Space/Science — HabitableZone

Space/Science » in reply to re: active geyser vs passive spot

re: active geyser vs passive spot
Greg Orme — (archived)

I think your theory is quite interesting and certainly better thought out than many I have seen over the years. However I see some problems with it. One is the spider branches seem to be approximately the same size and depth and become narrower and shallower often over hundreds of meters. So assuming a discharge can make a pattern this large then why is the center of the spider not showing more damage than areas much further away?
While the shape of the discharge is approximately correct you should remember this shape is also quite common, as it is a form of fractal. So the fact that one mechanism might form a similar shape doesn't mean other mechanisms might also do so. Look up viscous fingering for example.
I had thought for example a brine and fresher water or a different brine might form viscous fingers. It may also be some of the dark or other soil forms an oily fluid, perhaps from the amount of carbon from meteors. I have seen in rivers a clear demarkation between salty sea water and fresher river water so brines of different strengths need not intermix too rapidly to form the fingers. I assume Nick knows about viscous fingering from the oil industry.
I would assume though that one of the liquids would be sulphuric acid, which ties the chemistry in which other areas Nick has been researching.
If these fingers did form and then freeze the fingers might have a lower sublimation temperature and disappear to leave ravines in the correct shape, which would then slowly collapse and disappear as the rest of the material sublimated.
The surface would tend to stay hard and frozen because wind and exposure to vacuum would remove heat from it. Underneath that hard layer the viscous fingers might form. Another advantage for this theory is that temperature would be crucial and this would tend to have the small range of latitudes spiders would form in. Too far from the pole and the spiders might sublimate and the fingers would collapse as the two liquids would sublimate at around the same time. Too near the pole and they would not sublimate at all.
Also it accounts for the lack of spiders on the north pole, which would be too cold for any brines to form.
So to start the process there would need to be a concentrated deposit of suitable salts, which would melt under the ice, perhaps receiving heat through transparent ice. Then this forms a pool of brine, surrounded by salts of a different kind. These receive heat perhaps from the brine and start to melt, and the viscous fingering begins.
There could also be a kind of geyser mechanism here, where the center of the viscous fingering corresponds to the spider core. Being larger this might break through first and then the fluid in the ravines sublimates through the hole. Then as the surface weakens it eventually breaks and falls into the ravines, suddenly exposing the spider.
Since the viscous fingering would likely form near the surface and just under the frozen upper layer then most spiders would appear around the same time of year, in spring. Once the spider has sublimated the salts are left behind, and might tend to be blown by the wind into the spider ravines, setting the stage for renewed viscous fingering in the same ravines the next year, growing the branches each time.

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