About 4.6 billion years ago, the solar nebula transformed into the present solar system. In order to chemically model the processes which drove that transformation, we would, ideally, like to have a sample of that original nebula to use as a baseline from which we can track changes.
NASA’s Genesis sample-return mission 1 is designed to give us just such a baseline composition 2.
It has collected solar wind, material which is ejected from the outer portion of the sun, and returned it to Earth. 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. Moreover, for most rock-forming elements, there appears to be little fractionation of either elements or isotopes between the sun and the solar wind.
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