TerraForming Mars

Liquid water will exist at 273 kelvin at a pressure of 610 pascal. If the temperature is less than 273k liquid water will freeze. Mars is a lot colder than 273k and the atmospheric pressure is less than 600 pascal. How can any gas but carbon dioxide be held on Mars? Even CO2 would have a hard time staying on Mars it seems to me but I'm not really clear about how strong a gravity field is needed to hold gas at a specified temperature. And what would be temperature of the atmosphere of Mars if one could be generated?

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Hi Jim!

Thanks again for your input!

"Since the maximum surface pressure on Mars does not exceed 1200Pa, the maximum boiling point [of water] on Mars is only 283K...a surface pressure higher than 611 Pa and a surface temperature slightly above 273K would be required for pure liquid water to be stable...the applicable range is very limited.

"...water could temporarily exist even if it is not stable according to the phase diagram. For energetic reasons both evaporation and freezing of liquid water would be sluggish on Mars."

- T. Tokano (Univ. of Cologne), "Water on Mars & Life" (Springer, 2005), p. 203

I wonder if the source you quoted above is any good since it is very clear water would change to ice and/or vapor instantly on Mars or any where in the universe when the pressure got as low as 611pa. Is the surface pressure 1200pa? I was told it was less than that.

Most of the craters on Mars are older than a billion years. It might be that each of the 100 largest impact craters during the last billion years caused a wet era lasting a million years. It might be that these eras ended only because life failed to evolve. No one has proven that the recent impacts did not cause wet eras. Something caused the wet eras.

Mars hovers near the triple point of water, and near the limit of water vapor needed to form thicknesses of frost that significantly insulate against radiative heat loss at night. Its climate is teetering and can be pushed over.

A Phobos blast (see my post on metaresearch.org for more information) would produce 18 to 36 cubic km of craters total (more or less, depending on the details) on Mars. That's the volume of one crater, 6 to 8.4 km in diam. and 1 to 1.4 km. deep (typical 6:1 diam:depth ratio).

Here's a source for information about cratering rates on Mars:

www.psi.edu/projects/mgs/cratering.html

According to this, cratering rates for craters of this size are roughly the same for the "Amazonian" (i.e., relatively new) surface regions of Mars, and for the Lunar maria. The Lunar maria are estimated to be 3.4 billion yrs. old, and have about one crater per 30,000 sq. km., in this size range. Using 150,000,000 sq km as the surface area of Mars, that would be one such crater on Mars every 700,000 yrs., assuming that the cratering rate has been constant for the last 3.4 billion yrs. Really, the cratering rate has trended downward, so it's probably been longer than a million years since an impact of that size. I've seen a published estimate, that the most recent large-scale water erosion on Mars happened about a million years ago.

The subsurface blast on Phobos would produce many small fragments. Much energy from these meteors would go into exposing and thawing Martian permafrost. Mars gets about one calorie per minute per sq cm of cross section (normal incidence), from the sun. That's about 4*10^17 cal/min. The total energy of the meteors would be about 5 to 10 * 10^17 cal. So, it's about equal to 2 minutes of sunshine, and spread out over roughly an hour of time and a wide, very long arc on Mars. It won't boil or blast away the atmosphere.

This is a copy of a rebuttal I posted in an ongoing discussion on the "destinationmars" Yahoo group:

Nuclear winter (?): Mars' planet-wide dust storms don't lead to
anything resembling nuclear winter. The amount of debris excavated on
Mars would be comparable to Krakatoa, but would remain in the
atmosphere only about 1/100 as long, because the atmosphere is thinner.

Better than merely "retaining" heat: (rephrasing what I said
before) even a slight increase in the vapor pressure of water will
enable much more widespread, frost formation thicker than the critical thickness needed to block infrared radiation at night. Any increase in atmospheric pressure (e.g., the CO2 which sublimates because of the temperature rise caused by the increased frost insulation) will greatly increase the amount of liquid surface water, because in the daytime, Mars' surface conditions are, typically, near the triple point of water. Mars' climate is like an egg balanced on its end: no one knows how big a push is needed, but it will be surprisingly small. Mars has experienced wet eras in the past. What do YOU think caused the wet eras?

Optimistic (?) calculations: the calculations per se (see
metaresearch.org posts, "Joe Keller") are objective and involve
neither optimism nor pessimism. What will happen after this sudden
water vapor release, is a guess, I admit.

Practicality: this is by far the easiest and safest terraforming
option. It is the only option with any hope of success, which can be
done NOW, before our next nuclear war, or some other collapse/decay of our civilization, makes everything impossible. It could be done with one robotic mission not much larger or more complex than exploratory missions that have been successful in the past. New science & technology are not involved: no mining, factories, nanotechnology, etc. About 96% of the radiation will remain on Phobos or in interplanetary space, and almost all the radiation on Mars (many of the atomic tests on Earth released much more) will be decayed by the time humans arrive. By contrast, freon-type terraforming gases will pollute Mars with toxic fluorides.