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

Manganese-rich sandstones were discovered by NASAThe Curiosity spacecraft indicates habitable conditions exist in Gale Crater Mars.

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

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

Secrets of Martian oxidation

“On Mars, we have no evidence of life, and the mechanism of oxygen production in the ancient Martian atmosphere is unclear, so how manganese oxide forms and is concentrated here is really puzzling. “These results point to larger processes occurring in the Martian atmosphere or surface waters, and shows that more work needs to be done to understand oxidation on Mars.”

ChemCam, developed at Los Alamos and CNES (the French space agency), uses lasers to form plasma On the surface of a rock, this light is collected in order to determine the elemental composition in the rock.

Sedimentary visions

The sedimentary rocks explored by the rover are a mixture of sand, silt and clay. The sandstone is more porous, and groundwater can more easily pass through the sand than through the clay that makes up most of the lakebed rock at Gale Crater. The research team looked at how the manganese in these sands could be enriched – for example, by groundwater percolating through the sand on the shore of a lake or the mouth of a delta – and what oxidizing agent could be responsible for the deposition of manganese in the sand. Rocks.

On Earth, manganese becomes enriched due to oxygen 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 metabolism; If life had existed on ancient Mars, the increasing amounts of manganese in these rocks along the lake shore would have been a useful source of energy for life.

Mars and Earth: a comparative view

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

Reference: “Mn-rich sandstones as an indicator of ancient Oxyc Lake water conditions at Gale Crater, Mars” by P.J. Gasda, N.L. Lanza, P.-Y. Mislin, S.N. Lam, A. Kozin, R. Anderson, O. Forney, E. Swaner, J. Laredon, J. Friedenfang, N. Thomas, S. Goizd, N. Stein, W. W. Fisher, J. Horwitz, D. Sumner, F. Rivera Hernandez, L. Croci, A. Ollila, A. Easonfeld, H. E. Newsom, B. Clark, R.C. Wiens, O. Gasneault, S.M. Clegg, S. Morris, D. Delap, and A. Reyes-Newell, May 1, 2024, Journal of Geophysical Research: Planets.
doi: 10.1029/2023JE007923

Funding: NASA’s Jet Propulsion Laboratory