NASA Mission Suggests Sun and Planets Constructed Differently

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Dwayne Brown 202-358-1726
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News release: 2011-193 June 23, 2011

NASA Mission Suggests Sun and Planets Constructed Differently

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-193&cid=release_2011-193

PASADENA, Calif. – Researchers analyzing samples returned by NASA's 2004 Genesis mission
have discovered that our sun and its inner planets may have formed differently than previously
thought.

Data revealed differences between the sun and planets in oxygen and nitrogen, which are two of the
most abundant elements in our solar system. Although the difference is slight, the implications could
help determine how our solar system evolved.

"We found that Earth, the moon, as well as Martian and other meteorites which are samples of
asteroids, have a lower concentration of the O-16 than does the sun," said Kevin McKeegan, a
Genesis co-investigator from UCLA, and the lead author of one of two Science papers published this
week. "The implication is that we did not form out of the same solar nebula materials that created the
sun -- just how and why remains to be discovered."

The air on Earth contains three different kinds of oxygen atoms which are differentiated by the
number of neutrons they contain. Nearly 100 percent of oxygen atoms in the solar system are
composed of O-16, but there are also tiny amounts of more exotic oxygen isotopes called O-17 and
O-18. Researchers studying the oxygen of Genesis samples found that the percentage of O-16 in the
sun is slightly higher than on Earth or on other terrestrial planets. The other isotopes' percentages
were slightly lower.

Another paper detailed differences between the sun and planets in the element nitrogen. Like oxygen,
nitrogen has one isotope, N-14, that makes up nearly 100 percent of the atoms in the solar system, but
there is also a tiny amount of N-15. Researchers studying the same samples saw that when compared
to Earth's atmosphere, nitrogen in the sun and Jupiter has slightly more N-14, but 40 percent less N-
15. Both the sun and Jupiter appear to have the same nitrogen composition. As is the case for oxygen,
Earth and the rest of the inner solar system are very different in nitrogen.

"These findings show that all solar system objects including the terrestrial planets, meteorites and
comets are anomalous compared to the initial composition of the nebula from which the solar system
formed," said Bernard Marty, a Genesis co-investigator from Centre de Recherches Pétrographiques
et Géochimiques and the lead author of the other new Science paper. "Understanding the cause of
such a heterogeneity will impact our view on the formation of the solar system."

Data were obtained from analysis of samples Genesis collected from the solar wind, or material
ejected from the outer portion of the sun. This material can be thought of as a fossil of our nebula
because the preponderance of scientific evidence suggests that the outer layer of our sun has not
changed measurably for billions of years.

"The sun houses more than 99 percent of the material currently in our solar system, so it's a good idea
to get to know it better," said Genesis Principal Investigator Don Burnett of the California Institute of
Technology, Pasadena, Calif. "While it was more challenging than expected, we have answered some
important questions, and like all successful missions, generated plenty more."

Genesis launched in August 2000. The spacecraft traveled to Earth's L1 Lagrange Point about 1
million miles from Earth, where it remained for 886 days between 2001 and 2004, passively
collecting solar-wind samples.

On Sept. 8, 2004, the spacecraft released a sample return capsule, which entered Earth's atmosphere.
Although the capsule made a hard landing as a result of a failed parachute in the Utah Test and
Training Range in Dugway, Utah, it marked NASA's first sample return since the final Apollo lunar
mission in 1972, and the first material collected beyond the moon. NASA's Johnson Space Center in
Houston curates the samples and supports analysis and sample allocation.

The Jet Propulsion Laboratory, Pasadena, Calif., managed the Genesis mission for NASA's Science
Mission Directorate, Washington. The Genesis mission was part of the Discovery Program managed
at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems,
Denver, developed and operated the spacecraft. Analysis at the Centre de Recherches
Pétrographiques et Géochimiques, Nancy, France, was supported by the Centre National d'Etudes
Spatiales, Paris, and the Centre National de la Recherche Scientifique, Paris, France.

For more information on the Genesis mission, visit: genesismission.jpl.nasa.gov .

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