Mars clay, not water. Bob Zimmerman, BehindtheBlack.com

Photo: This image taken by NASA’s Mars Reconnaissance Orbiter shows ice sheets at Mars’ south pole. The spacecraft detected clays nearby this ice; scientists have proposed such clays are the source of radar reflections that have been previously interpreted as liquid water. 

Credit: NASA/JPL-Caltech/University of Arizona/JHU

Mars clay, not water.  Bob Zimmerman, BehindtheBlack.com

https://behindtheblack.com/behind-the-black/points-of-information/scientists-clay-not-liquid-water-explains-radar-data-under-martian-south-icecap/