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, Nate RELAB of Brown University CNS-Physics Department

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

3. 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.

4. 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)

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

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

7. Spectroscopy –the study of light

8. 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.

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

10. Crystal field A crystal field varies with crystal structure from mineral to mineral. Example: ion Fe 2+ Crystal structure of an Olivine

11. 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

12. 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

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

14. Meteorite measurement samples

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

16. Output data

17. Our Model Results

18. Conclusion A close match for Bishopville red wheras not for Ureilite Several different models match the spectrum. Restricted with major minerals Include minor minerals Further detailed studies on the alteration of minerals