What comets were the bearers of life in our solar system is something recognized and elements that would confirm they were encountered in past missions, but without the certainty that the cometary dust was not a contaminated once again came to our planet, such as the Stardust mission.
Now, thanks to ESA’s probe Rosetta and its encounter with the comet 67P / Churyumov- Gerasimenko , the figure seems certain. Among the ingredients found in her hair appear the amino acid called glycine, which is commonly found in proteins, and phosphorus, one of the key elements of DNA and cell membranes.
“This is the first unambiguous detection of glycine in a comet, “he says Kathrin Altwegg , principal investigator of the ROSINA instrument that performed the measurements and lead author of the study published in Science Advances. “At the same time we also detected the presence of other organic molecules, which can be precursors of the glycine, providing clues about the ways in which this amino acid may have formed.”
The measurements were carried out before the comet reach its closest approach to the Sun, called perihelion, which took place in August of 2015. the first survey was obtained in October 2014, while Rosetta was located 10 km away from the comet. The next opportunity arose during a close flyby in March 2015, when the probe was located at 15-30 km from the comet’s nucleus.
“The glycine is the only amino acid known to be able to form without liquid water, and the fact that we observe it together with the precursor molecules and the dust suggests that it is formed within the interstellar dust grains or by irradiation of frozen ice by ultraviolet light, to then be preserved for billions of years in the comet, “he adds Altwegg.
the new results collected show that comets may still have played a key role in the manifestation of life as we know it. Amino acids are organic compounds containing carbon, oxygen, hydrogen and nitrogen, and form the basis for the proteins, then play a biologically fundamental role.
“There is still much uncertainty as regards the chemical which was present on the early Earth, and there is also, of course, an enormous evolutionary gap to be filled between the arrival of these ingredients with cometary impacts, and the occurrence of life, “says Hervé Cottin , co- author of the study. “The most important aspect is that comets have not got to change over the past 4.5 billion years, and then provide us with a direct access to some of the ingredients that are probably finished in the great prebiotic soup that led to life on Earth “.
Read the article Advances in Science” Prebiotic chemicals – amino acid and phosphorus – in the coma of comet 67P / Churyumov-Gerasimenko “K. Altwegg et al
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