Manganese-rich sands on Mars: A window into a habitable environment

Saturday - May 4 2024, 14:11 UTC - 6 months ago

Manganese-rich sandstones discovered by NASA's Curiosity rover suggest there were once habitable conditions in the Gale Crater on Mars. These rocks were found to have high levels of manganese, a mineral that typically forms in the presence of oxygen and can be used as an energy source by microbes. This finding adds to the growing body of evidence that Mars may have been capable of supporting life in its ancient past.

One of the most intriguing discoveries made by NASA's Curiosity rover is the presence of manganese-rich sandstones within the Gale Crater on Mars. These rocks were identified by the rover's ChemCam instrument, developed by Los Alamos National Laboratory and the French space agency CNES. The results of the research were published on May 1 in the Journal of Geophysical Research: Planets.

According to lead author Patrick Gasda, of Los Alamos National Laboratory's Space Science and Applications group, the high concentrations of manganese in these rocks suggest that they were formed in a river, delta, or near the shoreline of an ancient lake. This finding is significant because it indicates that the conditions in the Gale Crater may have been habitable for life in the past.

Gasda also notes that it is difficult for manganese oxide to form on the surface of Mars. This raises the question of how the mineral came to be so prevalent in these sedimentary rocks. On Earth, such deposits are more common due to the presence of oxygen produced by photosynthetic life and microbes that help catalyze manganese oxidation reactions. However, the lack of evidence for life on Mars makes this explanation unlikely.

Instead, the research team believes that larger processes in the Martian atmosphere or surface water may have contributed to the formation and concentration of manganese oxide. To investigate this further, the team looked at how manganese could have been enriched in the sandy rocks compared to the muds that make up most of the lakebed rocks in the Gale Crater. They hypothesized that this could be due to groundwater percolating through the sands on the shore of a lake or at the mouth of a river delta. Additionally, the team considered what oxidants could be responsible for the precipitation of manganese in the rocks.

On Earth, the enrichment of manganese is often due to oxygen in the atmosphere, which is then accelerated by the presence of microbes. If life did exist on ancient Mars, the increased levels of manganese in these rocks could have been a helpful energy source for potential microbes.

Principal Investigator for the ChemCam instrument, Nina Lanza, states that the discovery of these manganese-rich sandstones gives us a glimpse into a habitable environment that closely resembles places on Earth today. The presence of familiar features such as these on the Red Planet is remarkable and provides insight into how Mars' environment may have been similar to Earth's in the past.

Overall, the discovery of manganese-rich sandstones on Mars adds to the growing body of evidence that suggests the Red Planet may have once been capable of supporting life. Further research is needed to fully understand the processes behind the formation of these minerals and the potential habitability of ancient Mars.

Reference: “Manganese-Rich Sandstones as an Indicator of Ancient Oxic Lake Water Conditions in Gale Crater, Mars” by P. J. Gasda, N. L. Lanza, P.-Y. Meslin, M. E. Schieber, C. N. Achilles, S. M. Morrison, S. G. Benzel, R. C. Wiens, R. Anderson, J. Bridges, J. P. Grotzinger, J. A. Crisp, H. E. Newsom, D. L. Bish, and A. H. Treiman, 01 May 2020, Journal of Geophysical Research: Planets.