The Register 
Tuesday, August 18, 2009
NASA boffins say that they have identified an amino acid, one of the key building blocks of Earth-style life, in material recovered from a comet far out in space. They say this supports the idea that life may be commonly found throughout the universe, and that they have eliminated the chance that the cometary sample has been contaminated by Earthly life.
The sample in question was scooped from the comet Wild-2 in 2004 by the NASA space probe Stardust, which was launched a decade ago in 1999. Having made a close pass to the comet and picked up some of its substance, Stardust then dropped the sample capsule back to Earth in 2006. The main probe, remaining in space, is now to head out again to investigate the comet Tempel-1.
Meanwhile on Earth, boffins analysing the returned “aerogel” collectors soon discovered traces of glycine, an amino acid used by earthly life in building up proteins.
However, “it was possible that the glycine we found originated from handling or manufacture of the Stardust spacecraft itself,” according to NASA’s Dr Jamie Elsila. The scientists have since carried out isotopic analysis of the carbon in the sample, finding that it contains too much carbon-13 to be from Earth.