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I kind of figured you'd show up for this discussion. Since I'm at home now, I'll counter a few of your theories with quotes from my favorite exobiology textbook, "The Search For Life in the Universe," by Drs. David Goldsmith and Tobias Owen (professors of astronomy at Berkley and Hawaii respectively).
"I personally think an earthlike planet would be TOTALLY covered in ice."
According to G&O, Turtledove is much closer to right:
"Despite the fact that C02 forms 95% of the present Martian atmosphere, most of the carbon dioxide near the planet's surface seems to be locked up in the polar caps and in carbonate rocks. We can calculate that if all the Co2 that now seems to be missing were present in gaseous form, then the atmospheric pressure could rise to a value similar to that prsently encountered at earth's surface. With a surface pressure of 1000 mb, liquid water could easily exist, and this atmosphere would have been able to keep the planet warm enough to maintain a fully developed rain-river-pond-rain cycle... Mars went through an early period that included a C02 rich atmosphere with a surface pressure about equal to the present sea-level pressure on earth. Such an atmosphere could produce a greenhouse effect that would be sufficient to warm a large fraction of the planet above the freezing point of water."
Beginning of your second paragraph: "It seems that you are overlooking the fact that it would take a lot more than increased pressure to make Mars livable, and it's hard to think of a way of increasing the pressure anyway."
Your second paragraph is kind of messy. Let's imagine for a second that it is easily possible to increase the air pressure of Mars (which I never said that it was, but you seem to think I did). You don't seem to realize, as the above quote states, that increasing the pressure to a sufficient point alone fixes every other problem Mars has. Oh, Mars has water-- almost as much as the earth. It's just all frozen in the polar caps and beneath the surface as permafrost. Once the pressure increases to significantly beyond the triple point, liquid water can exist, and because of the greenhouse effect, the temperature will also rise to the point that liquid water can exist. This would also give you the oceans to help counter the reducing atmosphere. As for your desire for a "neutral gas" and question about whether Mars has any nitrogen, I again quote from the book:
"The nitrogen that now forms 78% of our atmosphere came from outgassing, but the existence of life on Earth helps to explain the persistence of nitrogen in the atmosphere. Nitrogen readily combines with oxygen to form nitric oxides which wash away into the soil and oceans. If the earth lacked life, only the slow weathering of the rocks would return this nitrogen to the atmosphere. In fact, 'denitrifying bacteria' (those that break apart nitric oxides) live in the soil in HUGE numbers and play an important role in recycling the nitrogen back into the atmosphere."
Mars has plenty of nitrogen-- it's just all in nitric oxide compounds that need to be broken apart by those bacteria.
And another quote from them that kind of sums it up: "Life on earth has provided almost all of the oxygen in our atmosphere. It has helped to remove the carbon dioxide while retaining most of the nitrogen."
I tend to agree that in general, terraforming Mars is not practical and worth the time and energy-- I was just speaking hypothetically. However, if it was possible, G&O seem to be of the opinion that Mars would be able to hold onto its new, heavier atmosphere: "But would the thicker atmosphere have managed to maintain itself over billions of years? This would depend on how large a greeenhouse effect Mars would have established to counteract the lower temperatures that arise at its distance from the sun... the activity of water on Mars proved self-limiting, for the atmosphere eventually became too thin for liquid water to exist precisely because liquid water HAD existed. Without extensive tectonic activity, there was no means to feed the carbon dioxide back into the Martian atmosphere once it was locked up in the limestone." Basically they're saying, absent tectonic activity, Mars would require LIFE to keep a thick atmosphere going.
One final quote related to this subject: "From Mars we learn the importance of having sufficient mass to produce and sustain a thick atmosphere."
My personal belief is that, if we ever HAD to leave the earth, people would prefer Mars or even the moon to space, because that just seems too weird to the average person to not have true soil.
In reality, you're probably right about people living on Mars the way they currently live in Anarctica. Like I said, any habitation on Mars will mostly be for "funsies"-- or just because "its there." Here's an interesting quote from G&O on supposed "Mars scouts":
"Consider the challenge of boiling an egg. Hardy scouts on Mars couldn't build a fire due to the lack of oxygen. If they brought an electric stove and chipped ice from the polar caps, they still couldn't produce water-- it would simply sublime to vapor. Most pressure cookers would simply double the pressure, which would cause water to boil at 5 degrees Celsius! To keep water liquid at, say, 60 degrees C, the scouts would need a pressure cooker that raised the pressure 100 times above Mars' atmosphere."
Living on Mars would require too much energy for anything other than research-- all of the greenhouses and living habitats would have to be pressurized by about 100 times according to these guys-- God knows how much energy that will take. And basically it'd all have to be solar (highly inefficient) or nuclear ( A] do you want to take a nuclear reactor with you on a space ship? B] do you think you can actually build one on Mars with local materials?) The moon, of course, is much worse-- no atmosphere at all (requiring complete pressurization), no organic friendly soil (nothing wrong with Mars' soil-- would probably need a little fertilizer), no weather or seasons, no regular day and night (Mars has seasons, about twice as long as earth's, and a day just slightly over 24 hours). The only advantage the Moon has is that it's close; in fact, you might as well just live in space if you're going to live on moon since you'd have to bring everything with you anyway.
Plus there's no way in hell the moon can be terraformed. There's at least hope with Mars, although not much. Something else I left out about Mars' inhospitability: NO OZONE, meaning even if it had a high pressure oxygen rich atmosphere, ultraviolet radiation would kill all life-- at least until a sufficient amount of oxygen was converted into ozone. The only reasonable way to terraform Mars would be to heat up all of the water ice somehow and cause it to sublime into the atmosphere-- which will make the atmospheric pressure strong enough for some of the vapor to become water, at least temporarily. Whether it'd be strong enough to create a significant greenhouse effect is another story. The other part of the equation is to somehow breakup all of the carbonates and release the CO2 into the air. Needless to say neither idea is very practical with today's technology... although I do have an idea that I incorporated into my screenplay, but obviously I won't be going into that! But even that idea is somewhat outlandish.
I'm not sure what I was going to say about calcium carbonates, Drew. Any questions, anybody? On earth the calcium carbonates are mostly found in limestone, if you wondered where that much C02 is.
By the way, speaking of nitrogen earlier, Titan's mostly nitrogen atmosphere was created by outgassing as well. Apparently it doesn't have a mostly CO2 atmosphere (like the 3 inner planets did in the beginning) because its too cold. As far as ethane or methane seas and snow... who knows? All we know is Titan is close to the triple point of those compounds. The name of that probe, by the way, is Cassini-Huygens, and should be there in a couple of years. Unfortunately it doesn't have a regular light camera, just infrared, radar and spectrometers.
Triton's nitrogen/methane atmosphere is 1/16millionth of the earth's. Enough said. It does have geysers-- what it shoots out is beyond us, but this means that like Io and Titan, Triton is geologically active, apparently more so than Mars. Triton holds the significance of being the single coldest major land mass in the solar system-- about 37 degrees C above absolute zero.
The Creep, The Freak & The Loser
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