Tuesday, August 18, 2009

Ingredients for prebiotic life found in comet

The Stardust spacecraft encountered comet Wild 2 on January 2, 2004, and collected samples of the comet's coma and tail. Those samples parachuted to Earth on January 15, 2006, and have been studied in labs ever since. From these samples, Jamie Elsila at NASA/Goddard reports the first ever detection of glycine in a comet. Glycine is a common amino acid, which when combined with others can build proteins, which are important building blocks in the chemistry of life. The detection of glycine in comet Wild 2 strengthens the argument that comet impacts on the early Earth provided the prebiotic chemistry that ultimately allowed life to begin on Earth. However, critics of this cometary-delivery theory would argue that comet impacts are far too fiery and energetic to deposit complex organic molecules on Earth whole and unscathed. Regardless, this interesting finding highlights the value of sample-return missions, which can provide valuable insight into composition of ancient and primitive bodies, like as comets and asteroids, that are the primordial building blocks of the planets. See this press release for more details.

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