DOCSLIB.ORG

Investigations of Water-Bearing Environments on the Moon and Mars

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Investigations of Water-Bearing Environments on the Moon and Mars 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 ............................................................
Load more

Recommended publications
  • Washington Division of Geology and Earth Resources Open File Report
    l 122 EARTHQUAKES AND SEISMOLOGY - LEGAL ASPECTS OPEN FILE REPORT 92-2 EARTHQUAKES AND Ludwin, R. S.; Malone, S. D.; Crosson, R. EARTHQUAKES AND SEISMOLOGY - LEGAL S.; Qamar, A. I., 1991, Washington SEISMOLOGY - 1946 EVENT ASPECTS eanhquak:es, 1985. Clague, J. J., 1989, Research on eanh- Ludwin, R. S.; Qamar, A. I., 1991, Reeval­ Perkins, J. B.; Moy, Kenneth, 1989, Llabil­ quak:e-induced ground failures in south­ uation of the 19th century Washington ity of local government for earthquake western British Columbia [abstract). and Oregon eanhquake catalog using hazards and losses-A guide to the law Evans, S. G., 1989, The 1946 Mount Colo­ original accounts-The moderate sized and its impacts in the States of Califor­ nel Foster rock avalanches and auoci­ earthquake of May l, 1882 [abstract). nia, Alaska, Utah, and Washington; ated displacement wave, Vancouver Is­ Final repon. Maley, Richard, 1986, Strong motion accel­ land, British Columbia. erograph stations in Oregon and Wash­ Hasegawa, H. S.; Rogers, G. C., 1978, EARTHQUAKES AND ington (April 1986). Appendix C Quantification of the magnitude 7.3, SEISMOLOGY - NETWORKS Malone, S. D., 1991, The HAWK seismic British Columbia earthquake of June 23, AND CATALOGS data acquisition and analysis system 1946. [abstract). Berg, J. W., Jr.; Baker, C. D., 1963, Oregon Hodgson, E. A., 1946, British Columbia eanhquak:es, 1841 through 1958 [ab­ Milne, W. G., 1953, Seismological investi­ earthquake, June 23, 1946. gations in British Columbia (abstract). stract). Hodgson, J. H.; Milne, W. G., 1951, Direc­ Chan, W.W., 1988, Network and array anal­ Munro, P. S.; Halliday, R. J.; Shannon, W.
    [Show full text]
  • Section 5.4.3: Risk Assessment – Flood
    SECTION 5.4.3: RISK ASSESSMENT – FLOOD 5.4.3 FLOOD This section provides a profile and vulnerability assessment for the flood hazard. HAZARD PROFILE This section provides hazard profile information including description, extent, location, previous occurrences and losses and the probability of future occurrences. Description Floods are one of the most common natural hazards in the U.S. They can develop slowly over a period of days or develop quickly, with disastrous effects that can be local (impacting a neighborhood or community) or regional (affecting entire river basins, coastlines and multiple counties or states) (Federal Emergency Management Agency [FEMA], 2006). Most communities in the U.S. have experienced some kind of flooding, after spring rains, heavy thunderstorms, coastal storms, or winter snow thaws (George Washington University, 2001). Floods are the most frequent and costly natural hazards in New York State in terms of human hardship and economic loss, particularly to communities that lie within flood prone areas or flood plains of a major water source. The FEMA definition for flooding is “a general and temporary condition of partial or complete inundation of two or more acres of normally dry land area or of two or more properties from the overflow of inland or tidal waters or the rapid accumulation of runoff of surface waters from any source (FEMA, Date Unknown).” The New York State Disaster Preparedness Commission (NYSDPC) and the National Flood Insurance Program (NFIP) indicates that flooding could originate from one
    [Show full text]
  • Former Astronaut Visits Stennis
    Volume 7 Issue 8 www.nasa.gov/centers/stennis August 2012 Touchdown! Take it both ways – the Mars Science Laboratory rover, Curiosity, touched Sharp at a height of about 3.4 miles, taller than Mount Whitney in California. down on the surface of Mars early on the morning of Aug. 6 CDT, and the The Curiosity team hopes to drive the rover to the mountain to investigate NASA team scored a very big touchdown for space exploration. This image its lower layers, which scientists think hold clues to past environmental taken by Curiosity shows what lies ahead for the rover – its main science change. This image was captured by a rover camera shortly after it landed. target, Mount Sharp. The rover’s shadow can be seen in the foreground, It has been linearized to remove the distorted appearance that results from and the dark bands beyond are dunes. Rising up in the distance is Mount its fisheye lens. For additional coverage and photos, see pages 4-7. Page 2 LAGNIAPPE August 2012 “NASA is in a unique position to excite and inspire students about STEM education, and to help grow our technical workforce.” From the desk of Katie Wallace Director, Office of Education, Stennis Space Center he Mars Science Laboratory’s successful land- and over 8,000 students and parents. Our workshops ing on Mars early Aug. 6 was a huge engi- have a satisfaction rating of 99 percent. Tneering accomplishment! Years of research, planning, collaboration and dedication came down to In addition, we focus on student activities that enrich seven minutes.
    [Show full text]
  • Imaginative Geographies of Mars: the Science and Significance of the Red Planet, 1877 - 1910
    Copyright by Kristina Maria Doyle Lane 2006 The Dissertation Committee for Kristina Maria Doyle Lane Certifies that this is the approved version of the following dissertation: IMAGINATIVE GEOGRAPHIES OF MARS: THE SCIENCE AND SIGNIFICANCE OF THE RED PLANET, 1877 - 1910 Committee: Ian R. Manners, Supervisor Kelley A. Crews-Meyer Diana K. Davis Roger Hart Steven D. Hoelscher Imaginative Geographies of Mars: The Science and Significance of the Red Planet, 1877 - 1910 by Kristina Maria Doyle Lane, B.A.; M.S.C.R.P. Dissertation Presented to the Faculty of the Graduate School of The University of Texas at Austin in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy The University of Texas at Austin August 2006 Dedication This dissertation is dedicated to Magdalena Maria Kost, who probably never would have understood why it had to be written and certainly would not have wanted to read it, but who would have been very proud nonetheless. Acknowledgments This dissertation would have been impossible without the assistance of many extremely capable and accommodating professionals. For patiently guiding me in the early research phases and then responding to countless followup email messages, I would like to thank Antoinette Beiser and Marty Hecht of the Lowell Observatory Library and Archives at Flagstaff. For introducing me to the many treasures held deep underground in our nation’s capital, I would like to thank Pam VanEe and Ed Redmond of the Geography and Map Division of the Library of Congress in Washington, D.C. For welcoming me during two brief but productive visits to the most beautiful library I have seen, I thank Brenda Corbin and Gregory Shelton of the U.S.
    [Show full text]
  • Recurring Slope Lineae: Evidence of Liquid Water on Mars Today?
    Recurring Slope Lineae: Evidence of liquid water on Mars today? The High Resolution Imaging Science Experiment (HiRISE) on Mars Reconnaissance Orbiter (MRO) has monitored surface feature changes over several Mars years. One of the more intriguing observations has been of the seasonal occurrence of numerous (multi-thousand) dark streak features advancing down equator-facing slopes in several mid-latitude and equatorial regions of the southern hemisphere. Termed Recurring Slope Lineae (RSL), the streak behavior resembles that of a fluid mobilized by increasing surface temperatures – initiating in spring, incrementally extending downslope through summer, and then fading in the fall and winter seasons. The phenomenon is then seen to repeat the following spring. RSLs are narrow in width (meter-scale), requiring our best resolution imaging to see them, but may extend down-slope for hundreds of meters before terminating. Science teams involved in the discovery of RSL have been cautious in concluding a water-based origin since most of the RSL locations are found in environments well outside the pressure-temperature stability field for liquid water. However, the presence of salts such as perchlorate can depress freezing points by tens of degrees. MRO Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) observations of multiple RSL locations show hydrated mineral absorption signals most consistent with magnesium perchlorate, magnesium chlorate and sodium perchlorate. That raises the possibility of a Mg-, Na-, Cl-rich brine that would also leave these minerals as a kind of evaporite deposit. However, the amount of water, if present, has been constrained at one location by independent Thermal Emission Imaging System (THEMIS; Mars Odyssey) data analysis and a numerical heat transfer model to 0 wt.%, and up to 3 wt.% given observational uncertainties, unlikely to support a sustained flow.
    [Show full text]
  • LCROSS (Lunar Crater Observation and Sensing Satellite) Observation Campaign: Strategies, Implementation, and Lessons Learned
    Space Sci Rev DOI 10.1007/s11214-011-9759-y LCROSS (Lunar Crater Observation and Sensing Satellite) Observation Campaign: Strategies, Implementation, and Lessons Learned Jennifer L. Heldmann · Anthony Colaprete · Diane H. Wooden · Robert F. Ackermann · David D. Acton · Peter R. Backus · Vanessa Bailey · Jesse G. Ball · William C. Barott · Samantha K. Blair · Marc W. Buie · Shawn Callahan · Nancy J. Chanover · Young-Jun Choi · Al Conrad · Dolores M. Coulson · Kirk B. Crawford · Russell DeHart · Imke de Pater · Michael Disanti · James R. Forster · Reiko Furusho · Tetsuharu Fuse · Tom Geballe · J. Duane Gibson · David Goldstein · Stephen A. Gregory · David J. Gutierrez · Ryan T. Hamilton · Taiga Hamura · David E. Harker · Gerry R. Harp · Junichi Haruyama · Morag Hastie · Yutaka Hayano · Phillip Hinz · Peng K. Hong · Steven P. James · Toshihiko Kadono · Hideyo Kawakita · Michael S. Kelley · Daryl L. Kim · Kosuke Kurosawa · Duk-Hang Lee · Michael Long · Paul G. Lucey · Keith Marach · Anthony C. Matulonis · Richard M. McDermid · Russet McMillan · Charles Miller · Hong-Kyu Moon · Ryosuke Nakamura · Hirotomo Noda · Natsuko Okamura · Lawrence Ong · Dallan Porter · Jeffery J. Puschell · John T. Rayner · J. Jedadiah Rembold · Katherine C. Roth · Richard J. Rudy · Ray W. Russell · Eileen V. Ryan · William H. Ryan · Tomohiko Sekiguchi · Yasuhito Sekine · Mark A. Skinner · Mitsuru Sôma · Andrew W. Stephens · Alex Storrs · Robert M. Suggs · Seiji Sugita · Eon-Chang Sung · Naruhisa Takatoh · Jill C. Tarter · Scott M. Taylor · Hiroshi Terada · Chadwick J. Trujillo · Vidhya Vaitheeswaran · Faith Vilas · Brian D. Walls · Jun-ihi Watanabe · William J. Welch · Charles E. Woodward · Hong-Suh Yim · Eliot F. Young Received: 9 October 2010 / Accepted: 8 February 2011 © The Author(s) 2011.
    [Show full text]
  • No. 40. the System of Lunar Craters, Quadrant Ii Alice P
    NO. 40. THE SYSTEM OF LUNAR CRATERS, QUADRANT II by D. W. G. ARTHUR, ALICE P. AGNIERAY, RUTH A. HORVATH ,tl l C.A. WOOD AND C. R. CHAPMAN \_9 (_ /_) March 14, 1964 ABSTRACT The designation, diameter, position, central-peak information, and state of completeness arc listed for each discernible crater in the second lunar quadrant with a diameter exceeding 3.5 km. The catalog contains more than 2,000 items and is illustrated by a map in 11 sections. his Communication is the second part of The However, since we also have suppressed many Greek System of Lunar Craters, which is a catalog in letters used by these authorities, there was need for four parts of all craters recognizable with reasonable some care in the incorporation of new letters to certainty on photographs and having diameters avoid confusion. Accordingly, the Greek letters greater than 3.5 kilometers. Thus it is a continua- added by us are always different from those that tion of Comm. LPL No. 30 of September 1963. The have been suppressed. Observers who wish may use format is the same except for some minor changes the omitted symbols of Blagg and Miiller without to improve clarity and legibility. The information in fear of ambiguity. the text of Comm. LPL No. 30 therefore applies to The photographic coverage of the second quad- this Communication also. rant is by no means uniform in quality, and certain Some of the minor changes mentioned above phases are not well represented. Thus for small cra- have been introduced because of the particular ters in certain longitudes there are no good determi- nature of the second lunar quadrant, most of which nations of the diameters, and our values are little is covered by the dark areas Mare Imbrium and better than rough estimates.
    [Show full text]
  • Glossary Glossary
    Glossary Glossary Albedo A measure of an object’s reflectivity. A pure white reflecting surface has an albedo of 1.0 (100%). A pitch-black, nonreflecting surface has an albedo of 0.0. The Moon is a fairly dark object with a combined albedo of 0.07 (reflecting 7% of the sunlight that falls upon it). The albedo range of the lunar maria is between 0.05 and 0.08. The brighter highlands have an albedo range from 0.09 to 0.15. Anorthosite Rocks rich in the mineral feldspar, making up much of the Moon’s bright highland regions. Aperture The diameter of a telescope’s objective lens or primary mirror. Apogee The point in the Moon’s orbit where it is furthest from the Earth. At apogee, the Moon can reach a maximum distance of 406,700 km from the Earth. Apollo The manned lunar program of the United States. Between July 1969 and December 1972, six Apollo missions landed on the Moon, allowing a total of 12 astronauts to explore its surface. Asteroid A minor planet. A large solid body of rock in orbit around the Sun. Banded crater A crater that displays dusky linear tracts on its inner walls and/or floor. 250 Basalt A dark, fine-grained volcanic rock, low in silicon, with a low viscosity. Basaltic material fills many of the Moon’s major basins, especially on the near side. Glossary Basin A very large circular impact structure (usually comprising multiple concentric rings) that usually displays some degree of flooding with lava. The largest and most conspicuous lava- flooded basins on the Moon are found on the near side, and most are filled to their outer edges with mare basalts.
    [Show full text]
  • Special Catalogue Milestones of Lunar Mapping and Photography Four Centuries of Selenography on the Occasion of the 50Th Anniversary of Apollo 11 Moon Landing
    Special Catalogue Milestones of Lunar Mapping and Photography Four Centuries of Selenography On the occasion of the 50th anniversary of Apollo 11 moon landing Please note: A specific item in this catalogue may be sold or is on hold if the provided link to our online inventory (by clicking on the blue-highlighted author name) doesn't work! Milestones of Science Books phone +49 (0) 177 – 2 41 0006 www.milestone-books.de [email protected] Member of ILAB and VDA Catalogue 07-2019 Copyright © 2019 Milestones of Science Books. All rights reserved Page 2 of 71 Authors in Chronological Order Author Year No. Author Year No. BIRT, William 1869 7 SCHEINER, Christoph 1614 72 PROCTOR, Richard 1873 66 WILKINS, John 1640 87 NASMYTH, James 1874 58, 59, 60, 61 SCHYRLEUS DE RHEITA, Anton 1645 77 NEISON, Edmund 1876 62, 63 HEVELIUS, Johannes 1647 29 LOHRMANN, Wilhelm 1878 42, 43, 44 RICCIOLI, Giambattista 1651 67 SCHMIDT, Johann 1878 75 GALILEI, Galileo 1653 22 WEINEK, Ladislaus 1885 84 KIRCHER, Athanasius 1660 31 PRINZ, Wilhelm 1894 65 CHERUBIN D'ORLEANS, Capuchin 1671 8 ELGER, Thomas Gwyn 1895 15 EIMMART, Georg Christoph 1696 14 FAUTH, Philipp 1895 17 KEILL, John 1718 30 KRIEGER, Johann 1898 33 BIANCHINI, Francesco 1728 6 LOEWY, Maurice 1899 39, 40 DOPPELMAYR, Johann Gabriel 1730 11 FRANZ, Julius Heinrich 1901 21 MAUPERTUIS, Pierre Louis 1741 50 PICKERING, William 1904 64 WOLFF, Christian von 1747 88 FAUTH, Philipp 1907 18 CLAIRAUT, Alexis-Claude 1765 9 GOODACRE, Walter 1910 23 MAYER, Johann Tobias 1770 51 KRIEGER, Johann 1912 34 SAVOY, Gaspare 1770 71 LE MORVAN, Charles 1914 37 EULER, Leonhard 1772 16 WEGENER, Alfred 1921 83 MAYER, Johann Tobias 1775 52 GOODACRE, Walter 1931 24 SCHRÖTER, Johann Hieronymus 1791 76 FAUTH, Philipp 1932 19 GRUITHUISEN, Franz von Paula 1825 25 WILKINS, Hugh Percy 1937 86 LOHRMANN, Wilhelm Gotthelf 1824 41 USSR ACADEMY 1959 1 BEER, Wilhelm 1834 4 ARTHUR, David 1960 3 BEER, Wilhelm 1837 5 HACKMAN, Robert 1960 27 MÄDLER, Johann Heinrich 1837 49 KUIPER Gerard P.
    [Show full text]
  • Widespread Crater-Related Pitted Materials on Mars: Further Evidence for the Role of Target Volatiles During the Impact Process ⇑ Livio L
    Icarus 220 (2012) 348–368 Contents lists available at SciVerse ScienceDirect Icarus journal homepage: www.elsevier.com/locate/icarus Widespread crater-related pitted materials on Mars: Further evidence for the role of target volatiles during the impact process ⇑ Livio L. Tornabene a, , Gordon R. Osinski a, Alfred S. McEwen b, Joseph M. Boyce c, Veronica J. Bray b, Christy M. Caudill b, John A. Grant d, Christopher W. Hamilton e, Sarah Mattson b, Peter J. Mouginis-Mark c a University of Western Ontario, Centre for Planetary Science and Exploration, Earth Sciences, London, ON, Canada N6A 5B7 b University of Arizona, Lunar and Planetary Lab, Tucson, AZ 85721-0092, USA c University of Hawai’i, Hawai’i Institute of Geophysics and Planetology, Ma¯noa, HI 96822, USA d Smithsonian Institution, Center for Earth and Planetary Studies, Washington, DC 20013-7012, USA e NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA article info abstract Article history: Recently acquired high-resolution images of martian impact craters provide further evidence for the Received 28 August 2011 interaction between subsurface volatiles and the impact cratering process. A densely pitted crater-related Revised 29 April 2012 unit has been identified in images of 204 craters from the Mars Reconnaissance Orbiter. This sample of Accepted 9 May 2012 craters are nearly equally distributed between the two hemispheres, spanning from 53°Sto62°N latitude. Available online 24 May 2012 They range in diameter from 1 to 150 km, and are found at elevations between À5.5 to +5.2 km relative to the martian datum. The pits are polygonal to quasi-circular depressions that often occur in dense clus- Keywords: ters and range in size from 10 m to as large as 3 km.
    [Show full text]
  • Specials Resign Witb Stomach and Liver Trouble?
    DRY GOODH DRY GOODS. but has promised to issue a étalement ÍR6INIA TO-DAY'S TELEGRAPHIC NEWí* ^KOM WASHINGTON. alter tbe eeeeion of the convention to¬ IffiWfi of the Alexandria Oaaett·,] Holt F. ha* been appointed The Situation at Martinique LANSBURGH & BRO., f orr«»p-i'd»Ticw day. But, j'., 16 .M. gover¬ Wasbingtan, D. C , May 16. An csu-ed a sc-nnutional postmaster at Puitimoutb. Parie, May L'Heurre, Favorite Store. Englishman tele¬ Washington'* Dr. Jung, the physician of Lord some among aristocratic sped it« r-» of a Confederate Memorial Day was ob¬ nor pro tem of Mart.nique, today Pauricefote, tbe British Ambassador, circus io Madrid, yesterdav, 0] ti e Ing served at Norfolk yettarday witb ap¬ graphed the minia »r of colonies that Business Hours 8 a. rn. to ß p. na. «aid Ibis morning tbat bis patient wee the Duke of Arion with a laid« ? w bip. propriât» ceremonies. all the city achieves of St. Pierre were Saturdays 9 o'clock. from the disease man wanted to a club of «Lieh 10th, llthtBtlFSts.. N.W. in no serious danger The join Tbomas Savege bas been appointed los*, in the destruction of tbat be is sull-ring, and that the Duke is a member. A council of re¬ city. with wbicb postmaster to succeed W. L. Taylor, Mount tbe Governor reports that be wa9 thing were un¬ bonor, witb tbe Doke as president, signed, at Aebgrove, Fairfax county. Pelee, acting says, founded. "He bas gout io aa acute considered his application, and rejeve'ed Judge B.
    [Show full text]
  • Journal of Geophysical Research: Planets
    Journal of Geophysical Research: Planets RESEARCH ARTICLE On the relative importance of thermal and chemical buoyancy 10.1002/2016JE005221 in regular and impact-induced melting Key Points: in a Mars-like planet • Compositional buoyancy stabilizes melting-induced anomalies at the base of the lithosphere Thomas Ruedas1,2 and Doris Breuer2 • The anomalies may be detectable by gravimetry but not by seismics with a 1Institute of Planetology, Westfälische Wilhelms-Universität Münster, Münster, Germany, 2Institute of Planetary Research, sparse station network • Neglecting impact-induced mantle German Aerospace Center (DLR), Berlin, Germany anomalies results in overestimation of the local crustal thickness Abstract We ran several series of two-dimensional numerical mantle convection simulations representing in idealized form the thermochemical evolution of a Mars-like planet. In order to study the Supporting Information: • Supporting Information S1 importance of compositional buoyancy of melting mantle, the models were set up in pairs of one including •MovieS1 all thermal and compositional contributions to buoyancy and one accounting only for the thermal •MovieS2 contributions. In several of the model pairs, single large impacts were introduced as causes of additional strong local anomalies, and their evolution in the framework of the convecting mantle was tracked. The Correspondence to: models confirm that the additional buoyancy provided by the depletion of the mantle by regular melting T. Ruedas, can establish a global stable stratification of the convecting mantle and throttle crust production. [email protected] Furthermore, the compositional buoyancy is essential in the stabilization and preservation of local compositional anomalies directly beneath the lithosphere and offers a possible explanation for the Citation: Ruedas, T.
    [Show full text]