More on the Mars Ice Cap

bfwebster writes "In a striking example of how a preliminary (but wrong!) scientific conclusion can persist for decades, Space.com has a story about how the south polar ice cap on Mars is mostly water, not mostly carbon dioxide (dry ice), as has been stated since the late 1960s. The new finding is based on analysis of Mars Observer readings that show that the souther polar ice cap is too warm at certain seasons to be dry ice. This finding has negative implications both for those claiming that liquid flow structures on Mars were caused by C02 instead of H20, as well as those who were hoping to use all that CO2 for terraforming."

Comments

Martian Vacation

[Dukeofshadows]

Terraforming by CO2 looks like it is no longer immediately feasible. However, since most of the minerals are below the surface anyway, it should be possible to create domed structures using the terrain of mars currently in existence to build habitats. Greenhouses could easily be built on the surface to produce food or grown underground by artificial light. Extracting water from the caps could be done and piped into colonies elsewhere. We hoped it would be easy to drop algae or some other organism on mars, release the CO2, and let nature take its course to heat up the planet. Now we just have to work a little harder. I'd still like to vacation on mars before I die, regardless of whether a spacesuit would be necessary.

Re:Spectrometer?

[pdp11e]

What kind of spectrometer?

Mass?
Optical? (transmission, emission, raman, IR, UV...)
Nuclear? (alpha, beta, gamma, neutron activation, ...)

The only spectrometry possible from the orbit is a passive one. The optical spectrum of the solid chunk of (dry)ice does not contain any characteristic lines or bands. Good luck with determining the "exact chemical composition".

Now if you had a probe LANDED on a pole than you could determine composition with almost arbitrary precision.

Those guys were obviously trying to guess composition from the orbit

Terraforming is good.

[cosmosis]

Ok,

Here is why Terraforming is good. It turns an otherwise dead planet into a living one. Think beyond us mere humans, and thing of life as a whole and what it has done since its beginnings billions of years ago - life expands to fill every available niche. Life has expanded and become the massive and complex biosphere that it is today. Life has also experienced numerous near total extinction on numerous occasions. Life has now finally gained the capability of leaving its womb planet and expanding outwards to other worlds.

Of course we are talking about life expanding onto other worlds as long as there is no pre-existing life, especially complex life there already. As long as Terraforming meets those ethical requirments I have yet to hear a single reason not to terraform. After all we are only talking about the perpetuation of life itself. I almost would be bold enough to say, "that if you are against terraforming, then you are basically against life itself".

Planet P Blog

Re:Terraforming is good.

[susano_otter]

Here is why Terraforming is good. It turns an otherwise dead planet into a living one.

You're presupposing that "life" is inherently "good". Most gases expand to fill every available niche, too. So wouldn't vaporizing Mars be just as "good" as terraforming it? I mean, look beyond us mere humans. Think of all that interstellar hydrogen. Shouldn't we be devoted to making more of, rather than locking it up in our puny ecosystems, which are so limited and meaningless on a truly cosmic scale?

Seriously, though, if "life" is just the mindless expansion of a system to fill every niche, then terraforming is neither "good" nor "bad"--it just is. By your logic, the question isn't "why should we terraform Mars", the question is... well, there is no question. We will terraform Mars, because that's what "life" does. Terraforming is no more "good" than supernovas are "good", or the Second Law of Thermodynamics is "good".

I may be against terraforming not because I'm against life, but simply because I'm against this idea of life as mindless, cancerous Yog-Sothothery. If life is "good", it has to come up with a better reason for its actions than that. And if it can't, if life just is, then it needs no reasons at all, and this discussion is meaningless.

Terraforming could also use CO2 in soil...

[Stuntmonkey]

Mars also contains CO2 in its soil. This is in two forms: (1) CO2 directly adsorbed onto the (porous) rocks and dirt, and (2) CO2 in ice form mixed into the soil, possibly mixed with water ice as well.

Read here to learn more.

The extent of these soil deposits is almost completely unknown and difficult to estimate. Nevertheless, if the surface temperature were raised then some portion of this trapped CO2 would outgas. (This would be akin to obtaining liquid/vapor water by heating a section of Siberian permafrost.) Because CO2 is such a good greenhouse gas, there might therefore exist a temperature threshold beyond which the outgassing of CO2 and subsequent greenhouse heating would push the planet into a self-sustaining "hot" mode.

Or it may be the case that too much of the CO2 on Mars has either been lost to space, or is chemically locked up in carbonate rocks. This is a numerical question that won't get answered until we have the ability to bore into the surface and measure the free CO2 content.

I'm personally doubtful of these "heat it up and it will automatically fix itself" scenarios. If Mars did sustain a liquid water ocean at some point (an amazingly we still don't know the answer to that for sure), then something dramatic must have happened to make it shift into the cold, dry climate that exists today. My likeliest candidate would be the cooling and freezing of the planet's core, and the subsequent cessation of volcanic activity. Without volcanos, CO2 gets locked up in carbonate rocks and it never cycles back into gaseous CO2. The same thing could happen to the Earth someday, but fortunately the Sun will have long since gone supergiant and vaporized us in our tracks.