The Genesis mission sampled solar wind ions to document the elemental and isotopic compositions of the Sun and, by inference, of the protosolar nebula. Nitrogen was a key target element because the extent and origin of its isotopic variations in solar system materials remain unknown. Isotopic analysis of a Genesis Solar Wind Concentrator target material shows that implanted solar wind nitrogen has a 15N/14N ratio of 2.18 ± 0.02 × 10-3 (that is, ≈40% poorer in 15N relative to terrestrial atmosphere). The 15N/14N ratio of the protosolar nebula was 2.27 ± 0.03 × 10-3, which is the lowest 15N/14N ratio known for solar system objects. This result demonstrates the extreme nitrogen isotopic heterogeneity of the nascent solar system and accounts for the 15N-depleted components observed in solar system reservoirs.
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