NASA confirms building blocks of life found on comets
By Paul Lester
August 19, 2009
Fresh evidence has been revealed to support the theory that life on Earth began in space. NASA's Stardust probe, a specially-designed-comet ‘chaser’, successfully collected particles shed from Comet Wild 2 back in 2004, and NASA scientists have since confirmed for the first time that amino acids can indeed be found on these extraterrestrial bodies.
Amino acids, the building blocks of life, form the basis of proteins and are created when carbon compounds and water are energized by particles such as protons. Samples of Glycine were confirmed by NASA labs after extensive testing. Dr Jamie Elsila, lead author of a paper on the research, said: “Glycine is an amino acid used by living organisms to make proteins, and this is the first time an amino acid has been found in a comet. Our discovery supports the theory that some of life's ingredients formed in space and were delivered to Earth long ago by meteorite and comet impacts."
Stardust gathered samples from the comet’s trail by passing through gas and dust and using a special grid filled with aerogel to collect the debris. This was parachuted back to Earth in January 2006 and scientists have been analyzing it since. "We actually analyzed aluminum foil from the sides of tiny chambers that hold the aerogel in the collection grid," said Elsila. "As gas molecules passed through the aerogel, some stuck to the foil. We spent two years testing and developing our equipment to make it accurate and sensitive enough to analyze such incredibly tiny samples."
Before this announcement could be made, extensive testing took place to confirm that the Glycine did in fact originate in space and to rule out possible contamination from sources on our planet. This research used isotopic analysis of the foil and successfully confirmed that the comet-based Glycine contained more of the heavier Carbon 13 atoms than Glycine from Earth, which led Elsila to announce: “We discovered that the Stardust-returned Glycine has an extraterrestrial carbon isotope signature, indicating that it originated on the comet".
The next stage would be to gather more information from the main nucleus of a comet, which is likely to contain more complex mixtures of amino acids at higher levels. This is predictably quite tricky to do, though NASA is optimistic that Europe’s Rosetta spacecraft, the first designed to orbit and land on a comet, will successfully achieve its goal when it reaches Comet 67P in 2014, after a ten-year journey.