1 Introduction ................................................. 5
1.1 Motivation and Focus .................................... 5
1.2 Structure of the Thesis ................................. 7
2 Geology of Vesta ............................................. 9
2.1 Vestan Geology, Topography and Gravity .................. 9
2.1.1 Large Impact basins ............................. 13
2.1.2 Vestalia Terra .................................. 14
2.1.3 Troughs ......................................... 14
2.2 Mineralogy ............................................. 14
2.2.1 Dark Material ................................... 15
2.2.2 Bright Material ................................. 15
3 Cratering Mechanics on Small Bodies ......................... 19
3.1 Crater Morphologies .................................... 19
3.1.1 Simple Craters .................................. 19
3.1.2 Complex Craters ................................. 19
3.1.3 Asymmetric Craters .............................. 20
3.2 Influence of Physical Properties on Crater-forming
Processes on Asteroids ................................. 20
3.3 Crater Formation Process ............................... 21
3.4 Oblique Impacts ........................................ 22
3.5 Vestan Craters ......................................... 23
4 Mass Movements on Asteroids ................................. 27
4.1 Landslides In Craters, Sliding and Slumping on
Asteroids and Small Moons .............................. 28
4.2 Gully Morphologies ..................................... 29
4.2.1 Theories on Wet Formation of Gullies ............ 29
4.2.2 Theories on Dry Formation of Gullies ............ 30
4.2.3 Occurrence of Wet Gullies ....................... 30
4.2.4 Occurrence of Dry Gullies ....................... 31
4.3 Vestan Mass Movements Forms ............................ 31
4.3.1 Vestan Landslides ............................... 31
4.3.2 Vestan Gullies .................................. 33
II Data and Methods .......................................... 35
5 Instrument Data and Data Processing ......................... 37
5.1 Mission Overview ....................................... 37
5.1.1 Orbital Phases .................................. 38
5.1.2 Level 1 Objectives .............................. 38
5.2 Instruments and Data Processing ........................ 39
5.2.1 Framing Camera (FC) ............................. 40
5.2.2 Visible and Infrared Mapping Spectrometer
(VIR) ........................................... 41
6 Data Analysis and Methods ................................... 45
6.1 Geomorphologie and Geologic Mapping .................... 45
6.2 Geomorphometric Methods ................................ 46
6.3 Chronostratigraphic Methods ............................ 46
6.3.1 Techniques of Age Determination ................. 46
6.3.2 The Vesta Chronologies .......................... 47
6.4 Photometric Methods .................................... 49
6.5 Spectral Information ................................... 49
6.6 Numerical Simulations .................................. 51
III Studies of Key Features ................................... 53
7 Resurfacing Processes ....................................... 55
8 Mass movement on Vesta at steep scarps and crater rims ...... 61
8.1 Abstract ............................................... 61
8.2 Introduction ........................................... 61
8.3 Datasets and Methods ................................... 62
8.4 Geologic Setting ....................................... 63
8.4.1 Description of Map Units (DOMU) of Av-11 and
Av-12 ........................................... 68
8.5 Characterization of mass wasting features in the
Sextilia region ........................................ 71
8.5.1 Mass wasting in craters ......................... 71
8.5.2 Mass wasting at Matronalia Rupes ................ 76
8.6 Discussion ............................................. 76
8.6.1 Landslides and spur-and-gully morphology ........ 76
8.6.2 Scaling ......................................... 79
8.6.3 Mass Movement ................................... 80
8.7 Conclusions ............................................ 81
9 Asymmetric craters on Vesta: Impact on sloping surfaces ..... 83
9.1 Abstract ............................................... 83
9.2 Introduction ........................................... 84
9.3 Data and Methods ....................................... 85
9.3.1 Geologic Investigations ......................... 85
9.3.2 Three-dimensional Hydrocode Simulations ......... 85
9.3.3 Age Determination ............................... 87
9.4 Asymmetric Craters on Vesta - Geomorphologie
Investigation and Classification ....................... 89
9.4.1 Statistical Analysis ............................ 91
9.5 Discussion ............................................. 99
9.5.1 Age Determination ............................... 99
9.5.2 Numerical Modeling of Impacts Into Slopes ...... 102
9.6 Conclusion and Outlook ................................ 110
10 Summary and Conclusion ..................................... 115
10.1 Study of Mass Movements ............................... 115
10.2 Study of Asymmetric Crater Formation .................. 116
10.3 General Conclusions ................................... 117
List of Abbreviations ........................................... i
Curriculum Vitae .............................................. iii
Publications .................................................... v
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