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Posted by: glennwsmith Apr 1 2009, 02:28 AM

All, I know this isn't the right place for this post, but I've looked around and can't find an appropriate, current UMSF forum (Doug, perhaps you could give me some guidance on establishing such) -- so here goes: I think a [the] new paradigm for Martian geology is rapidly coalescing, namely, that Mars is very much like the Earth in terms of the preponderance of water -- except that it is all frozen, and covered under a thin layer of dust/regolith! See, for example, this article:

http://www.skyandtelescope.com/news/41995902.html

Hence the "seepages" found in crater walls; hence the evidence of catastophic flooding -- the result of volcanism melting huge pockets of ice. And I am going to add my own wrinkle (probably not original): that the differentiation of Mars into a rougher southern hemisphere and smoother northern hemsphere represents something like Earth's Pangea stage, ie, the northern hemisphere is a vast frozen sea covered with a thin layer of ice.

Posted by: glennwsmith Apr 1 2009, 02:31 AM

Oops, of course I meant thin layer of dust, not ice . . .

Posted by: djellison Apr 1 2009, 07:06 AM

New thread to move Glens posts in to.

And Glen - you should just 'edit' your first post, rather than replying to it to make a correction.

Posted by: dburt Apr 1 2009, 10:15 PM

Doug, thanks for moving this. And Glenn, not a particularly new paradigm for many scientists. Everyone wants to emphasize similarities with Earth, but you have spotted a major difference - that the water is all or mostly frozen. This has been speculated on for a long time; it's nice to find direct proof. Freezing/sublimating the water released all the salts that were held in solution; both rovers, plus orbiting satellites are continually finding more salts. Another difference is the extreme age of the martian crust - billions of years, owing to an apparent lack of plate tectonics on Mars since then (implying the comparison with Earth's Pangea stage may not be an appropriate one). The ancient crust has preserved the record of ancient Martian impact cratering much better than on Earth; even the hemispheric division of Mars has been blamed (by many scientists) on a giant impact.

Incidentally, the northern hemisphere is just as heavily cratered as the southern one, except that it is lower-lying, and so the ancient craters are mostly buried under a thin layer of dust and ice, as that article pointed out. Orbital studies involving detailed elevation and radar have allowed the northern buried craters to be detected (see numerous articles by Herbert Frey). The very thin atmosphere means that impact cratering is still a far more important process than on Earth - small meteorites do not burn up in the atmosphere. A final difference from Earth is that the martian crust and lavas are at least twice as rich in iron as on Earth - an important difference that probably relates to the initial degree of hydrogen loss (core oxidation) during the formation of Mars. In part, this iron-rich nature accounts for the rusty red color of Mars - and presumably accounts, in some fashion, for the prevalence of shiny gray hematite (iron oxide) spherules at the Opportunity landing site.

The big scientific question regarding Mars now is not its water-rich nature, but rather how much of, and for how long, this water might have remained liquid, rather than frozen, on ancient Mars, during and just after ancient impact cratering episode that ended about 3.8 billion years ago (age assumed from dating of Moon rocks sampled during the Apollo astronaut program). I find it easiest to relate abundant evidence for early liquid water to the impact cratering episode itself (an easy way to generate lots of heat, a temporary steamy atmosphere, and layered sediments resembling those seen by both rovers), but others prefer to relate liquid water to early volcanism, an unusual and dense atmosphere, or both. Impacts and volcanism are not mutually exclusive, of course - both were occurring at at a high rate at roughly the same time, and afterwards both continued at a greatly reduced rate.

-- HDP Don

Posted by: glennwsmith Apr 1 2009, 11:42 PM

Dburt, thanks for the thoughtful summary. I think I am agreeing with you in referencing Pangea -- given the lack of plate tectonics, the uber continent never split into smaller pieces.

Posted by: MarsIsImportant Apr 2 2009, 01:39 PM

Was it really ever an uber continent at all? Perhaps it is merely a remnant of the original ancient crust before Mars got hit by a HUGE dwarf sized planetary object. The idea is that Mars was struck similar to how the Earth was smashed early in its history (the Mars sized object that created the Moon). In this respect, perhaps Mars is similar to Earth.

Did a larger Moon on Mars once exist, then smashed into Mars again later in its history? That possibility of a second event could give us a false date concerning early bombardment (assumed to be 3.8 billion years ago because of the Apollo rock dating). Mars is not the Moon. It is possible that there was more than one extreme event and the evidence is mounting that this may have occurred, but it is still not convincing. Occam’s razor still suggests the more simple solution.

I’m keeping my mind open because there is still so much that we don’t know about Mars. Answers won’t come as quickly as we might want. But look at the speculation of frozen water on Mars! It has taken almost 30 years for it to now become established fact. Just a few years ago, I was almost laughed at because of my suggestion there might have been large numbers of glaciers on Mars at one time. Few are laughing at that idea now.

Posted by: glennwsmith Apr 4 2009, 03:41 AM

Marsisimportant, thanks for adding the primeval collision to the overall picture -- you and Dburt have covered all the important bases, and in doing so, you have clarified for me what I was hoping to do with my original post, which was to paint a picture -- at which I will now, thanks to the infinite patience of Doug Ellison and all you other UMSF members, take another whack. To wit: I have been looking at the global pictures of Mars for some years now, and I have never been able to make sense out of what I am seeing. Yes, it is Earth's sister planet, but it just hasn't made any sense to me. But suddenly -- seeing the Hirise photo of a recent meteor strike on the Northern plains throwing out rays of ice -- it has all become clear. Imagine Earth at the Pangea stage with its seas frozen, and the entire planet covered with a thin layer of dust -- it would look very much like Mars today (allowing for the fact that the dust covering Mars is rich in iron oxide). I hope I am not beating a dead horse, I am just trying to explain my eureka moment. But maybe I'm behind the curve, and all of this has been obvious to most UMSF members for some time . . .

Posted by: imipak Apr 5 2009, 06:49 PM

A picture of Mars with somewhat ubiquitous sub-surface ice seems to be emerging (for some value of "ubiquitous" yet to be firmly established, but certainly less than 1), and this is relatively new. I haven't seen any informed speculation about, or estimates at upper and lower bounds for, the thickness or volume of these layers (and would welcome some pointers, if anyone has any?) I like your "eureka moment" image, though, I just think it'll turn out to be a bit less dramatic than ocean-basin scale volumes.

Posted by: Fran Ontanaya Apr 5 2009, 11:17 PM

There's the Medusae Fossae radar profile.

http://www.nasa.gov/mission_pages/mars/news/marsis-20071101.html

Posted by: glennwsmith Apr 5 2009, 11:48 PM

Imipak and Fran, thanks for the excellent additions to this thread. And I'm wondering inf anyone else out there has been as confused as I have been in trying to decipher the big picture of Martian surface geology?

Posted by: glennwsmith Apr 6 2009, 02:16 AM

On behalf of all who have joined this thread, I am adding for discussion purposes an image (with which I have taken some BIG liberties) showing 1) an early, "earthlike Mars", 2) Mars with its "seas" frozen, and 3) the seas covered with a thin layer of [red] dust -- voila, current day Mars! But I am not nearly so good a graphic artist as many of you . . .

Posted by: Geert Apr 6 2009, 05:48 AM

A very interesting picture and discussion.

However, how much evidence is there really that all of the water was liquid at the same time? Would it not be possible that the effects were more local, resulting from various causes and not one 'tropical period'.

Lacking a large moon, http://en.wikipedia.org/wiki/Precession, http://en.wikipedia.org/wiki/Nutation, and http://en.wikipedia.org/wiki/Polar_motion of Mars rotational axis will probably be larger then on Earth, resulting in several cycle's of 'super seasons' imposed on the existing seasons (which are already stronger then on earth due to Mars more elliptical orbit). Area's with exposed ice around the poles might receive more solar heating due to this, resulting in the ice sublimating (increasing air pressure) or possible become liquid for a short while, however at the same time other area's might 'cool down' due to the same effect, and ice might start building up again on these area's (reducing air pressure again). So the ice would more or less shift from one area to the other and this might even be possible without a liquid phase in between??

Local effects might be vulcanism (volcanic heat might rapidly heat a layer of ice, resulting in the ice sublimating and possible a short local liquid period if the air pressure rises sufficiently locally during a short period) or impacts (same effects, local heating). So you might have local 'flood-waves' during short periods without the need for a planet-wide 'tropical period'.

How much prove do we have that we are looking at a planet-wide 'tropical period' instead of just a series of (more or less unrelated) local events?

Posted by: djellison Apr 6 2009, 07:27 AM

So basically, it's Tim Parkers old Northern Hemisphere Ocean idea. I saw it mentioned in a few books, but the evidence wasn't water-tight at the time.

Posted by: Phil Stooke Apr 6 2009, 07:42 PM

Glennwsmith, your map is OK ( and similar to other visualizations of this concept) except for one glaring error.. the ocean, if it existed, would be confined to low elevation areas, so you need to make its outlines fit contours, not albedo markings. The bright central part of your image, Arabia Terra, is actually highlands.

Doug, the first person I am aware of to promote this idea of a northern ocean was Victor Baker (U. Arizona). He called it Oceanus Borealis, I think. There was a paper in Nature about it. Tim Parker mapped possible shorelines of that ocean.

Phil

Posted by: glennwsmith Apr 7 2009, 12:02 AM

Geert, you are certainly justified in bringing up local constraints on ocean formation -- my simple-minded conception of a Mars ocean is like talking about "liberal" or "conservative" voters as if they have a uniform profile. And I stand properly corrected, Phil, for my simple-minded map-drawing technique. But it is the Dougmeister who has really got this thread unspooling into a nice, fat pile, with his mention of Tim Parker, the real pioneer of the northern ocean theory. I've done some quick (and belated?) research, and the theory of Dr. Parker and his colleagues is all over the web -- not to mention a lengthy discussion thereof on UMSF back in June of 2007! (And not to mention, as per Phil's comment, several scientific depictions of same.) Despite my discomfiture, the point remains that these photos of fresh, ice-penetrating craters will bring roaring back into well deserved focus the thought that oceans -- whether large or small -- lie frozen beneath them. Dr. Parker, we would love to hear from you!!!

Posted by: tim53 Apr 7 2009, 09:15 PM

My ears just burst into flames! (actually, a friend told me about this thread).

No, Phil. Vic Baker's work post-dates and is based loosely on mine...

"I started out as a child"...

Seriously, my own ruminations about a possible northern plains ocean on Mars began in 1985. Baerbel Lucchitta of the USGS and Heins-Peter Jons of Germany and I were looking at the same curious plains boundaries around the northern plains and interpreting them somewhat differently, but as indicating an ocean at that level of some sort or other. Mine was happy and "tropical" (as described above), with waves responsible for the erosional and arcuate constructional features along the margin. Lucchitta's was frozen over, with comparisons made with morphologies she saw around the Antarctic coastline. Jons' described his ocean as a "mud ocean", with the margins being flow fronts of freezing mud transgressing up the margins of the plains as catastrophic flooding dumped water and sediment into the plains.

With all the new high resolution data available now, I'm looking at the problem anew. Instead of a tropical early Mars, I think it's more likely that the planet has always been cold, modulated by pulses of greenhouse warming in a thicker atmosphere and possibly by higher internal heat flow. Most (but very interestingly not all) of the features I mapped as shorelines based on Viking data appear to exhibit debris-flow or even lava-flow front morphologies. But it's very interesting to note that these boundaries are still elevated, sometimes by hundreds of meters, with respect to the plains immediately interior to them. Tens or even hundreds of millions of cubic kilometers of water is "easier" to get rid of than the equivalent volume of lava, so I think it's more likely that these are some sort of ocean shorelines rather than volcanic plains margins.

I think it's likely that, if Mars had an ocean, that it was ice AND debris covered most of the time (not just dust, either, because the northern plains surface is rather rocky in MOC and HiRISE images). Also, if the marginal features are shorelines, Mars has lost a lot of its original water inventory over geologic time.

...subject to revision!

-Tim.

Posted by: lyford Apr 7 2009, 10:47 PM

Can I just say that I love this board?

Posted by: glennwsmith Apr 8 2009, 04:44 AM

I would like to second Lyford's point, and add my own expression of gratitude to Dr. Parker (Tim) for his post, especially appreciated given the understanding thay guys of his stature can't just rattle on like amateurs such as myself! Speaking of which, there are dozens of things I would like to say, but I will confine myself to one item at the moment. I have downloaded and read the brief article cited by Sky and Telescope, and it makes the point that, although several models confidently predict the presence in the Martian regolith of "pore-filling ice" which is a natural result of the inhalation and exhalation of atmospheric water vapor, "The ice exposed at this site [the one with the apron large enough to fill a CRISM pixel?] is not pore-filling ground ice but rather is relatively pure and is at least several cm thick." Oceanus Borealis ?!?!? Speaking for myself, Dr. Parker, but probably expressing a common sentiment among us UMSF members, please do not feel that you must respond tit-for-tat to our meanderings. We who are not on Mr. Olympus are pleased to think that you might be amused to follow from afar the enjoyment we mortals have in passing around the golden apple you have dropped in our midst!

Posted by: tim53 Apr 8 2009, 02:03 PM

It might be tempting to interpret these findings as "proof" that the vestiges of a frozen ocean lie just beneath the surface at these locations, but as the article points out, there are other reasonable explanations for near-surface ice - even pure ice that don't require former standing water.



I'm just a poor, humble country planetary geologist, lost in the Big City!


-Tim.

Posted by: Phil Stooke Apr 8 2009, 09:33 PM

Hi Tim - sorry about that, I had the order wrong. It's too long since I actually looked at Vic Baker's paper.

Phil

Posted by: ngunn Apr 8 2009, 10:29 PM

Tim Parker I'm really delighted you're here. I always believed in those shorelines, even when it turned out they aren't level now and even though their morphology is quite unlike terrestrial shorelines.

Posted by: Geert Apr 9 2009, 12:19 PM

I'm an absolute amateur in this so hopefully this isn't a too dumb question: but if these are ocean shorelines, does this imply that the water had to be liquid at that (or any other) time? What happens if the lava flows at the time just ran into ice instead of water, would we see the difference?

Giving the precession of the rotation axis, moving fields/glaciers of ice seem to my simple mind the easiest answer, the ice caps wonder around the surface pending the direction of the rotation axis at the time, without ever resulting in large liquid oceans. Ice sublimates in one spot and builds up again in another with at the very most only very short local periods of liquid water (due volcanic activity or impacts).
In an other threat on this forum we discussed already the theorie that the deposits we see at Meridiani could have been formed inside ice fields instead of in liquid water, so instead of a shallow liquid ocean the area might also have been covered by an icefield which later disappeared.

Posted by: tim53 Apr 9 2009, 06:17 PM

Not a dumb question at all. Ice has a tremendous heat capacity, so it's even possible that the surface (and the margins that I interpreted as shorelines) are plains lavas that flowed out over an entirely frozen ocean, and that as the water was lost over geologic time, the flows interior to the margins simply settled. Some melting and steam production would have occurred, of course, possibly explaining the abundant cones that many have interpreted as pseudocraters, but that others (myself included) interpreted as pingos.

-Tim.

Posted by: stevesliva Apr 9 2009, 07:45 PM

When the ice sheets on Earth retreat, the underlying crust springs up somewhat. If an entire ocean-size sheet on Mars sublimated, the crustal relaxation wouldn't necessarily be even. Nor would it necessarily be analogous to Earth, because a mantle might be necessary. I just mean to throw out the point that the elevations around that amount of mass might change once it disappears.
http://en.wikipedia.org/wiki/Post-glacial_rebound

Of course it's also interesting to think along the lines of the hemispherical elevation / cratering dichotomy as indicating that there wasn't a total rebound.

Posted by: ngunn Apr 10 2009, 12:57 PM

There was a nice paper that we discussed in an earlier thread which proposed polar wander caused by the growth of the Tharsis bulge as the main mechanism for disturbing the gravity equipotential from where it was in oceanic times. I'm sure somebody has the reference to hand.

EDIT Here:
http://www.google.co.uk/url?q=http://www.spacedaily.com/reports/Wandering_Poles_Could_Explain_Ups_And_Downs_Of_Ancient_Martian_Shoreline_999.html&ei=nUjfSffOAZWD-Aah_uT6CA&sa=X&oi=spellmeleon_result&resnum=2&ct=result&usg=AFQjCNFM-ycMeQCGO43gv0n5_UnwNJ0W6g

Posted by: marsbug Apr 18 2009, 12:26 PM

Reading http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2168.pdf, which i'm sure most people here already have, the thought has occured to me that occasional exceptional events , like small meteorite impacts , could bring preserved ice to the surface in areas where it would not ordinarily be stable, and that this ice might in a smallest of ways melt (short lived thin films on rocks in the debris field etc). Over bilions of years, could events like this account for some of the chemical evidence we see of liquid water on mars? That could have some bearing on theories like an ancient northern ocean.

Posted by: centsworth_II Apr 18 2009, 06:41 PM

I wonder what the relative contributions to water-mediated changes in mineralogy are of:
1) Hot steam released by the initial explosive impact
2) Lingering sub-surface water/mud created by the impact
3) micro-films as part of an ice-rich environment equillibrium

I wonder if the impacts add much to the changes caused already by near surface ice. There was evidence of water films at the Phoenix site as part of the normal equilibrium between ice, soil, and atmosphere. Why would the same films not exist in regions of near surface ice at lower latitudes even without the impacts?

Posted by: marsbug Apr 19 2009, 09:52 AM

Isn't the phoenix data relating to thin films of water kind of ambiguous? There were some things, like soil stickiness, that could be evidence for thin water films, but the one sensor that would have given an unambiguous answer, the TECP, told us the soil was bizarrely dry considering it was sitting on a slab of ice and the humidity in the air above could reach 100%.

I think that the effect small ice exposing impacts would have on Martian soil and rock would depend on how frequent they are. Ice exposed on the surface at low latitudes will be more active than ice sequestered a meter or so below. If small impacts are frequent then they might up the overall rate of water activity at the surface.

Posted by: Geert Apr 19 2009, 12:34 PM

I'm an amateur in this, but I still think those TECP readings are among the weirdest data Phoenix has been throwing at us, and with all the talk about water films on the lander etc I haven't seen any theorie which seems to explain those TECP readings. There is still a lot we don't know.

Getting back to the 'warm and wet Mars', I'm still wondering whether we have any data which absolutely requires a long period with large liquid 'oceans' on Mars, also given the fact that it now looks like mineral deposits can also be formed inside ice fields. I can imagine there might be short 'floodwaves' and such due to vulcanic activity or large impacts on (surface or sub-surface) icefields but it's still a big step from there to an 'earthlike mars'.

Posted by: Fran Ontanaya Apr 19 2009, 05:17 PM

They'll need to reproduce the TECP results and see what happens in that clay + salts + iron oxides + water solution. It looks like a funny mixture to do electric experiments with.

A quick Google search gave me this, which I don't know if it may be related:
http://soil.scijournals.org/cgi/content/abstract/67/2/518
http://www.agu.org/pubs/crossref/2006/2005WR004590.shtml

Posted by: glennwsmith May 2 2009, 07:11 PM

The work of UMSF members has, on several occasions, risen above the amateur level to represent a real contribution to space science. I refer, in particular, to the graphic work which has appeared in national publications.

May I suggest that the question of the existence of an Oceanus Borealis represents a similar opportunity for UMSF members, and that this opportunity has both a primary and a secondary aspect?

Primary, in that question of an Oceanus Borealis does not depend so much on esoteric data such as, say, methane concentrations, but is to a great extent a question of visual interpretation. What are we seeing when we look at photos of these smooth northern basins? UMSF, with its four thousand plus pairs of educated eyes, can certainly make a contribution. (Indeed, some of the Mars imaging teams have issued a general invitation to interested amateurs to help scan their photos.)

Secondary, in that we can serve as an informed sounding board. Dr. Parker, for example, seemed to enjoy the opportunity of reviewing with us various northern basin scenarios. And, ultimately, a hypothesis which can be explained clearly and convincingly to an educated public is better than one which cannot.

Indeed, what we have with a possible Oceanus Borealis is one of those eureka! moments in science, or, more properly, the emergence of a new paradigm as depicted by Thomas Kuhn in his "The Structure of Scientific Revolutions". (Another example can be found at http://www.worldenergysource.com/articles/text/halbouty_WE_v3n2.cfm -- a lovely instance of the primacy of an idea over the wealth and fame that may flow from it.)

To this end, I hope this thread will remain current, and posts added to it as additional findings become available, and as additional insights are gained.

In fact, I have a possible such insight of my own: Dr. Parker has cited the cobbled surfaces of the northern basin(s) as militating against the frozen ocean hypothesis; but surely someone in the professional ranks has had the idea that many of these cobbles, as on the Antarctic ice sheets, are accumulated meteorites?

(And thanks for the thoughts on relevance of Phoenix data.)

Posted by: dvandorn May 4 2009, 07:58 PM

My only problem with the concept going around that the *entire* Martian northern hemisphere was excavated down a few km below mean by an enormous impact, whose basin is the entire northern half of the planet, is that I'd have to think such an impact would disrupt the entire planet, causing it to re-accrete rather as Earth and Moon re-accreted after the impact of a Mars-sized body on the proto-Earth.

How could Mars retain its structural integrity during an impact whose crater is roughly half the size of the planet? I'm not a mathematician, but it seems to me that the energies released by such an impact would have to be enough to disrupt the entire planet... in other words, I can't imagine a solid body that wouldn't come apart under such an impact, no matter the angle of impact.

-the other Doug

Posted by: Tom Tamlyn May 4 2009, 10:26 PM

Doug,

There's an interesting paper by Melosh in Nature Geoscience summarizing recent work on the martian giant impact theory. see http://www.nature.com/ngeo/focus/planetary-science/index.html?gclid=CIG9zPvXo5oCFcZM5QodGTJbCA The paper was briefly available for free, but apparently no longer. (But I may be able to find it on my hard drive.)

If I recall correctly, Melosh said that the energy released by the putative impacter would have amounted to "only" about one percent of the total gravitational binding energy of the planet, and that accordingly disruption and re-accretion would not be expected.

TTT

Posted by: Juramike May 5 2009, 12:14 AM

As part of an imaging project I've been planning, I've made a list of all the Mondo Big Impacts in the Solar System.
"Mondo Big" I defined as rim or feature diameters > 350 km. Most of the data on the list comes from the USGS Gazetteer.

 Big_Craters_of_the_Solar_System_bigger_than_350_km_20090504.xls ( 21K ) : 834


This list is better entitled as "List of big impact features that have been preserved."

Kinda interesting on the list that in the Jovian and Saturnian system only the outer satellites have preserved craters.
And in the inner solar system, Earth and Venus are notably absent. Either they didn't get whapped (doubtful) or surface process have done a nice job of obliterating the evidence.

Relevant to this thread, the putative Vasititas Borealis on Mars fit's nicely with other basins seen on Mercury and the Moon. It's still on the big size, but not too weird when looking at the other planets.

-Mike

[EDIT: 20090504 2030 Updated coordinates for South Pole/Aitken basin]

Posted by: nprev May 5 2009, 01:38 AM

That's an interesting observation about Jupiter & Saturn, Mike. Shooting from the hip, I wonder if the fact that both planets probably have had a significant amount of small stuff orbiting in their equatorial planes (the ring systems being mere tattered remnants of the originals) has contributed greatly to erosion of large impact features on their moons, which would presumably tend to form more infrequently and therefore also generally be older.

FWIW, I think you're spot on assuming that Earth, Venus & Mars wipe out really big craters pretty fast, although Argyre & Hellas are proportionately huge. Plate tectonics cleans up Earth rather well, and even the largest expanse of old terrain (the Canadian Shield) preserves only a few hefty ancient craters. Venus' surface looks a little like warm taffy at macroscales, and I bet that it's pretty malleable as silicate planetary crusts go over short geological timescales.

Posted by: serpens May 5 2009, 09:24 AM

I thought that MOLA had detected a heavily cratered Northern landscape buried by a comparitively thin resurfacing layer - eolian or aqueous deposition or possibly both? If so this would indicate that even if the northern basin was the result of a very early impactor, this occurred before the LHB. So an impact origin and the later formation of a sea would not seem to be mutually exclusive events.

But the northern basin doesn't look particularly circular, nor does it seem to have the depth or the surrounding (kilometer deep) ejecta material that characterises Helles.

Posted by: glennwsmith May 6 2009, 04:45 AM

Relative to the current discussion, check out this picture of the Rembrandt impact basin on Mercury:

http://antwrp.gsfc.nasa.gov/apod/ap090504.html

This "mare" is clearly, to me, the result of lava flows -- and my money is still on actual H2O, though now frozen, forming the smooth surface of the northern Mars basin.

And as has just been pointed out, correctly I believe, there is no contradiction between an impact basin and a subsequent sea.

Posted by: marsbug May 21 2009, 08:50 AM

http://www.universetoday.com/2009/05/20/a-cold-and-wet-history-on-early-mars/on the idea of early mars being cold and wet.

Posted by: serpens May 22 2009, 01:59 AM

I have some difficulty with the concept that the current temperature conditions (cold) applied to Mars in the beginning. To put this in perspective Earth was apparently warm, then we had the snowball earth followed by continuous warmth (always areas above freezing regardless of cyclical swings) . Lots of speculation on sun activity levels, interstellar dust, tectonics etc but no definite explanation for this. So why do we think Mars has always been stable at sub zero temperatures and pass off the clear evidence of major liquid water effects as brines or short term impact phenomona?

Given the evidence of large impactors (including the one that formed Earth's moon) these, and near misses would have caused variations in orbits of the inner planets, particularly for Mars given its size in comparison to Earth and Venus. If we can accept that a Mars sized planetoid collided with Earth then we should accept that there is a possibility that it also had a close encounter with Mars which at that time had an orbit closer to the sun. Potentially such an encounter moving Mars away from the warmth and setting the other body on a collision course for Earth.

Flight of fantasy perhaps. But no more so than trying to explain the water features on Mars purely in terms of impact or brines

Posted by: marsbug May 22 2009, 10:12 AM

As I understand it we can explain the evidence of water using brines and impact phenomena at the average temperatures we see today, so why do we need to invoke some unknown force to warm the planet up?

I think this discussions been done before on this forum by people more knowledgable than me: http://www.unmannedspaceflight.com/index.php?showtopic=4953 and http://www.unmannedspaceflight.com/index.php?showtopic=4308. Have a read if you've got the time (lots of time) , it's interesting and quite heated in places!

Edit: Based on the last couple of paragraphs of http://www.space.com/scienceastronomy/090521-mars-cold-wet.html(I don't have access to the full nature article) the significance seems to be that, in the right combination, salts found at the landing sites of the MER's and viking could depress the freezing point of water enough for a stable liquid to form at those locations. There might be some room to discuss how that gels with the theories already discussed, but we'd need to be carefull not to run the discussion into the ground or cross any lines. Doug and the other mods run a zero tolerance / benevolant dictator regime here. You'll notice one of the threads I linked above has been locked for causing the mods headaches!

Posted by: Doc May 23 2009, 05:24 PM

That is the big problem with in our exploration of Mars. I myself took part in the 'great debate' with Professor Dburt and even though the idea that Mars was probably warm and wet in the past looked ok, I couldn't help but feel that maybe we are on the loosing side

For example, I used to wonder; if Mars was indeed warm in the past, how do we consider the fact that the solar output at that time was probably significantly less than now and probably we should be talking about a tundra Mars instead of an Earthly paradise. The announcement of a cold and wet Mars model ushers in yet another and seemingly more accurate way of how we view the martian geological record.

As for the locked topics; it was probably for the best (we would just be going in circles anyway )

Posted by: glennwsmith May 24 2009, 10:36 PM

Whoa! Marsbug and Doc, thanks for alerting me to the fact that the question of an Oceanus Borealis is entangled (as of course it must be) with the heated debates regarding basal surge versus water-based processes. I have been involved in that frustrating loop myself when I, along with Dvandorn and many others, remarked on the incredible layering of Meridiani. So part of my goal with this thread is to approach things from a different, simplistic angle: was there (or is there still, in frozen form) a vast ocean in the northern basin? When Phoenix landed on a sheet of ice, and when meteorites at widely spaced intervals are turning up ice, the presence of such seems likely to me. Interestingly, even Dburt advances the possibility of a northern ocean, in post #36 from the thread which Marsbug turned me on to, "Welcome Professor Brine Splat":

"Large amounts of water apparently survived in the subsurface, however, as both ice and (probably) deep brine (as evidenced by occasional catastrophic releases to outflow channels that possibly formed ephemeral seas in the northern lowlands)."

And I will now succumb to the temptation to use an emoticon:

Posted by: dburt May 25 2009, 07:26 AM

Thanks for the emoticon, Glenn, but do you have a question? If Mars has almost always been rather cold and icy compared to Earth, owing to a much greater distance from the Sun and a paucity of atmosphere, this does not prohibit temporary surface warming (i.e., for perhaps several thousands or hundreds of thousands of years) owing to major meteorite impacts or groups of impacts, nor does it prohibit liquid water from existing on present-day Mars as concentrated brines or as very ephemeral snowmelt in low elevations containing dark (easily heated) basaltic rocks or dust. It also does not exclude local warming and brine beakouts near volcanic centers, although these centers seem to have rapidly declined in number after the end of major meteorite bombardment (the so-called Late Heavy Bombardment or LHB). Given how ice-rich Mars seems to be, soon-to-be-frozen-over lakes filling impact basins or even a temporary sea filling the Northern Lowlands could easily form following a really major impact event or series of events.

That said, 5 years of two rovers wandering across the present-day surface of Mars has as yet revealed no direct geological evidence of standing or flowing liquid water (such as a single shale bed or single pebbly stream channel) in the bedded rocks that make up both rover sites, although various interpretations have been made, entirely on the basis of preexisting expectations and putative terrestrial analogs. All the exposed fine layering at both rover sites is consistently cross-bedded, generally at low angles, and both sites contain enigmatic concentrations of generally unclumped tiny spherules (in distinct layers) and of acid sulfate salts. One site, in which most of the layering is rather coarse (breccias with abunandant lava fragments), contains a distinct horizon with silica-rich fragments, such as might originally have been produced in a boiling (easy to do on low pressure Mars) hot spring related to an impact crater or volcano. AFAIK, both sites contain abundant evidence of meteorite impacts, including evidence of very recent impacts and of actual fragments of meteorites on the surface, but neither site contains locatable volcanic vents.

I don't care to discuss further my own rather obvious and by now way over-explained (to most readers) interpretations of these highly interesting and valuable scientific observations. Occam's Razor, the Rosenthal (experimenter expectation) effect, and all that. Nuff said, although new contrary observations and interpretations remain highly welcome (send me a private message if you wish).

-- HDP Don

Posted by: marsbug May 25 2009, 04:17 PM

I'd suggest that buried ice exposed by small impacts (http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2168.pdf) at low elevations might be a better source of ephemeral liquid water, as it's an idea I've taken a shine to.

Posted by: dburt May 25 2009, 06:01 PM

Thanks. No problem with that very good idea either, although keep in mind that on very low-humidity Mars, exposed white ice or snow (alone) is much more likely to sublime (simply evaporate) than to melt. That's why I hypothesized dark rock or dust.

-- HDP Don

Posted by: marsbug May 25 2009, 08:27 PM

An small impact could do a good job of mixing dark rock and dust with ice....ok like I said it's my pet idea this month!

But, with regards to the presence of a frozen northern ocean, wouldn't a census of small craters churning up ice be a nice cheap way to map ice distrubutions at depths greater than a meter? I assume that's beyond the limits of current techniques or the ice turned up at these craters wouldn't have been a surprise! A job for someone with patience who doesn't mind combing HIRISE images of mars I think, with some follow up by CRISM to confirm that it is ice not just light toned soil .

Posted by: dburt May 26 2009, 03:32 AM

Interesting thought. In fact, I'd be surprised if someone hasn't already submitted a proposal to NASA to do something very similar (not that I've seen one yet). If not, someone (not me!) may well do so now that you've posted that excellent idea. (Sometimes you just gotta love academia...)

-- HDP Don

Posted by: marsbug May 26 2009, 08:37 PM

http://dailyheadlines.uark.edu/15090.htm (who's been known to hang out on BAUTforum and answer questions on the Phoenix mission), whose university of Arkansas group do a lot of work simulating conditions on mars.

Posted by: serpens May 27 2009, 02:40 AM

Thanks for posting the link Marsbug, it has all been very quiet on the Phoenix results analysis front. But there is a gap between between 'potential' to exist and 'do' exist. The article doesn't make clear whether the Mg perchlorate brine was introduced to the experiment, or if it formed naturally from ice deposits in the in the simulated martian environment of pressure / temperature / atmospheric composition and regolith. As Vincent has rightly pointed out elsewhere, the contentious 'droplets' on the lander legs do not prove the existence of brines on Mars, but are (whatever they may be) the result of the alien environment created by the landing and operation of Phoenix. Introduction of a formed brine to an experiment has the same caveat and the use of 'potential' in the article could reflect Vincent's normal and laudable, conservative approach. The TECP results did not provide any evidence of the development of films or brines. That doesn't mean they are not there - but it does reduce the likelihood.

Posted by: marsbug May 27 2009, 12:07 PM

I suspect it was introduced to the chambre to, but I'll ask. For anyone following this topic we're talking with Prof Chevrier http://www.bautforum.com/space-exploration/82316-phoenix-mars-results-4.html.

The evidence doesn't point to the phoenix site being rich in brine, but if a brine formed from components present at the phoenix site can be stable under accurately reproduced conditions then, given the size of the martian arctic, I'd bet my favourite coat (and it's a very nice coat, if a bit matrix-esque for every day use) that brines do occur, even if only rarely.

There is another thread, http://www.bautforum.com/life-space/86187-liquid-saltwater-likely-present-mars-new-analysis.html, where we were taking over the formation of brines with Hanna Sizemore, a phoenix team postdoc. She is adamant that even under ideal conditions the most liquid water you'd see at the phoenix site is a few monolayers. However she was fending off talk of liquid droplets on the landers legs, and even open pools of brine, so she might be willing to go as far as 'ten monolayers, in the right spot under the best conditions imaginable' or similar if she doesnt feel like the only skeptic in the room. I hope there's room in the martian arctic for a few exceptional microclimates where brine can form in detectable amounts, becuse I reeally like that coat!

It seems that stable brines can exist on mars, using solutes available at the phoenix landing site, and at the MER's sites and the viking 1 site (see link on post 40), and there are reserves of water ice at lattitudes as low as 45 degrees north (see link on post 44), so I'll eat the coat if there aren't a few damp patches up there from time to time. It's leather so I'll have to get a big tenderiser

Posted by: glennwsmith Jun 6 2009, 07:40 PM

And here's something hot off the press from the Imperial College of London which supports the possibility -- no, let's say probability -- of a frozen Oceanus Borealis. The link is as follows:

http://www3.imperial.ac.uk/newsandeventspg...-10-59-30#fni-2

Their thesis is that the Late Heavy Bombardment added huge quantities of water to the surfaces of both Earth and Mars. I quote briefly:

"They found that on average, each meteorite was capable of releasing up to 12 percent of its mass as water vapour and 6 percent of its mass as carbon dioxide when entering an atmosphere . . .Using published models of meteoritic impact rates during the LHB, the researchers calculated that 10 billion tonnes of carbon dioxide and 10 billion tonnes of water vapour could have been delivered to the atmospheres of Earth and Mars each year . . . However, researchers say Mars’ good fortune did not last. Unlike Earth, Mars doesn’t have a magnetic field to act as a protective shield from the Sun’s solar wind. As a consequence, Mars was stripped of most of its atmosphere. A reduction in volcanic activity also cooled the planet. This caused its liquid oceans to retreat to the poles where they became ice."

Posted by: serpens Jun 7 2009, 02:25 AM

As Glenwsmith indicated on another thread, Oceanus Borealis is linked to the Meridiana lake/playa hypothesis. Taking another look at some of the features in the north it almost seems time to dust off some of Nick Hoffman 's White Mars observations, but with a view to reconsidering some of these northern outflow features as submarine water flow turbidites rather than Nick's proposed cyroclastic (CO2) cause.

Posted by: glennwsmith Jun 23 2009, 02:26 AM

The possibility that there is a frozen Oceanus Borealis beneath the dust of the northern plains has implications far beyond Mars, of course. If I may be allowed to speak in an enthusiastic vein for a moment, consider that Mars is only the second planet that we have been able to "sample". Finding large quantities of water there would thus, in a sense, double the amount of water likely to be extant among the universe's population of rocky planets.

The verification of an Oceanus Borealis also increases the liklihood that we will find significant quantites of water on our own moon; or -- to put this in negative terms -- if Mars is cold and dry, this does not bode well for the success of the current LCROSS mission to the moon.

By the way, I'm sure most of you are aware of yet another recent paper pointing to the presence, at least in the past, of a significant body of water on Mars; the link follows:

http://www.colorado.edu/news/r/7e9c22ec0cd6dabc007bb14ed2e29f16.html

Posted by: serpens Jun 23 2009, 12:16 PM

http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1939.pdf

One of a number of papers dealing with Mars Aqueous Processes on day 3 of the 40th Lunar and Planetary Science Conference 2009 held in March. Just a touch of home town enthusiasm in the CU media release page.

Posted by: tim53 Jun 23 2009, 09:53 PM

I looked at this paper after I was notified of the press release last week. Their "shoreline" is a fault scarp in alluvium, similar to this example from Nevada. I worked there 30 years ago. It can be difficult to distinguish shorelines from fault scarps across the alluvial fans in the Great Basin because they often are directly associated with one another. This example is "easy" because there's a graben in front of the main fault, but there isn't always one. In this valley ("Dry Valley" I think it was called, though the map software doesn't show the name) west of Caliente, Nevada, the paleolake was rather small and didn't rise to the elevation of the fault scarp.

Fortunately, of course, we could drive up to and walk on the feature to help us determine what it was.

In the martian example, we can't do that (not for a while, at least). So I'm afraid that in my view at least, the paper fails to provide the extraordinary proof that the claim "This is the first unambiguous evidence of shorelines on the surface of Mars" represents. ...in addition to it simply being an untrue statement.

-Tim

Posted by: mhoward Jun 23 2009, 10:18 PM

Yeah, I'm no expert on these things, but I cringed at the word "definitive." I also notice that the Wikipedia entry for Shalbatana Vallis has been updated with this info, including the word "definitive," which I think might be a little premature.

Posted by: tim53 Jun 23 2009, 10:23 PM

I hate the word "definitive." All it takes is a reasonable doubt to make one look silly for using it.

As a result, probably a lot of people think I'm less sure of myself than I think I am!

-Tim.

Posted by: SteveM Jun 24 2009, 03:32 AM

Agree that "definitive" is out of place in most articles, and particularly in this one. I'd just ease off the criticism a bit since this is from UC Boulder's press office, not from the researchers.

Posted by: tim53 Jun 26 2009, 09:53 PM

Well, they may not have used that specific word, but the title of the paper is "Positive Identification of Lake Strandlines in Shalbatana Vallis, Mars" and the abstract says "first direct evidence of strandlines" and the conclusions say "first direct evidence of unambiguous strandlines," which is about as strong a statement as one can make.

Even if the specific feature had merit (it doesn't, unless one is interested in local structural geology), the degree of certainty expressed in the paper is unwarranted.

-Tim.

Posted by: glennwsmith Jun 27 2009, 05:41 PM

Serpens, thanks for the link to the actual Shalbatana Vallis paper -- it's darned interesting; and tim53, thanks for making me want to take a closer look. The point is made in the conclusion that billions of years of aeolian activity (journalese for wind!) have eroded most former deltas and shorelines, but these in the Shalbatana Vallis have managed to survive to some greater or lesser extent -- making this area a possible candidate for future (Mars Sciene Laboratory aka "Curiosity"?) landings.

Also, is anyone out there good enough with the Hirise dataset to be able to post a non-3D, maximum resolution image of the area represented by Fig. 3A in the paper? (This shows the putative shorelines.) I would be forever in your debt.

Posted by: MarsIsImportant Jun 30 2009, 07:23 PM

I suppose it would help to see the images before registering a "definitive" opinion on the subject.

But on its surface, the word definitive is rather strong. Even if the paper does not actually use that word and it is a reporting error, it does say "first direct evidence". As far as "first" is concerned, I doubt it. "Direct evidence" maybe somewhat subjective. I want to see the images in unambiguous HiRise first.

Posted by: Marz Jul 1 2009, 06:10 AM

FYI: NOVA's latest Mars show, "Is There Life on Mars", does an excellent job summarizing the latest results & discoveries from MRO, Odyssey, Phoenix, and MER.

http://www.pbs.org/wgbh/nova/mars/

It also briefly describes:
-- the giant-impact theory for the northern basin
-- possible climatic history
-- comparison on how Meridiani was very acidic with evaporite deposits, yet the chemistry of where Phoenix sampled was slightly basic (Calcium carbonate!), lightly salty, with perchlorate present (and how perchlorate may improve the chances for microbial life).

Posted by: Dominik Jul 1 2009, 07:39 PM

Too sad, it's only available for the audience in the USA .

I really would love to watch "Is There Life on Mars?".

Posted by: SFJCody Jul 1 2009, 08:13 PM

I imagine life could certainly have occurred on Mars in the past and may still be present today provided there is sufficient water underground. We know from the Martian flood channels that there were once vast TORRENTS (hint hint) of water on the surface.

Posted by: Juramike Jul 10 2009, 03:49 AM

Well....looking at the morphology of the channel networks, it appears that the channel networks were not formed by rainfall, but rather from subsurface reservoirs.

Check out:
Gulick, V.C. Geomorphology 37 (2001) 241-268. "Origin of the valley networks on Mars: a hydrological perspective." (pay for article, link http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V93-42G772H-5&_user=4420034&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000063005&_version=1&_urlVersion=0&_userid=4420034&md5=de7627ca31c37411d2ecc5a1ed909eeb)

Fully freely accessible articles (confess I haven't read these yet):
http://www2.ess.ucla.edu/~nimmo/ess250/baker.pdf

Carr and Head, GEOPHYSICAL RESEARCH LETTERS, VOL. 30 (2003) , NO. 24, 2245. "Basal melting of snow on early Mars: A possible origin of some valley networks". doi:10.1029/2003GL018575
(accessible http://www.planetary.brown.edu/pdfs/2976.pdf)


The Gulick (and others) articles give very good evidence that the valley networks were formed from subsurface sources (amphitheatre-headed valleys, very low drainage densities, low-Strahler order networks with high bifurcation ratios, etc.).

The valley networks are also very localized. One example in the Gulick article was of a dense valley system in Warrego Valles that was situated along a topographic break - yet neighboring areas also on the topographic break (same geology, same climate) were totally devoid of channels.

Their hypothesis is that Mars was covered in snowfall and melted in a few places due to magmatic activity and released water catastrophically. Other regions of snowfall that didn't melt quickly simply sublimed away slowly.

Posted by: SFJCody Jul 10 2009, 07:13 AM

Well, yes! The word torrent, according to wikipedia "generally signifies a strong flow of something, especially fluids and particles". By using it I was not implying that the channels were caused by precipitation.

Posted by: glennwsmith Aug 2 2009, 11:47 PM

Here's an interesting reference (on an interesting site) to Oceanus Borealis (about halfway down the page):

http://oklo.org/2006/12/

Posted by: stewjack Aug 3 2009, 02:36 AM

For those who wanted to watch the NOVA show Is There Life on Mars? produced by PBS; the full show is now freely available for streaming in six "chapters." ( 1 Hour show )

QuickTime or Windows Media Player streaming formats are provided.

NOVA: http://www.pbs.org/wgbh/nova/mars/program.html

You won't get a review from me. No way!

Posted by: kohare Aug 3 2009, 09:41 PM

But only available within the USA

Posted by: RJG Aug 3 2009, 10:34 PM

Quite by chance I found that I could watch it on my laptop - then realised it was because I was running Hotspot Shield (http://anchorfree.com), a freebie on a recent cover disk. As a side effect, Hotspot Shield appears to confuse the server into thinking I'm in the US...

Rob
(UK)

Posted by: stewjack Aug 3 2009, 11:53 PM

I apologize. I don't see anything about that on the web page. They fail to mention it in the technical help section also.

Posted by: glennwsmith Sep 14 2009, 03:02 AM

Just a reminder to participants in this thread (which should really be entitled "Oceanus Borealis") that we are fast approaching the climax of the LCROSS mission to search for water at the lunar south pole, the results of which have a major bearing, it seem to me, on whether we can also expect to find a frozen ocean hidden beneath the dust of the northern plains of Mars.

Posted by: Juramike Sep 14 2009, 04:33 AM

Hmmm. Not sure on that. If I got it right, the volatiles on our Moon were delivered by comet impacts long after it's formation, spraying volatiles all over, some of which settled in cold traps (permanently shadowed craters).

The water on Mars presumably was there from it's formation and is residual from it's early days.

(Trying to figure out predicted H/D ratios, here....Mars should be HDO enriched from several cycles of evaporation/sputtering-loss of lighter mass H2O/recondensation. The Moon on the other hand should be closer to the primordial H/D ratio - thes more H2O. If anything ever evaporated it would be a one way trip off Luna....)

Posted by: glennwsmith Sep 16 2009, 05:01 AM

Yet another indication of -- dare I say it -- water on Mars:

http://spacefellowship.com/2009/09/15/evidence-of-dry-lake-beds-on-mars/

And in reference to Oceanus Borealis, the idea as I understand it is that a meteor impact can melt part of the underlying frozen ice ocean, which in turn dries up to leave the polygonal formations which we see today.

Posted by: Fran Ontanaya Sep 16 2009, 07:09 PM

If those cracks are so ancient, why aren't they filled here and there with dust?

Posted by: dvandorn Sep 17 2009, 01:03 AM

I would say that ground cracks that aren't filled up with dust occur because the process of dust deposition v. deflation has achieved a dynamic stability on Mars. The winds giveth, the winds taketh away...

-the other Doug

Posted by: glennwsmith Sep 22 2009, 12:57 AM

There's a new report out that results from the Indian lunar mapper (announcement coming up) indicate that there's "lots" of water on the Moon

If that's the case, then there's "lots^^2" water on Mars. I believe, in fact, that we are establishing a new paradigm -- just as we are now learning that planets are plentiful in the universe, so we are also learning that the rocky bodies among them are loaded with water -- Mars, the apparent desert planet, included.

I know this is the kind of wild statement that cautious thinkers abhor, but I can't help it -- it's in my genes.

BTW, I think Fran asked a good question about the desiccation cracks and the other Doug had an equally good answer.

Posted by: glennwsmith Sep 25 2009, 12:23 AM

Two back-to-back articles on the JPL web site about water on the moon and Mars, respectively -- in the unlikely event that there's a UMSFer somewhere who has not yet seen them:

http://www.jpl.nasa.gov/news/news.cfm?release=2009-147

http://www.jpl.nasa.gov/news/news.cfm?release=2009-148

Sept 24, 2009 -- a big day for space junkies indeed.

Posted by: MarsIsImportant Sep 25 2009, 12:53 AM

hhmmm! So water ice and sublimation is a much more significant process on Mars than previously thought...not a big surprise to me personally. The big surprise is the Moon. But if comets brought water to Earth, then it makes sense that they would bring it to the Moon too.

Posted by: Greg Hullender Sep 25 2009, 01:49 AM

It wouldn't have stayed on the moon very long, though, if it came from comets. Current thinking seems to be that the lunar water is produced by the solar wind. I'd doubt if very much (if any) Martian water arrived that way.

--Greg

Posted by: climber Sep 25 2009, 05:45 AM

"Water" on Mars guys! Ice visible at mid latitudes from HiRise: http://www.spaceref.com/news/viewpr.html?pid=29232
BTW, Astro, where is the new emoticon you shown us recently?

Posted by: serpens Sep 25 2009, 08:58 AM

The identification of ice in a new crater is a good find. But I feel that Shane Byrne is a bit quick off the mark to claim cause and effect and state that "This ice is a relic of a more humid climate from perhaps just several thousand years ago."

Ice underlying the regolith within centimeters of the surface as a recent deposit - perhaps. A relic of an older warmer wetter past - perhaps. Or the residue from ice meteorites that left icy residue that gradually sublimated. The latter would seem more in keeping with the observation that the ice was a thin layer overlying darker material.

Posted by: Julius Sep 25 2009, 05:21 PM

i think we should perhaps revisit Viking 2 science results...any news from the radar team as to th thickness of water ice in mid latitudes of Mars??

Posted by: Fran Ontanaya Sep 26 2009, 01:55 PM

Well, at the scalloped terrain of Utopia Planitia (46º) the sublimation pits are quite deep:

http://www.unmannedspaceflight.com/index.php?showtopic=5420&st=285&p=127173&hl=TRA_000856_2265&#entry127173

Posted by: Julius Sep 26 2009, 06:54 PM

Are we sure those craters spotted recently are impact craters or explosive??water ice sublimating ?similar to the spider structures seen at the poles except that the mechanism for the latter seems to be C02!

Posted by: djellison Sep 26 2009, 10:14 PM

If you can suggest a method by which they can suddenly appear, in a cluster, with ejecta and occasional airburst patterns....go for it.

Posted by: glennwsmith Sep 30 2009, 03:03 AM

Does anyone have a sense of the distribution of these ice paved craters relative to the presumed outline of Oceanus Borealis? And a related question: do these craters all fall within basins or low lying regions, or regions which were at one time low lying?

Posted by: glennwsmith Oct 28 2009, 04:58 AM

In an earlier post in this thread, I made the not-original observation that the many pairs of trained amateur eyes of UMSF members could play an important role in interpreting the visual evidence for an Oceanus Borealis.

That concept has now been endorsed in a big way on APOD, but in reference to galaxy structure. It's pretty darned interesting:

http://antwrp.gsfc.nasa.gov/apod/ap091026.html

Posted by: JohnVV Oct 29 2009, 03:06 AM

and to think i made this image 6 years ago ( 100% fictous ) based ONLY on an average mola height
1024x512
[attachment=19418:1kBlueMars.jpg]

too much ice ,no weathering , ...
it dose need to be remade

Posted by: glennwsmith Oct 30 2009, 04:26 AM

JohnVV -- way cool! My effort understandably did not pass Phil's muster, but perhaps yours will!

Posted by: JohnVV Oct 30 2009, 08:44 PM

mine is so old and has almost 0 scientificly included data it is just an "Artistic" interpertation
It dose look nise though ,I did get a request from a componey to use it in a video for Nat'l Geo chanel

Posted by: glennwsmith Nov 13 2009, 05:52 PM

Re the recent LCROSS press conference: At least some water at lunar poles = LOTS of frozen water -- indeed, an Oceanus Borealis -- under the dust of the northern Mars plains !!!!!!!!!!!!!!

Posted by: nprev Nov 13 2009, 08:37 PM

Uh...Not to put a damper on the ecstasy, Glenn, but we are talking about two completely different planetary bodies with equally different environments & apparently radically different means of acquiring/depositing water in their polar areas.

Don't think that you can reasonably infer an a=b relationship here.

Posted by: centsworth_II Nov 13 2009, 09:04 PM

Maybe he's just speaking semantics: If a few buckets full can be a lot of water on the Moon, then an Olympic pool volume of water on Mars can be an ocean.

Is Mars jealous? Are we making too much of the Moon's shiny new outfit?

Posted by: imipak Nov 23 2009, 09:02 PM

Luo and Serpinski, "Computer-generated global map of valley networks on Mars" in JGR-Planets (http://www.agu.org/pubs/crossref/2009/2009JE003357.shtml) is picking up a fair amount of coverage. (e.g., http://www.sciencedaily.com/releases/2009/11/091123094122.htm, http://www.universetoday.com/2009/11/23/large-ocean-extensive-river-network-rainfall-on-ancient-mars/.) The visualisations look plausible to this layperson; can anyone comment on the methodology?

Posted by: Phil Stooke Nov 23 2009, 09:57 PM

Oh dear... I dreaded this. It all looks so good. But it's based on computer analysis of topographic data. It shows where water would flow, but it does nothing to prove that water has actually flowed in those locations. The same algorithm applied to a lunar highlands topographic data set would identify similar valleys (Hint - someone please try this!). Sorry, but there it is. Here's a bit of Apollo topography (digitized stereo contours made into a DEM) from my atlas. Look at the topography on the rim of the Crisium basin. This algorithm would fill it with valleys.

Phil

Posted by: JohnVV Nov 23 2009, 11:51 PM

your statements above ARE one of the reasons i state that my map is 100% artistic

we do know that water was ( and is ) there juts not where and when the water was
0% information ( close to that, maybe 5% ) for what areas had it and when they had it .

and this will not change much until we have "boots on the ground" and can study it

Posted by: Phil Stooke Nov 24 2009, 02:57 PM

The map is very nice - but look how it's suddenly taken up in the press as proof of an ocean. It is suggestive, but so was the previous work. The fact of mapping more valleys than past workers did does not by itself prove there was more water. To my mind, every valley identified here must be compared with good modern images to determine whether or not it is real. I'm not trying to put down the hard work of doing the mapping, but I don't trust watershed algorithms very much. They create their own reality.

Phil

Posted by: glennwsmith Nov 25 2009, 03:56 AM

imipak, a most interesting post! And Phil, your points are well made also.

The thing that impresses me about the trajectory of modern astronomy is how familiar a place the universe is turning out to be. The surface of our own planet is four-fifths water; we have seen entire moons of Saturn and Jupiter which seem to be nearly 100% water worlds; and we have now found water on the moon. So I am not going to be surprised if the Mars map which imipak has pointed us to turns out to be correct.

Posted by: nprev Nov 25 2009, 05:19 AM

True. Considering that even the lunar maria were considered literally that not too long ago (relatively speaking), we seem to have had a predisposition to think of 'water on a planet' in terms of oceans by analogy with the Earth. No oceans=bone dry.

The thing to be wary of is swinging to either extreme (again!); the truth always lies somewhere in between.

Posted by: ustrax Nov 25 2009, 02:30 PM

Content deleted - AstroBio rule Ustrax!!!!!

Naughty.


ADMIN

Posted by: ustrax Nov 25 2009, 03:06 PM

Aaaaaargh!

Posted by: glennwsmith Nov 27 2009, 07:44 PM

imipak, your post has really added some fuel to the fire; so let me ask this question:

If -- as now seems likely -- there was an Oceanus Borealis, do we really have the physics to account for its subsequent "sublimation" (I know this is not the correct word) into space; or is it not more likely that -- as I believe -- much or most of this ocean lies frozen still beneath the dust of the northern plains?

Posted by: Doc Nov 27 2009, 09:22 PM

This research is quite interesting. But does not prove much as you guys have expertedly pointed out. The media are sure selling this discovery though...

However, what still strikes me as rather convincing evidence is the beautiful symmetry of the valley distribution. To say that they are random and so on would be rather unfair. Forgive me for being a little philosophical.

Posted by: mcaplinger Nov 27 2009, 09:31 PM

The likelihood that there was a lot of water on Mars at one time is old news (Mariner 9 at least) and certainly lots and lots of work has been done on the escape rate of water (see, for example, "Water loss and evolution of the upper atmosphere and exosphere over martian history", Valeille et al, in press at Icarus.) That paper concludes that "a conservative estimate of about 10 m of water is found to have escaped globally to space over the last ~3.5 Gyr."

I don't think that it's very controversial at all that there could be a lot of frozen water on Mars, so I'm a little confused by your implication that this is some big revelation and/or recent news. There is a long way between "has water" and "Earthlike".

Posted by: Doc Nov 27 2009, 09:42 PM

Interesting news about ALH 84001,

http://www.newscientist.com/blogs/shortsharpscience/2009/11/fresh-claim-for-fossil-life-in.html

Link to abstract,

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V66-4WJ3DX3-1&_user=10&_coverDate=11%2F01%2F2009&_alid=1110069163&_rdoc=1&_fmt=high&_orig=search&_cdi=5806&_sort=r&_docanchor=&view=c&_ct=120&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=16ee9b784c5954b574478541063feb26

Posted by: ngunn Nov 27 2009, 10:01 PM

Interesting, sure. (I heard it first on Cumbrian Sky - thanks Stu.)

But probably best not discussed here.

Posted by: djellison Nov 27 2009, 11:01 PM

Indeed - it's in direct breach of forum rules.

Posted by: JohnVV Nov 28 2009, 03:20 AM

that rock again??
but if one thinks about it ...
It was "unmaned" on it's way here ,BUT it is NOT a spacecraft.

Posted by: djellison Nov 28 2009, 06:20 AM

That's not why it's against forum rules.

Posted by: Loiserl Dec 3 2009, 02:03 AM

I was checking some stuff from Mars Global Surveyor and then I came across this image: http://ida.wr.usgs.gov/fullres/divided/r09011/r0901196a.jpg

You could see the rest here: http://ida.wr.usgs.gov/html/r09011/r0901196.html
It's very strange!

Posted by: nprev Dec 3 2009, 02:44 AM

Those are dust deposits left on the south polar ice from abrupt sublimation of subsurface CO2 deposits as spring approaches, Loiseri. http://news.bbc.co.uk/2/hi/science/nature/5268892.stm.

Posted by: JohnVV Dec 3 2009, 09:32 AM

Loiserl i had forgotten about that " pine tree" image

if one looks hard enough one can see many things in the images ,
i a diff. thread there is a pic of many "earth" things in a mer photo

Posted by: Juramike Jan 10 2011, 09:16 PM

Interesting paper in JGR: Arkani-Hamed, J. (2010), Possible crippling of the core dynamo of Mars by Borealis impact, J. Geophys. Res., 115, E12021, doi:10.1029/2010JE003602. Pay-for article abstract link: http://www.agu.org/pubs/crossref/2010/2010JE003602.shtml

According to the author, the whack that formed Vasitas Borealis may have also "quenched" the core. Did 120 Myr of no magnetosphere permanently alter Mars's evolutionary path?

Posted by: Fran Ontanaya Feb 7 2012, 07:33 AM

ESA's Mars Express radar gives strong evidence for former Mars ocean

http://www.esa.int/esaMI/Mars_Express/SEMVINVX7YG_0.html

Posted by: machi Feb 8 2012, 12:46 AM

And some support for this theory comes from different instruments.
Here is evidence from Odyssey's GRS spectrometer - http://www.watergeek.net/geek/GRS_oceans_in_press.pdf

Posted by: rlorenz Feb 8 2012, 01:00 AM

Emily's Blog
http://www.planetary.org/blog/article/00003365/
discusses this work (by Mouginot et al., in GRL) in nice detail. There is a
contour of dielectric constant that matches other estimates of the extent of
Oceanus Borealis : this must surely be the 'Mouginot Line'........

Posted by: elakdawalla Feb 8 2012, 01:13 AM

Aaargh!

Posted by: machi Feb 8 2012, 01:24 AM

That's almost Monty Python's grade!

Posted by: nprev Feb 8 2012, 02:28 AM

Thanks, Ralph. I may require surgery to remove the wince from my face....

Posted by: ngunn Feb 8 2012, 02:28 PM

A relevant LPSC abstract on the stability of subsurface ice:
http://www.lpi.usra.edu/meetings/lpsc2012/pdf/2260.pdf

Posted by: ngunn Feb 8 2012, 11:29 PM

I'll add a couple of comments about the abstract just posted. First, it shows that ice at 1m depth is stable down to latitude 40. That makes the story about the dielectric constant in the recent ESA press release (reported so clearly by Emily) a bit less tidy, I think. Second, they provide a graph on which there is really only one point of interest: for a single depth the critical latitude is 40 degrees. This leaves me with questions. How does the critical depth for ice survival vary with latitude? What is it at the equator?

Posted by: TheAnt Mar 31 2012, 04:30 PM

Once upon a time we thought that there had been lakes in Valles Marineris. It was actually not that long ago, but around the time of the Viking lander/orbiter mission.

Then more lately when "our" rover Opportunity started to drive around in Meridiani Planum. It was at first thought to be a lake bottom or even might have been part of one inland ocean.

This idea had the problem with the local geography that could not really contain a lake, but also that nobody could find any shoreline for it. Add to that the finding that the water must have been quite sulfurous it would not have been any ordinary lake at all. Our planetary scientists then proposed a sort of marshland surrounded by desert as mr Squires have talked about in his updates about the mission.

A solution to this problem might be found in the text below which describe research that show how glaciers could have collected sulfur and ash from volcanic eruptions and so would have become quite acidic and resulted in the landforms, sediment layers etc, that we previously have thought formed by running water.

I have not been ready to embrace the cold Mars theory for a number of reasons, among them some sedimentary deposits and what appear to be river beds.

Now glaciers do the same work in creating valleys with flowing curving paths that look what we humans think of a riverbeds.
Many river valleys in my area were in fact first made by glaciers, it is only later that water have taken the same path.
One lingering mystery on Mars have been that we found no clays at first, we've found some now in later years, yet rivers that would have flown for a longer would have produced clays, but glaciers can indeed have this impact on landforms without producing much so also this fit with the observations.

Now that it turn out that these non-volcanic sediments are glacial in nature. And that water located under the icesheets that might have hydrated the minerals. I have finally started to cave in to the idea.
So to me this appear the cold and dry Mars scenario get increasingly more plausible. And we might very well have had one earthlike Mars, but only very early in the history for the planet.
(And this the reason I posted this, and with any apology if there's another thread started on this matter elsewhere.)


http://www.marsdaily.com/reports/Dusty_Acidic_Glaciers_Could_Explain_Layered_Deposits_on_Mars_999.html

Posted by: Explorer1 Apr 1 2012, 06:21 AM

Aren't glacial valleys U-shaped while liquid rivers form V-shaped valleys? Basic physics are universal as far as I've heard.

Posted by: Phil Stooke Apr 1 2012, 11:59 AM

That may be true but it doesn't tell us much here, with 3 billion years of talus formation obscuring the original shape.

Phil

Posted by: TheAnt Apr 2 2012, 10:34 AM

Yes that is very true. And river like features might have been created in shorter time spans than what one might think.

Since the late Pliocene glacial period here on Earth glaciers and rivers have alternated in shaping the valleys of the arctic and sub arctic regions, in some cases creating new flows and breaking trough ridges as late as in the last 10.000 years.
So those valleys have been created in a very short time, and have either shape without conclusively telling which way it got started originally. And this might be a good analog for Mars, where some valleys have been carved by both water and ice.

@Explorer1: This finding by the Planetary science institute researchers do not rule out all formations as possible ancient lakes or river beds. There's no doubt there have been liquid water in some places like http://www.msss.com/mars_images/moc/2_2_98_release/8704/, that have relatively few craters and so appear to have had a flow in a more resent age.
The question is of that valley were filled with water in one of the 'flash floods' described in some models, or that water did flow for a longer time under one ice sheet or even beneath a glacier. Stating "Sustained Water Flow?" with a question mark there.

The main point of that Mars daily item is that the layered deposits that have been found in many other areas might have been created by glaciers and not by pools or lakes of liquid water as previously thought.
Since the studies by the MER rover is of great interest for many on this forum I found it interesting that the text mentioned that such glaciers might be the explanation for the deposits found by Opportunity at Meridiani. I still wonder if that is consistent with the hints of karst topography that's been seen there though.

Posted by: TheAnt Aug 18 2012, 01:22 PM

Well it seem that Mars have more signs of plate tectonic activity

The item describe this as entirely new, yet I am certain that many of us Marsophile people here on this forum are aware that the shield volcanoes of Tharsis montes looked quite similar to certain features on Earth where a continental plate have moved over a hot spot of the mantle. (Those from USA might compare to volcanos of Hawaii)
Whereas Valles marineris already have been suspected of being a feature similar to Rift valley in Africa.

http://www.sciencedaily.com/releases/2012/08/120809155831.htm>Science daily on Plate Tectonics On Mars</a>

Edit to get a working link.

Posted by: elakdawalla Aug 18 2012, 02:53 PM

If the press release is anything to go by, the paper is just plain bad. However I have enough experience with press releases to know that the release may not accurately represent what's in the paper. In either case, there is no evidence for Earth-like plate tectonics on Mars. The faulting in Valles Marineris is pretty convincingly a result of loading etc. from the Tharsis complex.

Posted by: Phil Stooke Aug 18 2012, 03:33 PM

There has also been an attempt to explain the northern 'ocean' basin as a product of plate spreading. I'm not at all convinced. If you want to demonstrate plate tectonics you would need a global pattern of tectonics, not a local one resembling a product of horizontal motion. The image I've seen, in Melas Chasma, doesn't look like strong evidence to me, but I will admit I have not yet seen the full paper.

Phil

Posted by: TheAnt Aug 18 2012, 04:04 PM

Thank you both.

Yes I did feel a bit hesitant on this item also, why I used 'signs of' (perhaps should have added 'that could have been interpreted as' in addition to the the 'look similar' and 'suspected'.

And I did indeed think the headline "Scientist Discovers Plate Tectonics On Mars" were a bit jumping to a one unproven conclusion. Yet I did find this item interesting enough for a heads up. =)

Posted by: Ron Hobbs Aug 18 2012, 05:17 PM

The author of the Science Daily article seems to unaware of the Mars Global Surveyor findings a decade ago. A search turned up the 1999 press release right away.

http://science.nasa.gov/science-news/science-at-nasa/1999/ast29apr99_1/

I wonder if Yin referenced that discovery in his paper. Anyway, he was certainly not the first to discover evidence of incipient Martian tectonics. At least the NASA release was a bit more tentative with the inclusion of the question mark.

Posted by: dvandorn Aug 19 2012, 03:12 AM

There are several Martian "features" which do resemble the results of plate tectonics on Earth, like the moving hot spot that seems to have left volcanoes all in a row in Tharsis, and the magnetically striped surface in the southern heavily cratered terrain.

However, as Phil very rightly points out, there are no features extant on Mars that suggest plate subduction. I can imagine a number of different possible models, including an early period when Mars' crust was rotationally uncoupled from the mantle, which could account for the tectonic-like features we do see. After all, there seems to be good evidence that the Moon's solid crust and nearly solid mantle are even now rotationally uncoupled from its small, purportedly molten core. Perhaps impacts large enough to leave enormous basins, like Imbrium or Hellas, have the ability to uncouple the crust from the mantle for shorter or longer periods of time.

-the other Doug

Posted by: Phil Stooke Aug 19 2012, 09:42 PM

On Earth hotspots stay fairly static and the crust moves over them. If Tharsis Montes are formed that way why is Olympus Mons alone? (you would need a massive strike-slip zone between them to keep OM single). Also there's no obvious age sequence from Arsia to Ascraeus and we have three giant shields instead of a chain of many small ones, so it's a very poor match to the terrestrial example. The magnetic anomalies are more on a scale with the 'fossil mountain ranges' recorded in magnetic maps of the Canadian shield (Grenville and so on - check out any mag map of North America) - not the narrow stripes that suggested seafloor spreading. So I have to say I'm not a big fan of any supposed Martian analog of Plate Tectonics.

Phil

Posted by: Ron Hobbs Aug 22 2012, 09:13 PM

Thanks, OD and Phil, for filling in some of the background on this debate. Until this topic popped up here, the MGS release was all that I knew about the issue. I naively assumed that the notion of incipient tectonics was fairly well accepted. Thanks for setting me (and us) straight.

That is what I love about this site; I learn all kinds of things I would not have access to otherwise.

Posted by: paraisosdelsistemasolar Aug 26 2012, 10:12 AM

I know and understand that the debate over plate tectonics in Mars is a very difficult one: It stopped a long time ago, the erosive and depositional processes might have erased and buried some superficial features linked to plate tectonics and also it's possible that Mars had a different kind of plate tectonics. But when someone asks me about plate tectonics in Mars, I show them this image, because I think it states my opinion better than I can do:

What do you think?

Posted by: TheAnt Aug 26 2012, 12:37 PM

You have one excellent example there, the bottom part as seen on this image have moved to the left, as seen in the center and near bottom left on that image.

It would be nice if you provided us with information of the location and scale of that image.

Posted by: paraisosdelsistemasolar Aug 26 2012, 02:25 PM

Of course I can give you the link. It's a HiRISE image taken in Ius Chasma. The link of the observation page is: http://hirise.lpl.arizona.edu/TRA_000823_1720

Posted by: elakdawalla Aug 26 2012, 03:51 PM

There's a big difference between "tectonics" and "plate tectonics." Nobody will dispute the claim that there has been tectonic activity on Mars, the brittle deformation of rocks in response to geologic stresses. Various events on Mars cause the kinds of stresses that result in tectonic deformation. Things like massive Tharsis volcanism loading the crust, making it bend downward and flex outward, caused a lot of fracturing etc. Things like true polar wander, where the outer rigid shell of Mars may have moved independently of the core as a result of uneven mass distrubution (again, Tharsis) making it rotationally unstable until the outer shell rotated to put the center of Tharsis on the equator. Since spinning planets are fatter through the middle than pole-to-pole, this motion would've required a shape change of the outer shell that would have caused major stresses that would have caused tectonic deformation. On a smaller scale, you see wrinkle ridges throughout volcanic plains that result from the downwarping of the crust after loading with the weight of those lava flows.

"Plate tectonics" is a specific theory of how a planet redistributes its internal heat through the convective motion of a mantle that behaves as a fluid, coupled to a rigid, brittle outer shell, such that the shell breaks into large plates and nearly all tectonic activity on the planet is concentrated at plate boundaries, which are (to a first-order approximation) also the boundaries between mantle convection cells. To say that plate tectonics is happening, you have to show that tectonic activity is only occurring along plate boundaries, and that it results from convection in the mantle.

Posted by: dvandorn Aug 26 2012, 04:02 PM

I was just preparing the exact same post, Emily. Tectonics are evident on every body we've looked at closely in the inner solar system. You can find such fault movements (I want to call it a strike/slip fault, but I'm not certain enough of my terminology to say that definitively), as shown in the Ius Chasma image above, on the Moon and Mercury fairly easily, if you know what to look for. I believe there are similar features on Venus, as well. And wrinkle ridges are quite common everywhere that the weight of enormous lava flows has put pressure on the underlying crust.

But the only place we've seen actual evidence of plate tectonics is here on Earth. At least, thus far.

-the other Doug

Posted by: paraisosdelsistemasolar Aug 26 2012, 05:07 PM

Hi again,

I perfectly understand what Emily and Doug want to say, and they are completely right. Of course there is a difference between tectonics and plate tectonics. But, why did I choose this image instead of using one of the thousand pictures of faults in Mars as a point to plate tectonics? Because it's inside the Valles Marineris system, and if we accept the idea that Valles Marineris is a martian rift system we can say that is a divergent margin between two plates.

Of course, I'm not saying that there is a plate tectonics like the one we have in Earth (we don't see, for example, a bimodal height distribution between continental crust and other kind of crust, except the difference of Northern highlands and Sourthern highlands), but accepting the idea of the rift system I think it's necessary to accept the presence of convective motion under the crust to create a rift system.

But, as everything in Mars, we need more data to create a better picture of it's crustal structure and thermal evolution. Maybe Mars lost a very important quantity of heat through vulcanism at a very high rate and wasn't able to develop a plate tectonics like the one we are used to.

Posted by: dvandorn Aug 26 2012, 05:29 PM

Now, *my* best understanding of the rift systems on Mars is that they were created as the weight of the Tharsis Bulge distorted and cracked the underlying crust. No mantle convection or crustal plate processes are required for a rift system to form, just enough weight on the crust to make it crack apart around the heavy weight that's distorting the crust in the first place.

What I have always found interesting is that it appears only the crust to the south and east of Tharsis cracked under the weight. The crust to the north of the bulge doesn't seem to show the same kind of crustal cracking that formed the rift systems.

-the other Doug

Posted by: paraisosdelsistemasolar Aug 26 2012, 05:51 PM

Of course, Tharsis Bulge was also responsible, but I think there is also necessary to have some ascending hot material coming from under the crust. I don't want to say that there is a lot of effusive volcanic activity in the rifts, of course, as there is no proof of that. Maybe a mixed mode rifting in which crustal extension due to Tharsis Bulge and a high thermal regime was able to form the rift.

That's my modest opinion, I wish we had more data (or even a field trip!)

Greetings

Posted by: dvandorn Aug 26 2012, 05:59 PM

This is one of the reasons I'm so excited about getting some actual heat flow information from Mars, so we can begin to intelligently model Mars' thermal history.

-the other Doug

Posted by: serpens Sep 1 2012, 11:43 PM

That makes good sense. So the Tharsis volcanic chain could be a result of this crustal movement (as opposed to plate migration as on Earth or the concept that the hot spot moved beneath a stable crust)? If so wouldn't the reasonably short chain length indicate that the Tharsis Bulge was close to the then equator and so the crustal rotation would have been fairly small?

Posted by: Dysgraphyk Sep 12 2012, 05:45 AM

I haven't found mentionned here this article of Nature geoscience, so I go for a fisrt post

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1560.htmlhttp://

Brian Hynek
Nature Geoscience
(2012)
doi:10.1038/ngeo1560


Abstract :
Clay minerals on Mars have been interpreted as an indication for a warm, wet early climate. A new hypothesis proposes that the minerals instead formed during brief periods of magmatic degassing, diminishing the prospects for signs of life in these settings.

apparently the author identified in Mururoa Atoll basalts (famously drilled and investigated during french nuclear testing experiments), clays mineral formed not by weathering, but by magmatic degassing (with of course water in magma gas ). This indicate an other possible way to produce clays, and deacrease the automatic link for martian geology beetween clays and liquid water.

Posted by: TheAnt Jan 4 2013, 08:14 PM

A small meteorite found in Sahara might be from the crust of the planet and from the Amazonian period.

NWA 7034 contains somewhat more water than what is usual for Martian meteorites, also organics of a type that suggest the molecules have been created in a non-biological process.

http://carnegiescience.edu/news/first_meteorite_linked_martian_crust

Posted by: stevesliva Jan 4 2013, 10:41 PM

They think most other martian meteorites came from the mantle?!

Posted by: centsworth_II Jan 5 2013, 01:38 AM

Re: "...researchers have identified a new class of Martian meteorite that likely originated from Mars’s crust."

I think the likeliest interpretation is that of all meteorites likely originating from Mars's crust, this represents a new class.

Posted by: TheAnt Jan 5 2013, 10:07 AM

I think not, mantle material would be something. =) I happened to mention that word 'crust' since the text is several times are phrased in a way that it make a point of: '"It is the first link thus far of any meteorite to the crust."
Without making the matter clear if they identified similar volcanic crust material on Mars from orbit, or something else.

The second part about the organic molecules are another piece of the puzzle, they do not say so directly only referring to "other Martian meteorites" but it have been noted that the magnetites found in AH 84001 could have worked as a catalyst for the organic macromolecules found in that meteorite. Now in the case of NWA 7034 it is feldspar and iron oxide. This work is important since such non-biological processes that produce macromolecules have implications for both current (MSL with SAM) or future instruments flown to Mars.

Posted by: stevesliva Jan 5 2013, 09:57 PM

This is a little clearer, even coming from Faux Scientist:
http://www.newscientist.com/article/dn23040-unique-meteorite-hints-mars-stayed-moist-for-longer.html

"This suggests the known meteorites came from deeper inside the Red Planet." -- I guess that means below any layer that's weathered?

Posted by: ngunn Jan 5 2013, 10:13 PM

When you have a pot on the boil the crust is easy to discern: it's the stuff that doesn't always sink. That's easy to identify on Earth, but what does 'crust' mean on Mars?

Posted by: TheAnt Jan 5 2013, 10:53 PM

Thank you stevesliva, a lot clearer even.
Your quote suggest that previous meteorites from Mars are thought to have been ejected in the most major and powerful impacts on Mars and so came from some depth, whereas this one perhaps got started somewhere on the perimeter of one such, or even from a grazing impact.

In some papers on Martian geology the authors have used the phrase 'The upper Martian crust" - I now tend to think that is what they intended to say in the Carnegie press release I linked at first.