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Using Messenger, scientists think they have obtained optical images of the ice that is thought to exist in the permanently shadowed craters of Mercury.
Although the polar deposits are in permanent shadow, through many refinements in the imaging, the WAC [Messenger’s camera] was able to obtain images of the surfaces of the deposits by leveraging very low levels of light scattered from illuminated crater walls. “It worked in spectacular fashion,” said Chabot.
The team zeroed in on Prokofiev, the largest crater in Mercury’s north polar region found to host radar-bright material. “Those images show extensive regions with distinctive reflectance properties,” Chabot said. “A location interpreted as hosting widespread surface water ice exhibits a cratered texture indicating that the ice was emplaced more recently than any of the underlying craters.” In other areas, water ice is present, she said, “but it is covered by a thin layer of dark material inferred to consist of frozen organic-rich compounds.” In the images of those areas, the dark deposits display sharp boundaries. “This result was a little surprising, because sharp boundaries indicate that the volatile deposits at Mercury’s poles are geologically young, relative to the time scale for lateral mixing by impacts,” said Chabot. [emphasis mine]
The image on the right is of the crater Kandinsky, and shows a very intriguing bright area on the crater’s central peak.
I highlighted that one word in the the scientist’s quote above to emphasize how preliminary these conclusions are. The images are intriguing, but I would not at this time bet a lot of money on these conclusions. Ice might be the best explanation for this data, at this time, but I would not be surprised at all if later research finds this conclusion to be false.