NASA’s Perseverance analyzed trace-free samples: hyper-salty water may have destroyed evidence of life on Mars.
There are two missions NASA has sent to Mars. These are Curiosity, with the aim of assessing the potential for habitability of the Martian surface, and Perseverance, which instead aims to find actual evidence of life on Mars. Both expeditions made use of rovers, i.e. vehicles used to transport on a celestial body, transported in orbit by a so-called lander.
As Perseverance is looking for traces of life on Mars
While Perseverance has recently landed on the soil of the Red Planet, the attention of Curiosity has focused on some sedimentary rocks in Gale crater, full of clay minerals. In terms of assessing past habitability, clay is a key element: its presence indicates the presence of liquid water, which we naturally associate with life.
Curiosity took two mineral samples less than 400 meters apart, but scientists analyzing the data sent back to Earth by the rover were baffled by the lack of clay minerals in one of the two samples.
For the researchers, who published the results of the analysis in the scientific journal Science, the difference in the samples depends on some geological phenomena that have erased traces of history and perhaps life from the rocky sediments.
Why the lack of clay embittered NASA scientists
In particular, the scenario hypothesized by the scientists sees water leaking into the clay from a sulfate deposit located directly above. The super-salty brines would then seep through the sand grains and, in doing so, forever alter the mineral-rich layers that could have preserved evidence of life on Mars.
“We thought that once formed, these layers of clay minerals, at the bottom of the lake, in Gale crater, would remain intact, preserving some features for billions of years.” Those are the words of Tom Bristow of NASA’s Ames Research Center. “But later brines destroyed these clay minerals in places,” essentially “resetting” the rocks’ historical memory.
For sure, the Red Planet is constantly getting attention from the scientific community. Sometimes hypotheses like mushrooms on Mars pop up. Sometimes instead the researchers pale in front of the images of strange alien auroras.
Giuseppe Giordano