[X] My Assistant

[djellison]

It seems to me that breaking specific conversations out into separate threads in the Mars topic would provide a natural order to this brawl,

And as I have said before - no. This remains a theory that is against the mainstream view. Don's efforts are appreciated Other members would have had posts deleted for that sort of behaviour he is getting away with here. We have decided within the admin subforum that this subject should remain within this one thread. He's already recieving more than fair treatment - the condition is that the subject remains contained here otherwise every thread turns into an athena-vs-burt argument, and that's not going to happen. There are other forums which might be more open to a fragmented debate about this issue - this is not one. End of issue.

Doug

[MarsIsImportant]

Dr. Burt

I have a lot to respond to, so please be patient with me. I may need a series of posts, especially when I start listing out evidence.

First of all, I compliment you for directly pointing out some of the possible faults of the Glotch paper and the source hematite sample used. That was needed, but it still is a strong piece of evidence. The conclusions you attributed to me were not mine. I cannot in all honesty take any credit. Let me quote directly from the Glotch paper itself:

Given the [001] dominated emission of the spherules, it
is likely that they formed at low temperature, thus ruling out
such formation mechanisms as impact melt spherules, volcanic
lapilli, or other mechanisms that do not create hematite dominated
by [001] emission.

I stated myself that it was only one piece of evidence. This was a laboratory experiment and just one comparison study. It is convincing but not absolute. You could always repeat the experiment yourself using a hematite sample that you feel is more appropriate.

....more posts to follow soon.

[MarsIsImportant]

...to respond to post #210

Dr. Burt

This may take a long time and many, many posts. Let me state that I had hoped to stay on topic target by discussing primarily your alternative hypothesis. I had hoped that you would provide distinguishing characteristics that would be found only if your alternative was more correct...distinctive characteristics that would reasonably be found from an impact surge, yet not with the mainstream theory. Instead of offering tests for your own hypothesis, you continually offer up only tests for the mainstream hypothesis. To be fair, you did list supposed positive evidence for the impact surge, yet everyone of them is POSITIVE evidence for the mainstream hypotheses if you interpret those features differently. So none of them provides any distinguishing characteristics. I must conclude now that I should not expect any. Is this fair? Well, there is no good Earthly analog to your impact surge hypothesis; so maybe some of these characteristics are difficult to predict. It's your hypothesis; but, I suspect that I should try to come up with some of my own.

I appreciate your listing the characteristics expected if the mainstream hypothesis is more correct. It will help tremendously, primarily because it is all in one place. It is rather a long list. I will deal them one at a time.

Before I get into them, I would like to point out that you did not respond to my one previously proposed test for your hypothesis. You did seem to respond to that particular post but not to the proposed test(unless I missed something). Unless you object, I will assume that it is a good test.

...to quote myself

Edit: http://volcanology.geol.ucsb.edu/saltlake.gif

http://volcanology.geol.ucsb.edu/hydro.htm

"Bedding sags form by the impact of ballistically ejected bombs, blocks and lapilli upon beds capable of being plastically deformed. They are common in hydroclastic deposits of many maar volcanoes, tuff rings and tuff cones. Beds beneath the fragments may be completely penetrated, dragged down and thinned, folded, or show micro-faulting (Heiken, 1971). Deformation is commonly asymmetrical, showing the angle and direction of impact if three-dimensional exposures are available. These differ from dropstones in glacial environments in that dropstones fall perpendicular to the bottom, symmetrically indenting bedding and rarely, if ever, penetrating."

The spherules would be the lapilli in this case.

We should see some sort of evidence similar to this, if the impact scenario is more on target.

Not all of the lapilli would be expected to completely solidify before hitting the ground. So we should also expect some evidence of deformity of some spherules that is indicative of impact. I know of no examples. I will be on the look out for them.

This whole process will take some time. This will require a good deal of primary research. And it must be done on my spare time. Please understand that I also have a day job that must be attended to. So, this may take quite a bit of time.

[ngunn]

A quickie - Why only haematite? Where are all the 'hailstones' made from the many other materials that presumably condense out of an impact surge in similar fashion? Oh . . I know - leached away by groundwaters.

[silylene]

A straw poll (and given the nature of forum software, such things are easily done ) of the two main rock formation theories would be an interesting thing. I think it's only fair to give HDP's hypothesis more airing time, and then we could do a poll to see which camp people fall down on.

Doug

I am far from being a geology expert, but I am a chemist.

I don't understand why the argument is one...or the other. I haven't seen any reason why both mechanisms could be operant at different times, and/or why one excludes the other. It does seem to me that "surges" can and do account for some observations, in addition to the MER team hypothesis.

[MarsIsImportant]

A quickie - Why only haematite? Where are all the 'hailstones' made from the many other materials that presumably condense out of an impact surge in similar fashion? Oh . . I know - leached away by groundwaters.

Good point.

That shows that both models would have a similar number of dead grandmothers whether we want to admit that or not. It just so happens that some of us want to ignore them.

[ngunn]

I don't understand why the argument is one...or the other. I haven't seen any reason why both mechanisms could be operant at different times, and/or why one excludes the other.

For the stratigraphy you can argue for a mixture, but the berries are an all or nothing bet. Nobody could seriously propose that half of them are hailstones and the other half concretions. They shout out common origin loud and clear.

[MarsIsImportant]

It is safe to say that the MER team has already carefully looked at the evidence for all scenarios from the beginning of Opportunity's traverse across Meridiani.

Here is a quote from Steve Squyres in a Press release from February 9, 2004.

"This is wild looking stuff," Squyres said. "The rock is being eroded away and these spherical grains are dropping out." The spheres may have formed when molten rock was sprayed into the air by a volcano or a meteor impact. Or, they may be concretions, or accumulated material, formed by minerals coming out of solution as water diffused through rock, he said.

Meteor impact...sounds like parts of Dr. Burt's model. They already considered it from the beginning.

[centsworth_II]

It is safe to say that the MER team has already carefully looked at the evidence...

I think that it would be inhuman for the MER scientists to be objective. I would
expect them to be advocates for their theories, as Dr. Burt is an advocate for his.
I'd like to hear what more independent geologists specializing in the pertinent areas
are thinking.

Meteor impact...sounds like parts of Dr. Burt's model. They already considered it from the beginning.

But did they think of base surge from the beginning?

[helvick]

Glotch et al 2006 "Fresnel modeling of hematite crystal surfaces and application to martian hematite spherules"

...So,hematite formation processes that occur at high temperatures,or preferentially create hematite crystals with roughly equal amounts of [001] and other rays are less likely to be responsible for the martian hematite spherules. These processes include the formation of impact-melt spherules (Chapman, 2005; Burt et al., 2005) at high temperature, or the high-temperature oxidation of volcanic lapilli (Knauth et al., 2005).

Burt:

What Glotch et al. fail to discuss is why a sedimentary concretion would consist of shiny blue-gray hematite (the specular form) in the first place. They claim to have grown some hematite at high temperatures by some unspecified process - but it wasn't a hydrothermal brine or salty steam, as far as I know. I think they probably just dry roasted red hematite

The point made here that the 2006 Glotch paper fails to explain the details of the high temperature formation process is not quite true - the claim that is initially made on page 10 references findings in an earlier paper that I have yet to find available openly online. There is a pay-per-view link and abstract here http://www.agu.org/pubs/crossref/2004/2003JE002224.shtml and I found a different 2003 LPS article\paper here http://www.lpi.usra.edu/meetings/lpsc2003/pdf/2008.pdf that may be an early version.* These two seem to constrain the formation to a process at or around 300-400C and appears to exclude higher temperature formation regimes (700C).

I'm a bit surprised at that 300-400C number - that doesn't seem like a particularly low temperature to me and I can't see how that ties up with the rest of the "concretions forming in a brine" hypothesis. Where exactly are we going to find a 300-400C brine?

Anyway my current question for HDP Burt is whether the additional detail in that referenced paper actually does prove that the hematite at meridiani is unlikely to have formed at the types of temperatures implied by impact surge hypothesis.

*<rant> As a complete aside am I the only one who absolutely detests paper based citation\referencing standards that make chasing up references like this such a trial. I know its not something that can be easily fixed but its about time that academia caught up with the 21st century. </rant>

[MarsIsImportant]

Well, here is a quote from the Glotch paper about the sample used. So some of Dr. Burt's characterization of it was not exactly accurate--unless he is suggesting some fudging somewhere. That's why we repeat experiments over and over again.

3.2. Sample
The hematite sample used in this study is a platy hematite
crystal from Brumado, Bahia, Brazil with a diameter of 2.4 cm
and a thickness of 3 mm. The small thickness of the crystal
posed a problem in measuring the emissivity of the (100)
face, so the crystal was cut into three pieces perpendicular to
the (001) face (c-face) and perpendicular the [100] axis. The
three pieces were then bound together with epoxy so that the
result was a crystallographic (100) face with an effective diameter
of 0.9 cm. The final 0.9-cm sample was polished to optical
smoothness, ensuring specular reflection at infrared wavelengths.

[helvick]

I don't think that the sample you reference was at issue. The lack of clarity was in relation to the structure of hematite that was formed in an experiment rather than this machined hematite crystal that was used to validate the spectral models.

[dburt]

...sounded pretty convincing to me!

However, why couldn't a less catastophic 'unimodal' process repeat itself many times (i.e., short-duration groundwater flooding events) and produce similar results? If other influences such as wind erosion (presumably minimal by our standards over medium time frames) and precipitation (utterly absent) are nullified, wouldn't this tend to generate much more uniform berry distribution if for no other reason than that the process is much simpler than its terrestrial analogs?

Good question, nprev. Sure, short duration groundwater flooding events are certainly possible. Almost anything is possible on a planet about which so little is known. However, there is no positive evidence of them anywhere at Meridiani, any more than there is positive evidence of past playa lakes, or flowing surface waters, so why invoke them if you don't need to? Wind erosion/deposition is possible, and obviously important, but wind does not seem to move the berries at all, so you cannot invoke it to make or alter the berry distribution. The simple process that can be repeated as often as you like, any time you like, and can be adjusted to any scale you like, for any target you like, and for which there is abundant evidence everywhere, including Victoria, Endeavor, and Eagle Craters, is impact. It does the work - it can produce absolutely every feature seen. It explains nearly identical features seen at Home Plate, as well as all of the coarser material there (e.g., on Husband Hill). It explains the boulders unexpectedly found to cover most of the northern plains - greatly restricting Phoenix landing sites. It explains the salty strata that are found in many high elevations around the highlands for which water deposition would be improbable to impossible. What bedrock feature found by the two rovers doesn't it explain?

It doesn't explain many other features of Mars - volcanoes, outflow channels, deltas, dunes, etc. I've never claimed it did. I just think its importance has been greatly underestimated in hypotheses - because of our earthly blinders. It's hasn't been an important process on Earth, compared to everything else going on, except for very occasionally (ask the dinosaurs). On Mars, other than wind, it has been the only constant geological workforce for the past 3.8 billion years (this constancy is depended upon for dating Mars surfaces). The other exciting processes (e.g., outflow channels, young gullies, glaciers, volcanoes) are the episodic exceptions, of local importance - analogous to the occasional role of impacts on Earth.

Keep in mind that the two rovers have increased by orders of magnitude the observational restrictions on any hypotheses - they offer the potential to revolutionize our understanding of Mars. To my way of thinking, huge earthly blinders have so far prevented them from doing so. (Have you ever noticed that Home Plate papers never mention Meridiani, and vice versa?) We so much want Mars to meet our earth-centered expectations, and are perfectly capable of increasing the size of our own blinders to maintain those illusions. I don't know about you, but I'm old enough to remember when Venus was a cloud-covered mystery, and anything was possible there too. People, especially science fiction writers, expected it to be a cloud-covered jungle with strange creatures and beautiful maidens. What a disappointment when it wasn't. Well, I think the same is about to happen to the warm, wet early Mars crowd. The utter lack of crystalline clays, and abundance of easily-altered igneous minerals such as olivine and pyroxene (all via orbital and ground spectroscopy), for any time other than at the height of the Late Heavy Bombardment (oldest, most cratered areas), is perhaps telling you something in this regard.

Ask me more specific questions, and I'll give you more specific answers.

--HDP Don

[MarsIsImportant]

Geothite with hematite...it looks fairly Martian to me.

http://ocw.mit.edu/ans7870/12/12.108/f04/i...b1/lab1-16.html

...very much like Meridiani, at least in a general sense.

[ngunn]

Dburt I have a genuine query for you. I'm trying to imagine the haematite hailstone formation process and I'd just like to be clear exactly how you picture it. Apologies if you have already covered this point here.

Are you postulating molten globules rounded by surface tension which then solidify, or spherules built up radially by successive plating of solid material onto a nucleus like the growth of a pearl?

Are both possibilities consistent with your theory, or only the (hotter?) molten version? (Perhaps the other would not happen quickly enough?)

I would imagine that the two would produce quite different crystalline structures and that the latter might resemble concretions more than the former.

Does the Glotch paper claim to rule out just the first process, or both?