Distribution and Orientation of Boulders on Asteroid 25143 Itokawa Sara Mazrouei-Seidani A Thesis submitted to the Faculty of Graduate Studies in Partial Fulfillment of the Requirements for the Degree of Master of Science Graduate Program in Earth and Space Science, York University, Toronto, Ontario September 2012 © Sara Mazrouei-Seidani 2012 Library and Archives Bibliotheque et Canada Archives Canada Published Heritage Direction du 1+1 Branch Patrimoine de I'edition 395 Wellington Street 395, rue Wellington Ottawa ON K1A0N4 Ottawa ON K1A 0N4 Canada Canada Your file Votre reference ISBN: 978-0-494-91769-5 Our file Notre reference ISBN: 978-0-494-91769-5 NOTICE: AVIS: The author has granted a non­ L'auteur a accorde une licence non exclusive exclusive license allowing Library and permettant a la Bibliotheque et Archives Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par telecommunication ou par I'lnternet, preter, telecommunication or on the Internet, distribuer et vendre des theses partout dans le loan, distrbute and sell theses monde, a des fins commerciales ou autres, sur worldwide, for commercial or non­ support microforme, papier, electronique et/ou commercial purposes, in microform, autres formats. paper, electronic and/or any other formats. The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in this et des droits moraux qui protege cette these. Ni thesis. Neither the thesis nor la these ni des extraits substantiels de celle-ci substantial extracts from it may be ne doivent etre imprimes ou autrement printed or otherwise reproduced reproduits sans son autorisation. without the author's permission. In compliance with the Canadian Conformement a la loi canadienne sur la Privacy Act some supporting forms protection de la vie privee, quelques may have been removed from this formulaires secondaires ont ete enleves de thesis. cette these. While these forms may be included Bien que ces formulaires aient inclus dans in the document page count, their la pagination, il n'y aura aucun contenu removal does not represent any loss manquant. of content from the thesis. Canada Abstract In the research of early planetary system evolution processes, the study of primitive aster­ oids is key. The objective of this thesis is to confirm and update any previously identified trends in the global and regional distribution of boulders on asteroid 25143 Itokawa, as well as, to discover new findings to better understand the history of this asteroid. Itokawa is a near-Earth object, and the first asteroid that was targeted for a sample return mission. Trends in boulder population should provide new insights in regards to Itokawa’s current appearance following the disruption of a possible parent body, and how its surface might have changed since then. The population of boulders will also be analyzed with respect to latitude for both Itokawa’s current state, and a hypothetical parent body. In particular, boul­ der distribution over the surface of the asteroid might provide a means to test the hypothesis of whether or not Itokawa is a contact binary. Dedication This thesis is dedicated to my parents, for giving me motivation and strength in moments of despair and discouragement. I would not be where I am today had it not been for their love and sacrifices. Acknowledgments It would not have been possible to write this thesis without the support of the kind people around me, to only some of whom it is possible to give particular mention here. First and foremost, I offer my sincerest gratitude to my supervisors Professors Michael Daly and Olivier Barnouin for their constant help, advice, and support. I would like to thank Carolyn Ernst for her input regarding this project, Eliezer Kahn for his support with the SBMT, and Mike Ilnicki for all his help with IDL programming. In my daily work, I have had the opportunity to work with the best group of people, so thank you to all the members of the Planetary Instrumentation Laboratory. I would also like to thank Paul Delaney for he has been invaluable on both an academic and a personal level, for which I am extremely grateful. Last but definitely not least, I would like to thank my beloved parents for their uncon­ ditional love and support as well as Shiva and Shahroukh for their endless motivation and encouragement. Table of Contents Contents Abstract ii Dedication iii Acknowledgments iv Table of Contents v List of Tables viii List of Figures ix 1 Introduction and Background 1 1.1 The Hayabusa M issio n .................................................................................. 1 1.2 Asteroid 25143 Itokawa .................................................................................. 5 1.2.1 How Did Itokawa E volve? ................................................................. 13 2 Tools and Datasets 15 2.1 Small Body Mapping Tool (SBMT) ............................................................. 15 2.2 Gaskell Shape M o d el ...................................................................................... 17 2.3 A M IC A ........................................................................................................... 22 2.4 LIDAR ........................................................................................................... 25 3 Distribution of Boulders on Asteroid Itokawa 29 3.1 Motivation and background ............................................................................ 29 3.2 M ethodology .................................................................................................. 31 v 3.3 Results and A n aly sis ....................................................................................... 37 3.3.1 Overall Distribution ........................................................................... 37 3.3.2 Head vs. B o d y .................................................................................... 41 3.3.3 East vs. W e st ...........................................................................................43 3.3.4 Conclusion .......................................................................................... 45 3.4 Mission Considerations ................................................................................... 48 3.4.1 Introduction to OSIRIS-REx .................................................................. 48 3.4.2 Boulder Distribution on the Muses Sea Lowlands .................................49 3.4.3 Boulder Distribution on the Sagamihara L ow lands ..............................51 ' 3.4.4 Conclusion .......................................................................................... 54 4 Itokawa Now and Then 55 4.1 Motivation and Background .......................................................................... 55 4.2 M ethodology ................................................................................................... 55 4.2.1 Volume and Centre of Mass C alculations ............................................. 57 4.2.2 Inertia Tensor Calculations ............................................................... 60 4.3 Analysis and R e su lts ...................................................................................... 65 4.3.1 The Difference between the rotation poles ............................................. 66 4.3.2 Latitude vs. Boulder D istribution ..........................................................68 5 Conclusion and Future Work 76 References xiv Appendices xxii Appendix A - Chi-square Error A nalysis .................................................................xxii Appendix B - P lo ts .................................................................................................... xxiii Cumulative Boulder Distribution Plots for the H e a d ........................................xxiii Cumulative Boulder Distribution Plots for the B o d y .......................................xxiv Cumulative Boulder Size Distribution Plots for the East S id e ........................xxv Cumulative Boulder Size Distribution Plots for the West S id e ........................xxvi Appendix C - Derivations for Rotation and Transformation ....................................xxvi List of Tables List of Tables 1 Hayabusa Spacecraft Specifications ............................................................... 4 2 Asteroid Itokawa Characteristics ..................................................................... 12 3 AMICA Instrument Specifications [ 1 ] ............................................................ 24 4 LIDAR Instrument Specifications [2] 27 5 Power-index Values for Cumulative Boulder Size Distribution over the En­ tire Surface of Itokawa .................................... 39 6 Power-index Values for Cumulative Boulder Size Distribution on the Head vs. Body .............................................................................................................43 7 Power-index Values for Cumulative Boulder Size Distribution on the East vs. W est................................................................................................................45 8 Power-index Values for Cumulative Boulder Size Distribution - Muses Sea . 51 9 Power-index Values for Cumulative Boulder Size Distribution - Sagamihara 54 viii List of Figures List of Figures 1 Hayabusa Spacecraft [3] 2 2 Asteroid Itokawa’s Orbit Around the Sun [4] 6 3 Itokawa’s Reflectance Spectrum [5] .............................................................