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A: Getting to Know Saturn Lesson A2: Saturn’s Moons PROMETHEUS PANDORA Courtesy of NASA/Voyager Courtesy of NASA/Voyager DATA ON PROMETHEUS DATA ON PANDORA Discovered by Stewart Collins and others, Discovered by Stewart Collins and others, Voyager 1, 1980 Voyager 1, 1980 Distance from center of Saturn Distance from center of Saturn 139,350 km (86,590 mi) 141,700 km (88,050 mi) Orbital Period Orbital Period 0.613 days (14.71 hours) 0.629 days (15.08 hours) Orbital Speed Orbital Speed 16.50 km/sec (10.23 mi/sec) 16.37 km/sec (10.15 mi/sec) Radius Radius 74 x 50 x 34 km 55 x 44 x 31 km average = 53km (33 mi) average = 43 km (27 mi) Mass Mass Unknown Unknown Surface Gravity Surface Gravity Unknown Unknown Moving outward from Saturn, Prometheus Moving outward from Saturn, Pandora [pan- [pro-MEE-thee-uss] is the third moon. To- DOR-uh] is the fourth moon. Together with gether with Pandora (the fourth moon) it acts Prometheus (the third moon) it acts as a as a shepherd moon for the F Ring. This shepherd moon for the F Ring. This means means the moons’ gravity nudges the F Ring the moons’ gravity nudges the F Ring particles particles into a thinner ring, much like shep- into a thinner ring, much like shepherds keep herds keep their flocks of sheep together. their flocks of sheep together. Cassini might Prometheus is extremely elongated, even more answer... How do Prometheus and Pandora so than an egg. Cassini might answer... What shepherd the F Ring? Are there other moons could have caused Prometheus’ odd shape? playing shepherding roles? How do Prometheus and Pandora shepherd the F Ring? Are there other moons playing CASSINI shepherding roles? Saturn Educator Guide Space Science Institute 10.

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Arxiv:1912.09192V2 [Astro-Ph.EP] 24 Feb 2020
Draft version February 25, 2020 Typeset using LATEX preprint style in AASTeX62 Photometric analyses of Saturn's small moons: Aegaeon, Methone and Pallene are dark; Helene and Calypso are bright. M. M. Hedman,1 P. Helfenstein,2 R. O. Chancia,1, 3 P. Thomas,2 E. Roussos,4 C. Paranicas,5 and A. J. Verbiscer6 1Department of Physics, University of Idaho, Moscow, ID 83844 2Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca NY 14853 3Center for Imaging Science, Rochester Institute of Technology, Rochester NY 14623 4Max Planck Institute for Solar System Research, Göttingen,Germany 37077 5APL, John Hopkins University, Laurel MD 20723 6Department of Astronomy, University of Virginia, Charlottesville, VA 22904 ABSTRACT We examine the surface brightnesses of Saturn's smaller satellites using a photometric model that explicitly accounts for their elongated shapes and thus facilitates compar- isons among different moons. Analyses of Cassini imaging data with this model reveals that the moons Aegaeon, Methone and Pallene are darker than one would expect given trends previously observed among the nearby mid-sized satellites. On the other hand, the trojan moons Calypso and Helene have substantially brighter surfaces than their co-orbital companions Tethys and Dione. These observations are inconsistent with the moons' surface brightnesses being entirely controlled by the local flux of E-ring par- ticles, and therefore strongly imply that other phenomena are affecting their surface properties. The darkness of Aegaeon, Methone and Pallene is correlated with the fluxes of high-energy protons, implying that high-energy radiation is responsible for darkening these small moons. Meanwhile, Prometheus and Pandora appear to be brightened by their interactions with nearby dusty F ring, implying that enhanced dust fluxes are most likely responsible for Calypso's and Helene's excess brightness.
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Cassini Update
Cassini Update Dr. Linda Spilker Cassini Project Scientist Outer Planets Assessment Group 22 February 2017 Sols%ce Mission Inclina%on Proﬁle equator Saturn wrt Inclination 22 February 2017 LJS-3 Year 3 Key Flybys Since Aug. 2016 OPAG T124 – Titan flyby (1584 km) • November 13, 2016 • LAST Radio Science flyby • One of only two (cf. T106) ideal bistatic observations capturing Titan’s Northern Seas • First and only bistatic observation of Punga Mare • Western Kraken Mare not explored by RSS before T125 – Titan flyby (3158 km) • November 29, 2016 • LAST Optical Remote Sensing targeted flyby • VIMS high-resolution map of the North Pole looking for variations at and around the seas and lakes. • CIRS last opportunity for vertical profile determination of gases (e.g. water, aerosols) • UVIS limb viewing opportunity at the highest spatial resolution available outside of occultations 22 February 2017 4 Interior of Hexagon Turning “Less Blue” • Bluish to golden haze results from increased production of photochemical hazes as north pole approaches summer solstice. • Hexagon acts as a barrier that prevents haze particles outside hexagon from migrating inward. • 5 Refracting Atmosphere Saturn's• 22unlit February rings appear 2017 to bend as they pass behind the planet’s darkened limb due• 6 to refraction by Saturn's upper atmosphere. (Resolution 5 km/pixel) Dione Harbors A Subsurface Ocean Researchers at the Royal Observatory of Belgium reanalyzed Cassini RSS gravity data• 7 of Dione and predict a crust 100 km thick with a global ocean 10’s of km deep. Titan’s Summer Clouds Pose a Mystery Why would clouds on Titan be visible in VIMS images, but not in ISS images? ISS ISS VIMS High, thin cirrus clouds that are optically thicker than Titan’s atmospheric haze at longer VIMS wavelengths,• 22 February but optically 2017 thinner than the haze at shorter ISS wavelengths, could be• 8 detected by VIMS while simultaneously lost in the haze to ISS.
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The Orbits of Saturn's Small Satellites Derived From
The Astronomical Journal, 132:692–710, 2006 August A # 2006. The American Astronomical Society. All rights reserved. Printed in U.S.A. THE ORBITS OF SATURN’S SMALL SATELLITES DERIVED FROM COMBINED HISTORIC AND CASSINI IMAGING OBSERVATIONS J. N. Spitale CICLOPS, Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301; [email protected] R. A. Jacobson Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 C. C. Porco CICLOPS, Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 and W. M. Owen, Jr. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 Received 2006 February 28; accepted 2006 April 12 ABSTRACT We report on the orbits of the small, inner Saturnian satellites, either recovered or newly discovered in recent Cassini imaging observations. The orbits presented here reflect improvements over our previously published values in that the time base of Cassini observations has been extended, and numerical orbital integrations have been performed in those cases in which simple precessing elliptical, inclined orbit solutions were found to be inadequate. Using combined Cassini and Voyager observations, we obtain an eccentricity for Pan 7 times smaller than previously reported because of the predominance of higher quality Cassini data in the fit. The orbit of the small satellite (S/2005 S1 [Daphnis]) discovered by Cassini in the Keeler gap in the outer A ring appears to be circular and coplanar; no external perturbations are appar- ent. Refined orbits of Atlas, Prometheus, Pandora, Janus, and Epimetheus are based on Cassini , Voyager, Hubble Space Telescope, and Earth-based data and a numerical integration perturbed by all the massive satellites and each other.
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Lesson 3: Moons, Rings Relationships
GETTING TO KNOW SATURN LESSON Moons, Rings, and Relationships 3 3–4 hrs Students design their own experiments to explore the fundamental force of gravity, and then extend their thinking to how gravity acts to keep objects like moons and ring particles in orbit. Students use the contexts of the Solar System and the Saturn system MEETS NATIONAL to explore the nature of orbits. The lesson SCIENCE EDUCATION enables students to correct common mis- STANDARDS: conceptions about gravity and orbits and to Science as Inquiry • Abilities learn how orbital speed decreases as the dis- Prometheus and Pandora, two of Saturn’s moons, “shepherd” necessary to Saturn’s F ring. scientific inquiry tance from the object being orbited increases. Physical Science • Motions and PREREQUISITE SKILLS BACKGROUND INFORMATION forces Working in groups Background for Lesson Discussion, page 66 Earth and Space Science Reading a chart of data Questions, page 71 • Earth in the Plotting points on a graph Answers in Appendix 1, page 225 Solar System 1–21: Saturn 22–34: Rings 35–50: Moons EQUIPMENT, MATERIALS, AND TOOLS For the teacher Materials to reproduce Photocopier (for transparencies & copies) Figures 1–10 are provided at the end of Overhead projector this lesson. Chalkboard, whiteboard, or large easel FIGURE TRANSPARENCY COPIES with paper; chalk or markers 11 21 For each group of 3 to 4 students 31 Large plastic or rubber ball 4 1 per student Paper, markers, pencils 5 1 1 per student 6 1 for teacher 7 1 (optional) 1 for teacher 8 1 per student 9 1 (optional) 1 per student 10 1 (optional) 1 for teacher 65 Saturn Educator Guide • Cassini Program website — http://www.jpl.nasa.gov/cassini/educatorguide • EG-1999-12-008-JPL Background for Lesson Discussion LESSON 3 Science as inquiry The nature of Saturn’s rings and how (See Procedures & Activities, Part I, Steps 1-6) they move (See Procedures & Activities, Part IIa, Step 3) Part I of the lesson offers students a good oppor- tunity to experience science as inquiry.
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Titan and the Moons of Saturn Telesto Titan
The Icy Moons and the Extended Habitable Zone Europa Interior Models Other Types of Habitable Zones Water requires heat and pressure to remain stable as a liquid Extended Habitable Zones • You do not need sunlight. • You do need liquid water • You do need an energy source. Saturn and its Satellites • Saturn is nearly twice as far from the Sun as Jupiter • Saturn gets ~30% of Jupiter’s sunlight: It is commensurately colder Prometheus • Saturn has 82 known satellites (plus the rings) • 7 major • 27 regular • 4 Trojan • 55 irregular • Others in rings Titan • Titan is nearly as large as Ganymede Titan and the Moons of Saturn Telesto Titan Prometheus Dione Titan Janus Pandora Enceladus Mimas Rhea Pan • . • . Titan The second-largest moon in the Solar System The only moon with a substantial atmosphere 90% N2 + CH4, Ar, C2H6, C3H8, C2H2, HCN, CO2 Equilibrium Temperatures 2 1/4 Recall that TEQ ~ (L*/d ) Planet Distance (au) TEQ (K) Mercury 0.38 400 Venus 0.72 291 Earth 1.00 247 Mars 1.52 200 Jupiter 5.20 108 Saturn 9.53 80 Uranus 19.2 56 Neptune 30.1 45 The Atmosphere of Titan Pressure: 1.5 bars Temperature: 95 K Condensation sequence: • Jovian Moons: H2O ice • Saturnian Moons: NH3, CH4 2NH3 + sunlight è N2 + 3H2 CH4 + sunlight è CH, CH2 Implications of Methane Free CH4 requires replenishment • Liquid methane on the surface? Hazy atmosphere/clouds may suggest methane/ ethane precipitation. The freezing points of CH4 and C2H6 are 91 and 92K, respectively. (Titan has a mean temperature of 95K) (Liquid natural gas anyone?) This atmosphere may resemble the primordial terrestrial atmosphere.
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Gravitoelectrodynamics in Saturn's F Ring: Encounters with Prometheus and Pandora
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CLARK PLANETARIUM SOLAR SYSTEM FACT SHEET Data Provided by NASA/JPL and Other Official Sources
CLARK PLANETARIUM SOLAR SYSTEM FACT SHEET Data provided by NASA/JPL and other official sources. This handout ©July 2013 by Clark Planetarium (www.clarkplanetarium.org). May be freely copied by professional educators for classroom use only. The known satellites of the Solar System shown here next to their planets with their sizes (mean diameter in km) in parenthesis. The planets and satellites (with diameters above 1,000 km) are depicted in relative size (with Earth = 0.500 inches) and are arranged in order by their distance from the planet, with the closest at the top. Distances from moon to planet are not listed. Mercury Jupiter Saturn Uranus Neptune Pluto • 1- Metis (44) • 26- Hermippe (4) • 54- Hegemone (3) • 1- S/2009 S1 (1) • 33- Erriapo (10) • 1- Cordelia (40.2) (Dwarf Planet) (no natural satellites) • 2- Adrastea (16) • 27- Praxidike (6.8) • 55- Aoede (4) • 2- Pan (26) • 34- Siarnaq (40) • 2- Ophelia (42.8) • Charon (1186) • 3- Bianca (51.4) Venus • 3- Amalthea (168) • 28- Thelxinoe (2) • 56- Kallichore (2) • 3- Daphnis (7) • 35- Skoll (6) • Nix (60?) • 4- Thebe (98) • 29- Helike (4) • 57- S/2003 J 23 (2) • 4- Atlas (32) • 36- Tarvos (15) • 4- Cressida (79.6) • Hydra (50?) • 5- Desdemona (64) • 30- Iocaste (5.2) • 58- S/2003 J 5 (4) • 5- Prometheus (100.2) • 37- Tarqeq (7) • Kerberos (13-34?) • 5- Io (3,643.2) • 6- Pandora (83.8) • 38- Greip (6) • 6- Juliet (93.6) • 1- Naiad (58) • 31- Ananke (28) • 59- Callirrhoe (7) • Styx (??) • 7- Epimetheus (119) • 39- Hyrrokkin (8) • 7- Portia (135.2) • 2- Thalassa (80) • 6- Europa (3,121.6)
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Observing the Universe
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Shepherd Moon Face-Off! 21 December 2012, by Jason Major
Shepherd Moon face-off! 21 December 2012, by Jason Major Here's Pandora, as seen by Cassini on September 5, 2005: False-color image of Pandora. Credit: NASA/JPL/SSI Raw Cassini image acquired on Dec. 18, 2012. Credit: NASA/JPL/SSI …and here's Prometheus, seen during a close pass in 2010 and color-calibrated by Gordan Ugarkovic: Two of Saturn's shepherd moons face off across the icy strand of the F ring in this image, acquired by the Cassini spacecraft on December 18, 2012. In the left corner is Pandora, external shepherd of the ropy ring, and in the right is Prometheus, whose gravity is responsible for the subtle tug on the wispy ring material. (Please don't blame the moon for any recent unsatisfying sci-fi films of the same name. There's no relation, we promise.) Similar in size (Pandora is 110 x 88 x 62 km, Prometheus 148 x 100 x 68 km) both moons are porous, icy, potato-shaped bodies covered in craters—although Prometheus' surface is somewhat smoother in appearance than Pandora's, perhaps due to the gradual buildup of infalling material from the F ring. Check out some much closer images of these two moons below, acquired during earlier flybys: 1 / 2 Prometheus casting a shadow through F ring haze. Credit: NASA/JPL/SSI/Gordan Ugarvovic The external edge of the A ring with the thin Keeler gap and the wider Encke gap can be seen at the right of the top image. Both of these gaps also harbor their own shepherd moons—Daphnis and Pan, respectively.
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1247 (Created: Wednesday, April 14, 2021 at 1:32:54 PM Eastern Standard Time) - Overview
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PDS4 Context List
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Accretion of Saturn's Mid-Sized Moons During the Viscous
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