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An Early Surprise from Stardust

There seems to be an emerging maxim in deep space studies: every new mission will overturn at least one enshrined assumption Thus the early Stardust results, studying the cometary debris from Wild 2. Because comets come out of the outer dark in their long arc toward the inner system, one would expect them to be made of materials that were born in cold temperatures. But Stardust has brought us cometary dust that’s packed with minerals formed at high temperatures.

What a fascinating set of challenges now face the Stardust researchers. They’ve found olivine in the Wild 2 materials; it’s a compound of iron, magnesium and various other things (the Stardust sample is primarily magnesium). Most astronomers believe that olivine crystals are formed from glass that has undergone heating near stars. So how crystals of olivine can show up in the Wild 2 samples bears scrutiny — after all, Wild 2 is thought to have formed well beyond the orbit of Neptune.

And olivine isn’t the only oddity about the Stardust samples. They also contain high-temperature minerals that are rich in calcium, aluminum and titanium. The message seems clear, as stated by principal investigator Donald Brownlee (University of Washington): “I would say these materials came from the inner, warmest parts of the solar system or from hot regions around other stars.”

About 150 scientists around the world are working on the Stardust samples. They’re studying grains that are embedded in the aerogel used to trap them during the mission’s encounter with the comet in January of 2004. And there’s no shortage of material to work with, since thousands of cometary grains are now available. Brownlee notes that his laboratory has worked on only two particles so far, and has yet to cut into the main part of the first of them.

Centauri Dreams‘ take: We now have samples from the farthest regions of the Solar System that were clearly formed at high temperatures. So perhaps we’re looking at a formation mechanism for planetary systems that involves a constant flow of materials from the center to the outer regions. Or — and this is just as interesting a possibility — it may be that cometary materials like these actually came from other solar systems through transfer mechanisms yet to be explained. Much remains to be done, especially with regard to possible organic materials in the Stardust grains. The payoff just might be a revision of key planetary formation theories. We’ll keep a close eye on this one.

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  • ljk January 4, 2008, 14:29

    U of M physicist reads the history of the solar system in
    grains of comet dust

    http://www.spaceref.com/news/viewpr.nl.html?pid=24417

    Stardust formed close to sun

    http://www.spaceref.com/news/viewpr.nl.html?pid=24420

    “Samples of the material picked up during the NASA Stardust
    mission indicate that parts of the comet Wild 2 actually formed
    in an area close to the sun.”

  • ljk January 25, 2008, 9:53

    Stardust Comet Dust Resembles Asteroid Materials

    Livermore CA (SPX) Jan 25, 2008 – Contrary to expectations
    for a small icy body, much of the comet dust returned by the
    Stardust mission formed very close to the young sun and was
    altered from the solar system’s early materials.

    When the Stardust mission returned to Earth with samples from
    the comet Wild 2 in 2006, scientists knew the material would
    provide new clues about the formation of our solar system,
    but they didn’t know … more

    http://www.spacedaily.com/reports/Stardust_Comet_Dust_Resembles_Asteroid_Materials_999.html

  • ljk December 14, 2008, 22:20

    Announcement from Planetary Science Research Discoveries [PSRD]

    New article online: Wee Rocky Droplets in Comet Dust

    Tiny flash-melted objects in dust collected from comet Wild 2 were transported from the inner Solar System to the outer reaches where
    comets formed.

    We invite you to READ FULL ARTICLE at:

    http://www.psrd.hawaii.edu/Dec08/cometDust.html