[meteorite-list] NASA Researchers Discover Life's Building Block in Comet

[Meteorites USA]

Nancy Neal Jones / Bill Steigerwald
Goddard Space Flight Center, Md.
301 286 0039 / 5017
RELEASE : 09-100AR
SOURCE: http://www.nasa.gov/centers/ames/news/releases/2009/09-100AR.html

August 17th 2009
NASA Researchers Discover Life's Building Block in Comet
MOFFETT FIELD, Calif. -- NASA scientists have discovered glycine, a 
fundamental building block of life, in samples of comet Wild 2 returned 
by NASA's Stardust spacecraft.

"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," said 
Jamie Elsila of NASA's Goddard Space Flight Center, Greenbelt, Md. "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."

Elsila is the lead author of a paper on this research accepted for 
publication in the journal Meteoritics and Planetary Science. The 
research was presented during the meeting of the American Chemical 
Society at the Marriott Metro Center, Washington, DC, Aug. 16, 2009.

"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, director of the NASA Astrobiology 
Institute headquartered at NASA Ames Research Center, which co-funded 
the research.

Proteins are the workhorse molecules of life, used in everything from 
structures like hair to enzymes, the catalysts that speed up or regulate 
chemical reactions. Just as the 26 letters of the alphabet are arranged 
in limitless combinations to make words, life uses 20 different amino 
acids in a huge variety of arrangements to build millions of different 
proteins.

Stardust passed through dense gas and dust surrounding the icy nucleus 
of Wild 2 (pronounced "Vilt-2") on January 2, 2004. As the spacecraft 
flew through this material, a special collection grid filled with 
aerogel – a novel sponge-like material that's more than 99 percent empty 
space – gently captured samples of the comet's gas and dust. The grid 
was stowed in a capsule which detached from the spacecraft and 
parachuted to Earth on January 15, 2006. Since then, scientists around 
the world have been busy analyzing the samples to learn the secrets of 
comet formation and our solar system's history.

"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."

Earlier, preliminary analysis in the Goddard labs detected glycine in 
both the foil and a sample of the aerogel. However, since glycine is 
used by terrestrial life, at first the team was unable to rule out 
contamination from sources on Earth. "It was possible that the glycine 
we found originated from handling or manufacture of the Stardust 
spacecraft itself," said Elsila. The new research used isotopic analysis 
of the foil to rule out that possibility.

Isotopes are versions of an element with different weights or masses; 
for example, the most common carbon atom, Carbon 12, has six protons and 
six neutrons in its center (nucleus). However, the Carbon 13 isotope is 
heavier because it has an extra neutron in its nucleus. A glycine 
molecule from space will tend to have more of the heavier Carbon 13 
atoms in it than glycine that's from Earth. That is what the team found. 
"We discovered that the Stardust-returned glycine has an 
extraterrestrial carbon isotope signature, indicating that it originated 
on the comet," said Elsila.

The team includes Daniel Glavin and Jason Dworkin of NASA Goddard. 
"Based on the foil and aerogel results it is highly probable that the 
entire comet-exposed side of the Stardust sample collection grid is 
coated with glycine that formed in space," adds Glavin.

"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, Seattle, Wash. "It 
is also a remarkable triumph that highlights the advancing capabilities 
of laboratory studies of primitive extraterrestrial materials."

The research was funded by the NASA Stardust Sample Analysis program and 
the NASA Astrobiology Institute. NASA's Jet Propulsion Laboratory, 
Pasadena, Calif., manages the Stardust mission for NASA's Science 
Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, 
developed and operated the spacecraft. For images, refer to:

http://www.nasa.gov/mission_pages/stardust/news/stardust_amino_acid.html



NASA Discovers Life's Building Blocks 1st Delivered to Earth By 
Meteorite & Comets

http://www.dailygalaxy.com/my_weblog/2009/08/nasa-discovery-lifes-building-blocks-1st-delivered-to-earth-by-meteorite-comets.html

Regards,
Eric Wichman
Meteorites USA
www.meteoritesusa.com