INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adverselyaffect reproduction. In the unlikely. event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyrightmaterial had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand corner and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book. Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. U·M·I University Microfilms International A Bell & Howell Information Company 300 North Zeeb Road. Ann Arbor. MI 48106-1346 USA 313/761-4700 800/521-0600 Order Number 9416048 Investigations of asteroid family geology Granahan, James Charles, Ph.D. University of Hawaii, 1993 V·M·I 300 N. Zeeb Rd. Ann Arbor, MI48106 INVESTIGATIONS OF ASTEROID FAMILY GEOLOGY A DISSERTATION SUBMITTED TO THE GRADUATE DMSION OF THE UNIVERSITY OF HAWArI IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN GEOLOGY AND GEOPHYSICS DECEMBER 1993 By James Charles Granahan Dissertation Committee: Jeffrey Bell, Chairperson Klaus Keil Paul Lucey B. Ray Hawke David Tholen I ACKNOWLEDGEMENTS Funding for this dissertation research was provided by: The NASA Planetary Astronomy Program (Grant NAGW 712) The NASA Planetary Geology Program (Grant NAGW 802) Hawaii Space Grant College The Galileo Project I would also like to acknowledge all ofthe following people who have provided me with valuable help in completing this dissertation: Cornell University (Brian Carcich, Paul Helfenstein, David Simmonelli, Peter Thomas, and Joe Veverka) Jet Propulsion Laboratory (Elias Barbinis, Bob Carlson, Lucas Kamp, Ken Klassen, Rosaly Lopes, Adriana Ocampo, Marcia Segura, Bill Smythe, and Paul Weissman) Massachusetts Institute ofTechnology (Rich Binzel) NASAlInfrared Telescope Facility ( Lars Bergnet, Charles Kamiski, Daryll Watanabe, and the rest ofthe staft) NASA/Johnson Space Center (Faith Vilas) Planetary Science Institute (Clark Chapman and Don Davis) Rensselaer Polytechnic Institute (Michael Gaffey) United States Geological Survey/FlagstafT(Kris Becker, Tammy Becker, Debbie Cook, Kay Edwards, Hugh Kieffer, Larry Soderblom, Alfred McEwen, and Jim Torson) University ofHawaii - Institute For Astronomy (JeffGoldader and David Tholen) University of Hawaii - Planetary Geosciences (puanani Akaka, Charlotte Albert­ Thenet, Jeff Bell, Jim Bell, Beth Clark, Fraser Fanale, Harold Garbeil, B. Ray Hawke, Karl Hinck, Keith Horton, Klaus Keil, Paul Lucey, Tim McCoy, Marc Norman, Kevin Polk, Mark Robinson, Scott Rowland, Ed Scott, Greg Smith, JeffTaylor, and Tim Williams) and my wife, Dianne Granahan iii ABSTRACT An asteroid family is a collection of asteroids that have very similar proper orbital elements. These clusters are thought to be the products ofan impact disruptive collision ofan asteroid. This idea is used to test two recently proposed asteroid family taxonomies (Zappala et al. 1990 and Williams 1989) with the use ofasteroid spectra. These asteroid family classification systems were tested by seeing if the asteroid family members would be geologically compatible if they were reassembled into one planetoid. The Zappala taxonomy was more accurate in classifying these "genetic" asteroid families than the Williams taxonomy. By recreating the parent bodies ofthe asteroid families it is possible to reconstruct the recent geologic history of the asteroid belt. The Zappala dependent model shows fluctuations in the solar radial distribution of asteroid types through time while the Williams dependent model shows a nearly static solar radial distribution of asteroid belts through time. Infrared observations of the Eos asteroid family revealed a minimum of 10 new K asteroids indicating that the parent body of the Eos family was composed of CO/CV chondrite like material instead of an igneous differentiated planetesimal. Crater count ages of 951 Gaspra indicate that it was the product of impact disruptive asteroid family forming processes. A multi-spectral synergistic mineralogic study of 951 Gaspra utilizing data from the SSI and NIMS Galileo instruments indicate mineralogic heterogeneities on its surface. This data set also indicates that the olivine/orthopyroxene abundances are significantly higher than ordinary chondrite abundances. This multi-instrument study provides a spatially resolved spectral data set of an asteroid family member for comparison with Earth-based spectral data sets. IV TABLE OF CONTENTS Chapter Page Acknowledgments iii Abstract. iv List ofTables vii List. 0 fF'igures IX. Preface ,, ,, xiii Chapter 1: On the Reality of Recently Proposed Asteroid Families 1 1.1 Abstract 1 1.2 Introduction 2 1.3 The Asteroid Family Geologic Model 5 1.4 The Williams Asteroid Families 19 1.5 The Zappala'Asteroid Families 29 1.6 Interloping Asteroids 36 1.7Zappala and Williams AsteroidFamilies 37 1.8 Caveats 38 1.9 Conclusion 39 Chapter 2: The Recent Geologic History of the Asteroid Belt .41 2.1 Abstract 41 2.2 Introduction: Asteroid Families and Parent Bodies 42 2.3 An Asteroid Belt Chronology .48 2.4 Williams' Parent Bodies 50 2.5 The Williams' Geologic History 54 2.6 ZappalaParent Bodies 63 2.7 Zappala Geologic History 65 2.8 A Comparison of Williams and Zappala Geologic Histories 73 2.9 Caveats 74 2.10 Conclusion 75 Chapter 3: Infrared Studiesof the Eos Asteroid Family 78 3.1 Abstract 78 3.2 Introduction: The Eos Asteroid Family 79 3.3 SCAS Instrument Development.. 82 3.4 SCAS Eos Observations 90 3.5 The Eos Family Observations 93 3.6 Caveats 127 3.7 Conclusions 128 Chapter 4: 951 Gaspra: A Resolved End Member Sample 129 4.1 Abstract 129 4.2 Introduction - Ground based observations of951 Gaspra and the family significance of951 Gaspra 130 4.3 Introduction - Historyofthe Galileo project 135 4.4 SSI Instrument Description 142 v TABLE OF CONTENTS (Continued) Chapter Page 4.5 NIMS Instrument Description 144 4.6 Lunar NIMS Calibration Efforts 145 4.7 SSI Analysis Summary 160 4.8 Initial NIMS Analysis Summary 162 4.9 The Gaspra Synergy Analysis 163 4.10 Caveats 177 4.11 Conclusion 177 References 182 VI LIST OF TABLES Table Page 1. Approximate Asteroid Type Equivalence 6 2. Assumed Compositional Interpretations ofAsteroid Types 7 3. Williams' Asteroid Families: Tholen Classified Asteroids 26 4. Williams' Asteroid Families: Barucci Classified Asteroids 27 5. Williams' Asteroid Families: Tedesco Classified Asteroids 28 6. Zappala Asteroid Families: Tholen Classified Asteroids 31 7. Zappala Asteroid Families: Barucci Classified Asteroids 32 8. Zappala Asteroid Families: Tedesco Classified Asteroids 32 9. Zappala Asteroid Families: Statistics 34 10. Zappala Asteroid Families: Relative Velocities 35 11. Assumed Compositional Interpretations ofAsteroid Types .44 12. Williams' Asteroid Families: Tholen Classified Asteroids 47 13. Zappala Asteroid Families: Tholen Classified Asteroids .48 14. Williams' Parent Bodies Characteristics 52 15. Williams' Largest FamilyMembers 53 16. Williams' Parent Bodies Orbital Elements 54 17. Zappala Parent Body Characteristics 64 18. Zappala FamilyLargest Members 64 19. Zappala Parent Bodies Orbital Elements 65 20. The SCAS Filters 89 21. Eos Family Infrared Observations 94 22. Eos Family Albedos ofInfrared Observed Members 126 23. Asteroid 951 Gaspra - Physical Constants 132 VII LIST OF TABLES (Continued) Table Page 24. Scientific Objectives ofthe Galileo Mission 137 25. Galileo's Scientific Payload 139 VlIl LIST OF FIGURES Figure Page 1. Asteroid Proper Elements: Semi-Major Axis and Sine(IncIination) 3 2. Asteroid Proper Elements: Semi-Major Axis and Eccentricity 4 3. Proto-Hungaria 11 4. Proto-Apollo 12 5. Proto-Vesta 13 6. Proto-Koronis 15 7. Proto-Eos 16 8. Proto-Amalsuntha 17 9. Proto-Themis 18 1O. Proto-Trojan 18 11. Asteroid Type Abundance Plot.. .45 12. Superclass Abundance Plot. 46 13. WilliamsFlora Era: Asteroid Types 56 14. WilliamsFlora Era: Asteroid SupercIass 57 15. WilliamsLydian Era: Asteroid Types 58 16. WilliamsLydian Era: Asteroid SupercIass 59 17. WilliamsKoronis Era: Asteroid Types 60 18. WilliamsKoronis Era: Asteroid SupercIass 61 19. Zappala Flora Era: Asteroid Types 67 20. Zappala Flora Era: Asteroid SupercIass 68 21. Zappala Lydian Era: Asteroid Types 69 22. Zappala Lydian Era: Asteroid SupercIass 70 23. Zappala Koronis Era: Asteroid Types 71 IX LIST OF FIGURES (Continued) Figure Page 24. Zappala Koronis Era: Asteroid Superclass 72 25. Asteroid Proper Elements: Eos Family 80 26. Asteroid 639 83 27. 52 Color Survey Eos FamilyK Asteroids 84 28. A Comparison ofK, C, and S Asteroids 85 29. CVICO Chondrites 86 30. S Asteroid Comparison 96 31. K Asteroid Comparison 97 32. Asteroid 221 Eos 98 33. Asteroid 653 Berenike 99 34. Asteroid 661 Cloelia 100 35. Asteroid 513 Centesima 101 36. Asteroid 562 Saloma 102 37. Asteroid 633 Zelima 103 38. Asteroid 742 Edisona l04 39. Asteroid 1075 Helina 105 40. Asteroid 1129 Neujmina l06 41. Asteroid 1148 Rarahu 107 42. Asteroid 1416 Renauxa l08 43. Asteroid 1533 Saimaa 109 44. Asteroid 1199 Geldonia 110 45. Asteroid 1604 Tombaugh lll 46. Asteroid 1234 Elyna 112 47. Asteroid 1799 Koussevitzky l13 x LIST OF FIGURES (Continued) Figure Page 48. Asteroid 1903 Adzhimushkaj 114 49. Asteroid 2091 Sampo 115 50. Asteroid 2957 Tatsuo 116 51. Asteroid 1087 Arabis 117 52. Asteroid 1882 Rauma 118 53. Asteroid 2345 Fucik 119 54. Asteroid 529 Preziosa 120 55.