21 October 2008
Posted by Ryan Anderson
Today marks my twenty-fourth revolution around the sun! To commemorate this momentous occasion, I am going to be a lazy blogger and just let you drool over some HiRISE images instead. The image above is a small crater in the polar layered deposits. It’s filled with ice because the crater walls keep the floor shaded, so frost can collect there. You can read more about this crater at the HiRISE site.
The second image is of dunes and what appears to be a very fresh crater near Uzer crater. The small crater in this image is surrounded by dark ejecta which hasn’t been eroded away yet. If you have a sharp eye, you can also see that there are strange raised cracks in the plains west of the small crater. My guess is that those are ridges formed when water flowed through cracked bedrock and altered the rock near the cracks, making it erosion-resistant. You can read more about this image at the HiRISE site, though they focus on the bigger crater that is outside the field of view of this close-up.
Ihe impression I do get is that this depression possibly has its own water supply.
Evaporation would cause a drop in temperature insite it refreezing some of the evaporation. The fuzzy area surrounding the ice could indicate water vapour or temperature differences.
The feature would then indicate that the iced-up area is sheltered from the wind.
What is missing in all explanations is the likely effect of biological activity!
To form such variety of complex deposits the planet must have been very dynamic at the time.
It appears that this lively period did not last long enough to get beyond the usage of the lighter original surface material. Waste products of early life-forms (sepiolite) would have covered any liquid water bodies while arresting oxigen in it rather than carbon as happened later here on Earth.
The persistance of dust in the Mars atmosphere is puzzling.
is it possible that the required lift is obtained by bonding with hydrogen?
The depression does not have its own water supply. It is a crater in the polar cap, and it is never warm enough for there to be liquid water. In fact, the pressure is so low that H2O skips the liquid phase altogether.
There is absolutely no evidence of biological activity in these images.
Martian dust is lifted by the wind. It forms “fluffy” aggregates that can easily be lifted, but then fragment into small particles which get entrained in the wind and are carried a long way.
What then settles our dust?
The finest particles settle even in water!
Wind may move but does not lift anything without a resistance.
A picture is worth a thousand words!
The suggested system works very well near the coldest area, like in a freezer. The polar air can be assumed to still contain little water in any form.
However if there is ice there must be a source!
Lots of it in one locality suggests this source to be nearby.
Emerging water (from underground) freezes, or under high pressure may even be forced out as ice!
Sublimation does just as evaporation involve heat exchange and create water vapour. The hint would be the fuzzy area around the visible ice.
The wind sheltered part of the crater wound then contain saturated air that readily deposits ice upon cooling. Smaller ice deposites are then also formed down-wind by the escaping saturated air upon contact with the ground, this is also visible opposite from the iced-up part of the sunlit crater.