Round Stain Near Purgatory Dune, round stain visible in the sand Options

[Guest_Richard Trigaux_*]

Hello all,


some of us (in the Free! thread) noticed a round dark stain near Oppy:
visible here on the NASA site (look bottom right, just above Oppy's solar panel).
So I open this thread for this.

What such a stain could be? It looks just like a mere change in color, with the same texture than around it.

The more trivial explanation would be a drop of lubricant fallen from the apparatus at the end of Oppy's solar panels, when she passed here just before she got stuck. With a temperature of 20° oil could spread, and certain oil compositions would not evaporate, at least not fast.

But there would be more enthralling explanations. For instance a colony of bacteria could look like this. Or other really unexpected explanation.

In any case we do not know what it is and it may be potentially very interesting. So I think it is worth a bit of examination with the instruments. Just be cautious not to place the microscope right on it, if it is oil it would irremediably dirty the lens.

[Guest_Richard Trigaux_*]

Sol 503 navcam released a round panoramic view of the landscape (still unchanged since the beginning of this thread).

Our tiny round stain is still visible here (right bottom) together with the tiny crater (top centre).

Two other dark spots are visible here although more blurred. And they are not aligned with Oppy's traces, which seems to exclude some oil leak. But an oil drop may roll on dry sand before infiltrating in it...

Another tiny crater is visible here top left.


This discution is somewhat mixed with the one on tiny craters although there are no evidences that the two objects are linked.

[Phillip]

My guess (admittedly reading tea leaves) is that if the stains were in fact leaked oil, Sqyres would have mentioned it by now. If nothing else than from the perspective of maintenance/health of vehicle. I did not realize that there was oil to be leaked or that the conditions would allow for it. I also see no evidence that NASA is trying to take pictures of the stains, which leads me to conclude that they have a pretty good idea of what the stains are and they have decided the stains do not merit further investigations. So maybe some type of infill of tiny craters is the most likely answer after all. It will be interesting to see if they bring the arm over an "oil patch." Otherwise, I am in the camp that the stains are more curiousities than anything else. On the other hand, I sure would like to understand them better!