The top photo has the frost shaded and the second is an oblique representation. Are there any true-color images of these frost patches on Olympus Mons? They were never noticed before ?
“They were never noticed before ?’
Picture has to be within a few hours after sunrise in order for the frost to be evident. Sun has to be high enough to shine in the crater but not so high it melts the frost. Probably not that many photos are from just the right circumstances.