric processor.

Again you mistake random events with intentional bio-engineering. The historical events included lots of processes that were pulling the wrong directions and the microbes doing most of the work were competing with others that were not doing anything "useful".

Only a tiny percentage of the total biomass was doing the "terraforming", most of which was continually counteracted by some of the rest of the biomass.

Doing it intentionally, you would seed the whole planet at once with a mix of extremely fast growing and spreading plants/algae and similar, with a very intensive lifespan, to get soil as a byproduct, with nothing counteracting it until you have reached close to the desired atmosphere.

You´re basically saying that because it takes millenia for weather to erode a mountain, then people doing it with a high pressure water slicer can´t do it in a few days.

namelessfly wrote:Most suggested procedures for terraforiming are predicated on rather minimal energy inputs at the Terrawatt level that are smaller than the energy flow from photosynthesis. If you are envisioning using the same fusion technology that would be needed for an interstellar colony ship, then your energy input can be in the multiple Exawatt range. The amount of free Oxygen that can be liberated with that much energy flow would probable exceed the reaction rate of the various reducing agents in the biosphere. Itprobablywouldnot be stable over centuries, but given enough energy you can maintain a habitable planet.

I would expect that early colonist live in polar regions until the energy nputscan be reduced.

Terraforming Mars should be no big deal. You need an atmosphere andoceanswould be nice.

Surface area is on the order of 25eex12 square meters.

Atmospheric mass is then 250eex15 Kg or 250eex12 tons or about 1eex3 Km^3 or ~12 Km diameter comet.

Assuming thatnthe Delta Vee to nudge such a comet into an impact trajectory is about 1 Km/s, then we need about one megajoule per Kg.

You need only 250eex18 Joules or 50,000 Megatons.

BFD

You have a good point that massive use of energy could be used to modify the atmosphere, instead of biological means. But the problem is not merely a limitation on energy use. There is also the sheer mass to be affected.

Suppose you have an Earth-sized planet, and want to produce an atmosphere similar to Earth's. That means you need to create 1.16e18 kilograms of free oxygen. Any oxygen you find on the planet, or on a comet for that matter, will not be free oxygen. It will be bound up as various kinds of oxides. You need to convert those oxides into free oxygen, through biological, chemical, or mechanical processes. Tenshinai thinks you can do this in a few decades. If you want to do it in 30 years, that means you need to produce 1,200,000,000 kilograms of free oxygen per second. The volume of that mass at standard atmospheric density is 1,000,000,000 cubic meters. One billion cubic meters of free oxygen gas produced every second, in addition to any other gasses your devices are passing through.

Okay,

I will bite.

You need to process 1eex9 m^3 per second.

Assumethat you have many gas processors.

Each gas processor is flying through the atmosphere at 300 m/s.

Each gas processor is somewhat over 10 meters in diameter giving a frontal area of 100 m^2

100m^2 x 300m/s = 3eex4 m/s

You need 3eex4 flying gas processors which is comparable to the number of commercial aircraft in the world.

SWM wrote:

namelessfly wrote:Most suggested procedures for terraforiming are predicated on rather minimal energy inputs at the Terrawatt level that are smaller than the energy flow from photosynthesis. If you are envisioning using the same fusion technology that would be needed for an interstellar colony ship, then your energy input can be in the multiple Exawatt range. The amount of free Oxygen that can be liberated with that much energy flow would probable exceed the reaction rate of the various reducing agents in the biosphere. Itprobablywouldnot be stable over centuries, but given enough energy you can maintain a habitable planet.

I would expect that early colonist live in polar regions until the energy nputscan be reduced.

Terraforming Mars should be no big deal. You need an atmosphere andoceanswould be nice.

Surface area is on the order of 25eex12 square meters.

Atmospheric mass is then 250eex15 Kg or 250eex12 tons or about 1eex3 Km^3 or ~12 Km diameter comet.

Assuming thatnthe Delta Vee to nudge such a comet into an impact trajectory is about 1 Km/s, then we need about one megajoule per Kg.

You need only 250eex18 Joules or 50,000 Megatons.

BFD

You have a good point that massive use of energy could be used to modify the atmosphere, instead of biological means. But the problem is not merely a limitation on energy use. There is also the sheer mass to be affected.

Suppose you have an Earth-sized planet, and want to produce an atmosphere similar to Earth's. That means you need to create 1.16e18 kilograms of free oxygen. Any oxygen you find on the planet, or on a comet for that matter, will not be free oxygen. It will be bound up as various kinds of oxides. You need to convert those oxides into free oxygen, through biological, chemical, or mechanical processes. Tenshinai thinks you can do this in a few decades. If you want to do it in 30 years, that means you need to produce 1,200,000,000 kilograms of free oxygen per second. The volume of that mass at standard atmospheric density is 1,000,000,000 cubic meters. One billion cubic meters of free oxygen gas produced every second, in addition to any other gasses your devices are passing through.