2023-07-03 13:15:51
A new study on the formation of certain gullies on Mars indicates that their origin is in the periodic flow of meltwater during a geologically recent time. The discovery is important within the framework of Martian geology but also in that of astrobiology, taking into account the key role of water for life and that the more recent the presence of significant masses of liquid water on Mars, the more the chances of finding vestiges of ancient ways of life and even redoubts with current life.
The research has been carried out by Jay Dickson’s team, from Brown University in Providence, Rhode Island, United States, and now at the California Institute of Technology (Caltech), in the United States.
The study provides new and revealing data on how meltwater may have recently generated certain canal-like gullies that cut into the sides of some impact craters on Mars.
The study focuses on Martian gullies that bear a fascinating resemblance to those that form in some parts of the Earth, specifically in the Dry Valleys of Antarctica, and that are caused by the erosion of water from melting glaciers.
The researchers built a model that simulates a sweet spot where conditions on Mars allow the planet to warm above freezing temperatures, leading to periods of liquid water on Mars as ice above and below the surface melts. .
The researchers have found that under the right conditions, including the temporary tilt of 35 degrees in the planet’s axis of rotation, the density of the Martian atmosphere could increase enough to allow brief episodes of melting ice in places now occupied by those ravines. This may solve the puzzle of the rapid, downslope expansion of ravines in the Terra Sirenum region during certain times. That expansion cannot be explained without the occasional presence of significant amounts of liquid water.
The Terra Sirenum region with its ravines, captured from orbit around Mars by NASA’s MRO (Mars Reconnaissance Orbiter) space probe. (Image: NASA JPL / Univ. of Arizona)
The results of the new study suggest that the formation of such gullies was driven by periods of melting water ice, and by evaporation of carbon dioxide frost at other times of the year. The researchers found that this was likely to have occurred repeatedly over the past few million years, dating the most recent occurrence to around 630,000 years ago.
The results show, in short, that the global distribution of gullies is better explained by liquid water during the last million years. Water explains the height distribution of gullies in a way that carbon dioxide alone cannot explain. This means that Mars has been able to generate liquid water in sufficient volume to erode the channels in the last million years, which is very recent on the scale of Mars’ geological history.
The study is titled “Gullies on Mars could have formed by melting of water ice during periods of high obliquity”. And it has been published in the academic journal Science. (Source: NCYT from Amazings)
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