Possible Organic Compounds Found in Mars Crater Rocks

A study published in Science analyzes several rocks found at the bottom of Jezero crater on Mars, where the Perseverance rover landed in 2020, revealing a significant interaction between rocks and liquid water. These 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 by non-biological processes. A future mission returning the samples to Earth would be needed to determine this.

The study, led by Caltech researchers, was carried out by an international team including researchers from Imperial.

Professor Mark Sephton, from Imperial’s Department of Earth Science and Engineering, is a member of the science team that took part in the rover’s operations on Mars and examined the implications of the findings. He said: “I hope that one day these samples can be returned to Earth so that we can examine evidence for water and possible organic matter, and explore whether conditions were suitable for life at the start of the story of Mars.”

moving water

Perseverance has already found organic compounds in the Jezero Delta. Deltas are fan-shaped geological formations created at the intersection of a river and a lake at the edge of the crater.

Mission scientists were particularly interested in the Jezero Delta because such formations can retain microorganisms. Deltas are created when a river carrying fine sediment enters a deeper, slower body of water. As the water in the river spreads out, it suddenly slows down, depositing the sediments it carries and trapping and preserving any microorganisms that might exist in the water.

However, the bottom of the crater, where the rover landed for safety before heading to the delta, was more of a mystery. In the beds of the lakes, the researchers expected to find sedimentary rocks, because the water lays down layer after layer of sediment. However, when the rover touched down there, some researchers were surprised to find igneous rocks (cooled magma) on the crater floor containing minerals that not only recorded igneous processes but also significant contact with the water.

These minerals, such as carbonates and salts, require water to flow through igneous rocks, carving out niches and depositing dissolved minerals in different areas like voids and fissures. In some places, the data shows evidence of organic material in these potentially habitable niches.

Discovered by SHERLOC

Minerals and possible co-localized organic compounds were discovered using SHERLOC, or the Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals instrument.

Mounted on the rover’s robotic arm, SHERLOC is equipped with a number of tools, including a Raman spectrometer which uses a specific type of fluorescence to look for organic compounds and also see how they are distributed in a material, giving insight how they have been preserved. in this location.

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. past environments.”

As the rover rolled toward the delta, it collected several samples of water-modified igneous rock and cached them for a possible future sample-return mission. The samples would have to be sent back to Earth and examined in laboratories equipped with state-of-the-art instruments to definitively determine the presence and type of organic matter and if it has anything to do with life.