Talk:Terraforming

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)