Passage to a Ringed World - NASA's History Office

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IN THE EYE OF THE BEHOLDER Taken from Christiaan Huygens’ Systema Saturnium, these early drawings of Saturn represent the views of: I. Galileo, 1610; II. Scheiner, 1614; III. Riccioli, 1614 or 1643; IV–VII. Hevel; VIII, IX. Riccioli, 1648, 1650; X. Divini, 1646–1648; XI. Fontana, 1636; XII. Biancani, 1616; Similar measurements made by the Ultraviolet Imaging Spectrograph (UVIS) and the Visible and Infrared Mapping Spectrometer (VIMS) as the Sun disappears behind Saturn (as seen from the Orbiter) are also very informative. These experiments will observe the atmosphere’s variation in composition and opacity with depth by measuring the intensities of various colors of sunlight as the Sun sets into haze and clouds. Each molecule in Saturn’s atmosphere can be identified by its unique absorption and emission of the sunlight. Cassini–Huygens’ three spectrometers complement each other in measure- XIII. Fontana, 1644– 1645. Some of the drawings, such as IX, had a very ring-like appearance years before Huygens’ theory was accepted. ments of atmospheric composition. The UVIS and the VIMS measure chemical composition at wavelengths spanning the ultraviolet and near infrared — useful in determining many expected atmospheric components. The CIRS and the UVIS can measure atomic composition as well; the former can delineate the atomic composition of molecules, while the latter can measure atoms directly. The important abundances of deuterium and other interesting isotopes will be investigated to shed light on the origin of our solar system. The UVIS will follow up on Hubble Space Telescope observations with studies of the energetics of Saturn’s aurora. The VIMS and potentially the CIRS can contribute also, and the imaging system will monitor the aurora’s changing morphology. The Imaging Science Subsystem (ISS) will play a major role in understanding the dynamics of Saturn’s clouds and weather systems. With wind speeds of 1800 kilometers per hour at the equator, the cloud bands seen beneath the haze layer are subject to considerable turbulence. Indeed, the bands themselves are defined by the winds, separated by zones of high wind shear. In addition, storms can be discerned among the bands, and THE RINGED WORLD 25
26 PASSAGE TO A RINGED WORLD their dynamics are of considerable interest. Images of the same region made with different filters can be interpreted to indicate the altitudes of various phenomena. “Saturn-annual” white spots, which appear at approximately 30-year intervals, are not expected during the portion of the cycle when Cassini is studying the planet, but other white spots may fortuitously appear and will be studied by all the optical remote-sensing instruments. Cassini may be able to confirm the theory that the white spots are caused by the upwelling and condensation of ammonia-ice crystals in the atmosphere. By carefully tracking the Cassini Orbiter’s motion around Saturn, data on the deep layers — all the way to the core — of Saturn can be acquired. In these studies, radio signals from the spacecraft will be monitored for changes, especially Doppler shifts of frequency that are different from those predicted from a simple base model. Using the new measurements from the Cassini Orbiter, more detailed models of the internal structure of Saturn will be constructed.
Page 1: Passage to a Ringed World The Cassi
Page 4 and 5: On the Cover: A collage of images s
Page 6 and 7: FOREWORD This book is for you. You
Page 8 and 9: ACKNOWLEDGMENTS This book would not
Page 10 and 11: Three separate images, taken by Voy
Page 12 and 13: descent to the surface. The Huygens
Page 14 and 15: address the challenges of the missi
Page 16 and 17: Participant Nations* * First flag i
Page 18 and 19: PROBING A MOON OF MYSTERY Huygens
Page 20 and 21: TOUR T18-3 TARGETED SATELLITE FLYBY
Page 22 and 23: SATURN CASSINI-HUYGENS MISSION SCIE
Page 24 and 25: Cassini-Huygens designed to determi
Page 26 and 27: In this diagram from his book, Syst
Page 28 and 29: This Voyager 1 image shows Saturn
Page 30 and 31: An Extended Atmosphere From Liquid
Page 32 and 33: Haze layers are also observed above
Page 36 and 37: This spectacular view of the edge o
Page 38 and 39: the interaction was described as a
Page 40 and 41: have a signature of a tone decreasi
Page 42 and 43: CONSTITUENTS OF THE TITAN ATMOSPHER
Page 44 and 45: The processes of plate tectonics an
Page 46 and 47: tan was accreting, it is possible t
Page 48 and 49: Surface Science. The highest resolu
Page 50 and 51: This enhanced Voyager 2 image shows
Page 52 and 53: Voyager 1 captured this striking im
Page 54 and 55: Prometheus and Pandora, two tiny sa
Page 56 and 57: In the stellar occultation experime
Page 58 and 59: scattering than are larger particle
Page 60 and 61: In fact, Saturn’s rings — as we
Page 62 and 63: The satellites of Saturn comprise a
Page 64 and 65: Before the advent of spacecraft exp
Page 66 and 67: The bright surface of Saturn’s mo
Page 68 and 69: Galilean satellites. Most of what i
Page 70 and 71: duced that one hemisphere is compos
Page 72 and 73: patches on the surface. Although it
Page 74 and 75: Artist’s conception of Ithaca Cha
Page 76 and 77: An artist’s rendition of Saturn
Page 78 and 79: The MAPS Instruments Coordinated ob
Page 80 and 81: field reverses direction across the
Page 82 and 83: SATURN’S MAGNETIC FIELD Saturn’
Page 84 and 85:
Solar Wind Magnetosheath Titan neut
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per atmosphere. Energetic particles
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and plasma wave emissions from narr
Page 90 and 91:
CHAPTER 7 Space mission design aims
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(SOI) propulsive maneuver to initia
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the tour cannot continue. Of course
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crease inclination to this value. T
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This illustration shows the main de
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discussed earlier) and data handlin
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of the spacecraft! Below the oxidiz
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• Opening or shutting thermal lou
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management subsystem and the Probe
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falls below its storage temperature
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The Cassini-Huygens spacecraft stan
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The Imaging Science Subsystem (ISS)
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• Map the composition and thermal
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cise distance between the surface f
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• Study the interaction of the ma
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• Study the erosional and electro
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midway out on the magnetometer boom
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The RPWS instrument will be used to
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altitudes down to 40 kilometers abo
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dex. A group of platinum resistance
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CHAPTER 10 Mission operations are t
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PLANETARY MISSION OPERATIONS Functi
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two low-gain antennas 1 and will pr
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During much of Cassini’s orbital
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articulation control subsystem’s
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AFTERWORD It has been said that in
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Developments tied to the Cassini-Hu
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APPENDIX A Command. A data transact
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APPENDIX A 138 PASSAGE TO A RINGED
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APPENDIX A Plasma wave. A wave char
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APPENDIX A 142 PASSAGE TO A RINGED
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APPENDIX B H O 2 + Water molecule w
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APPENDIX C 146 PASSAGE TO A RINGED
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APPENDIX D 148 PASSAGE TO A RINGED
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APPENDIX D 150 PASSAGE TO A RINGED
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APPENDIX F 152 PASSAGE TO A RINGED
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APPENDIX F 154 PASSAGE TO A RINGED
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APPENDIX F Peralta, F. and S. Flana
Page 168:
National Aeronautics and Space Admi
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