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

7. Goethite, Akagenite, Maghemite, Magnetite, Carbonates and/or sulfides of Magnesium Olivine, Pyroxene Troilite olivine goethite akagenite troilite Iddingsite (on rims of olivine)

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. Example: ion Fe 2+ Crystal structure of an Olivine

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

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

17. Sample data RELAB Spectral Catalog - TB-RPB-011Brown University Keck/NASA Spectrum TB-RPB-011/LATB11 Wavelength(micron)ReflectanceError 0.320.1235290.0001 0.330.1219210.0001 … 2.59987 0.3419590.0001 2.60117 0.3432730.0001 Data for a weathered urelite meteorite

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

19. Output data

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

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