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Amino Acid Detected in Comet Debris

stardust_wild2a

Chalk up another win for the ‘life is ubiquitous’ school of thought. We now know that when the Stardust spacecraft passed through the gas and dust surrounding comet Wild 2 back in 2004, it captured samples that include glycine. Living things use glycine to make proteins, which made the preliminary detection of this amino acid a significant event, though one that had to be carefully analyzed. After all, terrestrial contamination could have accounted for the glycine gathered up by Stardust.

Image: The comet Wild 2 as imaged by the Stardust spacecraft. Credit: NASA/JPL.

Ensuing work, however, has ruled out the contamination scenario. The space-gathered samples show significantly more Carbon 13 than glycine from Earth, an isotopic marker that identifies the material as originating in the comet. That gets us back to a welcome thought, that life is common in the universe. Carl Pilcher (NASA Astrobiology Institute) has this to say:

“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.”

We’ve never found an amino acid on a comet before, but we’re now gaining evidence that points to the delivery of critical ingredients to the early Earth by comet and meteor impacts. Donald Brownlee (University of Washington) calls the discovery “a remarkable triumph that highlights the advancing capabilities of laboratory studies of primitive extraterrestrial materials.” More in this NASA news release. The paper is slated to appear in Meteoritics and Planetary Science.

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Comments on this entry are closed.

  • Ron S August 18, 2009, 11:46

    “…we’re now gaining evidence that points to the delivery of critical ingredients to the early Earth by comet and meteor impacts.”

    I would interpret this discovery differently. These compounds are easily synthesized by natural processes, even those in supposedly hostile environments, and so should be expected to have been easily synthesized on Earth itself in its early history.

  • kurt9 August 18, 2009, 13:32

    Finding amino acids in comets is not unexpected. Amino acids have been detected in stellar gas clouds and there is also the famous Murchison meteorite, which had many amino acids not found on Earth. The outer planets’ moons have amino acids as well.

    It is a big jump from amino acids to RNA.

    http://www.pahworld.com/

    A presentation of one possible jump.

  • ljk September 21, 2009, 9:11

    “Atlas of Secular Light Curves of Comets”

    Authors: Ignacio Ferrin

    (Submitted on 18 Sep 2009)

    Abstract: In this work we have compiled 37,692 observations of 27 periodic and non-periodic comets to create the secular light curves (SLCs), using 2 plots per comet. The data has been reduced homogeneously.

    Our overriding goal is to learn the properties of the ensemble of comets. More than 30 parameters are listed, of which over ~20 are new and measured from the plots.

    We define two ages for a comet using activity as a proxy, the photometric age P-AGE, and the time-age, T-AGE. It is shown that these two parameters are robust, implying that the input data can have significant errors but P-AGE and T-AGE come out with small errors. This is due to their mathematical definition. It is shown that P-AGE classifies comets by shape of their light curve.

    The value of this Atlas is twofold: The SLCs not only show what we know, but also show what we do not know, thus pointing the way to meaningful observations. Besides their scientific value, these plots are useful for planning observations. The SLCs have not been modeled, and there is no cometary light curve standard model as there is for some variable stars (i.e. eclipsing binaries).

    Comets are classified by age and size. In this way it is found that 29P/Schwassmann-Wachmann 1 is a baby goliath comet, while C/1983 J1 Sugano-Saigusa-Fujikawa is a middle age dwarf.

    There are new classes of comets based on their photometric properties. The secular light curves presented in this Atlas exhibit complexity beyond current understanding.

    Comments: Accepted for publication in Planetary and Space Science. This is a revised, upgraded, corrected, full color, large size, high resolution, landscape format version of the Atlas, containing 27 comets, 54 SLCs, 109 pages. This version has gone through 15 revisions. With a size of 7.7 Mb, it may take some time to download. Please be patient. Set your printer to color

    Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

    Cite as: arXiv:0909.3498v1 [astro-ph.EP]

    Submission history

    From: Ignacio Ferrin [view email]

    [v1] Fri, 18 Sep 2009 18:21:21 GMT (7609kb)

    http://arxiv.org/abs/0909.3498

  • ljk November 2, 2009, 23:50

    ‘Ultra-primitive’ particles found in comet dust

    Mon, 11/02/2009 – 18:39 – NLN

    Dust samples collected by high-flying aircraft in the upper atmosphere have yielded an unexpectedly rich trove of relicts from the ancient cosmos, report scientists from the Carnegie Institution.

    The stratospheric dust includes minute grains that likely formed inside stars that lived and died long before the birth of our sun, as well as material from molecular clouds in interstellar space. This “ultra-primitive” material likely wafted into the atmosphere after the Earth passed through the trail of an Earth-crossing comet in 2003, giving scientists a rare opportunity to study cometary dust in the laboratory.

    At high altitudes, most dust in the atmosphere comes from space, rather than the Earth’s surface. Thousands of tons of interplanetary dust particles (IDPs) enter the atmosphere each year.

    “We’ve known that many IDPs come from comets, but we’ve never been able to definitively tie a single IDP to a particular comet,” says study coauthor Larry Nittler, of Carnegie’s Department of Terrestrial Magnetism. “The only known cometary samples we’ve studied in the laboratory are those that were returned from comet 81P/Wild 2 by the Stardust mission.” The Stardust mission used a NASA-launched spacecraft to collect samples of comet dust, returning to Earth in 2006.

    Full article here:

    http://machineslikeus.com/news/ultra-primitive-particles-found-comet-dust