Headlines > News > NASA Researchers Make First Discovery of Life's Building Block in Comet

NASA Researchers Make First Discovery of Life's Building Block in Comet

Published by Klaus Schmidt on Tue Aug 18, 2009 6:52 am via: source
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PASADENA, Calif., (NASA) — 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 in 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.”

This is an artist's concept of the Stardust spacecraft beginning its flight through gas and dust around comet Wild 2. The white area represents the comet. The collection grid is the tennis-racket-shaped object extending out from the back of the spacecraft. Credit: NASA/JPL

This is an artist's concept of the Stardust spacecraft beginning its flight through gas and dust around comet Wild 2. The white area represents the comet. The collection grid is the tennis-racket-shaped object extending out from the back of the spacecraft. Credit: NASA/JPL

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 in Washington, D.C., August 16.

“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, 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 Jan. 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 that detached from the spacecraft and parachuted to Earth on Jan. 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 Donald E. Brownlee, a professor at the University of Washington, Seattle. “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.

7 Comments
stan57
How is it impossible that the comet was actually from earth to begin with? If what scientist say is true that the dinosaurs died from a huge comet,wouldn't it make since that part of our ocean was ejected into space and frozen with life inside of it?? Shouldn't there be dinosaurs frozen floating in space somewhere? Wouldn't there be life particles/actual dinosaurs on our moon from the life ending impact or even on mars and other moons?
My questions are why haven't we found more life signs,why are there not more comets made from salt water since the comet hit the ocean so they say. Why isn't our moon loaded with signs of a comet hit on our earth,it should be if what scientist say is true of a huge comet/asteroid ended life on our planet.
mkrug2
regarding stan57: The whole point of finding life elsewhere is to prove that our earth's life came firstly from outside the earth to begin with (not the other way around i think youre a bit confused). The only thing that escapes the earth's atmosphere and makes it out in space are molecules light enough to not be held down by the earth's gravity (ie hydrogen, helium). Salt being Sodium and Chloride are both too large of structures to simply leave the earths atmosphere. Being ejected into space is a possibility but a very miniscule one.

So basically there is still no proof but a stronger correlation for the idea that life (as we know it on earth) originated outside the earth itself and most likely outside our solar system as well. This is an astounding find and I'm happy to be alive to see it!
perezfranco
You tell them, Stan57!

Furthermore, how do we know that Satan did not plant the amino acids in the space probe to confuse us and stray believers from the righteous path?

;D
rocketeer
'that life (as we know it on earth) originated outside the earth'
@mkrug2: I think you skip ahead a little to much here. The finding of Glycine indicates that amino acids (one of the buildigs blocks of life as we know it) might be ubiquitous in space, not necessarily life itself. Furthermore, it could indicate that amino acids on earth are from space, not life.
stan57
@mkrug2
You mean to tell me a comet the size of Mount Everest is incapable of ejecting part of our ocean and life that was in it at the time?? The Comets that hit Jupiter sure ejected matter into space by the pictures i have seen.
eluthria
@stan57
There are theories out there to support the idea that an impact could cause part of the Earth to be ejected into space but the impact would need to be pretty extreme. I give the example of one theory surrounding the formation of our moon.

It is thought that in the early days of planet formation the Earth was hit by a planetary body about 1/3 the size of the Earth. This impact was so powerful that a piece of the Earth was torn off and the impacting bodies coalesced to form the Earth. This piece that was torn off was then locked into orbit around the earth and thus our moon was formed. This theory was given some credibility after the analysis of moon rocks brought back from the moon showed common traits with rocks found on Earth. Such an impact like this also creates massive amounts of heat and in this scenario it is thought that the heat created by the impact is responsible for the geological activity on Earth and was a contributing factor to the formation of life on Earth. It is also thought that the tilt on which the Earth rotates may be due to this theory.

So while there are credible theories to support the idea that a piece of the Earth could be ejected into space it would take a great deal of energy to do this and thus would need to be a very large impact. Such a large impact would leave tell tale signs on our planet of which none have been discovered. If you take as an example the Caloris basin on the planet Mercury it is believed that the impact in this region was so extreme that the seismic waves caused the formation of a chaotic mountain range on the complete other side of the planet.
stan57
@eluthria
There are signs of this impact just off the coast of south America,the one they claim that ended the dinosaurs. At any rate,if we have found mars rocks on the earth, it makes sense that earth particles can be found on our moon and beyond. Besides our planets surface is in constant motion from plate tectonics,it makes complete sense an impact of this size would have been warn away after a few million years
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