Scientists have made an important discovery on Comet 67P/Churyumov-Gerasimenko, confirming for the first time that it contains two important building blocks of life: the simple amino acid glycine, and phosphorous.

The discovery was made by the ROSINA instrument on board ESA’s Rosetta spacecraft. It suggests that, while comets may or may not have played a part in bringing water to Earth, they may have been responsible for kickstarting life here. The findings are published in the journal Science.

“You would need 10 million comets to supply Earth’s water, but only a few hundred to supply the organic material,” the study’s lead author, Kathrin Altwegg from the University of Bern, told IFLScience. “It’s not proof they started life on Earth, but certainly if you start from amino acids, you could make life. And we know that comets impacted Earth.”

To make the finding, ROSINA detected and sorted gas molecules in the comet’s coma when Rosetta made its closest approach in August 2015. This is not technically the first time that glycine has been found in cometary material; that honor is reserved for NASA’s Stardust mission, which returned samples from Comet Wild 2 to Earth in 2006. However, scientists were unsure if those samples had been contaminated by Earth-based material, so they couldn’t be sure of the discovery.

Now with this latest finding, we know that comets do contain glycine, which is a biologically important organic compound found in proteins. Phosphorous, meanwhile, is a key element that plays a major role in the structural framework of RNA and DNA.

^{The Rosina instrument is on the top back left corner of Rosetta here. ESA/AOES Medialab}

“This shows that comets had the potential to deliver organic-rich material throughout the Solar System, in particular Earth,” Rosetta project scientist Matt Taylor, who was not directly involved in the study, told IFLScience. “The combination of such a delivery with a water-rich environment like Earth then provides the next step to the formation of life itself.”

Other organic compounds have been detected on comet 67P, but this latest finding is a new breakthrough. We still don’t know for sure how life began on Earth, and the theory it had a helping hand from comets is a tantalizing one. It also has implications for finding life on other worlds; if comets played a part here, could they have done the same elsewhere?

“What could have happened to Earth could have happened everywhere,” said Altwegg.

^{Main image: ESA/Rosetta/NAVCAM, CC BY-SA IGO 3.0}