Extraterrestrial Building Blocks of Life
Glycene Amino Acids Found in Wild 2 Comet Samples
Back in 2004 NASA's Stardust Spacecraft collected samples from the gas and dust surrounding the nucleus of the Wild 2 comet.
A collection grid made of aerogel, which is a sponge-like material that's made of 99 percent empty space, was used to capture particles from the gaseous comet material.
The aerogel grid gently collected samples from the comet's gas and dust. The grid was then stowed in a capsule which detached from the spacecraft and parachuted back to Earth.
Extraterrestrial Amino Acid Samples Found on Wild 2 Comet
When Stardust returned to Earth with the samples, scientists all over the world went to work to see what had been gathered by the aerogel.
Some particles of interest were discovered and analyzed to make sure they were indeed extraterrestrial and to rule out any contamination from Earth sources. After a number of tests were performed, it was confirmed that glycene, an amino acid that is used by living organisms to make proteins, had been found in the Wild 2 comet.
Further confirmation came when scientists found that the isotopes in the Stardust amino acids were heavier than those found on Earth. The glycene from the Wild 2 comet has an extraterrestrial carbon isotope signature and that indicates it originated in the comet.
"The discovery of amino acids in the returned comet sample is very exciting and profound," said Stardust Principal Investigator Professor Donald E. Brownlee of the University of Washington in Seattle.
Brownlee also stated that this is a great accomplishment that shows the remarkable capabilities of laboratory studies of primitive extraterrestrial materials.
Fundamental Life Building Blocks may be Prevalent in Space
The Glycene discovered in the Wild 2 comet greatly increases the likelihood of the idea that space contains the fundamental building blocks that produce life.
This also strengthens the argument that life in the universe is more common than previously thought, said Dr. Carl Pilcher, the Director of the NASA Astrobiology Institute where the research was co-funded.
In a NASA article from August 17th, 2009 by Bill Steigerwald titled "NASA Researchers make First Discovery of Life's Building Block in Comet", Dr. Jamie Elsila of NASA's Goddard Space Flight Center in Maryland states that this is the first time an amino acid has been found in comet.
Dr. Elsila is the lead author of a paper that describes this research and which will appear in the Meteoritics and Planetary Science journal. The findings described in the paper were also presented at an American Chemical Society meeting on August 16th, 2009.
Life on Earth Could Have Been Brought by Comets
"The Early Earth was bombarded with comets and meteorites," said Dr. Elsila. The comet findings are another clue as to how ingredients on Earth first got there, she added.
Lab studies by Ralf I. Kaiser, a physical chemist at the University of Hawaii at Manoa and NASA's Astrobiology Institute, show how life could be spurred in space by energy from solar winds and UV light.
Cosmic rays are able to penetrate deep into meters of ice, therefore other amino acids could also form in the icy body of a comet, Kaiser said.
More Comet Sample Collections Planned
Because glycine is small and can volatilize easily, it is not hard to detect it in a comet's gassy halo. Looking into the nucleus of more comets could very well reveal more of life's molecules.
In 2011 the Stardust-NeXT Mission will use the existing Stardust spacecraft to fly by the Tempel 1 comet and observe changes in the comet since the Deep Impact visited it on 2005.
Then, a small lander is scheduled to be released onto comet 67P/Churyumov-Gerasimenko's nucleus by the European Space Agency's Rosetta spacecraft in the year 2014.
This is a very interesting new discovery that could lead to more understanding of how life begins, how it can reach habitable planets and how it can even form anywhere in the Universe.
Comet Wild 2 and Stardust
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