High above the southern highlands of Mars, the European Space Agency's Mars Express orbiter has captured something that looks like frozen metal but speaks to something far older — dark volcanic dunes inside Kaiser Crater, dusted with seasonal carbon dioxide frost, shimmering as a record of a planet that was once far more alive than it appears today. The frost reflects light against sand that absorbs it, producing a visual paradox that is also a geological truth: these towering dunes, some rising over 100 meters, are monuments to an atmosphere that once had the power to move worlds. In studying