Researchers using NASA’s Curiosity probe have determined the amount of organic carbon – an essential element in the molecules that make up life – within Martian Rocks for the first time.
“Total organic carbon represents just one of a variety of measurements or indexes] that allow us to know the quantity of carbon that is available to feed biochemistry and prebiotics,” said Jennifer Stern of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We discovered at least 200 – 273 parts per million in organic carbon. This is similar to or even greater than the amount that is found in rocks from very low-life regions on Earth including areas that are part of the Atacama Desert of South America, and more than was found by Mars meteorites.”
Organic carbon is carbon bonded to hydrogen atoms. It is the base for organic molecules that are made and used by all types of life. However, the presence of organic carbon found on Mars does not necessarily prove that there is life since it can also be obtained from non-living resources, like volcanic rocks and meteorites, and be formed by surface reactions. Organic carbon was detected on Mars previously, however previous measurements provided information on specific compounds or represented measurements that captured only part of the carbon found in the rocks. The new measurement indicates the entire quantity of carbon organic found in the rocks.
While Mars’s surface Mars is not suitable for life today but there is evidence that millions of years ago, the environment was similar to Earth, with a thicker atmosphere as well as liquid water that ran into oceans and rivers. Because liquid water is essential for living things as we know it, scientists believe Martian life could have evolved, if ever may have been supported through key elements like organic carbon, if it was present in sufficient amounts.
Curiosity is making progress in the field of Astrobiology by studying Mars’s habitability and the climate as well as geology. The rover has drilled samples from 3.5-billion-year-old rock formations of mudstone in the Yellowknife Bay formation of Gale crater which is the location of an ancient lake located on Mars. The mudstone in the Gale crater was formed by extremely fine sediment (from the chemical and physical weathering and even the alteration of volcanoes) in the waters that settled on the bottom of the lake and was then buried. Organic carbon was present in the material and was later in the mudstone. Apart from organic carbon and liquid water, Gale crater had other conditions that were conducive to life including chemicals as energy sources, low levels of acidity, and other elements that are essential to life, like nitrogen, oxygen, and sulfur. “Basically this crater could have provided a suitable living space even if it never was there,” said Stern, the lead author of a study on this research that was published at the end of June in Proceedings of the National Academy of Sciences.
The process also allowed SAM to analyze carbon isotope ratios. These aid in understanding the origin of carbon. Isotopes are the variants of elements with slight variations in weight (masses) in the form of neutrons that are located in the middle (nucleus) in their atoms. For instance, Carbon-12 has six neutrons, and Carbon-13, which is heavier, has Carbon-13 includes seven neutrons. Since heavier isotopes generally react slower than lighter ones, the carbon in life is more abundant in Carbon-12. “In this scenario, the isotopic composition will be used to determine the proportion of carbon is organic and which part is mineral carbon” stated Stern. “While biological origins cannot be totally excluded, isotopes can’t be used to prove an evolutionary origin for this carbon either since the range is overlapping with the range of igneous (volcanic) carbon as well as meteoritic organic materials that are likely to be the origin of organic carbon.”
The research was supported by NASA Mars Exploration Program. The Curiosity Mars Science Laboratory mission is directed by NASA’s Jet Propulsion Laboratory in Southern California; JPL is managed by Caltech. SAM was designed as well as tested in NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Charles Malespin is SAM’s principal investigator.