How much must be added to the atmosphere for terraforming?
We can figure out the mass of the atmosphere on Earth and from that estimate what is lacking on Mars. Atmospheric pressure results from the weight of the atmosphere between the planetary surface and outer space. Over every square inch of Earth's surface at sea level there is a one square inch column of air reaching to outer space that weighs 14.7 pounds. 99.9% of the atmosphere is below the altitude of 34 miles. At that height there are only about 0.9% more square inches than there are at the surface. So we can estimate the mass of Earth's atmosphere as 14.7 pounds times the number of square inches of Earth's surface. That overestimates the mass by neglecting the fact that there is no air in the space taken up by mountains. That overestimation is the figure we want for estimating the mass of gas needed to be added to Mars' atmosphere. The radius of Earth is 3.96 E 3 (3960) miles. So the area equals 1.969 E 8 (19690000) square miles or 7.906 E 17 square inches. So the atmosphere of Earth weighs 1.16 E 19 pounds or 5.28 E 18 kilograms. To get the amount of gas needed to have an atmospheric pressure on Mars equal to Earth sea-level pressure we multiply by the ratio of Mars' area to Earth's area by the ratio of Mars' gravity to Earth's gravity. This underestimates the mass because Mars' atmosphere extends to heights at which the gravity is less than the surface gravity and overestimates the mass because it neglects the lessening of the scale height on Mars by the higher average molecular weight of the gas we will use (carbon dioxide, sulfur hexafluoride and 1,1,1-trichloroethane). We assume that the combined effect of these factors is insignificant. So the mass of atmosphere needed on Mars is 3.89 E 15 metric tons. If we raise the pressure to only one tenth of Earth's sea-level pressure and only one tenth of the atmosphere is to be added manufactured gasses, then these gasses would mass 3.89 E 13 metric tons. Spreading the manufacture of the gas over 1000 years we get 3.80 E 10 metric tons per year or 4.44 E 6 tons per hour. The Edmund Fitzgerald carried 26,000 tons. So, what would be needed would be 170 Edmund Fitzgerald cargo mass equivalents per hour for a thousand years. --Farred 05:57, 8 September 2010 (UTC)
- Doctor Robert Zubrin and Doctor Christopher McKay came up with a somewhat different figure for the amount of artificial greenhouse gases needed to be manufactured to raise the atmospheric pressure of Mars. They published Technological Requirements for Terraforming Mars For a 10 degree centigrade rise in temperature they suggest that 878 tons per hour of greenhouse gasses over a period of 20 years would be sufficient. This in turn should trigger a run-away greenhouse effect until all carbon dioxide available to be released into Mars' atmosphere is released. They suggest that for a 500 millibar reservoir of carbon dioxide in the polar caps and the soil of Mars and a characteristic energy of releasing carbon dioxide from the soil of 20 K, the atmospheric pressure should stabilize at 400 millibar and the temperature at 1 C. There are problems with that. First, there is the unknown characteristic energy of releasing carbon dioxide from the soil and the unknown amount of carbon dioxide in the planetary reservoir waiting to be released. Zubrin & McKay suggest that manned exploration will provide the answers. Second, the equilibrium temperature they indicate allows some lakes to form in the equatorial region. Water and a thick carbon dioxide atmosphere on Mars means carbonate rocks will form, which will take the carbon dioxide out of the atmosphere again until the greenhouse effect is no longer sufficient to sustain the liquid water. Then Mars will freeze over again, like it did the last time this happened, billions of years ago.
- Why do Zubrin and McKay get their futile terraforming for so much less manufactured greenhouse gasses than I indicated? I picked 10 millibars out of a hat as the partial pressure of greenhouse gasses that would be sustained and they used 4 hundred-thousandths of a millibar as the needed partial pressure of greenhouse gas to raise the temperature on Mars 10 K. Zubrin & McKay's figure may be more reasonable, but there is still plenty worth discussing on this topic. --Farred 22:53, 21 September 2010 (UTC)
- I, too, find it futile. Terraforming consumes so much effort, it is surely better invested in a comfortable colony. Human pioneer spirit will find a way to live and thrive even under original Martian conditions. However, I agree, it is an interesting topic all right. Farred, why don't you polish your calculations a little bit and put it directly on the article's page? Very good investigative work!-- Rfc 20:33, 27 September 2010 (UTC)
- Thank you, Rfc, for the encouragement. I will look into moving information from the talk page into the article. I will try to do it right. --Farred 00:34, 13 October 2010 (UTC)
Of course something will be futile, if people see only problems and deny the possibility of solutions.
Obviously you don't want something as stupid as flying Edmund Fitzgeralds to Mars. You want to rely primarily on local resources, and only import volatiles if needed- which would be quite difficult, even with advanced technology.
It isn't impossible to change things on a planetary scale. We're doing it right now, and we've been changing the landscape of the Earth for thousands of years already. Of course, this is different from creating a whole new planetary biosphere, but it shows that humans are by far, not insignificant. Life has the power to change an environment- in fact, the whole reason we exist, the reason why the ecological diversity and habitable environment of Earth exists- is because of the waste products of single-celled organisms billions of years ago. Their evolution was so instrumental in the history of life- their force so significant, that they overturned the chemistry of the atmosphere and lead to a huge extinction of life, and led the way for the environment we see today.
The key to terraforming Mars is to do the most with the least. For example, by manufacturing highly efficient greenhouse gases from local resources, tipping the balance and outgassing more CO2.
I seriously doubt that minor fluvial activity will completely sequester a 400-500 millibar CO2 atmosphere into carbonates over human timescales. Indeed if this can occur at such a rapid rate, Earth's active hydrosphere should have sequestered CO2 at a much faster rate than it has in reality, or it should have least offset anthropogenic CO2 increase.
If you want a vaguely Earth-like environment, you won't want 400 millibars of CO2 anyway. You'll need to replace that with oxygen (so animals and higher plants can breathe) and add nitrogen (so things don't spontaneously combust, and so some organisms have an atmospheric source of N2). Those two things are pretty much the hardest part of Martian terraforming- you'll need to seperate the oxygen from the carbon and... store the carbon away somewhere, while putting enough nitrogen into the atmosphere (nitrogen is unfortunately pretty sparse on Mars, but there are indications of nitrates in regolith, and concentrations which might increase as you dig down from the surface, though presumably it isn't the easiest thing to liberate this from the regolith).
What most people forget is that terraforming is an ongoing process- you may have a habitable planet, but you need to maintain it. On Earth, we're lucky enough that the natural setup happens to do this automatically, but on Mars, the global environment would need more attention- obviously things would be set up to be as self sustaining as possible, but this can't be done for everything.
"The money would be better off spent on a colony" makes absolutely no sense. For one, terraforming is many orders of magnitude more demanding than a colony, and offers orders of magnitude more returns. Yes, terraforming is very difficult, and it's a gargantuan task, but a properly terraformed Mars could support billions of people. A large colony could support maybe a million people, and by then, it would be the size of a city- a very large colony indeed.
People on Mars would by far have it harder in the default, harsh environment, than they would on a planet where they would not freeze and asphyxiate upon exiting a habitat. Even a Mars with a thicker CO2 atmosphere would be more hospitable to human operations. T.Neo 15:46, 12 April 2011 (UTC)
- T.Neo wrote that "you don't want something as stupid as flying Edmund Fitzgeralds to Mars." I agree. I never suggested doing such a thing. The "170 Edmund Fitzgerald cargo mass equivalents" I referred to above were just a way to present the suggested amount of greenhouse gas in a way that might be familiar to some readers. Of course it would need to be manufactured on Mars. That is a difficulty that requires a self reproducing industrial economy on Mars like the one we had on Earth from 1850 to 1912. That self reproducing economy included the people who were workers supporting it. The needed economy on Mars could not be based on burning coal like the Earthly example but would be similar in the characteristic of self reproduction. From the industrial equipment that can be sent to Mars from Earth, it would require quite a few doubling times before the "878 tons per hour" that McKay calls for would be available. To go from 100 settlers to 200,000,000 settlers would require about 21 doublings. Maybe that is required before the intended release of greenhouse gasses is practical. If the doubling time is 25 years, that is 525 years. There will be a long time of living in underground shelters with a near vacuum outside before terraforming begins. I had a reference for the formation of carbonate rocks from the CO2 in lake water dissolving minerals from the lake bottom and depositing carbonates, but I lost that issue of Scientific American. I might find it again or a better reference. Anyway it was suggested that sulfur dioxide in the lake water would reduce the amount of dissolved carbon dioxide. That might take care of the problem. I do not accept the statement that since depositing CO2 as carbonates in Earth's seas took on the order of a hundred million years a similar process on Mars would take as long. Reaction rates are proportional to a function of concentrations. McKay suggested 400 millibar of CO2 on Mars as opposed to 0.38 millibar on Earth, a thousand times higher concentration on Mars than on Earth. The reaction taking out the CO2 ought to go much faster on Mars. This is something I can look up, but I do not know if I will ever get it done well enough to add to the article. The important point is that the thousand times higher concentration of carbon dioxide is what is needed for terraforming on Mars and that is just the thing that greatly increases the removal of carbon dioxide.
- T.Neo also wrote about "the waste products of single-celled organisms billions of years ago" changing the environment on Earth. On Mars the changes required to have liquid water would have to come first, then single-celled organisms might have their chance to do something.
- T.Neo also wrote that the 400 millibar CO2 should be replaced with oxygen and nitrogen. A problem with that is that once the 400 millibar CO2 is gone Mars freezes again unless T.Neo is thinking of a different way of warming the planet. Then the 400 millibar carbon dioxide would never have been needed in the first place.
- If instead of terraforming Mars settlers strip mine it and send the material into space to make habitats, trillions of people could be supported from the stuff of Mars. So if supporting more people is T.Neo's concern, strip mining Mars down to the core should be the favored process. As far as economic mass shipment to orbit, this is one of many technologies that might solve the problem. - Farred 03:04, 2 January 2013 (UTC)
==Bioforming==(think this is the correct term)
perhaps a compromise solution would be to make humans a bit more tolerant to co2 and low pressures not feasible for short term missions but might be interesting for medium to long term stays. - The above comment was added by internet protocol address 184.108.40.206 on the 3rd of January at 19:00 hours UTC.
The ordinary concentration of CO2 is currently about 0.38 millibar. The suggestion above to make people more tolerant of CO2 would require tolerance of 400 millibar of CO2 to be beneficial. At 10 millibar people begin to feel drowsiness. At 100 millibar CO2 people suffer dizziness, headache, unconsciousness and eventually death. Biologically altering people to tolerate 400 millibar of CO2 would be quite a bit of a change. Surgery to correct for nearsightedness is something I would consider within the range of potentially acceptable. Biologically altering people to tolerate CO2 I would not consider. Wearing a suit or just a face mask connected to a CO2 scrubbing system could protect from CO2. It would be considerably less trouble and expense than a space suit such as required for the current atmosphere of Mars. However, such a condition on Mars would be noticeably inferior to Earth. - Farred 19:05, 8 January 2013 (UTC)