Investigations of Water-Bearing Environments on the Moon and Mars by Julie Mitchell A Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Approved November 2017 by the Graduate Supervisory Committee: Philip R. Christensen, Chair James F. Bell III Steven Desch Hilairy E. Hartnett Mark Robinson ARIZONA STATE UNIVERSITY December 2017 ABSTRACT Water is a critical resource for future human missions, and is necessary for understanding the evolution of the Solar System. The Moon and Mars have water in various forms and are therefore high-priority targets in the search for accessible extraterrestrial water. Complementary remote sensing analyses coupled with laboratory and field studies are necessary to provide a scientific context for future lunar and Mars exploration. In this thesis, I use multiple techniques to investigate the presence of water- ice at the lunar poles and the properties of martian chloride minerals, whose evolution is intricately linked with liquid water. Permanently shadowed regions (PSRs) at the lunar poles may contain substantial water ice, but radar signatures at PSRs could indicate water ice or large block populations. Mini-RF radar and Lunar Reconnaissance Orbiter Camera Narrow Angle Camera (LROC NAC) products were used to assess block abundances where radar signatures indicated potential ice deposits. While the majority of PSRs in this study indicated large block populations and a low likelihood of water ice, one crater – Rozhdestvenskiy N – showed indirect indications of water ice in its interior. Chloride deposits indicate regions where the last substantial liquid water existed on Mars. Major ion abundances and expected precipitation sequences of terrestrial chloride brines could provide context for assessing the provenance of martian chloride deposits. Chloride minerals are most readily distinguished in the far-infrared (45+ μm), where their fundamental absorption features are strongest. Multiple chloride compositions and textures were characterized in far-infrared emission for the first time. i Systematic variations in the spectra were observed; these variations will allow chloride mineralogy to be determined and large variations in texture to be constrained. In the present day, recurring slope lineae (RSL) may indicate water flow, but fresh water is not stable on Mars. However, dissolved chloride could allow liquid water to flow transiently. Using Thermal Emission Imaging System (THEMIS) data, I determined that RSL are most likely not fed by chloride-rich brines on Mars. Substantial amounts of salt would be consumed to produce a surface water flow; therefore, these features are therefore thought to instead be surface darkening due to capillary wicking. ii DEDICATION This dissertation is dedicated to my cats, who provided unwavering love and used litter throughout my years of graduate school. May their paw prints fly to Mars. iii ACKNOWLEDGMENTS This work was made possible by the support, encouragement, collaboration, and mentorship from the residents of the Mars Space Flight Facility (MSFF), including: Dr. Phil Christensen (graduate advisor and committee chair), the fellow MSFF graduate students (Chris Haberle, Jon Hill, Amber Keske, Chris Mount, Sean Peters, Allie Rutledge, Andy Ryan, Becky Smith, Mike Veto), Tara Fisher, Ashley Toland, the MSFF researchers (Briony Horgan, Jun Huang, Mike Kraft, Steve Ruff, Mark Salvatore), and the ever-patient JMARS and Davinci developers. I also thank Bill O’Donnell and the OTES team for taking the time to show me the ropes of instrument testing. The LROC team was a source of both wisdom and positivity, including: Drs. Mark Robinson (dissertation and oral exam committee member), Sam Lawrence (oral exam committee member), Brett Denevi, and Ernest Cisneros, Kristen Paris and Emerson Speyerer. I also thank the rest of my dissertation committee – Drs. Jim Bell, Steve, Desch, and Hilairy Hartnett – for your honest and helpful feedback. At the department level, I thank Becca Dial and Becky Polley for both your kindness and competence. This work would not have been completed if not for the incredible support – and patience – from my closest friends in SESE: Heather Meyer and Alli Severson, who made me better in every way; my roommates, Kim Ward-Duong, Prajkta Mane, Abhi Rajan, and Taisiya Kopytova; and the rest of the SESE graduate students. I also thank my family: Renae Mitchell (for showing me college is an option), Tracy Mitchell, Vitaliy Gyrya, and Nina Gyrya. And finally, I thank my team at Gracie Barra Brazilian Jiu-Jitsu (Arizona and Texas) for keeping me sane through this whole process. iv TABLE OF CONTENTS Page LIST OF TABLES ................................................................................................................... xi LIST OF FIGURES ............................................................................................................... xii CHAPTER 1 INTRODUCTION ................................................................................................ ... 1 1.1 Motivation and Purpose .......................................................................... 1 1.2 Background ............................................................................................. 4 1.2.1 The Moon ................................................................................. 4 1.2.2 Mars ......................................................................................... 6 2 AN INVESTIGATION OF THE LIKELIHOOD OF WATER ICE AT THE LUNAR NORTH POLE USING RADAR AND VISIBLE IMAGES ........... ... 13 2.1 Introduction ........................................................................................... 13 2.1.1 Preface .................................................................................. 13 2.1.2 Permanently Shadowed Regions ......................................... 14 2.1.3 Previous Results ................................................................... 15 2.1.4 Rationale for This Work ...................................................... 20 2.2 Data Sources and Methods ................................................................... 21 2.2.1 LROC Narrow Angle Cameras ........................................... 21 2.2.2 Miniature Radio Frequency Experiment (Mini-RF) ........... 23 2.2.3 M-chi Decomposition Maps ................................................ 23 2.2.4 Quantifying the Abundance of Blocks ................................ 27 v CHAPTER Page 2.2.5 Size-Frequency Distributions .............................................. 27 2.2.6 Targets of Interest ................................................................ 28 2.3 Results ................................................................................................... 33 2.3.1 Polar CPR-Anomalous Craters ............................................ 33 2.3.2 Polar CPR-Normal Craters .................................................. 44 2.3.3 CPR-Anomalous Equatorial Craters ................................... 44 2.3.4 Circular Polarization Ratio and Lunar Polar Craters .......... 48 2.4 Discussion ............................................................................................. 49 2.4.1 Introduction .......................................................................... 49 2.4.2 Resolution Limitations ......................................................... 49 2.4.3 Implications of Crater Freshness and Age .......................... 50 2.4.4 The Presence of Water-Ice Deposits ................................... 52 2.4.5 Whipple Crater ..................................................................... 54 2.5 Outstanding Questions .......................................................................... 55 2.6 Conclusions ........................................................................................... 57 2.7 Acknowledgments ................................................................................. 58 3 CHLORIDE-RICH BRINES: ANALOGS FOR WATER ON ANCIENT MARS .......................................................................................................................... 59 3.1 Introduction ........................................................................................... 59 3.1.1 Motivation for This Study ................................................... 60 3.2 Background ........................................................................................... 62 vi CHAPTER Page 3.2.1 Brine Genesis ....................................................................... 62 3.2.2 Brine Transport and Water-Rock Reactions ....................... 65 3.2.3 Chemical Evolution of Evaporating Waters ....................... 68 3.2.4 Cold Processes ..................................................................... 73 3.2.5 Influences on Trace Metals .................................................. 75 3.2.6 Seawater ............................................................................... 76 3.2.7 Mars ...................................................................................... 77 3.3 Terrestrial Localities with Chloride-Rich Brines ................................. 79 3.3.1 Hydrothermal Continental Brines........................................ 79 3.3.2 Hydrothermal Oceanic and Mid-Ocean Ridge Brines ........ 81 3.3.3 Temperate Endorheic Basinal Brines .................................. 83 3.3.4 Cold Endorheic Basinal Brines............................................ 85 3.3.5 Deep Basinal Brines ............................................................