A study published in Science analyzes more rocks found on the floor of Jezero crater on Mars, where the Perseverance rover landed in 2020, revealing a significant interaction between the rocks and liquid water. Those rocks also contain evidence consistent with the presence of organic compounds.
The existence of organic compounds (chemical compounds with carbon-hydrogen bonds) is not direct evidence of life, as these compounds can be created through non-biological processes. Determining this would require a future mission that returns the samples to Earth.
The study, conducted by researchers at Caltech, was conducted by an international team that included Imperial researchers.
Professor Mark Sephton, from Imperial’s Department of Earth Sciences and Engineering, is a member of the science team that took part in the Mars rover operations and considered the implications of the findings. He said, “I hope these samples can someday be brought back to Earth so we can look at evidence of water and possible organic matter and explore whether conditions were right for life in Mars’ early history.”
Perseverance had previously found organic compounds in the Jezero delta. Deltas are fan-shaped geological formations created at the intersection of a river and lake at the crater rim.
Mission scientists were particularly interested in the Jezero delta because such formations can preserve microorganisms. Deltas are created when a river carrying fine-grained sediment enters a deeper, slower-moving body of water. As the river water expands, it slows down sharply, depositing the sediment it carries and trapping and preserving any microorganisms that may exist in the water.
However, the crater floor, where the rover landed for safety before traveling into the delta, was more of a mystery. In the bottoms of the lakes, the researchers expected to find sedimentary rocks, because the water deposits layer after layer of sediment. However, when the rover landed there, some researchers were surprised to find igneous rocks (cooled magma) on the crater floor with minerals in them that recorded not only igneous processes but significant contact with water.
These minerals, such as carbonates and salts, require water to circulate in igneous rocks, carving out niches and depositing dissolved minerals in different areas such as voids and cracks. In some places, data show the presence of organic substances within these potentially habitable niches.
Discovered by SHERLOC
The minerals and possible co-localized organic compounds were discovered using SHERLOC, or the Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals tool.
Mounted on the rover’s robotic arm, SHERLOC is equipped with an array of instruments, including a Raman spectrometer that uses a specific type of fluorescence to look for organic compounds and also see how they’re distributed in a material, providing insight into how they’ve been stored in that locality.
Bethany Ehlmann, co-author of the paper, professor of planetary sciences and associate director of the Keck Institute for Space Studies, said: “SHERLOC’s microscopic compositional imaging capabilities have really opened up our ability to decipher the temporal order of Mars fits to environments.”
As the rover rolled toward the delta, it took several samples of the water-altered igneous rocks and cached them for a possible future sample return mission. The samples should be brought back to Earth and examined in laboratories with advanced instrumentation to definitively determine the presence and type of organic substances and if they have anything to do with life.
Eva L. Scheller et al, Aqueous weathering processes in Jezero crater, Implications on Mars for organic geochemistry, Science (2022). DOI: 10.1126/science.abo5204
Provided by Imperial College London
Citation: Possible Organic Compounds Found in Mars Crater Rocks (2022, Nov 24) Retrieved Nov 25, 2022 from https://phys.org/news/2022-11-compounds-mars-crater.html
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