关于这张图
This VIS image of Olympia Undae was collected during north polar spring. The crests of the dunes and other surfaces are light colored, indicative of a frost covering. The density of dunes and the alignments of the dune crests varies with location, controlled by the amount of available sand and the predominant winds over time. As the season changes into summertime, the dune crests will lose the frost and reveal the darker sand beneath. Olympia Undae is a vast dune field in the north polar region of Mars. It consists of a broad sand sea or erg that partly rings the north polar cap from about 12…
