Scientists assessing data from Nasa’s Curiosity Mars rover have found levels of life ingredient molecules in Martian rocks comparable to the amount found in rocks in very harsh “low-life places” on Earth.
The research, published in the journal PNAS on Tuesday, measured total organic carbon – a key component in the molecules of life – in Martian rocks for the first time.
Organic carbon is carbon bound to a hydrogen atom, and forms the basis for organic molecules that are created and used by all known forms of life.
Total organic carbon is a measurement that indicates how much material is available for the chemistry that sustains life-precursour reactions, and potentially life itself, scientists including Jennifer Stern from Nasa’s Goddard Space Flight Center in Maryland, explained.
While organic carbon has been found on Mars before, researchers say prior measurements only produced information on particular compounds, or represented measurements capturing just a portion of the carbon in the rocks.
The new study, they say gives the total amount of organic carbon in these rocks.
The study found “at least 200 to 273 parts per million of organic carbon,” a quantity that is comparable to or even more than that found in rocks in “very low-life places on Earth such as parts of the Atacama Desert in South America,” Dr Stern said.
The discovery of organic carbon does not conclusively prove the existence of life on Mars as these molecules can also arise from non-living sources like meteorites and volcanoes.
However, with previous research suggesting that the Martian climate billions of years ago was more Earth-like, scientists say alien life, if it ever evolved on the Red Planet, could have been sustained by key ingredients like organic carbon, if present in sufficient amount.
In 2014, I placed rock samples in my SAM (Sample Analysis at Mars) instrument to measure the chemical compounds. After years of careful analysis from my team, they measured the total organic carbon in those Martian rocks for the first time. https://t.co/LeWXQ0nBny
— Curiosity Rover (@MarsCuriosity) June 28, 2022
In the new study, researchers assessed data from the Curiosity rover’s assessment of samples drilled from 3.5 billion-year-old mudstone rocks in the Yellowknife Bay formation of Gale crater, the site of an ancient lake on Mars.
They found that organic carbon was part of this mudstone material, and other than liquid water and organic carbon, the Martian crater also had other conditions conducive to life, such as chemical energy sources, low acidity, and elements essential for life like oxygen, nitrogen, and sulfur.
“While results suggest this carbon was largely refractory or mineral-bound in nature, whichattests to its preservation over billions of years, it remains to bedetermined if there is chemical information preserved within itthat pinpoint how it was formed and what processing may havealtered it since deposition,” scientists wrote in the study.
“Basically, this location would have offered a habitable environment for life, if it ever was present,” Dr Stern said.
In the analysis, Curiosity delivered Martian samples to its Sample Analysis at Mars (SAM) which measured ratios of various forms of carbon atoms called isotopes present in the rocks, that help determine the source of the carbon.
“While biology cannot be completely ruled out, isotopes cannot really be used to support a biological origin for this carbon, either, because the range overlaps with igneous (volcanic) carbon and meteoritic organic material, which are most likely to be the source of this organic carbon,” Dr Stern added.