8. Mars "Ray" Crater
Most young and small craters on Mars are not “sploshes” (slide #7) but look more like craters on the Moon. Like this unnamed crater, a bit west of Olympus Mons, the ejecta of small young craters makes many smaller craters and rays emanating from the center. The contrast between Mars’ older “splosh” craters and younger “ray” craters (see also slide #31) suggests that Mars’ crust has become drier over time. This change may have happened as Mars lost its water to space. Without water at its surface, Mars became the inhospitable desert we see today.
Scene is 110 kilometers across, Viking Orbiter image 512A45; unnamed crater is at 24.3°N, 142°W. Image processing by Allan Treiman (Lunar and Planetary Institute).