We may never come across evidence of former Martian life, NASA researchers have announced. The reason for this is that the clay minerals that preserved ancient traces of life may have been destroyed. However, the process not only destroyed but also created.
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Mars today is a planet of extremes – cold, dry and strong radiation reaches its surface. However, this was not always the case; once there were huge lake systems in which even microorganisms could settle. The climate of the planet has changed drastically over time and the lakes have dried up.
The landing site of the Curiosity Martian, Gale Crater, was also home to a huge lake in the past, and the vehicle is still being explored in this area. It is primarily of interest to the deeper clayey rocks, as they provide a snapshot of the planet’s state billions of years ago and preserve evidence of possible past life.
But it could easily be that Curiosity is searching in vain for traces of life; they may have been wiped out by the extremely salty water seeping through the rocks. The analysis was performed by the Martian with an instrument called CheMin, and the results were published by NASA experts in the journal Science.
Previously, we believed that clay minerals were formed at the bottom of Lake Gale Crater and, if left unchanged, show the environmental conditions that prevailed on Mars billions of years ago, at the time of their formation. However, the salt water broke down these rocks in some places – rewriting the previous soil history. “ – writes the in a communication issued Tom Bristow, one of the researchers responsible for operating CheMin, is a senior author of the study.
The mystery of the missing clay
The research tool used the CheMin instrument to examine rocks at two locations about a quarter of a mile apart.
Much to his surprise, experts in one area have noticed a lack of clay minerals, instead of iron oxide-rich, sedimentary rocks – these materials give Mars its characteristic reddish color.
The researchers were quite sure that the sample obtained from the two sites was contemporaneous and began its “career” as a clay-rich rock in the same way.
Question, what could have removed clayey rocks from one region that contained possible traces of life?
The water of the increasingly salty lake may have wiped out the traces
Previous studies have already described that groundwater seeped into the deeper layers not only during the life of Gale Crater Lake, but even after it dried up. In the process, chemicals dissolved from the rocks and transported to more distant locations. Upon contact with the water transporting various compounds, changes also took place in the sediments, turning into rock. This is called diagenesis.
Diagenesis can change the history of the soil or completely rewrite it; it can destroy evidence of past life, but in the meantime create an environment conducive to the emergence of new life forms.
Comparing samples from the two sites, NASA researchers found that as the climate changed, the lake system in the Gale Crater became more and more saline, and the saline fluid could sweep down to deeper layers to erase evidence of ancient life, but also embed new life forms.
Through the discovery, researchers can deduce where Martian life is worth looking for.
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