DOCSLIB.ORG

Iapetus-Rätsel Gelöst

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Iapetus-Rätsel Gelöst Welt der Wissenschaft: Planetenforschung das iapetus-rätsel ist gelöst Wie ein saturnmond schwarz-weiß wurde Iapetus, ein Mond des Planeten Saturn, gehört zu den ungewöhnlichsten Objekten im Sonnensystem: Während eine Hemisphäre fast so hell wie Schnee ist, erscheint die andere nahezu schwarz. Kein anderer Körper im Sonnensystem besitzt eine auch nur annähernd vergleichbare Struktur. Diese »Helligkeitsdichotomie« des Iapetus wurde vor mehr als 330 Jahren entdeckt, doch erst jetzt können wir hierfür eine schlüssige Erklärung geben. Von Tilmann denk ie entstand die Helligkeits- tem einzigartigen Eigenschaften sowie die dichotomie des Saturn- Geschichte seiner Erforschung beschrei- in Kürze monds Iapetus? Das war ben. Mit diesen Hintergrundinformatio- ó Schon dem Entdecker des Iapetus, eine der letzten noch of- nen sowie den Messungen der Cassini- Jean-Dominique Cassini, fiel im fenenW Fragen, die sich die Planetenfor- Sonde lässt sich dann unsere Lösung des Jahr 1673 auf, dass der Mond scher bereits im 17. Jahrhundert gestellt Iapetusrätsels gut nachvollziehen. starke Helligkeitsschwankungen hatten. Die Entstehung von Sonnen- und während eines Umlaufs um Mondfinsternissen, die Phasen der Venus, der eigentümliche saturnmond Saturn zeigt. die wahre Natur der Kometen oder der Iapetus ist der drittgrößte der 62 be- ó Bereits Cassini vermutete, dass »Henkel« des Saturn, die Größe der Erde kannten Saturnmonde und steht in der Iapetus eine sehr helle und eine oder die Distanzen zwischen den Planeten Durchmesser-Rangliste der bislang be- sehr dunkle Hemisphäre aufweist, – zu all diesen Fragen kennen wir längst kannten 168 Planetenmonde immerhin was in den 1980er Jahren durch gute, oft sogar vollständige Antworten. an elfter Stelle. Sein Durchmesser beträgt die beiden Voyager-Raumsonden Aber die Helligkeitsdichotomie des Iape- fast 1500 Kilometer, die Dichte liegt bei bestätigt wurde. tus (siehe die Bilder rechts), die erste je auf 1,1 Gramm pro Kubikzentimeter. In sei- ó Mit neuen Bildern und Messdaten einem Trabanten jenseits des Erdmonds nem Inneren besteht er überwiegend aus der US-Raumsonde Cassini gelang entdeckte Oberflächenstruktur, entzog Wassereis, dasselbe gilt für weite Teile der nun die schlüssige Erklärung der sich bislang allen Erklärungsversuchen. Oberfläche. Seine Rotation erfolgt syn- ungewöhnlichen Oberfläche: Ver- Dieser Artikel will hierfür eine Antwort chron, Iapetus weist Saturn also immer dunstung von Wassereis mit einer anbieten. Sie basiert auf zwei Veröffentli- dieselbe Seite zu. Die häufigste Gelände- Reihe von Nebenbedingungen. chungen in der Wissenschaftszeitschrift formation auf der Oberfläche sind Ein- Science vom Januar 2010 und kombiniert schlagkrater, die nach Figuren im altfran- frühere Erklärungsversuche mit Entde- zösischen Rolandslied benannt sind und ckungen durch die Raumsonde Cassini. deshalb Namen wie Roland, Charlemagne, Bevor ich die Erklärung vorstelle, möchte Marsilion, Engelier oder Timozel tragen ich aber zuerst Iapetus selbst und einige (siehe die Karte auf S. 42). Die gemessenen seiner merkwürdigen und im Sonnensys- Temperaturen an der Oberfläche betragen 40 April 2010 STERNE UND WELTRAUM aufnahmen des saturnmonds iapetus der raumsonde cassini zeigen die in umlauf- richtung weisende dunkle Bugseite (links) und die in gegenrichtung weisende helle heckseite (rechts). NASA / JPL Berlin NASA / SSI FU iapetus-steckbrief Iapetus Erde Äquatordurchmesser: 1491 km 12 756 km Poldurchmesser: 1424 km 12 714 km Abplattung: 0,045 0,003 Umfang am Äquator: ~4700 km oder 40 024 km oder ~13 km/Grad ~111 km/Grad Oberfläche: 6,7 ∙ 106 km2 5,1 ∙ 107 km2 Volumen: 1,7 ∙ 109 km3 1,08 ∙ 1012 km3 Masse: 1,806 ∙ 1021 kg 5,974 ∙ 1024 kg Mittlere Dichte: 1,083 g/cm3 5,515 g/cm3 Mittlere Anziehungskraft: 0,223 m/s2 9,807 m/s2 Entweichgeschwindigkeit: 580 m/s 11 186 m/s Große Bahnhalbachse: 3 560 851 km 149 597 870 km Siderische Umlaufzeit 1904 h = – um Saturn: 79,33 d Mittlere 3,26 km/s 29,78 km/s Bahngeschwindigkeit: Damit Schüler aktiv mit den Inhalten dieses Beitrags arbeiten Bahnexzentrizität: 0,0293 0,0167 können, stehen auf unserer Internetseite www.wissenschaft- Bahnneigung: 15° zum 0° (definiert) Saturn äquator schulen.de didaktische Materialien zur freien Verfügung. Darin wird gezeigt, wie das Thema im Rahmen des Physikunterrichts in der gymnasialen Oberstufe behandelt werden kann. Unser Projekt »Wissenschaft in die Schulen!« führen wir in Zusam- menarbeit mit der Landesakademie für Lehrerfortbildung in Bad Wildbad und dem Haus der Astronomie in Heidelberg durch. www.astronomie-heute.de April 2010 41 90° N Roland Besgun Godefroy Bevon Milon Berenger Lorant Olivier 60° N Geboin Turpin Almeric Charlemagne Dapamort Ogler Basan Acelin Climborin Othon Basan Falsaron Falsaron oth 30° N Marsilion Roncevaux Terra a M. a M. Valdebron e M. e M. v Margaris Turgis Ivon Grandoyne v Clarin Jurfaleu Adelr do do enc Baligant enc or Johun Astor or Corsablis Haltile Mons Haltile Mons C Eudropin C Escremiz Hamon Sor Rugis Malun Hamon Sor eite 0° Samson 1 Br Naimon Toledo Montes Tortelosa Montes Seville Garlon Carcassone Montes y Mons Timozel Malprimis ttha yne Mons yne Mons Cassini Regio Saragossa Terra Ma Ga -30° S Ga Nevelon alterne Mons alterne Mons V V Pinabel Ganelon AnseÏs Engelier 1: Priamon Gerin Torleu Gerin Basile Basbrun Thierry -60° S Rabel 500 Kilometer -90° S Berlin FU 180° O 150° O 120° O 90° O 60° O 30° O 0° W 330° W 300° W 270° W 240° W 210° W 180° W Länge Anti-Saturn-Punkt Zentrum Bugseite Sub-Saturn-Punkt Zentrum Heckseite Anti-Saturn-Punkt auf dieser Karte des saturnmonds iapetus Iapetus ist übrigens derart weit von Kugel, wie es sich für einen Körper dieser in zylinderprojektion sind die namen der Saturn entfernt, dass sich seine Bahnebe- Größe und Zusammensetzung eigent- oberflächenstrukturen eingetragen. große ne bereits nicht mehr so wie diejenigen lich geziemt, sondern ein zweiachsiges impaktbecken sind rot beschriftet, Krater der anderen inneren Monde nahe der Rotationsellipsoid. Tatsächlich fällt der gelb. Blaue namen weisen auf Krater hin, Äquatorebene Saturns befindet, sondern Poldurchmesser fast 70 Kilometer gerin- die bereits nach den Voyager-Vorbeiflügen in einem Übergangsbereich zwischen der ger aus als der Äquatordurchmesser. Ein anfang der 1980er Jahre benannt worden Saturn-Äquatorebene und der Bahnebe- gewaltiger Bergrücken, der mehr als den sind. Berge und Bergketten des äquatori- ne Saturns um die Sonne. Während sich halben Äquator umspannt und ebenfalls alen Bergrückens sind grün markiert, folglich von den inneren Monden aus nur eine einzigartige Besonderheit von Iape- größere regionen orange. die schmale Ringkante zeigt, würde sich tus darstellt, trägt zusätzlich zur »unför- einem Astronauten auf Iapetus ein unge- migen Form« des Mondes bei. wöhnlich prachtvoller Blick auf das Ring- Schließlich – als mit Abstand am längs- zwischen –144 und –220 Grad Celsius, es system bieten, das am Iapetushimmel ten bekannte und schon von Weitem gibt keine Atmosphäre. Iapetus entstand sechsmal größer erschiene als der Mond offensichtliche Merkwürdigkeit – ist das sehr wahrscheinlich vor mehr als 4,5 Mil- von der Erde aus. Thema dieses Artikels, die Helligkeitsdi- liarden Jahren praktisch zeitgleich mit Als weitere Besonderheit ist die ex- chotomie oder Albedodichotomie, das Saturn und den anderen Planeten. In der treme Tageslänge von 1904 Stunden oder Merkmal von Iapetus schlechthin: Wäh- Tabelle auf S. 41 finden sich einige seiner 79,3 Tagen zu nennen. Da auf Iapetus ein rend die entgegen der Bewegungsrichtung astronomischen und physikalischen Para- Sonnentag und ein Sterntag fast gleich zeigende »Heckseite« und die Polregionen meter im Vergleich zur Erde. lang sind, entspricht dies auch seiner Ei- fast so hell wie Schnee sind, ist die in Flug- Iapetus hat viele ungewöhnliche Eigen- genrotationsperiode beziehungsweise sei- richtung weisende »Bughemisphäre«, die schaften: Zuerst fällt seine äußere Lage im ner siderischen Tageslänge. Von allen Ob- etwa 40 Prozent der Oberfläche oder rund Saturnsystem auf. Seine mittlere Distanz jekten im Sonnensystem, von denen mir 2,7 Millionen Quadratkilometer bedeckt, zum Ringplaneten beträgt 3,6 Millionen etwas über die Eigenrotation bekannt ist, fast so schwarz wie Druckerschwärze (sie- Kilometer, kein anderer »regulärer« dreht sich nur die Venus noch langsamer he Bilder auf S. 41). Planetenmond ist so weit von seinem (243 Tage), und nur auf Merkur (176 Tage) Zentralkörper entfernt. Seine nächsten und Venus (117 Tage) ist der Tag-Nacht- aus der geschichte inneren Nachbarn sind die Monde Hy- Zyklus länger. der iapetusforschung perion (Abstand zu Saturn 1,5 Millionen Auf Iapetus findet sich im Vergleich zu Am 25. Oktober 1671, zu Zeiten der Re- Kilometer) und der bei Weitem größte den anderen Saturnmonden eine über- gentschaft von Louis XIV, entdeckte der Saturnbegleiter Titan (rund 1,2 Millionen durchschnittlich große Anzahl an großen italienisch-französische Astronom Jean- Kilometer). Nur die so genannten äußeren Impaktbecken mit Durchmessern von bis Dominique Cassini (1625 – 1712) von der oder irregulären Monde, von denen man zu 700 Kilometern, diese geben Iapetus königlichen Sternwarte in Paris aus den annimmt, dass sie eingefangene Objekte eine ziemlich »verbeulte« Form (siehe Saturnmond Iapetus. Cassini konnte sei- sind, umkreisen Saturn in deutlich größe- SuW 9/2007, S. 18 – 20). Jedoch auch ohne ne Neuentdeckung bis zum 6. November ren Abständen. die großen Krater wäre Iapetus keine verfolgen, danach verhinderten Wolken 42 April 2010 STERNE UND WELTRAUM
Load more

Recommended publications
  • Annualreport2005 Web.Pdf
    Vision Statement The Space Science Institute is a thriving center of talented, entrepreneurial scientists, educators, and other professionals who make outstanding contributions to humankind’s understanding and appreciation of planet Earth, the Solar System, the galaxy, and beyond. 2 | Space Science Institute | Annual Report 2005 From Our Director Excite. Explore. Discover. These words aptly describe what we do in the research realm as well as in education. In fact, they defi ne the essence of our mission. Our mission is facilitated by a unique blend of on- and off-site researchers coupled with an extensive portfolio of education and public outreach (EPO) projects. This past year has seen SSI grow from $4.1M to over $4.3M in grants, an increase of nearly 6%. We now have over fi fty full and part-time staff. SSI’s support comes mostly from NASA and the National Sci- ence Foundation. Our Board of Directors now numbers eight. Their guidance and vision—along with that of senior management—have created an environment that continues to draw world-class scientists to the Institute and allows us to develop educa- tion and outreach programs that benefi t millions of people worldwide. SSI has a robust scientifi c research program that includes robotic missions such as the Mars Exploration Rovers, fl ight missions such as Cassini and the Spitzer Space Telescope, Hubble Space Telescope (HST), and ground-based programs. Dr. Tom McCord joined the Institute in 2005 as a Senior Research Scientist. He directs the Bear Fight Center, a 3,000 square-foot research and meeting facility in Washington state.
    [Show full text]
  • Reddy Saturn's Small Wonders Astronomy 46 No 03 (2018)-1.Pdf
    Saturn’s small wonders Usually known for its rings, the Saturn system is also home to some of our solar system’s most intriguing moons. by Francis Reddy Above: NASA’s Cassini mission took images as the spacecraft approached ye candy is not in short supply at Saturn. and Calypso orbit along with Tethys — an (left) and departed (right) For visitors who tire of watching the plan- arrangement thus far unseen among any other Saturn’s moon Phoebe et’s stormy atmosphere or gazing into the moons in the solar system. during its only close flyby of the satellite. Cassini solar system’s most beautiful and complex And this is just for starters. “The Saturn sys- passed just 1,285 miles ring system, there's always the giant satel- tem is full of surprises,” says Paul Schenk, a plan- (2,068 km) above the lite Titan to explore. This colossal moon etary geologist at the Lunar and Planetary surface on June 11, 2004. is bigger than Mercury and sports a hazy Institute in Houston. There’s a satellite that likely Phoebe is thought to be a centaur that might have orange atmosphere denser than Earth’s, originated in the Kuiper Belt, the storehouse of become a Jupiter-family producing methane rains that flow across icy bodies beyond Neptune’s orbit; a piebald comet, had Saturn not Titan’s icy landscape and pool into vast lakes. moon nearly encircled by an equatorial ridge captured it. NASA/JPL-CALTECH But look again. Even Saturn’s small moons containing some of the tallest mountains in the display some unusual dynamic relationships.
    [Show full text]
  • Mission Science Highlights and Science Objectives Assessment
    CASSINI FINAL MISSION REPORT 2019 1 MISSION SCIENCE HIGHLIGHTS AND SCIENCE OBJECTIVES ASSESSMENT Cassini-Huygens, humanity’s most distant planetary orbiter and probe to date, provided the first in- depth, close up study of Saturn, its magnificent rings and unique moons, including Titan and Enceladus, and its giant magnetosphere. Discoveries from the Cassini-Huygens mission revolutionized our understanding of the Saturn system and fundamentally altered many of our concepts of where life might be found in our solar system and beyond. Cassini-Huygens arrived at Saturn in 2004, dropped the parachuted probe named Huygens to study the atmosphere and surface of Saturn’s planet-sized moon Titan, and orbited Saturn for the next 13 years making remarkable discoveries. When it was running low on fuel, the Cassini orbiter was programmed to vaporize in Saturn’s atmosphere in 2017 to protect the ocean worlds, Enceladus and Titan, where it discovered potential habitats for life. CASSINI FINAL MISSION REPORT 2019 2 CONTENTS MISSION SCIENCE HIGHLIGHTS AND SCIENCE OBJECTIVES ASSESSMENT ........................................................ 1 Executive Summary................................................................................................................................................ 5 Origin of the Cassini Mission ....................................................................................................................... 5 Instrument Teams and Interdisciplinary Investigations ...............................................................................
    [Show full text]
  • Cassini Mission Science Report – ISS
    Volume 1: Cassini Mission Science Report – ISS Carolyn Porco, Robert West, John Barbara, Nicolas Cooper, Anthony Del Genio, Tilmann Denk, Luke Dones, Michael Evans, Matthew Hedman, Paul Helfenstein, Andrew Ingersoll, Robert Jacobson, Alfred McEwen, Carl Murray, Jason Perry, Thomas Roatsch, Peter Thomas, Matthew Tiscareno, Elizabeth Turtle Table of Contents Executive Summary ……………………………………………………………………………………….. 1 1 ISS Instrument Summary …………………………………………………………………………… 2 2 Key Objectives for ISS Instrument ……………………………………………………………… 4 3 ISS Science Assessment …………………………………………………………………………….. 6 4 ISS Saturn System Science Results …………………………………………………………….. 9 4.1 Titan ………………………………………………………………………………………………………………………... 9 4.2 Enceladus ………………………………………………………………………………………………………………… 11 4 3 Main Icy Satellites ……………………………………………………………………………………………………. 16 4.4 Satellite Orbits & Orbital Evolution…………………………………………………….……………………. 21 4.5 Small Satellites ……………………………………………………………………………………………………….. 22 4.6 Phoebe and the Irregular Satellites ………………………………………………………………………… 23 4.7 Saturn ……………………………………………………………………………………………………………………. 25 4.8 Rings ………………………………………………………………………………………………………………………. 28 4.9 Open Questions for Saturn System Science ……………………………………………………………… 33 5 ISS Non-Saturn Science Results …………………………………………………………………. 41 5.1 Jupiter Atmosphere and Rings………………………………………………………………………………… 41 5.2 Jupiter/Exoplanet Studies ………………………………………………………………………………………. 43 5.3 Jupiter Satellites………………………………………………………………………………………………………. 43 5.4 Open Questions for Non-Saturn Science ………………………………………………………………….
    [Show full text]
  • Typical Spacecraft Contents
    Appendix A: Typical Spacecraft This appendix contains descriptions and images of a dozen spacecraft selected from the many that are currently operating in interplanetary space or have successfully completed their missions, plus one that is now preparing for launch. Included is at least one representative of each of the eight spacecraft classifications described in Chapter 7 (see page 243). The scheme of limiting coverage of each spacecraft to a two-page spread in this appendix allows the reader to easily compare the various craft, their specifications, their missions, and their classifications, but it does not allow room to list all of a spacecraft’s activities, discoveries and questions raised; indeed entire books can and have been written on each. Complete profiles of these and other spacecraft are, how- ever, readily available at a single web site: http://nssdc.gsfc.nasa.gov/planetary. Contents: Spacecraft Classification Page Voyager Flyby 294 New Horizons Flyby 296 Spitzer Observatory 298 Chandra Observatory 300 Galileo Orbiter 302 Cassini Orbiter 304 Messenger Orbiter 306 Huygens Atmospheric 308 Phoenix Lander 310 Mars Science Laboratory Rover (launch: 2009) 312 Deep Impact Penetrator 314 Deep Space 1 Engineering 316 294 Appendix A: Typical Spacecraft The Voyager Spacecraft Fig. A.1. Each Voyager spacecraft measures about 8.5 meters from the end of the science boom across the spacecraft to the end of the RTG boom. The magnetometer boom is 13 meters long. Courtesy NASA/JPL. Classification: Flyby spacecraft Mission: Encounter giant outer planets and explore heliosphere Named: For their journeys Summary: The two similar spacecraft flew by Jupiter and Saturn.
    [Show full text]
  • NI\S/\ 1111111111111 IIII 11111 11111 I1I1I I1II1 I1II 1111 NF00989 NASA Technical Memorandum 86147
    NASA-TM-8614719840025249 NASA Technical Memorandum 86147 A Geographic Comparison of Selected Large-Scale Planetary Surface Features Stephen Paul Meszaros JANUARY 1985 LIBRARY COpy : \ '1 '.: » .LANGLEY RESEARCLl CENTER LIBRARY, NASA HAMPTON, VIRGINIA NI\S/\ 1111111111111 IIII 11111 11111 I1I1I I1II1 I1II 1111 NF00989 NASA Technical Memorandum 86147 A Geographic Comparison of Selected Large-Scale Planetary Surface Features Stephen Paul Meszaros Goddard Space Flight Center Greenbelt, Maryland NI\SI\ National Aeronautics and Space Administration Scientific and Technical Information Branch 1985 This Page Intentionally left Blank ABSTRACT This publication is a compilation of photographic and cartographic comparisons of large, well­ known geographical features on planets and moons in the solar system. Included are structures caused by impacts, volcanism, tectonics, and other natural forces. Each feature is discussed individually and then those of similar origin are compared at the same scale. 1Il This Page Intentionally left Blank CONTENTS Abstract. iii Introduction .................................................................... Global Planetary Comparisons. 2 Part I: Impact Features. 5 The Cal oris Basin..... 6 The Orientale Basin.............................................................. 8 Mare Imbrium................................................................... 10 The Hellas and Argyre Basins. 12 Valhalla and Asgard.. 14 Galileo Regio. 16 Mimas and Tethys. 18 Crater Comparisons. 20 Impact Basins Compared.........................................................
    [Show full text]
  • Formation of Iapetusl Extreme Albedo Dichotomy by Exogenically
    REPORTS vealing peak dark- and bright-terrain temper- atures of 129 and 113 K, respectively. Thermal model fits to these temperatures, using thermal Formation of Iapetus’ Extreme Albedo inertias from (22), yield dark- and bright-terrain albedos of 0.04 and 0.39, respectively. The bright-terrain albedo is substantially higher than Dichotomy by Exogenically Triggered the 0.31 value determined from the FP1 data (which have lower spatial resolution), probably Thermal Ice Migration because those data included some dark terrain within the bright-terrain measurements. 1 2 John R. Spencer * and Tilmann Denk Diurnal thermal models, constrained by mea- sured thermal inertias and albedos (22), yield di- ’ The extreme albedo asymmetry of Saturn s moon Iapetus, which is about 10 times as bright on urnally averaged upward H2O sublimation rates its trailing hemisphere as on its leading hemisphere, has been an enigma for three centuries. for the icy saturnian satellites (Fig. 2A), using the Deposition of exogenic dark material on the leading side has been proposed as a cause, but this known vapor pressure dependence on tempera- alone cannot explain the global shape, sharpness, and complexity of the transition between ture (24). Iapetus’ long rotation period (79 days) Iapetus’ bright and dark terrain. We demonstrate that all these characteristics, and the asymmetry’s yields substantially higher daytime temperatures large amplitude, can be plausibly explained by runaway global thermal migration of water ice, for a given albedo than on the other saturnian triggered by the deposition of dark material on the leading hemisphere. This mechanism is unique satellites, because there is more time for temper- to Iapetus among the saturnian satellites because its slow rotation produces unusually high atures to equilibrate with sunlight and a smaller daytime temperatures and water ice sublimation rates for a given albedo.
    [Show full text]
  • Saturn's Icy Satellites Investigated by Cassini-VIMS. IV. Daytime
    Saturn's icy satellites investigated by Cassini - VIMS. IV. Daytime temperature maps Gianrico Filacchionea,∗, Emiliano D'Aversaa, Fabrizio Capaccionia, Roger N. Clarkb, Dale P. Cruikshankc, Mauro Ciarnielloa, Priscilla Cerronia, Giancarlo Belluccia, Robert H. Brownd, Bonnie J. Burattie, Phillip D. Nicholsonf, Ralf Jaumanng, Thomas B. McCordh, Christophe Sotine, Katrin Stephang, Cristina M. Dalle Orec aINAF-IAPS, Istituto di Astrofisica e Planetologia Spaziali, Area di Ricerca di Tor Vergata, via del Fosso del Cavaliere, 100, 00133, Rome, Italy bPSI Planetary Science Institute, Tucson, AZ, USA cNASA Ames Research Center, Moffett Field, CA 94035-1000, USA dLunar and Planetary Laboratory and Steward Observatory, University of Arizona, Tucson, AZ 85721, USA eJet Propulsion Laboratory, California Institute of Technology, 4800 Oak Groove Drive, Pasadena, CA 91109, USA fCornell University, Astronomy Department, 418 Space Sciences Building, Ithaca, NY 14853, USA gInstitute for Planetary Exploration, DLR, Rutherfordstaße 2, 12489, Berlin, Germany hThe Bear Fight Institute, Winthrop, WA 98862, USA Abstract The spectral position of the 3.6 µm continuum peak measured on Cassini-VIMS I/F spectra is used as a marker to infer the temperature of the regolith particles covering the surfaces of Saturn's icy satellites. This feature is characterizing the crystalline water ice spectrum which is the dominant compositional endmember of the satellites' surfaces. Laboratory measurements indicate that the position of the 3.6 µm peak of pure water ice is temperature-dependent, shifting towards shorter wavelengths when the sample is cooled, from about 3.65 µm at T=123 K to about 3.55 µm at T=88 K. A similar method was already applied to VIMS Saturn's rings mosaics to retrieve ring particles temperature (Filacchione et al., 2014).
    [Show full text]
  • Surface Ages of Mid-Size Saturnian Satellites
    Surface ages of mid-size Saturnian satellites Romina P. Di Sistoa,b, Macarena Zanardib aFacultad de Ciencias Astron´omicas y Geof´ısicas, Universidad Nacional de La Plata bInstituto de Astrof´ısica de La Plata, CCT La Plata-CONICET-UNLP, Paseo del Bosque S/N (1900), La Plata, Argentina Abstract The observations of the surfaces of the mid-sized Saturnian satellites made by Cassini-Huygens mission have shown a variety of features that allows study of the processes that took place and are taking place on those worlds. Research of the Saturnian satellite surfaces has clear implications not only for Saturn’s history and Saturn’s surroundings, but also for the Solar System. Crater counting from high definition images is very important and could serve for the determination of the age of the surfaces. In a recent paper, we have calculated the production of craters on the mid-sized Saturnian satellites by Centaur objects considering the current configuration of the Solar System. Also, we have compared our results with crater counts from Cassini images by other authors and we have noted that the number of observed small craters is less than our calculated theoretical number. In this paper we estimate the age of the surface for each observed terrain on each mid-sized satellite of Saturn. All the surfaces analyzed appear to be old with the exception of Enceladus. However, we have noticed that since there are less observed small craters than calculated (except on Iapetus), this results in younger ages than expected. This could be the result of efficient endogenous or exogenous process(es) for erasing small craters and/or crater saturation at those sizes.
    [Show full text]
  • LESSON A2 Saturn's Moons
    A: Getting to Know Saturn Lesson A2: Saturn’s Moons LESSON A2 Saturn’s Moons Science Content Standards: UNIFYING CONCEPTS AND PROCESSES -Systems, order and organization SCIENCE AS INQUIRY -Abilities necessary to do scientific inquiry EARTH AND SPACE SCIENCE -Earth in the Solar System Description: Students use the data provided on a set of 18 Saturn’s eight icy moons. Courtesy, NASA/JPL Saturn Moon Cards to compare Saturn’s moons to Earth’s moon, and to explore moon properties and physical relationships within a planet-moon system. For example, the farther the moon is from the center of the planet, the slower its orbital speed, and the longer its orbital period. The lesson enables students to complete their own Moon Card for a “mystery moon” of Saturn whose size, mass, and distance from the center of Saturn are specified. Prerequisite Skills: Working in groups MATERIALS Reading in the context area of science AND TOOLS Basic familiarity with concepts of mass, 1 23 99 3 81 9 10 92 38 019 238 20 3 94 85 28 40 5 582 90 59 surface gravity, orbital period, and Q¢ orbital speed (see next page) For the teacher: Overhead projector Interpreting scientific notation Earth Moon Chart* (T) Using Venn diagrams Sorting and ordering data For each student group of 2-3: Set of 18 Saturn Moon Cards* Estimated Time for Lesson: 2 to 3 paper clips 3 hours (may vary with grade level) Paper Background Information: For each student: Background for Lesson Discussion Earth’s Moon Chart * (see next page) Mystery Moon Card* Question & Answer Section 1 - 21: The Planet Saturn *Master is included T = Transparency 35 - 50: The Moons CASSINI Space Science Institute Saturn Educator Guide 1 A: Getting to Know Saturn Lesson A2: Saturn’s Moons Saturn and its Moons Background for Lesson Discussion Its orbit around the Sun Other factors affecting density and mass QQQQ¢¢¢¢ Students may ask about the quantities listed on the Saturn Moon Cards: QQQQ¢¢¢¢ Radius/Size: To determine the actual size of a moon or a planet, scientists make images of it and use the resolution or “scale” of the image (e.g.
    [Show full text]
  • Surface Features
    Surface Features Valles Marineris, a large canyon on Mars. Solar System 2014 Surface Features Wednesday, April 16, 14 Titan Bright Albedo Features Legendary sacred or enchanted places Dark Albedo Features Legendary primordial seas or enchanted waters Craters and Lakes Earth lakes Fluvial Channels Earth Rivers Other features Deities of happiness, harmony, and peace Solar System Lakes on the North Pole of Titan 2014 Surface Features Wednesday, April 16, 14 Titan Equatorial region Shangri-la Region Xanadu Region Boselunus Lacus Ksa Crater Guabonito Crater South Pole Solar System 2014 Surface Features Wednesday, April 16, 14 Enceladus Cities from R.F. Burton’s translation of The Book of the Thousand Nights and a Tiger Stipes Night Characters from R.F. Burton’s translation of The Book of the Thousand Nights and a Craters Night Planitiae, Dorsa, Sulci, Locations from R.F. Burton’s translation of The Book of the Thousand Nights and a Fossae Night Tiger Stripes Shahrazhad Al-Haddar Baghdad Sulcus Alexandria Sulcus Cairo Sulcus Damascus Sulcus X South Pole Solar System Dunzayad 2014 Surface Features Wednesday, April 16, 14 Enceladus Hamah Sulci Ebony Dorsa Cufa Dorsa Labtayt Sulci Samarkand Sulci Saraband Planitia Solar System 2014 Surface Features Wednesday, April 16, 14 Mars Large Craters Deceased writers and scientists who contributed to understanding of Mars Small Craters World Villages with population less than 100,000 Large Valles Names for Mars in different languages Small Valles Historical or modern words for rivers North Pole South Pole
    [Show full text]
  • Saturn's Moons
    GETTING TO KNOW SATURN LESSON Saturn’s Moons 2 3 hrs Students use the data provided on a set of Saturn Moon Cards to compare Saturn’s moons with Earth’s Moon, and to explore moon properties and physical relationships within a planet–moon system. For example, the farther the moon is from the center of MEETS NATIONAL the planet, the slower its orbital speed, and SCIENCE EDUCATION the longer its orbital period. The lesson STANDARDS: enables students to complete their own Unifying Concepts and Processes Moon Card for a mystery moon of Saturn Saturn’s eight large icy moons. • Systems, order, and organization whose size, mass, and distance from the Science as Inquiry center of Saturn are specified. • Abilities necessary to do scientific inquiry PREREQUISITE SKILLS BACKGROUND INFORMATION Earth and Space Background for Lesson Discussion, page 32 Science Working in groups • Earth in the Reading in the context area of science Questions, page 37 Solar System Basic familiarity with concepts of mass, surface Answers in Appendix 1, page 225 gravity, orbital period, and orbital speed 1–21: Saturn Interpreting scientific notation 35–50: Moons Using Venn diagrams Sorting and ordering data EQUIPMENT, MATERIALS, AND TOOLS For the teacher Materials to reproduce Photocopier (for transparencies & copies) Figures 1–21 are provided at the end of Overhead projector this lesson. Marker to write on transparencies FIGURE TRANSPARENCY COPIES Chalkboard, whiteboard, or easel with 1 1 1 per student paper; chalk or markers 2–19 1 set per group 20 1 optional For each group of 2–3 students 21 1 per student Clear adhesive tape Notebook paper; pencils 31 Saturn Educator Guide • Cassini Program website — http://www.jpl.nasa.gov/cassini/educatorguide • EG-1999-12-008-JPL Background for Lesson Discussion LESSON 2 Students may ask about the quantities listed on Orbital period: The orbital period of a moon the Saturn Moon Cards.
    [Show full text]