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Genesis

Researchers interested in meteorites and planetary materials would, ideally, like to have a sample of our original solar nebula to use as a baseline from which to track changes as the Sun and the planets were formed from this nebula.

So, perhaps it is not a surprise that two CMS researchers—Meenakshi Wadhwa and Amy Jurewicz—are working on samples from NASA’s Genesis sample-return mission1,2,3,4 which was designed to give us just such a baseline composition by collecting samples of solar wind.

Solar wind samples are a good surrogate for the solar nebula because (1) a preponderance of scientific evidence suggests that the outer layer of the Sun preserves the composition of the early solar nebula, and (2) for most rock-forming elements, the process of solar wind ejection from the Sun does not appear to cause significant fractionation of either elements or isotopes.

genesisLeft: Artist's conception of the Genesis spacecraft in flight with its collectors deployed.

Both Wadhwa and Jurewicz are working on complementary projects focused on determining the Mg and Fe composition of the solar wind. Wadhwa’s laboratory has validated Mg-isotopic standards used for analyses of elemental abundances by secondary ion mass spectrometry.

Wadhwa will also measure Mg isotopes in a suite of Genesis solar wind samples, each one collected from a different deployable array on the spacecraft that was designed to collect samples of specific solar wind regimes (bulk, fast, slow, or coronal mass ejection) (image, bottom right). The study of Mg isotopes from different regimes can also be considered a solar physics experiment, because if different isotopic compositions are observed among the different regimes, they will represent fractionation by distinct solar processes.

Jurewicz’s research focuses on measuring Fe and Mg abundances in the bulk solar wind. However, she is additionally working with members of the Genesis science team and the Johnson Space Center (JSC) Genesis curatorial staff on a variety of other tasks, including technique development and standardization, sample surface preparation, and outreach activities.

genesis2Above: Genesis payload being tested in the JSC cleanrooms. The stack of plates are arrays of solar-wind collectors (colored hexagons) to be deployed for different solar wind regimes (bulk on top). The gold dish is an electrostatic mirror designed to concentrate solar wind and embed it in the center target.
  1. Official Genesis Mission website http://genesismission.jpl.nasa.gov/
  2. Burnett et al. (2003) The Genesis Discovery Mission: return of solar matter to Earth. Space Sci. Rev. 105: 509-534.
  3. Genesis sub-index of Official NASA website on past missions http://www.nasa.gov/mission_pages/genesis/main/index.html
  4. Genesis sub-index of Astromaterials website of NASA’s Johnson Space Center http://curator.jsc.nasa.gov/genesis/index.cfm