Jet Propulsion Laboratory, Pasadena, Calif.
WASHINGTON -- Analysis of samples returned by NASA’s Genesis mission indicates our sun and its inner planets may have formed differently than scientists previously thought.
The data revealed slight differences in the types of oxygen and nitrogen present on the sun and planets. The elements are among the most abundant in our solar system. Although the differences are slight, the implications could help determine how our solar system evolved.
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 also are 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, the moon, and meteorites. The other isotopes’ percentages were slightly lower.
"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," said Kevin McKeegan, a Genesis co-investigator from the University of California, Los Angeles and the lead author of one of two Science papers published this week.
The second paper detailed differences in the amount of nitrogen on the sun and planets. Like oxygen, nitrogen has one isotope, N-14, that makes up nearly 100 percent of the atoms in the solar system, but there also is 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.
"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 Petrographiques et Geochimiques in Nancy, France and the lead author of the second 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 Genesis samples collected from the solar wind -- the 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 in 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 made a hard landing as a result of a failed parachute in the Utah Test and Training Range in Dugway, Utah. This 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.
NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed the Genesis mission for NASA’s Science Mission Directorate in 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 in Denver developed and operated the spacecraft. Analysis at the Centre de Recherches Petrographiques et Geochimiques was supported by the Centre National d’Etudes Spatiales and the French National Center for Scientific Research in Paris.
For more information on the Genesis mission, visit http://genesismission.jpl.nasa.gov.
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