A fundamental building block of life has been found in a comet for the first time, bolstering the theory that the raw ingredients of life arrived on Earth from outer space.
Traces of the amino acid glycine were discovered in a sample retrieved by Nasa from the tail of comet Wild 2. They were captured 242million miles from Earth in January 2004 by the Stardust spacecraft.
An artist’s rendering of the Stardust spacecraft collecting a sample from the comet Wild 2 (left). The composite image of the comet (right) was taken by the spacecraft during its 2004 flyby
Comets are believed to contain well-preserved grains of material dating from the dawn of the solar system billions of years ago, and thus clues to the formation of the sun and planets.
Chains of amino acids are strung together to form protein molecules in everything from hair to the enzymes that regulate chemical reactions inside living organisms.
The latest findings add credence to the notion that extraterrestrial objects such as meteorites and comets may have seeded ancient Earth, and other planets, with these raw materials of life that formed elsewhere in the cosmos.
‘The discovery of glycine in a comet supports the idea that the fundamental building blocks of life are prevalent in space, and strengthens the argument that life in the universe may be common rather than rare,’ said Carl Pilcher, the director of the Nasa Astrobiology Institute in California, which co-funded the research.
The initial detection of glycine, the most common of 20 amino acids in proteins on Earth, was reported last year, but it took time for scientists to confirm that the compound in question was extraterrestrial in origin.
‘We couldn’t be sure it wasn’t from the manufacturing or the handling of the spacecraft,’ said Nasa astrobiologist Jamie Elsila, who was the principal author of the latest research.
‘We’ve seen amino acids in meteorites before, but this is the first time it’s been detected in a comet,’ she said.