Mars rover Curiosity continues to uncover the secrets of an ancient Martian lake
A research team using the ChemCam instrument aboard NASA's Curiosity rover has made a discovery in Gale Crater on Mars. Scientists have found elevated concentrations of manganese in rocks they believe are sediments from an ancient lake. These results were published in the prestigious scientific journal Journal of Geophysical Research: Planets.
Patrick Gasda, the study leader at Los Alamos National Laboratory, explained the significance of this discovery: «There are not enough conditions on Mars for the formation of manganese oxides, so we did not expect to find them in such high concentrations in sediments& raquo;.
On Earth, such manganese-rich deposits form regularly due to the high oxygen content in the atmosphere, which is the result of photosynthetic life, as well as microbes that catalyze manganese oxidation reactions. However, there is no evidence of life on Mars, and the mechanism for oxygen production in the ancient Martian atmosphere remains unclear.
«How manganese oxide formed and concentrated here is puzzling. These results point to larger processes occurring in the Martian atmosphere or surface waters and indicate that more research is needed to better understand oxidation processes on Mars», — Gasda added.
ChemCam, an instrument developed at Los Alamos and the French space agency CNES, uses a laser to create plasma on the surface of rock and analyzes it to determine the rock's elemental composition.
The sedimentary rocks studied are a mixture of sand, silt and clay. Researchers have studied how manganese could have become enriched in these sands — for example, by seepage of groundwater through sands on the shore of a lake or at the mouth of a delta.
On Earth, microbes actively use various oxidation states of manganese as an energy source for their metabolism. If life existed on ancient Mars, the elevated manganese content of these coastal rocks could have been a valuable source of energy.
«The environment of Gale Lake offers us a window into habitable environments that are remarkably similar to places on Earth today. Manganese minerals are common in shallow oxygenated waters on the shores of lakes on Earth, “It's amazing to find such recognizable features on ancient Mars,” said Nina Lanza, principal investigator for the ChemCam instrument.