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What is the possibility that Opportunity rover got stuck in dust/snow at the crest of Purgatory Dune? Comments?
Rex G. Carnes
If the Meek Inherit the Earth, Where Do All the Bold Go?
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What is the possibility that Opportunity rover got stuck in dust/snow at the crest of Purgatory Dune? Comments?
*Hi Rex. I haven't seen mention of snow in that regard, from the science articles. Someone mentioned a "fine white powder" in the O & S #9 thread, relative to the area Oppy was stuck in (now known as "Purgatory Dune"), but I don't recall reading that in an article/source. There are photos and a video clip of Oppy's wheels getting unstuck.
Shaun Barrett mentioned the possibility of brine. I recall reading in at least 1 article (which I couldn't relocate) the soil around Oppy's wheels at that point being "moist." Squyres mentioned it was a quality/type of soil not yet encountered.
Dust doesn't seem likely, but that's based on what I've read (and granted my memory could be faulty and of course I'm not qualified to speculate too much).
--Cindy
We all know [i]those[/i] Venusians: Doing their hair in shock waves, smoking electrical coronas, wearing Van Allen belts and resting their tiny elbows on a Geiger counter...
--John Sladek (The New Apocrypha)
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*Also, I seem to recall that the soil around Oppy's wheels within "Purgatory Dune" was described as sticky or clinging. Which would hold with moist/dampness.
Hope this helps.
--Cindy
We all know [i]those[/i] Venusians: Doing their hair in shock waves, smoking electrical coronas, wearing Van Allen belts and resting their tiny elbows on a Geiger counter...
--John Sladek (The New Apocrypha)
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If there is slush to freeze in the time it took to roll off the bouncing lander, it must be functioning in a transitional area between ice and liquid temperature ranges.
"Oh for a sponge, a robot arm and a sample return vehicle"
The wheels are at a slightly higher temperature than the soil, the colder fine grain soils will expand in contact with the warmer metal wheels. The opp could be "digging its own grave" so to speak.
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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.
Rex G. Carnes
If the Meek Inherit the Earth, Where Do All the Bold Go?
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Regarding the possibility of snow at purgatory, precipitation is out of the question. The environment is too dry, and at the the daytime pressure and temperature involved, surface snow would sublime away rather than melt and percolate into the dust below.
That said, there is very obvious evidence of water at Purgatory dune. The surface of the dune is crusted over, for starters, suggesting dissolved salts. There are also suspicious looking cracks and holes in the salt crust that suggest very recent activity of some sort, most likely within the past few years. There's no telling what they really are, except to say that they are now quite dry.
I suspect they're calcera, deposited by water vapor venting from a source below the dune.
All that we have now is "suggest" and "suspect". Opportunity isn't equipped to give a definitive answer. However, if I'm right, active vents are possible in that area. That means that leaving Purgatory Dune (a dry hole) and going prospecting is the right thing to do at this point.
"We go big, or we don't go." - GCNRevenger
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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.
Rex G. Carnes
If the Meek Inherit the Earth, Where Do All the Bold Go?
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