An Oasis Found

Millions of miles away, on the surface of Mars, inside an enormous crater, a little NASA rover is taking some pictures. The view is quite stunning there—miles of undisturbed cinnamon terrain scattered with pebbles and boulders, with silky dunes where the craggy bedrock doesn’t peek through. But when the rover, named Perseverance, sent the photos back home from the crater, known as Jezero, scientists saw something more.

© NASA / JPL-Caltech

The arrangement of the sediment? It resembled a certain familiar landscape on Earth. Those boulders? A strong current had carried them in. Jezero, scientists could now see, wasn’t always dry and desolate. It was once a lake. The Perseverance rover was roaming what used to be a delta, where a small river met calm waters. A few billion years ago, the ground beneath its tires might have been sloshing with water.

On Earth, when a river pours into a lake, it carries grains of silt with it. Over time, that sediment builds up in layers that fan out from a narrow point where the running water meets the still. Observations from previous spacecraft missions, orbiting Mars from above, had shown something similar on the red planet’s surface, so scientists already suspected that Jezero crater, formed after a meteor impact, had been filled in with water. But they couldn’t be sure until Perseverance was there, snapping pictures like a mesmerized tourist. Here was history, the ancient ruins of Mars. The rover had looked out across the quiet terrain and observed not a barren wasteland, but a lost oasis.  TO READ MORE, CLICK HERE...