Water On Mars May Have Flowed For a Billion Years Longer Than Thought

Observations by a long-running Mars mission suggest that liquid water may have flowed on the Red Planet as little as 2 billion years ago, much later than scientists once thought. Space.com reports: Scientists charted the presence of chloride salt deposits left behind by flowing water using years of data from NASA's Mars Reconnaissance Orbiter (MRO), which has been orbiting the Red Planet since 2006. By studying dozens of images of salt deposits taken by the spacecraft's Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), the scientists interpreted a younger age for the salt deposits using a method 'crater counting.' The younger a region is, the fewer craters it should have, with adjustments for aspects such as a planet's atmosphere, allowing scientists to estimate its age. The new results push forward the existence of water on Mars from 3 billion years ago to as little as 2 billion years ago, based on the observations, which could have implications for life on Mars and more broadly, the planet's geological history.

The scientists also created elevation maps using MRO's wide-angle context camera, and the zoomed-in views provided by the High-Resolution Imaging Science Experiment (HiRISE) that can spot craters as small as the Curiosity or Perseverance Mars rovers. The salt minerals were first spotted by a different spacecraft 14 years ago, called Mars Odyssey, but MRO's advantage is it has higher resolution instruments than its older (and still operational) companion in orbit. The study based on the research was published in AGU American Geophysical Union Advances.

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