NASA’s Curiosity rover discovers signs of an Earth-like environment on ancient Mars

NASA’s Curiosity rover discovers signs of an Earth-like environment on ancient Mars
NASA’s Curiosity rover discovers signs of an Earth-like environment on ancient Mars

NASA’s Curiosity rover continues to search for signs that conditions at Gale Crater on Mars could support microbial life. Credit: NASA/JPL-Caltech/MSSS

Sandstones rich in manganese discovered by NASAThe Curiosity rover says there were once habitable conditions in Gale Crater on March.

A research team using the ChemCam instrument aboard NASA’s Curiosity rover has discovered higher than usual amounts of manganese in lake bed rocks in Gale Crater on Mars, indicating that the Sediments formed in a river, delta, or near the shore of an ancient lake. . The results were published on May 1 in the Journal of Geophysical Research: Planets.

“It is difficult for manganese oxide to form on the surface of Mars, so we did not expect to find it in such high concentrations in a coastal deposit,” said Patrick Gasda, of the Space Sciences and Applications Group. from Los Alamos National Laboratory. author of the study. “On Earth, these types of deposits occur all the time due to the high concentration of oxygen in our atmosphere produced by photosynthetic life and microbes that help catalyze these manganese oxidation reactions.

Mysteries of Martian oxidation

“On Mars, we have no evidence of life, and the mechanism for producing oxygen in Mars’ ancient atmosphere is unclear, so how manganese oxide formed and concentrated here is really confusing. These findings highlight larger processes occurring in the Martian atmosphere or surface waters and show that more work needs to be done to understand oxidation on Mars,” Gasda added.

ChemCam, developed at Los Alamos and CNES (the French space agency), uses a laser to form a plasma on the surface of a rock and collects this light in order to quantify the elemental composition of the rocks.

Sedimentary overviews

The sedimentary rocks explored by the rover are a mixture of sands, silts and muds. Sandy rocks are more porous, and groundwater can pass through the sands more easily than the muds that make up most of the rocks at the bottom of Gale Crater’s lakes. The research team studied how manganese might have been enriched in these sands – for example, by percolation of groundwater through sands located at the edge of a lake or at the mouth of a delta – and what oxidizer could be responsible for the precipitation of manganese in the sand. rocks.

On Earth, manganese is enriched by oxygen present in the atmosphere, and this process is often accelerated by the presence of microbes. Microbes on Earth can use the many oxidation states of manganese as energy for their metabolism; If life was present on ancient Mars, the increased amounts of manganese in these lakeside rocks would have provided a useful Source of energy for life.

Mars and Earth: a comparative view

“The Gale Lake environment, as revealed by these ancient rocks, gives us a window into a habitable environment that looks strikingly similar to places on Earth today,” said Nina Lanza, principal investigator of the ChemCam instrument. . “Manganese minerals are common in shallow oxic waters found on the shores of lakes on Earth, and it is remarkable to find such recognizable features on ancient Mars. »

Funding: NASA Jet Propulsion Laboratory

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