So this crater is at 70° N? Hmmmm.

A thick water ice deposit entirely covers a dune field -- except for the ring of dark material barely visible around the edge of the ice deposit and the little notch in the upper edge were we can actually see some dark dunes poking out.

There appear to be no dunes of any kind anywhere else in the crater (though they may be there, just not visible at this resolution.)

Where has the water ice come from and why is it confined to the dark dune field off center in the crater? It is so brightly lit, it's hard to argue that there is a lack of sunlight right here.

Did this ice start as snow? Think of how much snow must have fallen for there to be a 200m deposit of ice today. Is this a single year's deposit, or does this deposit endure through the years (as in some other high latitude craters).

Could there be any liquid water at the base of this (for Mars) thick deposit of ice? Could this actually be an analog for a glacier, and could the dark dunes we see (or sort of see) be partially a consequence of glacial action?

If there is any liquid water associated with this deposit, what would be the implications for biology, if any?

What of the icy deposits in other craters? Are they also water ice? And if they are, could there be any subsurface connection between these craters? Could the deposits have originated beneath the surface rather than from atmospheric deposition?

Many more questions arise. But for the moment, I just want to reiterate that you do some outstanding and illuminating work to help us all appreciate (and further question) the fourth rock from the sun.

Thanks.