7. Mars “Splosh” Crater

Meteorite impact craters also give evidence of abundant water in Mars’ crust. “Splosh” craters like this one near the equator are common all over Mars, and are thought to have formed when a meteorite hit an area rich in water. Around the crater itself is its ejecta, the material that was thrown out of the crater on impact. Around “splosh” craters, the ejecta forms smooth-edged, overlapping lobes, just like you might see if you threw a rock into runny mud. This suggests that the crater’s ejecta behaved like a liquid, probably because it was wet with water. Of course, there is no liquid water inside Mars near the equator now, but there may have been water, or maybe ice, in the ground when this ancient crater formed.

Scene is 160 kilometers across, Viking Orbiter image 378X28; unnamed crater is at 8.7°S, 258.7°W. Image processing by Allan Treiman (Lunar and Planetary Institute).

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