Genesis Mission Suggests Science May Need To Be Adjusted
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.
Genesis Spacecraft
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.
Genesis Collection Wafers
"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.
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