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Deconvolving Terrestrial Alteration Mineral Signatures from Meteorite Reflectance Measurements

Deconvolving Terrestrial Alteration Mineral Signatures from Meteorite Reflectance Measurements. …to derive a precise and accurate spectrum of a weathered meteorite to find its true parent body…. Sweta Shah Physics Dept. Ithaca College. Acknowledgements: Prof: Beth Clark

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Deconvolving Terrestrial Alteration Mineral Signatures from Meteorite Reflectance Measurements

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  1. Deconvolving Terrestrial Alteration Mineral Signatures from Meteorite Reflectance Measurements …to derive a precise and accurate spectrum of a weathered meteorite to find its true parent body… Sweta Shah Physics Dept. Ithaca College Acknowledgements: Prof: Beth Clark RELAB of Brown University CNS-Physics Department

  2. Earth’s atmosphere chemically alters the original minerals in a meteorite.

  3. Spectroscopy- links a meteorite to its corresponding asteroid in space. Credit: Cornell University and NASA

  4. Goal of the project: Reproduce an uncontaminated spectrum Importance: It will give us a better vision of the source and thus help understand our solar system and its history.

  5. Terrestrial age of a meteorite. Terrestrial age and original chemistry determine the degree to which a meteorite is weathered. A weathered iron meteorite StoneChondrite_Olivine-Hypersthene_L6(weathered crust)

  6. Kind of Weathering Antarctic meteorite samples – * rusty and evaporitic Hot desert samples- *iron oxides and hydroxides Billygoat Donga meteorite

  7. Olivine, Pyroxene Troilite Iddingsite (on rims of olivine) olivine troilite akagenite goethite

  8. Spectroscopy –the study of light

  9. Reflectance spectroscopy Study of light as a function of wavelength that has been reflected or scattered from an object. Reflected light is ALBEDO Absorption occurs in many ways.

  10. Absorption processes Electronic absorption

  11. Charge transfer The absorption of a photon causes an electron to move between ions.

  12. Crystal field A crystal field varies with crystal structure from mineral to mineral. Crystal structure of an Olivine Example: ion Fe2+

  13. Vibrational processes Exmaples: water and hydroxyl

  14. Approach • Spectra Download • Minerals (altered and non-altered) • Weathered samples Samples’ name: Bishopville-red and META78008,34 Thanks to RELAB of Brown University! – A NASA facility

  15. Bishopville-red Achondrites – Aubrites • Enstatite • Sodic Plagioclase • Diopside • Olivine • Troilite, and Metal BISHOPVILLE Stone. Achondrite aubrite (AUB)Lee County, South Carolina, USAFell March 25, 1843Total recovered weight 5.9 kg Specimen weight: 7.8 grams

  16. Ureilite • Like Bishopville • Carbonaceous material (graphite and microscopic diamond) META78008,34

  17. Sample data RELAB Spectral Catalog - TB-RPB-011Brown University Keck/NASA Spectrum TB-RPB-011/LATB11 Wavelength(micron) Reflectance Error 0.32 0.123529 0.0001 0.33 0.121921 0.0001 … 2.59987 0.341959 0.0001 2.60117 0.343273 0.0001 Data for a weathered urelite meteorite

  18. The Mixing Model Program • Optimix • written in IDL • Combines endmembers • Simulates a model spectrum

  19. Output data

  20. What we learned • Restricted with major minerals • Several different models match the spectrum.

  21. Future work • Need more minerals • Further detailed studies on the alteration of minerals

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