The Curiosity Mars rover Strange amounts of manganese have found intriguing chemical evidence in the form of oxides. tuesday Billions of years ago, not only the environment was habitable, but also microbes.
NASA’s Curiosity Exploring the giant 154-kilometer (about 96-mile) diameter Gale CraterThe rover landed in 2012. Curiosity’s findings have already established that the crater was at least partially flooded. Evidence for this has been denied. However, the rover’s latest findings not only strengthen the argument for an ancient lake, but also suggest that conditions within the lake were conducive to life.
The proof is related to the composition of manganese oxide. Curiosity first detected small amounts of manganese oxide in Gale Crater in 2016, but now it has found large amounts of manganese oxide in sedimentary rocks of a mudstone geological unit called the Murray Formation. In the middle of the crater the Murray Formation is found on the edge of Mount Sharp.
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The manganese oxide was identified by Curiosity’s ChemCAM instrument, which fires a laser at rocks that scientists want to study. The laser heats a small area of a rock’s surface, thereby vaporizing it, resulting in a small cloud of plasma that ChemCam’s internal camera and spectrometer can study from a distance. ChemCam found mudstone enriched in up to 45% manganese oxide.
On that day Earth, manganese oxides are commonly found in lake basins or river deltas where there are highly oxidizing conditions. Also, the microorganisms present in that environment help promote the oxidation process.
Usually, this process requires a steady supply of oxygen, which is in short supply on Mars. In 2016, small amounts of manganese oxide were discovered on Mars Explained without significant amounts of oxygen, but the large abundances discovered in the Murray Formation are another matter entirely. To achieve such abundance, the oxidation process would require significant amounts of oxygen.
„Manganese oxide is difficult to form on the surface of Mars, so we did not expect to find it in such high concentrations in coastal deposits,” said lead researcher Patrick Costa of Los Alamos National Laboratory. Report. „On Mars, we have no evidence of life, and the mechanism for producing oxygen in the ancient Martian atmosphere is not clear, so how manganese oxides formed and accumulated here is really puzzling.”
A clue lies in the nature of the mudstone deposits in which manganese oxide is found. Manganese oxide-enriched rocks were found in a location between two geological units in the Murray Formation. One unit is nicknamed Sutton Island and represents sediments deposited at the edge of the lake; The other, nicknamed Blunt’s Point, would have been deeper in the lake.
The manganese-oxide-enriched mudstone is coarser, with larger grains than the rocks in the crater, where only small abundances of the compound have been found. This supports the theory that the Sutton Island/Blunt’s Point area is the site of an ancient river delta that once emptied into the lake, or the shore of the lake. under. The larger grains would have contributed to a more porous bedrock than the finer mudstone found elsewhere in Gale Crater – presumably from the depths of the lake. This porosity would have allowed groundwater to flow freely. Scientists say that manganese may have seeped from this groundwater when coarse mud was passed through the rock, thus becoming concentrated in the rocks. Where oxidizing oxygen came from remains a mystery.
„These findings point to larger processes occurring in Martian atmosphere Or show that more work needs to be done to understand surface water and oxidation on Mars,” Costa said.
The presence of manganese oxides reinforces the possibility that microbial life may have existed within the lake. Microorganisms not only catalyze the oxidation of manganese, but they can use the multiple oxidation states of manganese as a source of chemical energy for their metabolism, as microbes do on Earth. In other words, an excess of manganese oxide may be implicit Vital signature.
„The Gale Lake environment revealed by these ancient rocks provides a window into a habitable environment that looks remarkably similar to places on Earth today,” said Nina Lanza of Los Alamos, ChemCam’s principal investigator. „Manganese minerals are common in shallow, oxic waters found along lake shores on Earth, and finding such recognizable features on ancient Mars is remarkable.”
The findings were released on May 1 Journal of Geophysical Research: Planets.
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