Blue/green Fans
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by doowac
Has anyone any views on these. The blue/green fans seem to be previous, more violent plumes from the same eruptions. Does the colour indicate copper?
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by Portyankina scientist
The color images are combinations of 3 color filters, their appearance is nowhere close to the realistic color. Usually they are stretched to highlight the interesting features best. This leads to some images being greener, others - redder. If the surface has fresh frost on it, it will normally appear greener and bluer in HiRISE.
No copper 😃 Sorry.Anya
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by doowac
Thanks for the clarification on the colour caste. How does this explain these features. The black fans seem to be the most recent activity - on top. The blue colouration seems to show previous fan activity from the same (and additional) exit points. If blue green indicates recent frost activity, does that indicate that the first stage of these "eruptions" is a vapour which re-freezes in fan shape, followed by a final eruption of dust which overlays the blue fan but to a lesser extent?
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by Portyankina scientist
There might be several explanation or several sequences of events, you plotted out one of them. It also, for example, could be that the fresh frost is directly deposited on the previous dark fan and we are able to see it as blue on the outer parts of fan - where the dust layer is thinner. Or that thin layer of dust does something to the ice on which it falls (warms it up, sinks through it) that makes it visible again. Scientists did not yet find agreement on which scenario is the one. This is where your marking work might help us!
Anya
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by doowac
Ok, thanks Anya.
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by BrianMartian
Found a similar image here.
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