Martian rock samples collected by NASA’s Curiosity rover show signs of key ingredients for life as we know it on Earth.
The venerable Curiosity Rover drilled samples from Gale Crater, the site of an ancient lake on Mars. Using these samples, scientists were able for the first time to measure the total amount of organic carbon in Martian rocks, according to NASA statement (opens in a new tab).
Organic carbon, which is carbon attached to a hydrogen atom, is a prerequisite for organic molecules created and used by all known life forms. However, organic carbon can also come from inanimate sources, such as meteorites and volcanic eruptions. While previous studies have found organic carbon in smaller amounts in Martian rock samples, new measurements give an idea of the total amount of carbon in organic compounds.
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“Total organic carbon is one of several measurements [or indices] which help us understand how much material is available as a raw material for prebiotic chemistry and potentially biology, “said Jennifer Stern, lead author of the study and space scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.” We found at least 200 to 273 parts per million of organic carbon. This is comparable to or even more than the amount found in the rocks of very low-life areas on Earth, such as parts of the Atacama Desert in South America, and more than was found in meteorites on Mars. “
Today, Mars is not a suitable habitat, but there is evidence to suggest that the Red Planet was more The Earth-as billions of years ago, with a denser atmosphere and liquid water on the surface – key ingredients for life as we know it on Earth.
Martian samples have been collected from 3.5 billion years of mud rocks in the Yellowknife Bay formation at Gale Crater, which Curiosity has been exploring since 2012. Scientists believe the sediment was formed by physical and chemical weathering of volcanic rocks before settling to the bottom of the lake.
The rover analyzes the fragments using its Mars Sample Analysis (SAM) tool, which uses oxygen and high heat to convert organic carbon in the samples into carbon dioxide. From the amount of carbon dioxide produced, the instrument calculates how much organic carbon was in the original sample and tells the exact isotope ratio, which helps scientists understand the source of the carbon, according to the statement. Isotopes are forms of the same chemical element that differ in the number of neutrons in their core.
“In this case, the isotopic composition can really only tell us what part of the total carbon is organic carbon and what part is mineral carbon,” Stern said. “Although biology cannot be completely ruled out, isotopes cannot really be used to maintain the biological origin of this carbon, as the range overlaps with igneous (volcanic) carbon and meteorite organic material, which are most likely to be a source of this organic carbon. “
However, in addition to organic carbon, researchers have identified other signs that suggest the Gale crater may they once sustained lifeincluding the presence of chemical energy sources and chemical compounds such as oxygen, nitrogen and sulfur and low acidity.
“In principle, this place would offer a habitable environment if it ever existed,” Stern said in a statement.
Their findings were published Monday (June 27) in Notices of the National Academy of Sciences.
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