Even if comets did not play as big a role in delivering water as once thought to the Earth they certainly had the potential to deliver the ingredients of life, new research has found.The possibility that water and organic molecules were brought to the early Earth through impacts of objects like asteroids and comets have long been the subject of debate.The European Space Agency's (ESA) Rosetta probe has now shown a significant difference in composition between Comet 67P/C-G's water and that of Earth.“The multitude of organic molecules already identified by ROSINA, now joined by the exciting confirmation of fundamental ingredients like glycine and phosphorus, confirms our idea that comets have the potential to deliver key molecules for prebiotic chemistry," explained Matt Taylor, Rosetta project scientist of the European Space Agency (ESA).
While more than 140 different molecules have already been identified in the interstellar medium, amino acids could not be traced. However, hints of the amino acid glycine, a biologically important organic compound commonly found in proteins, were found during NASA's Stardust mission that flew by “Comet Wild 2” in 2004.
Now, for the first time, repeated detections at a comet have been confirmed by Rosetta in Comet 67P/C-G's fuzzy atmosphere or coma.“This is the first unambiguous detection of glycine in the thin atmosphere of a comet," says Kathrin Altwegg, principal investigator of the ROSINA instrument at University of Bern. At the same time, the researchers also detected the organic molecules methylamine and ethylamine which are precursors to forming glycine. Unlike other amino acids, glycine is the only one that has been shown to be able to form without liquid water. "The simultaneous presence of methylamine and ethylamine, and the correlation between dust and glycine, also hints at how the glycine was formed," Altwegg noted.Another exciting detection by ROSINA made for the first time at a comet is of phosphorus. It is a key element in all living organisms and is found in the structural framework of DNA and RNA.“Demonstrating that comets are reservoirs of primitive material in the solar system and vessels that could have transported these vital ingredients to Earth is one of the key goals of the Rosetta mission, and we are delighted with this result,” Taylor pointed out in a paper forthcoming in the journal Science.