Despite the passing years, the rover Curiosity from NASA continues to make interesting discoveries about the planet March. Recently, scientists discovered a essential to life as we know it in the samples taken by the robot at the level of the Gale crater. It’s about organic carbon.
Organic carbon is a carbon bonded to a hydrogen atom. It is the building block of organic molecules created and used by all known life forms. Organic carbon may, however, come from sources that are not living such as meteorites or volcanic eruptions.
According to the scientists, previous studies had already detected organic carbon in small quantities in samples of Martian rocks. But the new measurements provide insight into the total amount of carbon in organic compounds.
Sample analysis by Curiosity
Mars is hostile to life today, but there is some evidence to suggest that the planet was quite similar to Earth billions of years ago, with a thicker atmosphere and liquid water. The Curiosity rover took the samples from clayey rocks dating from 3.5 billion years ago, and which are in an ancient lake. Scientists believe the sediment was formed by the physical and chemical weathering of volcanic rocks before settling to the bottom of the lake.
The samples were analyzed by Curiosity using its SAM or Sample Analysis at Mars instrument. The latter uses oxygen and high temperature to convert the organic carbon in the samples into carbon dioxide. The amount of carbon dioxide formed makes it possible to deduce the amount of organic carbon in the sample and gives the exact isotopic ratio. This allows researchers to know the source of the carbon.
The obtained results
According Jennifer Sterna scientist at NASA’s Goddard Space Flight Center and first author of the study, they found at least 200 to 273 parts per million organic carbon. It is the equivalent – and even more – of the quantity found in the rocks of very sparsely inhabited areas of the Earth such as the Atacama desert in South America. This quantity is also greater than what has been found in Martian meteorites.
Stern added that in the case of samples analyzed by Curiosity, the isotopic composition can only indicate how much of the total carbon is organic, and how much is mineral. Isotopes cannot be used to confirm biological origin because the range overlaps volcanic carbon and organic matter from meteorites. The latter are most likely to be the source of this organic carbon.
However, scientists have also identified other signs that Gale Crater may have once supported life. For example, there is the presence of chemical energy sources and chemical elements such as nitrogen, oxygen and sulphur. Low acidity levels were also measured.