..could this have kept the planet warm, with a denser atmosphere?

Plate tectonics could have recycled volatile components like CO2 and H2O into the atmosphere.

I haven't seen this topic discussed very much.

(in case anyone was wondering, I don't have any photoshop pix to share)

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Olsen the moderator.

Is this a stupid question?

It got 60+ reads and no replies.

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Olsen the moderator.

It may be more that no one feels qualified to give an answer. If I have the chance, I'll check some of my references and get back to you.

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I guess you're kind of asking what would Mars be like if it was a different planet. This is a tricky question to answer. Without a different composition the planet was really almost going to behave as we see it. Things on the planetary scale don't leave too much to chance.

Certainly, it would have helped. Mars obviously has had too few processes that conserve heat. But it may have still been prolonging the inevitable. Mars to me seems too much of a lightweight to truly hang on to any promise...

There are a number of processes other than plate tectonics that can cycle volatiles between the lithosphere and the atmosphere. Resurfacing through meteorite impact (as may have been the case on the early Earth) or volcanism (as on Venus and Io), and vertical density-driven tectonics (silicate versions of what may happen on some of the ice moons) are possibilities.

I suspect though the main reason why Mars has lost much of its volatiles is partly because its lower gravity and nonexistant magnetic field. the first is not able to hold gases as efficiently and the second means that the solar wind is able to erode the amosphere.

Jon

I suppose I am asking what Mars would be like if..., but this is out of my field of expertise.

Where better to ask this question than here?

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Olsen the moderator.

Plate tectonics are a by-product of having a hot magma core. The flowing magma causes the plates to shift and move, like a cracked crust of ice on a lake.

Once that core cools down, though, the flows stop supplying new rock on once side of the plate or melting rock as it's pushed under another plate on the opposite side. The motions slow, the core keeps cooling, and eventually all the plates lock in place.

One of the theories is that this is exactly what happened, which led to a massive shift in Mars' environment. Giving us the planet we have today.

I have a stupid theory about this. If Mars had plate tectonics it shuld have a liquid core. That would generate a magnetic field. The magnetic field would have stopped the solar wind from wearing away the atmosphere. Hence Mars would have a denser atmosphere. It would also be warmer due the dense atmosphere.

Well I don't think plate tectonics ha anything to do with what you said, but I'm no expert. I know what really happened to Mars and if your interested Message me on MSN or AIM.

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Since plate tectonics only operates on earth we don't really know what the preconditions are. I certainly would not like to say that having a molten core means you must have plate tectonics. venus, for example, probably has a molten core but is dominated by vertical tectonics, not horizontal.

Mars certainly had a molten core in its youth but this does not mean it had plate tectonics.

Jon

What is the traditional wisdom for the major reason mars has such a thin atmosphere?

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Olsen the moderator.

Based on what we know about plate tectonics and planetary heat engines:

(1) Perhaps. It probably would have had to have been rather larger to maintain its internal heat longer (and produce more to begin with). The larger planet would als o have higher gravity, and retain it's atmosphere better.

(2) Possibly. It depends if the tectonics were truly Earthlike. We have no other example of plate tectonics, so while it could make sense, it's still a pretty open question how a larger or otherwise tectonic Mars would behave.

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I haven't seen anyone mention just the lack of a recharge for the atmosphere. Lack of active volcanism (although that can be related to tectonics, it doesn't have to be), lack of evaporation of water (no oceans), lack of life that generates gasses (with the possible exception of methane producing bacteria). The cold temperature reduces the speeds of reactions at the surface.

Well, I refer you back to my previous post. The idea is that the core cooled, which means the currents in the magma slow. The planet's magnetic field is a by-product of this movement, so when it slows, the field weakens. If the core cools down enough, the magma comes to a virtual standstill, and the magnetic field becomes so weak it's practically immesurable.

One of the theories is that this is what happened to Mars a long, long time ago. The core cooled, the plates stopped moving, the magnetic field disappeared, and the atmosphere was sloughed off by the solar wind over time.

I would think (but I don't know for sure) that Mars' small size / lower gravity also may have been part of it. Smaller gravity well to keep stuff in. I wonder also, if much of Earth's volatiles were delivered by comets, maybe Mars' position nearer to Jupiter meant it had fewer comet hits?

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But it is thought that the atmosphere fluctuates to some extent due to changes in the tilt of the rotational axis over geologically short time scales. When one hemishere is tilted towards the Sun during perihelion, the atmospheric pressure may increase to 50 - 100+ mb. Obliquity excursions from the low angle state to high angle and back (mostly in the range of 15 deg to 40 deg) probably are on the order of 120,000 years.

that's interesting, I agree the change in tilt had a large impact.

But, if several volcanoes were outgassing into the atmosphere, that would certainly make a big difference on the atmospheric pressure.

Reuters story
I tried the link to the NASA simulation given in the article, but it did not seem to be correct.

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Try here.

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