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The Physical Properties of Asteroids University of Central Florida STARS Electronic Theses and Dissertations, 2020- 2020 The Physical Properties of Asteroids Leos Pohl University of Central Florida Part of the Physics Commons Find similar works at: https://stars.library.ucf.edu/etd2020 University of Central Florida Libraries http://library.ucf.edu This Doctoral Dissertation (Open Access) is brought to you for free and open access by STARS. It has been accepted for inclusion in Electronic Theses and Dissertations, 2020- by an authorized administrator of STARS. For more information, please contact [email protected]. STARS Citation Pohl, Leos, "The Physical Properties of Asteroids" (2020). Electronic Theses and Dissertations, 2020-. 269. https://stars.library.ucf.edu/etd2020/269 THE PHYSICAL PROPERTIES OF ASTEROIDS by LEOS POHL B.S. Charles University, Prague, 2011 M.S. Charles University, Prague, 2014 A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physics in the Department of Physics in the College of Sciences at the University of Central Florida Orlando, Florida Summer Term 2020 Major Professor: Daniel T. Britt © 2020 LEOS POHL ii ABSTRACT The Small Bodies of the Solar System are leftover material from the formation of planets. Compared with planetary bodies, they have undergone relatively little transfor- mation. Embedded in their physical properties, are clues to the conditions and processes that took place since the condensation of the Solar Nebula. Furthermore, asteroids are sources of raw materials that have become a topic of significant interest. In this dis- sertation, I explore several properties of asteroid material: strength of asteroids, their shielding properties against high energetic particles and their water content. First, I gather all available data on strength of meteoritic material from original papers, unify them into a single data source. Several sources have suggested to apply the Scale Effect to extrapolate the measurements on meteorites to the strength of asteroid size objects. I show that such claims are not supported by available measurements and argue that the strength of asteroids is mostly driven by their extreme heterogeneity. Additionally, I observe inverse relationship between porosity and compressive strength for Ordinary Chondrites. This is not observed for Carbonaceous Chondrites. Next, I study how well material of carbonaceous chondrites acts to decrease and potentially stop charged parti- cles that are found in Cosmic Galactic Rays and Solar protons. Using relativistic quantum mechanical treatment by Bethe with additional high energy corrections, it is found that phyllosilicate materials with hydroxyl interlayer outperform Aluminium in the ability to iii slow down charged particles of energies typical for Solar protons and Galactic Cosmic Rays. Finally, I investigate the loss of water on asteroids on two fronts, experimental and theoretical. I quantify how the major components of Carbonaceous Chondrites de- hydrate. Then, I demonstrate the possibility of loss of water due to orbits that are close to the Sun. iv ACKNOWLEDGMENTS I am grateful to my advisor, Dr. Daniel Britt, for his support, insight, and fruitful discus- sions during my study. He is a wonderful mentor who has provided me with invaluable opportunities to present my research in the conferences to the global scientific community, and has helped me grow both professionally and personally. I would like to express my thanks to the UCF Physics Department for their support throughout this process; my committee members, and all office staff, especially Esperanza Soto for all her assistance and incredible patience. v TABLE OF CONTENTS LIST OF FIGURES .................................................. xii LIST OF TABLES ................................................... xxi LIST OF ACRONYMS ................................................ xxviii CHAPTER 1 : INTRODUCTION ...................................... 1 1.1 Robotic Visits to Asteroids . .2 1.2 Sample Return Missions from Asteroids . .2 1.3 Observations of Asteroids . .3 1.3.1 Asteroid Shapes . .4 1.3.2 Orbital Elements . .5 1.3.3 Spin Period . .6 1.3.4 Spectra . .9 1.4 Analyses of Meteorites . 10 1.4.1 Measurements on Meteorites . 10 1.4.2 Classification of Meteorites . 32 vi CHAPTER 2 : STRENGTHS OF ASTEROIDS AND METEORITES ......... 36 2.1 Background . 36 2.2 Introduction . 41 2.2.1 Definition of Quantities Related to the Measurements of Strength 41 2.2.2 Conditions Affecting the Experimental Results . 47 2.2.3 System of Units and Significant Figures . 49 2.2.4 Extracting Data from Plots . 50 2.3 Data Sources . 51 2.4 Data and Plots . 63 2.4.1 Overview of All Measurements . 63 2.4.2 Size Dependence of Strength . 66 2.4.3 Relationship Between Strength and Density and Porosity . 72 2.4.4 The Final Dataset . 80 2.5 Discussion and Conclusions . 81 2.5.1 Discussion . 81 2.5.2 Conclusions . 86 CHAPTER 3 : INTERACTIONS OF HIGH ENERGETIC PARTICLES WITH AS- TEROIDAL MATTER ................................................ 88 3.1 Background . 88 vii 3.2 Introduction . 89 3.2.1 Sources of Energetic Particles in Space . 93 3.2.2 Asteroidal Mineralogy . 98 3.3 Methodology . 103 3.3.1 Analytical Methods . 103 3.3.2 Numerical Method . 110 3.4 Results and Discussion . 111 3.4.1 Benchmarking . 111 3.4.2 Asteroidal Materials . 116 3.4.3 Asteroidal Minerals . 120 3.4.4 Discussion . 122 3.5 Conclusion . 125 CHAPTER 4 : LOSS OF WATER IN ASTEROIDS BY DEHYDRATRION .... 127 4.1 Background . 127 4.2 Introduction . 130 4.2.1 Hydrated Minerals . 130 4.2.2 Existing Studies . 133 4.3 Samples and Techniques . 150 4.3.1 Samples . 150 viii 4.3.2 Methods . 152 4.4 Results . 174 4.4.1 Serpentines under Inert Gas Flow . 174 4.4.2 Results of Dehydroxylation Viewed by XRD . 182 4.4.3 Results of Dehydroxylation Viewed by FTIR . 184 4.4.4 Heating Rate Effects . 187 4.4.5 Sample Size Effects . 189 4.4.6 Effects of Varying Grain Size . 190 4.4.7 Serpentines under Vacuum . 192 4.5 Discussion . 196 4.5.1 Parameters Affecting the Results . 196 4.5.2 Dehydroxylation of Serpentine Minerals . 198 4.6 Conclusions . 202 CHAPTER 5 : LOSS OF WATER BY ASTEROIDS — APPLICATION ...... 204 5.1 Introduction . 204 5.2 Methods . 205 5.2.1 The Heat Conduction Equation . 205 5.2.2 Summary of Methods and Assumptions . 208 5.3 Results . 212 ix 5.4 Discussion and Conclusions . 217 5.4.1 Discussion of the Simplifying Assumptions . 217 5.4.2 Discussion of the Results . 220 5.4.3 Further Comments . 222 5.4.4 Conclusions . 224 CHAPTER 6 : SUMMARY AND OUTLOOK ............................ 225 6.1 Discussion . 225 6.2 Summary. 234 6.3 Outlook . ..
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