The rocks inside Gale crater hint there may not have been a large lake there after all NASA/JPL-Caltech/University of ArizonaResearchers believe that a purported ancient lake on Mars was much smaller than originally thought. NASA's Curiosity rover has been studying Gale crater since 2008, and although early observations suggested that the whole crater might once have been filled by water, new analysis suggests that it may just have had a series ponds.Curiosity data analysis has relied heavily upon a measure called chemical index of altation to assess how rocks have weathered over time. Joseph Michalski from the University of Hong Kong, and his colleagues suggested that this measure may not be applicable in extreme Martian conditions because it was originally developed for Earth.Instead, they examined the changes in various compounds as a function of different weathering patterns. The researchers found that Curiosity layers did interact with water in the past. However, more likely they were to have formed without water.AdvertisementContinue reading: NASA's rover may have been a mere step behind microbes that emit methane on Mars.Michalski says that out of hundreds of meters of strata, the lowest few metres are the only ones that can be shown to have been lacustrine (formed in a lake). The rover found that only 1% of the rocks were lacustrine.These rocks were found in the lowest few meters of the sediments in Gale crater. This suggests that the lake wasn't as deep or as extensive as we thought. Michalski says that there was probably a small lake, or more likely, a series small lakes, in the Gale crater floor. However, these were shallow ponds.Michalski believes that the rocks that did not form in water were volcanic and that they might have been formed from ash from volcanic eruptions that occurred after the water in Gale Crater had dried up. Other Mars missions' observations have shown that these sediments were not deposited by water but by wind. This may help to solve the mismatch.Journal reference: Science Advances, DOI: 10.1126/sciadv.abh2687Subscribe to the Launchpad newsletter and take a journey across the galaxy every Friday!
