Abstract
Solar abundances are important to planetary science since the prevalent model assumes that the composition of the solar photosphere is that of the solar nebula from which planetary materials formed. Thus, solar abundances are a baseline for planetary science. Previously, solar abundances have only been available through spectroscopy or by proxy (CI). The Genesis spacecraft collected and returned samples of the solar wind for laboratory analyses. Elemental and isotopic abundances in solar wind from Genesis samples have been successfully measured despite the crash of the re‐entry capsule. Here we present science rationales for a set of 12 important (and feasible postcrash) Science and Measurement Objectives as goals for the future (Table 1). We also review progress in Genesis sample analyses since the last major review (Burnett 2013). Considerable progress has been made toward understanding elemental fractionation during the extraction of the solar wind from the photosphere, a necessary step in determining true solar abundances from solar wind composition. The suitability of Genesis collectors for specific analyses is also assessed. Thus far, the prevalent model remains viable despite large isotopic variations in a number of volatile elements, but its validity and limitations can be further checked by several Objectives.
Highlights
Purpose of the Genesis MissionThe goal of Genesis sample analysis is to determine the average isotopic and elemental compositions of the solar system at levels of precision required for 21st century planetary science by measuring the composition of the solar wind
We focus on Mn, Ga, and Rb because the CI abundances of these elements differ from photospheric abundances by greater than 20% (Palme et al 2014)
The Genesis Ion Monitor (GIM) and diamond-like-C collectors (DOS) He fluences for the bulk, H, and L arrays agree better than 3%; the E array DOS He fluence is higher than GIM by 12%
Summary
The goal of Genesis sample analysis is to determine the average isotopic and elemental compositions of the solar system at levels of precision required for 21st century planetary science by measuring the composition of the solar wind. A major use of the regime samples is to help understand the fractionation (both elemental and isotopic) caused by the processes of extraction and acceleration of ions from the Sun during solar wind formation. Corrections for this fractionation are needed to derive solar abundances from solar wind data. Array collectors were to be used to measure heavy, low concentration, elements (Ir, Nd, Sm, etc.) plus C isotopes by analyzing large (10–50 cm2) areas Damage to these important collectors has slowed the achievement of Genesis science goals.
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