The Rosetta spacecraft has detected glycine - a crucial amino acid - and a variety of organic molecules in the atmosphere of comet 67P/Churyumov-Gerasimenko. The new findings suggest that icy comets could have played a role in bringing some of the ingredients for life to Earth.
The Rosetta spacecraft has been orbiting comet 67P/Churyumov-Gerasimenko since 2014. Although NASA's Stardust mission previously extracted glycine from cometary dust samples that were brought to Earth, the new findings mark the first time that the compound has been detected in space in a naturally vaporized form.
"With all the organics, amino acid and phosphorus, we can say that the comet really contains everything to produce life - except energy," said Kathrin Altwegg of the University of Bern and first author of the study. "Energy is completely missing on the comet, so on the comet you cannot form life. But once you have the comet in a warm place - let's say it drops into the ocean - then these molecules get free, they get mobile, they can react, and maybe that's how life starts."
Glycine is one of the simplest amino acids, and due to its typical nature as a solid, it is difficult to detect from far away. Previous attempts to find glycine in space using telescopes have had no success, and the new finding was only possible due to the proximity of the orbiting Rosetta to the comet's dust grains.
Scientists believe that the new results are a strong confirmation of earlier studies on Earth that suggested the presence of life's building blocks in comet material.
"We know the Earth was pretty heavily bombarded both with asteroidal material and cometary material," said Michael A'Hearn, a comet researcher at the University of Maryland who was not involved in the study. "There have been various claims of amino acids in meteorites, but all of them have suffered from this problem of contamination on Earth."
"The Stardust [samples] - which are from a comet, not an asteroid - are probably the least susceptible to the terrestrial contamination problem, but even there the problem is severe," he added. "I think they [Stardust] really did have glycine, but this is a much cleaner detection in many ways."
In addition, the discovery will help researchers in their understanding of the conditions of the early solar system and the other time periods when Earth was hit by comets similar to 67P/Churyumov-Gerasimenko.
"For astrobiology, it's a very important measurement," Altwegg said. "And it's not only life on Earth; the material in comets has been formed in a protostellar cloud, and what could have happened here in our protostellar cloud could have happened everywhere in the universe."
"Then you can ask yourself the question: How many Earths are there, how many evolved life or re-evolved life?" she added.
The findings were published in the May 27 issue of the journal Science Advances.
