Update on Mars' atmosphere, Media briefing on NASA Jan 15th |
Update on Mars' atmosphere, Media briefing on NASA Jan 15th |
Jan 12 2009, 06:01 PM
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The Poet Dude Group: Moderator Posts: 5551 Joined: 15-March 04 From: Kendal, Cumbria, UK Member No.: 60 |
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Jan 16 2009, 05:36 AM
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
While there will be an awful lot of study and theorizing about the source(s) of the observed methane, and an awful lot of modeling of said sources, I think perhaps one of the things that needs to be really pinned down hard before those models gain any credibility is the volume of methane being released over time. I know they have some figures right now, but they're only showing plumes in three small-ish areas of Mars. Are those the *only* sources? Or have we not looked closely enough at the rest of the planet to find others?
Once you know how much you're releasing, you can project total release levels over much longer periods, like millions and billions of years. If it turns out, for example, that the current release rate (which is really very low on a planetary scale, I believe) would over a billion years require that a methane ocean has to have been sealed up and slowly leaked out over that period, that makes the ancient origin theory unlikely. If it would only require a few thousand tons of clathrated methane, spread out over only perhaps several thousand total cubic kilometers (a very small percentage of Mars' upper crust), then the ancient origin theory looks a lot better. If the release volume, as projected against a variety of assumption sets, seems to require constant (if very low-level) production of methane over time, then the various other theories gain more ground. (And yes, I know that release rates have probably changed over time. You can plug such changes into the release-over-time models, if you wish, as long as your changes are in some way supported by actual data.) One thing that was just mentioned at the press conference (I recorded it on my DVR and am watching it now) is the possibility that there might be a layer of permafrost under the entire Martian crust, even the equatorial plains. Do we have any real evidence of this from either of the radar experiments? Or is this simply another model they're tossing around? More and more, I want to get heat flow data from Mars. An awful lot of what's actually happening under the first few km of Mars' crust depends on the temperature regimes of its crust, mantle and core. We have very little idea of how much remanent heat may yet be contained within the planet, how heterogenous (or not) its distribution might be, and very specifically at what locations and depths water (and other things, like methane) might exist as solids, liquids and even gasses. -the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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