Mineralogy and Geology of asteroid (4) Vesta from Dawn Framing Camera Guneshwar Thangjam International Max Planck Research School for Solar System Science at the University of Göttingen Mineralogie und Geologie des Asteroiden (4) Vesta von Dawn Framing Camera Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften (Dr. rer. nat.) vorgelegt von Guneshwar Thangjam aus Manipur, Indien genehmigt von der Fakultät für Energie- und Wirtschaftswissenschaften der Technischen Universität Clausthal Tag der mündlichen Prüfung 07 September 2015 Dekan Prof. Dr. Wolfgang Pfau (TUC) Vorsitzender der Promotionskommission Prof. Dr. Hans-Jürgen Gursky (TUC) Erster Gutachter Prof. Dr. Kurt Mengel (TUC) Weitere Gutachter Dr. Andreas Nathues (MPS) Prof. Dr. W. van Berk (TUC) Self-published by Guneshwar Thangjam All rights reserved -To my mother and eldest brother- Contents Zusammenfassung .......................................................................................................................... 5 Summary ............................................................................................................................................ 7 Outline of the thesis ....................................................................................................................... 9 1. Asteroid (4) Vesta in the light of Dawn ............................................................................. 11 1.1 (4) Vesta, HEDs, and the Dawn mission ..................................................................................... 11 1.1.1 Some general aspects of the minor planet Vesta .......................................................................... 11 1.1.2 HED meteorites .......................................................................................................................................... 13 1.1.2.1 Eucrites ...................................................................................................................................................... 13 1.1.2.2 Diogenites.................................................................................................................................................. 14 1.1.2.3 Howardites ............................................................................................................................................... 15 1.1.3 The Dawn mission and the Framing Camera ................................................................................. 15 1.2 Geology and petrology of Vesta .................................................................................................... 17 1.2.1 Petrologic models: ..................................................................................................................................... 20 1.2.1.1 Fractional crystallization .................................................................................................................... 20 1.2.1.2 Partial Melting ......................................................................................................................................... 20 1.2.1.3 Magma Ocean ........................................................................................................................................... 20 1.2.1.4 Serial-magmatism .................................................................................................................................. 22 1.2.2 Towards a model of Vesta’s internal structure ............................................................................. 23 1.3 Laboratory spectra of HEDs, and implications for Vesta .................................................... 31 1.3.1 Two-dimensional spectral analysis: Mid Ratio and Band Tilt ................................................. 34 1.3.2 Three-dimensional spectral analysis: Mid Ratio, Band Tilt and R0.55µm ............................... 37 1.4 Concluding remarks ......................................................................................................................... 38 1.5 References ............................................................................................................................................ 39 2. Lithologic Mapping of HED Terrains on Vesta using Dawn Framing Camera Color Data ........................................................................................................................................ 49 2.0 Abstract ................................................................................................................................................. 50 2.1 Introduction ........................................................................................................................................ 51 2.2 HED analyses ....................................................................................................................................... 52 2.2.1 1-µm Pyroxene Band Parameters and HEDs:................................................................................. 52 2.2.2 Band Curvature (BC): ............................................................................................................................... 57 2.2.3 Band Tilt (BT): ............................................................................................................................................ 57 2.2.4 Band Strength (BS): .................................................................................................................................. 58 2.2.6 Band Strength (BS) and Albedo at 0.749-µm: ................................................................................ 60 2.3 Data Reduction and Analysis ......................................................................................................... 60 2.4 FC data analyses ................................................................................................................................. 61 2.4.1 Band Curvature (BC): ............................................................................................................................... 61 2.4.2 Band Tilt (BT): ............................................................................................................................................ 62 2.4.3 Band Strength (BS): .................................................................................................................................. 62 2.4.4 Lithological mapping using pyroxene band parameters: ......................................................... 63 2.5. Conclusions ......................................................................................................................................... 64 2.6 Acknowledgment ............................................................................................................................... 66 1 2.7 References ............................................................................................................................................ 66 3. Olivine-rich exposures at Bellicia and Arruntia craters on (4) Vesta from Dawn FC ......................................................................................................................................................... 73 3.0 Abstract: ................................................................................................................................................ 74 3.1 Introduction ........................................................................................................................................ 75 3.1.1 Olivine in HEDs and pre-Dawn Vesta background ...................................................................... 76 3.1.2 Olivine versus High-Ca pyroxene in 1 & 2 µm: .............................................................................. 77 3.2 Laboratory-derived Spectra .......................................................................................................... 79 3.2.1 Band Tilt (BT) .............................................................................................................................................. 83 3.2.2 Mid Ratio (MR)............................................................................................................................................ 84 3.2.3 Mid Curvature (MC) .................................................................................................................................. 84 3.2.4. Band depth and albedo at 0.75 μm .................................................................................................... 85 3.2.5 Band parameter approach ..................................................................................................................... 86 3. 3 FC data analyses ................................................................................................................................ 87 3.3.1 Arruntia crater ............................................................................................................................................ 88 3.3.2 Bellicia crater .............................................................................................................................................. 89 3.4 Discussion ............................................................................................................................................ 90 3.4.1 Source of the olivine-rich material: .................................................................................................... 94 3.4.1.1 Excavations from