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In a somewhat related point, have you noticed how much the most recent images from the Spirit rover at or near the summit of it's hill, seem to show nearby features that look a lot like snow drifts?
If they are, raise temperature slightly and/or combine with surface salts forming a liquid solution and it would run down the hill and perhaps form a gully, ditch, or aroyo, depending on where you are from and your terminology preferences.
There are also features in Opportunity images which suggest to me the presence of water in some form. I realize that conventional, (or consensus) wisdom says that there can be no water present, but believe that there is some awfully simplistic modeling going on to come to that conclusion.
The situation is analogous to the classic "Theoretically bumble bees can not fly" statement when obviously bumble bees do fly and therefore the theoretical model that is referred to is terribly flawed and/or simplistic. The quoted statement says more about the speaker or theoretician than about any truth implied in the quote.
To those involved,
It's great to have this general topic area come alive again after a long time silent.
Tholzel, the insight you have as a professional propagandist (as long as you are being relatively forthright with us), can be very interesting.
Except for the effects of dust/gravity on the various seals and equipment, why do you believe that living on a body with significant mass under high vacuum conditions is a significant step beyond living in a vacuum in orbit? Mars seems to provide so much more as to potential insitu resources for potential expedition use, and in my opinion, the development of technologies for prospecting and utilization of such resources (water or CO2 and...?) should be the highest priority.
Belinda, yours is an unequivocal reference, but I also see evidence from our current rovers' images which is very suggestive to me of present day H2O within easy access.
Tholzel,
This URL seems to be a good one, providing tools to scientifically evaluate, and perhaps, prove or disprove your position statements. It would be interesting if the math works out. There are a couple of built in calculators for CO2 conditions included in this site:
http://www.airliquide.com/en/business/p … p?GasID=26
Best Wishes,
To C M Edwards,
Thanks for the reply, I was beginning to think that no one was out there.
I agree that snow will sublime under the conditions at Purgatory dune. After all, it is easy to show that it will sublime in the winter at my location in a temperate zone of the Earth's surface. No problem. The real question that should be considered is where does the water vapor go as it sublimes? Is there a cycle where it has a chance to come back?
The model I tend to subscribe to considers that the molecular weight of the prevalent gas in Mars' atmosphere, CO2, with a molecular weight of 44, is much lighter than agglomerated water molecules (call it snow if you are willing, even if it is very fine in texture). It only takes three water molecules stuck together to make a particle heavier than a CO2 molecule, and water molecules do tend to stick together at the temperatures involved.
It's not a great stretch to think that much larger groups of water molecules could exist, perhaps even large enough to fall back out of the atmosphere considering the atmosphere's temperature about a meter (or even less) above the average ground surface level. It would also be possible that the rather sharper edges of the wave-like dunes could cool off at night enough to be direct condensation sites. We then have a relatively closed system with very little of the water escaping into the atmosphere and then diffusing out toward and into space.
It's just this boundary layer type of effect that would not be contrary to our accumulated observations. In fact it explains some of the observations which the simpler and more ingenuous, although widely accepted, standard models do not.
As I've said before, I believe there is reason to believe that there is water based 'weather' extending to about a meter above the martian surface at the latitudes of the present rovers. This is in agreement with Dr. Levine's observations pertaining to the Viking missions in the late 70's.
Granted, NASA's overall, if unspoken, policy has been to regard the good doctor as some sort of pariah, (Science by Opinion and Doctrine?) even though his physics is sound.
That said, The images we are getting from Opportunity, and the fact that it got stuck on the crest of Purgatory dune in sand including some light colored stuff would be expected if the light colored stuff is simply water frost/snow where the vapor is eminating from the lower portions of the terrain and condensing at the dune crests. Again I decry the lack of instrumentation to detect and analyze such a situation. We don't need a sample return to detect water by, I suspect, several different remote robotic means. I could delineate some of them, if asked.
The problem may be that the mission objectives of detecting, by geology, signs of water that had been there millions or billions of years ago would seem totally rediculous in light of an easy discovery of water there at the surface today. And then there must be consideration of the NASA-originated statement "Where there is water there is life"???
Comments of substance, please.
For those of you who don't haunt the image pages of the Lyle site pertaining to the rovers, I think you might find the following image from the microscopic imager interesting. It's the strongest indication of sizable crystals I've seen. They seem to have a cubic growth habit of some type.
Lyles]http://www.lyle.org/mars/imagery/2M173592641EFFACAQP2977MM2M1.JPG.html]Lyle's Mars image page
This is from the Spirit rover.
What is the possibility that Opportunity rover got stuck in dust/snow at the crest of Purgatory Dune? Comments?
I suspect, that if we wait long enough for the complete data to come in for a larger portion of Mars, that a bucket and rope, or maybe an ice ax, will be sufficient in certain places, as opposed to a drilliing rig.
Rob S,
Why do you invoke electrostatic attraction? It doesn't seem to explain flat piles at all, to me. Totally neutral (at least in the aggregate) material would tend to behave that way under the influence of gravity.
Doug,
The last sentence of your last post is not true. Lighting conditions are very critical and non-linear as one approaches the ideal configuration for viewing surface contamination. A simple experiment will confirm this.
Take a piece of clean window glass and look at it's surface in a dark room with the aid of a moderately collimated light source (a slide projector or microscope illuminator works well) such that the specular reflection from the surface hits your forehead, but not your eye, and you will be able to see the tiniest surface contamination or imperfections with high contrast. With a clean piece of glass, a slight increase in angle between your eye and the reflected beam will cause the surface flaws/contamination to disappear.
I commend your work, you've done a lot of it with these images, but don't take appearances of the two landers' solar cells too far. The fact that the metallic surfaces on Spirit do not show a great deal of dust still raises questions in my mind.
There is a difference between the images given of Opportunity's and Spirit's solar cells. The problem is that the lighting is slightly different, so that a judgement of performance on the basis of these two images is difficult to make.
Judging by the shadows, and the brightness of the metallic pads, both at the base of the screw and the solder tabs in the lower mid right, the Spirit image is taken at a viewpoint just barely out of line with a specular glint of the sun from the cell surfaces. At this position, we probably are observing cell surface brightness due to scattering, as such a sun angle provides a most sensitive view of scattering from small defects or dust particles.
The fact that the metal pad and tabs are so much brighter in the Spirit image than in the Opportunity image indicates that we are not in as good a position to observe possible scattering centers on the Opportunity solar cells with nearly the same degree of sensitivity.
If I were going to really make an assuredly valid comparison of the two unit's solar collection surfaces, I'd want an image from the start of the mission for each unit's solar collection surfaces taken under the exact same sun angle to compare with the 300-plus-day images we now have. This is probably an unrealistic want, especially after the fact.
I'd also want to know if the solar cells from both rovers were from the same production run. On a material with such a high index of refraction as silicon, functional antireflection coatings can have somewhat differing colors in reflection and yet still be effective at their job, and pass their specification criteria.
Shaun, I share your color vision type. It should be pointed out that the formal descriptions of color vision are derived from surveys and tests on many people to determine what proper color vision is. It's essentially majority rules and all that. In my studies into the subject I've found hints that those with our type of color vision are more sensitive at low light levels than those with "standard" color vision; something with a slight survival advantage in certain situations.
Finally, to cover the "dust devil" topic, reiterating from past posts, I don't believe that the size, energy, and persistance of the rotating cyclones on Mars could be supported by heated dry atmosphere and dust. I believe they are powered by phase changes of water from a very near surface vapor layer rising and freezing to fine solid particles. Such particles could, by the way, scour a solar cell surface clean.
Thanks Shaun,
I'm certain that I, and surely many others, appreciate the attention you've paid to these matters.
The B-S detectors of many of us are saturated now days. Please keep up your efforts while you still can.
Rxke,
You are obviously right in saying that the finer particles of a given substance appear lighter. This is because a larger proportion of the light coming to an observer is due to Fresnel reflections at the interface between the medium the sample is immersed in (air or near vacuum, in this case) and the substances' many surfaces.
If one has electrical engineering tendencies, one can think of this as reflectances due to impedence mismatches at the interfaces between the solid particles and the medium they are immersed in.
Most of the color of a finely divided substance which has optical absorbtion bands is given its characteristic hues by passage through small particles where the absorbed light is reduced exponentially as a function of distance through the substance before emerging, only to be scattered on to the observer from other particles or by being reflected back from the second surface of the same particle. Smaller particles can absorb light less because of the smaller distance the light must travel before emerging. If the substance is a perfect absorber, this could not take place so only the light due to Fresnel reflectances from the surfaces would reach the observer as some shade of grey.
White titanium oxide is white because it has little visible absorption and also because of it's very high index of refraction (large impedance mismatch; large Fresnel reflectances at surfaces). Iron oxide, Fe2O3, is red because of it's significant visible absorbtion bands.
CM Edwards and RXKE,
I see your points about weak signals implying water in both instruments, but find these methods underwelming as a means of positively detecting water.
If NASA found it impossible to admit to the presence of surface moisture in the face of the Viking image showing a transient overnight accumulation of apparent snow, how could they possibly admit that weak signals from instruments not designed to detect water imply the presence of water?
Let's, however, continue to keep a close eye on them. The best to you all!
atomoid,
Finer particles scatter more because of their fine particle size. They do not reflect more than coarse particles, although in certain cases the effects might seem similar.
RXKE,
The Mossbauer spectrometer only provides information relative to iron atoms and their bonds, nothing more.
"Apparent Timescale" is the key pair of words. Not everything in a sensor's "view" has to have been produced at the same time, although there is strong incentive to make that assumption in order to seek simplicity. It is still just an assumption.
Please forgive me for stating what may be obvious, but the fact that it is difficult to reconcile may mean that it is not a valid assumption.
I whole-heartedly agree with Atomoid and others about the suspicious appearance of the material in the bottom of the crater. It certainly suggests dirty snow drifts to me. Whether the powers that be will make any move, (if they have any means on this probe to identify the material's composition) or not, is something we'll watch for and see.
It seems that with the nearly half a billion dollars which this probe cost with the goal of researching past water on the red planet there should be some provision to tell if it's feet could be wet (or frost covered) at the present time.
Atomoid, and others,
As to the spherules as being volcano-strewn glass or meteorite-strewn tectites, they have cut through many of them in situ in the bedrock and they dont seem to be composed of such material.
As to the hematite contents, or coating, I work (at my day job) at a company which does research on specialty glasses. I have seen many examples of magnetic coatings of metallic oxides on glass microspheres caused by imputities in our source materials. They were identified as magnetic simply because they were removed from our product by a magnetic separator.
We also make iron phosphate based glasses which by appropriate modification can be as insoluble as silicate glasses or can be tailored to degrade in an environment (alkaline as in concrete, or biological as in temporary bone replacement) at a given rate.
Some of these glasses can contain enough iron and/or other magnetic materials to be magnetic in themselves. I have a sample of glass shot produced in some of our experiments which shares some of the appearance and morphology of the spheres seen on the surface of Mars, and am hoping to work up a paper on the similarities in the near future. Some Mossbauer measurements have even been done, but I may not have ready access to those.
Anyway, don't rule out thermally produced glass as a possible candidate for the makeup of the "blueberries".
I don't believe the concretion hypothesis has as much merit as the concept that the spheres are a glass-type material similar to the "Apache Tears" volcanic glass spheres.
The fact that the spheres on Mars are seen within a rock-like matrix, as well as free on the surface, may simply mean that the 'rocks' they are seen within are simply accumulations of volcanic ash (or high energy release impact debris) laid down at the same time the spheres were being laid down.
This in no way excludes their having been exposed to water at some time during their existance, as some 3D views produced with the microscopic imager seem to show surface etching. (while also showing that some of the image details of select spheres seem to be bubbles near, but within, semitransparent surfaces.)
Shaun,
The liquid itself does not have to be dark. At the viewing angles it's being observed at, the liquid could be completely transparent and the Mars surface/liquid interface could be dark.
Also, the darkness characteristics seem to be spectrally dependent, with the red/IR views showing them most and the shorter visible/UV views showing it least, hardly at all. This hints at the presence of some pigment (bio or otherwise).
Images that should be taken to try to determine if a surface is as flat as a lake would include viewing angles for which one would expect sun glints from the flat surface.
Atomoid,
Thanks for the links. I remembered in the back of my mind the 22 degree value for water ice, but had not done the research to determine the values for CO2 crystal halos. By the way, I think the extreme lines you pointed out are multiple reflections or saturation effects in the camera system, and on closer examination of some of the images I can see lens flares as images of a system iris near, but slightly to the side of, the sun image. The partial halo after sunset and some of the other, more subtle, effects still have me intrigued.
Your linked images definitely show the pillar phenomenon, but I've personally seen much more dramatic examples at the edge of Lake Ontario in which the pillar extended all the way from my second story window, where I could see the glints from the surfaces of falling individual snow flakes, to the distant, near horizon, sun's disk.
Thanks again, we might come up with a valid inference yet. It would be interesting to see if a real time movie image would show scintillations, although I don't think we have that capability there.
Cindy,
At the very bottom of this page at JPL: http://marsrovers.jpl.nasa.gov/home/]JPL Rovers Home
there is a questions and comments entry. It seems like a fair question to ask of them and see if they respond.
No word from official folks yet that I know about, Cindy.
Atomoid, to clarify my last post to you, the "pillar of light" is a phenomenon of reflection rather than refraction as in a rainbow, but they both can manifest themselves as superimposed over a ground-level background.
Sun dogs are likewise a refraction based effect. The sun dog would become a complete circular arc around the sun if the ice crystals responsible for the effect were uniformly distributed in the sky rather than just in a band near the horizon.
Sun dogs and rainbows separate light into its spectral colors, but the "pillar of light" should not.
Atomoid,
I am replying to your May 18 post to point out that typically lens flares take place with the light source off axis rather than on axis. Also, the pillar of light phenomenon, similar to a rainbow, can typically appear superimposed over the ground surface. I've seen beautiful displays while living next to lake Ontario in Rochester, New York, where we got a lot of lake effect snow, even while the sun was shining.
Is there anyone from some place like Rochester, or Buffalo out there willing to concur? Rochester is, after all, a Mecca for optics.
Mr. Lyle was most helpful in showing me where to look for the image I saw yesterday.
He rightly cautioned me about taking the colors too seriously, and I sent him an e-mail that the possible presence of the ring around the just-set sun (see last "sun" image in the link) was more important than what color it was.
Cindy, the 17:52:33 image was the one containing the (partial) ring in the upper portion of the view.
![Lyles]http://www.lyle.org/mars/imagery/2M173592641EFFACAQP2977MM2M1.JPG.html]Lyle's](http://www.lyle.org/mars/imagery/2M173592641EFFACAQP2977MM2M1.JPG.html){kind=link}