The Zhurong Mars rover used its ground-penetrating radar to uncover evidence of ancient coastlines and beaches on Mars. The rover spent a year, from May 2021 to May 2022, moving along the base of a steeply-sloped rock outcrop at the edge of a wide, flat plain.
Along Zhurong's 1.2-mile (1.9-kilometer) route, its ground-penetrating radar beamed radio waves 262 feet (80 meters) down into the Martian ground. The way those radio waves reflected back to the instrument revealed underground features they came into contact with, like the boundaries between layers of rock and sediment. Thirty-three feet (10 meters) beneath the surface, the radar revealed smooth, gently-sloping layers of sand, several yards thick. Those layers appear to run parallel to the rocky cliff, and they rise toward that cliff at a shallow 15-degree slope — which is typical of beaches here on planet Earth.
The buried beach could represent the first evidence of a true ocean from Mars' ancient past, and its presence means the Red Planet must have had an ocean for millions of years — long enough to leave behind the thick layers of sand Zhurong's radar measured. And that ocean must have been fed by rivers, the scientists reason, as those rivers would have dumped sediment into the ocean. Waves would eventually have spread that resulting sediment along the shore, forming a beach that'd have been strikingly familiar to us.
Map depicting where Zhurong (orange) and Perseverance (yellow) landed
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