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A question here, behaviour of water on Mars
spdf
post May 24 2007, 12:38 AM
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A question here

There are signs that in the past there was liquid water on Mars. So lets assume thats true.
Since the gravity on Mars is much lower than on Earth, so how does water (waves) behave on Mars compared to Earth?
Someone did say, that waves would have been much higher but also much slower. Is this true? Does anyone have an animation where you can see a waive on Earth in comparsion to a wave on Mars?

Thanks
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Juramike
post May 15 2008, 07:03 PM
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Space.com article says that the crust of Mars is colder (and thicker) than previously thought.

From the article:

"Unexpectedly, the radar scans also revealed the massive weight of the ice cap does not deform any underlying sediment. This implies the crust beneath the cap is strong — more than 180 miles thick (300 km).

To have such a thick crust, "Mars might be colder than we thought," Phillips told SPACE.com. As a result, any liquid water that might be underground has to be buried even deeper than once speculated. "If one thought that liquid water was 5 kilometers deep (3 miles), it's now at least 30 percent deeper than that," he said."

(The article to be published in the May 15 issue of Science is not yet available.)


I have a really ignorant question, here: What is the ductile strength of sediment with interstitial ice? Is it stronger or weaker than normal sediment?

-Mike


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dburt
post May 17 2008, 01:14 AM
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QUOTE (Juramike @ May 15 2008, 12:03 PM) *
Space.com article says that the crust of Mars is colder (and thicker) than previously thought.

From the article:

"Unexpectedly, the radar scans also revealed the massive weight of the ice cap does not deform any underlying sediment. This implies the crust beneath the cap is strong — more than 180 miles thick (300 km).
..."

I have a really ignorant question, here: What is the ductile strength of sediment with interstitial ice? Is it stronger or weaker than normal sediment?

Mike - So here's an ignorant answer. If by "normal sediment" you mean unconsolidated sediment (i.e., loose particles) where the pore space is filled with liquid water (below the water table) or air (above the water table), presumably ice-cemented sediment should be somewhat stronger, because ice is a solid. However, ice expands as it freezes, and can move sedimentary particles around (e.g., in ice polygons inferred on the Martian surface), so that ice-cemented sediment could be weaker than an actual sedimentary rock (if the particles in the rock were cemented by something stronger than ice).

That ambiguous answer may be irrelevant, though, because the space.com quote appears to be inadvertently misleading. They are not really talking about deformation of a thin, weak sedimentary veneer, but about deformation of the much stronger and thicker underlying igneous (metamorphic?) crust and uppermost olivine-rich mantle (i.e., what geophysicists call the lithosphere on Earth). The colder the underlying solid rock, the less easily deformable it is. So what they are mainly saying, if I am guessing correctly, is simply that Mars is somewhat more rigid (and therefore colder by inference) inside than was formerly modeled (at least beneath the poles). Calling this cold, rigid layer "the crust" appears to be PR-speak for "cold and rigid lithosphere". The present-day lack of plate tectonics on Mars (i.e., the fact that Mars is a one-plate planet) already implies that Mars has a very thick, rigid, non-deformable lithosphere. The lack of deformation owing to the weight of polar ice caps strengthens (pardon the double-entendre) this inference. Again, just my ignorant answer - I'm not a geophysicist and haven't read more than what you quoted. (I do know enough to state that a seismic network on Mars could provide badly-needed data about the martian interior.) Hope this clarifies rather than confuses.

-- HDP Don
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dvandorn
post May 17 2008, 07:06 AM
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QUOTE (dburt @ May 16 2008, 08:14 PM) *
...I do know enough to state that a seismic network on Mars could provide badly-needed data about the martian interior...

Oh, we are *so* in agreement! If there are two sets of data I dearly want from Mars, one is from a sustained seismic network, and the other is from a carefully designed heat flow network.

Those two sets of data could seriously constrain a lot of the current theories of Martian history, IMHO.

-the other Doug


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Posts in this topic
- spdf   A question here   May 24 2007, 12:38 AM
- - tuvas   This is just a guess, but I would guess waves woul...   May 24 2007, 08:19 PM
- - ugordan   I believe the higher-and-slower waves is the corre...   May 24 2007, 08:44 PM
- - nprev   Another major variable would have been atmospheric...   May 24 2007, 11:17 PM
- - dvandorn   Actually, liquid water on Mars would behave consis...   May 25 2007, 07:50 AM
- - AndyG   ...and add bigger drops. Surface tension will play...   May 25 2007, 08:31 AM
- - nprev   Great story, oDoug! Yeah, I should have bee...   May 25 2007, 11:50 AM
- - Juramike   While there would be no really big tides on a Mart...   May 25 2007, 03:41 PM
- - helvick   On earth the average atmospheric pressure of ~101k...   May 25 2007, 04:52 PM
|- - marsbug   I have a question I've not been able to resolv...   Nov 15 2007, 06:14 PM
|- - dburt   QUOTE (marsbug @ Nov 15 2007, 11:14 AM) I...   Nov 15 2007, 11:30 PM
|- - Gsnorgathon   Not to rain (metastably or otherwise) on anyone...   Nov 16 2007, 12:41 AM
|- - Juramike   QUOTE (Gsnorgathon @ Nov 15 2007, 08:41 P...   Nov 16 2007, 08:57 PM
|- - nprev   QUOTE (Juramike @ Nov 16 2007, 12:57 PM) ...   Nov 17 2007, 03:49 PM
|- - Juramike   QUOTE (nprev @ Nov 17 2007, 10:49 AM) .....   Nov 17 2007, 05:02 PM
|- - ElkGroveDan   QUOTE (Juramike @ Nov 17 2007, 09:02 AM) ...   Nov 17 2007, 05:38 PM
- - Greg Hullender   Here's a couple of useful comments from a NASA...   Nov 15 2007, 06:41 PM
- - djellison   And of course, the fact that water can exist, at s...   Nov 15 2007, 07:12 PM
|- - rlorenz   QUOTE (djellison @ Nov 15 2007, 02:12 PM)...   Nov 16 2007, 01:47 AM
|- - ngunn   QUOTE (rlorenz @ Nov 16 2007, 01:47 AM) I...   Nov 16 2007, 01:03 PM
- - Juramike   Both theory and experiment agree that cold brine s...   Nov 15 2007, 10:41 PM
- - nprev   Mike or HDP Don, how different are the curves for ...   Nov 16 2007, 01:06 AM
|- - dburt   QUOTE (nprev @ Nov 15 2007, 06:06 PM) Mik...   Nov 16 2007, 08:27 PM
|- - nprev   QUOTE (dburt @ Nov 16 2007, 12:27 PM) Ver...   Nov 17 2007, 01:17 AM
|- - dburt   QUOTE (nprev @ Nov 16 2007, 06:17 PM) Tha...   Nov 17 2007, 01:40 AM
- - ngunn   Thanks for that Hecht link. Definitely some counte...   Nov 16 2007, 08:51 PM
- - nprev   They don't call ya Herr Doktor Professor for n...   Nov 17 2007, 01:50 AM
|- - dburt   QUOTE (nprev @ Nov 16 2007, 06:50 PM) The...   Nov 17 2007, 03:03 AM
- - marsbug   Thank you very much one and all, I can look foward...   Nov 17 2007, 05:25 PM
- - nprev   Rats...knew I shoulda gone to EGD's alma mater...   Nov 18 2007, 12:15 AM
- - Juramike   Space.com article says that the crust of Mars is c...   May 15 2008, 07:03 PM
|- - dburt   QUOTE (Juramike @ May 15 2008, 12:03 PM) ...   May 17 2008, 01:14 AM
||- - dvandorn   QUOTE (dburt @ May 16 2008, 08:14 PM) ......   May 17 2008, 07:06 AM
||- - Juramike   QUOTE (dburt @ May 16 2008, 08:14 PM) Hop...   May 17 2008, 12:53 PM
||- - dburt   QUOTE (Juramike @ May 17 2008, 05:53 AM) ...   May 19 2008, 02:58 AM
||- - SickNick   QUOTE (Juramike @ May 17 2008, 10:53 PM) ...   Jun 8 2008, 02:38 PM
|- - Juramike   QUOTE (Juramike @ May 15 2008, 02:03 PM) ...   May 18 2008, 06:35 PM
- - dvandorn   As a general comment to the "discovery" ...   May 17 2008, 07:17 AM
- - silylene   QUOTE (spdf @ May 24 2007, 12:38 AM) A qu...   May 24 2008, 03:21 AM
|- - rlorenz   QUOTE (silylene @ May 23 2008, 11:21 PM) ...   May 24 2008, 01:27 PM
|- - Juramike   QUOTE (rlorenz @ May 24 2008, 09:27 AM) M...   May 24 2008, 03:05 PM
|- - silylene   I agree that the problem with resonance waves make...   May 25 2008, 02:05 AM
- - Juramike   A rotovap simulation experiment! That...is......   May 24 2008, 04:28 AM


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