ESA announced on May 27, 2016 that the Rosetta spacecraft has identified the chemical elements glycine and phosphorus in the dusty halo around Comet 67P/Churyumov–Gerasimenko. The craft has been orbiting this comet since August of 2014. Scientists say the discovery is “the first unambiguous detection of glycine at a comet” and provides further evidence supporting the theory that the building blocks for life came to Earth from outer space.
Glycine is the simplest amino acid and one of the molecules needed to make proteins, while phosphorus is a key component of DNA and cell membranes.
ESA’s statement about the discovery said:
Scientists have long debated the important possibility that water and organic molecules were brought by asteroids and comets to the young Earth after it cooled following its formation, providing some of the key building blocks for the emergence of life.
While some comets and asteroids are already known to have water with a composition like that of Earth’s oceans, Rosetta found a significant difference at its comet – fueling the debate on their role in the origin of Earth’s water.
But new results reveal that comets nevertheless had the potential to deliver ingredients critical to establish life as we know it.
Kathrin Altwegg, principal investigator of the ROSINA instrument that made the measurements, and lead author of the paper published in Science Advances on May 27, said:
This is the first unambiguous detection of glycine at a comet.
At the same time, we also detected certain other organic molecules that can be precursors to glycine, hinting at the possible ways in which it may have formed.
The scientists explained that “hints of glycine” were found in samples returned to Earth in 2006 from Comet Wild-2 by NASA’s Stardust mission. However, they said, possible terrestrial contamination of the dust samples made the analysis extremely difficult.
Rosetta obtained its measurements before the comet reached perihelion (its closest point to the sun in its 6.5-year orbit) in August 2015.
It made the first detection in October 2014 while Rosetta was just 6 miles (10 km) from the comet’s nucleus or core.
The next occasion was during a flyby in March 2015, when the craft was about 20-10 miles (30–15 km) from the nucleus.
Bottom line: The Rosetta spacecraft has made the unambiguous detection of the simplest amino acid glycine, plus phosphorus (a key component of DNA and cell membranes), at Comet 67P/Churyumov–Gerasimenko.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.