(ORDO NEWS) — Scientists using data from NASA’s Curiosity rover have measured the total content of organic carbon – a key component in the molecules of life – in Martian rocks for the first time.
“We found at least 200-273 ppm of organic carbon. This is comparable to, or even greater than, the amounts found in rocks in very sparsely inhabited places on Earth, such as part of the Atacama Desert in South America, and more than what has been found in Mars meteorites,” said Jennifer Stern of NASA’s Goddard Space Flight Center. in Greenbelt, Maryland.
Organic carbon is carbon bonded to a hydrogen atom. It is the basis for the organic molecules that are created and used by all known life forms.
However, the presence of organic carbon on Mars does not prove the existence of life there, since it can also come from non-living sources such as meteorites and volcanoes, or be formed in situ as a result of surface reactions.
Organic carbon has been found on Mars before, but previous measurements only provided information on specific compounds or were measurements that captured only a fraction of the carbon in rocks. The new measurement makes it possible to determine the total amount of organic carbon in these rocks.
Although the surface of Mars is now unsuitable for life, there is evidence that billions of years ago the climate was similar to Earth’s, with a denser atmosphere and liquid water that flowed into rivers and seas.
Since liquid water is essential for life, scientists believe that Martian life, if it ever evolved, could have been supported by key ingredients such as organic carbon if it was present in sufficient quantities.
Curiosity is advancing the field of astrobiology by exploring the habitability of Mars by studying its climate and geology.
The rover has drilled samples from a 3.5-billion-year-old mud rock in the Yellowknife Bay Formation in Gale Crater, the site of an ancient lake on Mars.
The mud rocks in Gale Crater were formed as a result of very thin sediment (as a result of physical and chemical weathering of volcanic rocks) in the water settling to the bottom of the lake and was buried. Organic carbon was part of this material and incorporated into the mudstone.
In addition to liquid water and organic carbon, Gale Crater had other conditions favorable to life, such as chemical energy sources, low acidity, and other elements necessary for biology: oxygen, nitrogen, and sulfur.
To take measurements, Curiosity took the sample to the Sample Analysis at Mars (SAM) instrument, where a furnace heated the powdered rock to gradually increasing temperatures. In this experiment, oxygen and heat convert organic carbon into carbon dioxide (CO2).
The addition of oxygen and heat allows the carbon molecules to break down and react with the oxygen to form CO2. Some of the carbon is trapped in the minerals, so the oven heats the sample to very high temperatures to break down those minerals and release the carbon to convert it to CO2.
The experiment was carried out in 2014, but it took years of analysis to understand the data and put the results in the context of other Gale crater mission discoveries. This resource-intensive experiment has only been done once in Curiosity’s 10 years on Mars.
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