关于这张图
This VIS image of Olympia Undae was collected during north polar spring. The dune crests are losing the winter frosts, revealing the dark sand beneath. 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. 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 120° to 240°E longitude and 78° to 83°N latitude. The dune field covers an area of approximately 470,000 km2 (bigger than Califo…
