Gullies in Mars crater suggest liquid water flow in recent past

Los Angeles Times : Water may have flowed freely on Mars as recently as within the last million years, according to a study published in Nature Communications. Using the HiRISE camera on NASA’s Mars Reconnaissance Orbiter, researchers mapped the well-defined gullies of Istok crater and compared them with gullies on Earth. They found that carving the distinctive tracks would have required frequent debris flows with about 20% to 60% water content about every 10 to 100 years. The researchers explain the change in Mars’s liquid water content by the fact that the planet’s axial tilt has shifted over time, between 15 degrees and 35 degrees. When the planet is tilted more sharply, the Sun may cause ice at the poles to sublimate and drive the water cycle. Whether there are more craters like Istok is unknown, but the possibility of abundant water in Mars’s recent past could mean that microbial life also existed there.