Signs in Martian soil point to long-term habitable conditions

Signs in Martian soil point to long-term habitable conditions

Is there life on Mars? Have there already been? This is one of the biggest questions we ask about our planetary neighbor; now the research points to a particular part of the Red Planet that may have harbored life multiple times over billions of years.

Through extensive study of images captured by the Mars Reconnaissance Orbiter, planetary scientists have identified clay sediments in northern Ladon Valles, southern Ladon Basin and the southwestern highlands around Ladon Basin. Ladon – all part of the Margaritifer Terra region.

Clay indicates the long-term presence of water because it forms under neutral pH conditions with minimal water evaporation. The team believe water flowed here from around 3.8 billion years ago until around 2.5 billion years ago, a large part of Martian history.

“Additionally, light-toned colored stratified sediments that display relatively low bedding dips and contain clays for 200 kilometers [124 miles] distance is evidence that a lake was most likely present in Ladon Basin and northern Ladon Valles,” says Catherine Weitz, senior scientist at the Planetary Science Institute in Arizona.

“The low-energy lacustrine environment and the presence of clay favor an environment that would have been favorable to life at that time.”

While this isn’t exactly proof of life – we’d need to go looking for fossils on Mars to really confirm it – it does suggest conditions that may well have supported life. This is the latest research to interpret conditions on Mars by what we can see from its surface and sediments.

Researchers believe the clays originally formed around higher ground above the Ladon Basin, before being eroded by water channels and transported downstream into a lake in the Ladon Basin and the north of Ladon Valles.

According to the team, the most recent water flow would have occurred along the southwestern basin of Ladon. The deposits here correspond to another part of Mars, the Eberswalde delta, just south of the region covered by this study.

“Our results indicate that clayey sediments deposited by running water at Eberswalde were not unusual in more recent times, as we see many examples of similar young valleys that deposited clays in the area,” Weitz says.

We know there is ice on Mars, but the search for liquid water continues. This latest study confirms the idea that running water was once an important part of the Martian landscape – and that it may have brought life with it.

Whether or not the presence of water on Mars is transient is crucial in determining whether or not life could have been supported at any given time. The distribution of clays and other rocks spotted by the researchers is consistent with the persistent water.

In addition, clays are sources of nutrients and stabilizers of the environment around them. Put water, nutrients, and stable conditions together, and the odds that organisms can survive increase dramatically.

“Habitable conditions may have repeatedly occurred in the region, at least periodically, until relatively late in the history of Mars,” the researchers write in their published paper.

The research has been published in Icarus.

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