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RGClark
2008-Oct-12, 01:48 PM
Large deposits of carbonates had been expected to be wide spread on Mars because of the extensive water in the distant past and because of the CO2 atmosphere. Previously however deposits of carbonates had not been seen from orbit. What was seen from orbit was small amounts of carbonate in the form of dust sprinkled over the planet at perhaps the 2% amount. This was confirmed on the ground by the MER rovers which also saw carbonate only in the form of dust in small amounts.
However, the Phoenix lander has found carbonates in significant amounts at its landing site, perhaps in the 6%-8% range. The presence of the carbonate here might be due to the alkalinity of the soil at the Phoenix site compared to acidic soil, as indicated by the presence of sulfates, at the other lander sites.
A new report however to be presented at the upcoming "Workshop on Martian Phyllosilicates: Recorders of Aqueous Processes?" will argue that carbonate best fits the spectra in a deposit in the Nili Fossae region on Mars:

PHYLLOSILICATES, ZEOLITES, AND CARBONATE NEAR NILI FOSSAE, MARS: EVIDENCE FOR DISTINCT ENVIRONMENTS OF AQUEOUS ALTERATION. B.L. Ehlmann1, J.F. Mustard1, G.A. Swayze2, J.J. Wray3, O.S. Barnouin-Jha4, J.L. Bishop5, D.J. Des Marais6, F. Poulet7, L.H. Roach1, R.E. Milliken8, R.N. Clark2, S.L. Murchie4, and the MRO CRISM Team. 1Dept. of Geological Sciences, Brown University, 2U.S. Geological Survey, Denver, 3Cornell University, 4JHU-Applied Physics Laboratory 5SETI Institute 6NASA Ames 7IAS, Université Paris-Sud, 8JPL-Caltech (****@brown.edu)
http://www.lpi.usra.edu/meetings/aqueous2008/pdf/7019.pdf

This is to be published in an upcoming article in Science.

Other interesting reports from this conference:

Program
Workshop on Martian Phyllosilicates: Recorders of Aqueous Processes?
October 21–23, 2008
http://www.lpi.usra.edu/meetings/aqueous2008/pdf/program.pdf


Bob Clark

PraedSt
2008-Oct-13, 09:46 PM
Large deposits of carbonates had been expected to be wide spread on Mars because of the extensive water in the distant past and because of the CO2 atmosphere

Sorry RGClark, I have a slightly off-topic question for you. I need your help.

I'm researching the Faint Young Sun paradox (for fun). I was wondering if you have any information on the concentration of C02 and Methane in the early (4bn years) Mars atmosphere?
I'm trying to find out whether or not greenhouse gases were responsible for the higher temperatures back then.

Thanks

JonClarke
2008-Oct-13, 11:23 PM
Try the results of this search...

http://scholar.google.com.au/scholar?hl=en&lr=&q=Noachian+Mars+atmosphere+climate&as_subj=phy

jon

PraedSt
2008-Oct-14, 02:46 AM
Try the results of this search...

Hey, thanks Jon. Now I have to find one of those overview, state-of-the-art articles...
Thanks again

RGClark
2008-Oct-14, 02:55 PM
Sorry RGClark, I have a slightly off-topic question for you. I need your help.

I'm researching the Faint Young Sun paradox (for fun). I was wondering if you have any information on the concentration of C02 and Methane in the early (4bn years) Mars atmosphere?
I'm trying to find out whether or not greenhouse gases were responsible for the higher temperatures back then.

Thanks

BTW, I have an unorthodox (as usual) explanation for the apparent warmer temperatures on Earth and Mars early in the solar systems history when the Sun was actually supposed to be fainter than now: the inner planets were closer to the Sun then.

Bob Clark

PraedSt
2008-Oct-14, 06:30 PM
BTW, I have an unorthodox (as usual) explanation...the inner planets were closer to the Sun then...

I think I've heard about this one. A more massive Sun?
There is this 2003 study that I found (on BAUT) that suggests 7% more.
http://www.journals.uchicago.edu/doi/full/10.1086/345408

A Solar explanation does sound appealing; it should account for both Earth and Mars simultaneously. But I haven't looked into any of the other bodies yet...

JonClarke
2008-Oct-15, 02:29 AM
BTW, I have an unorthodox (as usual) explanation for the apparent warmer temperatures on Earth and Mars early in the solar systems history when the Sun was actually supposed to be fainter than now: the inner planets were closer to the Sun then.

It would solve some problems. I know of several mechanisms proposed that can move plants inward. What's your proposal for moving them outward?

Jon

PraedSt
2008-Oct-15, 03:00 AM
I know of several mechanisms proposed that can move plants inward. What's your proposal for moving them outward?

If he does mean a more massive sun, then you'd have to have mass loss as the mechanism for moving them back out. Although that's something else that's being debated. It's in that article above, first section after the intro.

I'd be interested to know of your several mechanisms though. Might help with my problem...

Warren Platts
2008-Oct-15, 03:39 PM
If a star gradually lost mass, other things being equal, shouldn't that cause any planets to gradually migrate outwards? The higher the mass of the primary, the faster a planet has to move in order to maintain a steady distance (assuming minimum eccentricity). So if the parent star lost mass through solar flares converting matter to energy, or whatever, that would cause a planet to have too much velocity for its orbit based on the primitive stellar mass level. Thus, the planet would migrate outwards.

Should be simple to figure out using GravitySimulator (http://www.orbitsimulator.com/gravity/articles/what.html)

RGClark
2008-Oct-15, 05:03 PM
Some possible reasons why a planet might migrate outward are described in this thread on Uplink.space.com:

Planetary accretion in the inner Solar System.
posted at 7/19/2004 2:50 PM EDT
http://www.space.com/common/community/forums/?plckForumPage=ForumDiscussion&plckDiscussionId=Cat:c7921f8b-94ec-454a-9715-3770aac6e2caForum:d148ee4c-9f4c-47f9-aa95-7a42941583c6Discussion:70acb9c7-f1e2-4d34-ae84-c72d8d6243cf

and in this thread on this forum:

"Hot Jupiters" might have disrupted the early Solar System.
RGClark
19-July-2008, 12:19 AM
http://www.bautforum.com/astronomy/76843-hot-jupiters-might-have-disrupted-early-solar-system.html


Bob Clark