Genesis samples reveal new clues about sun's chemical makeup

Wed, 06/29/2011 - 5:40am

JPL GenesisEver since a crash landing on Earth grounded NASA's Genesis mission in 2004, scientists have been gathering, cleaning, and analyzing solar wind particles collected by the spacecraft. Now, two new studies published in Science reveal that Earth's chemistry is less like the sun's than previously thought.

Because the sun, moon, planets, and meteorites in our solar system started from the same cloud of dust and gases, a long-held assumption has been that these objects share the same chemistry. However, data obtained from samples of material ejected from the outer portion of the sun, which Genesis collected over a two-year time period, show differences in isotopic content of both oxygen and nitrogen when compared to the Earth's atmosphere. Isotopes are variants of a particular element that differ and are identified by their number of neutrons.

One study found that the percentage of oxygen-16—the most prevalent kind of oxygen isotope in the solar system—was slightly higher in solar wind samples than it is in air on Earth and the other terrestrial planets. The second study examined nitrogen isotopes and found that although both the sun and Jupiter appear to have slightly more nitrogen-14 than Earth, they have 40% less N-15. These variations offer insight into how our solar system evolved.

"The sun houses more than 99% of the material currently in our solar system, so it's a good idea to get to know it better," said Don Burnett, professor of nuclear geochemistry, emeritus, at Caltech, and Genesis Principal Investigator. "While it was more challenging than expected, we have answered some important questions, and like all successful missions, generated plenty more."

Burnett says that the Genesis team will continue to mine the salvaged spacecraft for usable samples.


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