My interpretation of the large dark patch is that BECAUSE it looks similarly dark in all views, at all lighting angles, it's actually a patch of dark dust. But I'll take you on for the price of a steak dinner, with wine.

To make things more fair, since I have no need of a steak dinner, if I win you can donate the cost to a non-political charity for hungry or disadvantaged children.

And let's define a cave as something large enough to park the rover in, not just a hollow where one boulder has fallen out of a hillside. (As mentioned before, access is irrelevant).

I'm sure there enough witnesses on this board to judge the outcome in the event of us disagreeing.