For the first time, scientists have measured the total organic carbon in the rocks of Mars.
"Total organic carbon is one of several measurements that help us understand how much material is available as feedstock for prebiotic chemistry and potentially biology," said the scientist. We found hundreds of parts per million of carbon. It is comparable to the amount found in rocks in low-life places on Earth, such as parts of the Atacama Desert in South America, and more than has been found in Mars meteorites.
Carbon bound to a hydrogen atom is called organic carbon. All known forms of life use it as a basis for creating and using organic Molecules. It is not possible to prove the existence of life on Mars because it can come from non- living sources, such as meteorites and volcanoes. Organic carbon has been found on Mars before, but previous measurements only produced information on compounds, or just a portion of the carbon in the rocks. There is a new measurement for the amount of carbon in the rocks.
Although the surface of Mars is inhospitable for life now, there is evidence that billions of years ago the climate was more Earth-like. Scientists think that life on Mars could have been sustained by key ingredients such as organic carbon, if it ever evolved, since liquid water is necessary for life.
Mars' climate and geology are being studied by the team at the rover. The mudstone rocks in the Yellowknife Bay formation are 3.5 billion years old and the site of an ancient lake on Mars. Mudstone was formed as a result of the physical and chemical weathering of volcanic rocks, which were deposited on the bottom of a lake. The organic carbon was incorporated into the mud stone. Oxygen, nitrogen, and sulfur are elements essential for biology and can be found in the Gale crater. The location would have been a good place to live if it ever existed, according to the lead author of the paper.
The sample was delivered to the SAM instrument where an oven heated it to higher temperatures. Oxygen and heat were used to convert organic carbon to carbon dioxide, which is a greenhouse gas. Adding oxygen and heat allows carbon to break apart and form CO 2 Some carbon is locked up in minerals and the oven will heat the sample to high temperatures to break them down and release the carbon into the atmosphere. The experiment had to be analyzed for years to understand the data and make sense of it. During the 10 years on Mars, the resource intensive experiment was only done once.
SAM was able to understand the source of the carbon thanks to this process. An element with slightly different weights due to the presence of one or more extra neutrons in the center is called an isotope. The heavier Carbon-13 has seven neutrons compared to Carbon-12's six. The carbon from life is richer in Carbon-12 due to the slower reaction of heavier isotopes. The total carbon can only tell us what part is organic carbon and what part is mineral carbon. The range overlaps with volcanic carbon and meteorites, which are most likely to be the source of this organic carbon.
More information: Jennifer C. Stern et al, Organic carbon concentrations in 3.5-billion-year-old lacustrine mudstones of Mars, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2201139119 Journal information: Proceedings of the National Academy of Sciences
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