The Curiosity Rover, which was sent to explore Mars 7 years ago, recently took samples of rocks in Mar’s Gale Crater. This crater is located about 5^o below the Martian equator and was formed about three and a half billion years ago by a meteor collision. Scientists believe that it at one point held liquid water.

Last month, a team of researchers reported the results of a model that predicted the properties of the water that was once in the lake. They made these predictions based on the properties of rocks collected by the rover Curiosity. They determined that the water was more salty than freshwater lakes on earth, but considerably less salty than earth’s ocean. For comparison, there are lakes on earth with similar amounts of dissolved salts, particularly in semi-arid climates, such as those that neighbor the deserts of Australia and Africa.

The researchers also estimated the pH of the water in the lake before it dried. By analyzing whether the materials in the collected rocks would be stable at different pH ranges, they determined that the water in the lake likely had a pH between 7 and 7.8. Neutral water has a pH of 7 and existing bodies of water on earth can have a pH between 6 and 8. Other chemicals in the rocks suggest that Mars may have experienced a changing climate that warmed the lake’s water before it dried up.

This research is exciting because the pH, salt content, and chemical composition of the water is consistent with the properties of bodies of water that we know can support the chemistry that life needs to form. The rover will be able to collect more data about the rocks and atmosphere on Mars. It will provide data on whether many of prerequisites for the formation of life might have at one point been present on Mars.  NASA will be sending another rover to Mars in 2021. This rover will perform further research on the ancient climate of Mars and its potential to support life.

Managing Correspondent: Emily Kerr

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Original Scientific Article: Semiarid climate and hyposaline lake on early Mars inferred from reconstructed water chemistry at Gale

Image Credit: Colorized shaded relief map of the crater Gale. The general landing area for Curiosity on the northwestern crater floor, named Aeolis Palus, is circled. (HRSC data)