Passage to a Ringed World - NASA's History Office

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The Imaging Science Subsystem (ISS) narrow-angle camera. The Imaging Science Subsystem (ISS) wideangle camera. The Visible and Infrared Mapping Spectrometer (VIMS). map the surface spatial distribution of the mineral and chemical features of a number of targets, including the rings and satellite surfaces and the atmospheres of Saturn and Titan. The VIMS science objectives are as follows: • Map the temporal behavior of winds, eddies and other features on Saturn and Titan. • Study the composition and distribution of atmospheric and cloud species on Saturn and Titan. • Determine the composition and distribution of surface materials on the icy satellites. • Determine the temperatures, internal structure and rotation of Saturn’s deep atmosphere. • Study the structure and composition of Saturn’s rings. • Search for lightning on Saturn and Titan and active volcanism on Titan. • Observe Titan’s surface. The VIMS comprises a pair of imaging–grating spectrometers that are designed to measure reflected and emitted radiation from atmospheres, rings and surfaces to determine their compositions, temperatures and structures. The VIMS is an optical instrument that splits the light received from objects into its component wavelengths. The instrument uses a diffraction grating for this purpose. The VIMS obtains information over 352 contiguous wavelengths from 0.35 to 5.1 micrometers. The instrument measures the intensities of individual wavelengths. The data are used to infer the composition and other properties of the object that emitted the light (such as a distant TOOLS OF DISCOVERY 103
The bar charts at right show the operating wavelength coverage for the optical remote-sensing investigations (above) and energy range for the fields, particles and waves investigations (below). 104 PASSAGE TO A RINGED WORLD star), that absorbed specific wavelengths of the light as it passed through (such as a planetary atmosphere), or that reflected the light (such as a satellite surface). The VIMS provides images in which every pixel contains high-resolution spectra of the corresponding spot on the ground. The VIMS has separate infrared and visible sensor channels. The infrared channel covers the wavelength range 0.85–5.1 micrometers. Its optics include an ƒ/3.5 Ritchey–Chretien telescope that has an aperture of 230 millimeters, and a secondary mirror that scans on two axes to produce images varying in size from 0.03 degree to several degrees. Radiation gathered by the telescope passes through a diffraction grating, which disperses it in wavelength. A camera refocuses it on to a linear detector array. The detector array is radiator-cooled to as low as 56 kelvins; the spectrometer’s operating temperature is 125 kelvins. The visible channel produces multispectral images spanning the spectral range 0.35–1.05 micrometers. It utilizes a Shafer telescope and a grating spectrometer. The silicon CCD array is radiator-cooled to 190 kelvins. Composite Infrared Spectrometer. The Composite Infrared Spectrometer (CIRS) will measure infrared emissions from atmospheres, rings and surfaces. The CIRS will retrieve vertical profiles of temperature and gas composition for the atmospheres of Titan and Saturn, from deep in their tropospheres (lower atmospheres), to high in their stratospheres (upper atmospheres). The CIRS instrument will 10 –8 0.001 VIMS IR UVIS UV UVIS EUV VIMS VIS ISS WAC ISS NAC also gather information on the thermal properties and compositions of Saturn’s rings and icy satellites. The CIRS science objectives are as follows: • Map the global temperature structure in the Saturn and Titan atmospheres. • Map the global gas composition in the Saturn and Titan atmospheres. CIRS 10 0.0001 –7 10 –6 10 –5 Wavelength, meters 0.001 0.01 0.1 MIMI LEMMS e INMS 10 1000 Particle Energy, electron volts MIMI CHEMS MIMI LEMMS p CAPS IMS CAPS IBS CAPS ELS 10 5 10 7 • Map global information on hazes and clouds in the Saturn and Titan atmospheres. • Collect information on energetic processes in the Saturn and Titan atmospheres. • Search for new molecular species in the Saturn and Titan atmospheres. • Map the global surface temperatures at Titan’s surface.
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Passage to a Ringed World The Cassi
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On the Cover: A collage of images s
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FOREWORD This book is for you. You
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ACKNOWLEDGMENTS This book would not
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Three separate images, taken by Voy
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descent to the surface. The Huygens
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address the challenges of the missi
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Participant Nations* * First flag i
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PROBING A MOON OF MYSTERY Huygens
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TOUR T18-3 TARGETED SATELLITE FLYBY
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SATURN CASSINI-HUYGENS MISSION SCIE
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Cassini-Huygens designed to determi
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In this diagram from his book, Syst
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This Voyager 1 image shows Saturn
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An Extended Atmosphere From Liquid
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Haze layers are also observed above
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IN THE EYE OF THE BEHOLDER Taken fr
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This spectacular view of the edge o
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the interaction was described as a
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have a signature of a tone decreasi
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CONSTITUENTS OF THE TITAN ATMOSPHER
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The processes of plate tectonics an
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tan was accreting, it is possible t
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Surface Science. The highest resolu
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This enhanced Voyager 2 image shows
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Voyager 1 captured this striking im
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Prometheus and Pandora, two tiny sa
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In the stellar occultation experime
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scattering than are larger particle
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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
Page 86 and 87: per atmosphere. Energetic particles
Page 88 and 89: and plasma wave emissions from narr
Page 90 and 91: CHAPTER 7 Space mission design aims
Page 92 and 93: (SOI) propulsive maneuver to initia
Page 94 and 95: the tour cannot continue. Of course
Page 96 and 97: crease inclination to this value. T
Page 98 and 99: This illustration shows the main de
Page 100 and 101: discussed earlier) and data handlin
Page 102 and 103: of the spacecraft! Below the oxidiz
Page 104 and 105: • Opening or shutting thermal lou
Page 106 and 107: management subsystem and the Probe
Page 108 and 109: falls below its storage temperature
Page 110 and 111: The Cassini-Huygens spacecraft stan
Page 114 and 115: • Map the composition and thermal
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Page 118 and 119: • Study the interaction of the ma
Page 120 and 121: • Study the erosional and electro
Page 122 and 123: midway out on the magnetometer boom
Page 124 and 125: The RPWS instrument will be used to
Page 126 and 127: altitudes down to 40 kilometers abo
Page 128 and 129: dex. A group of platinum resistance
Page 130 and 131: CHAPTER 10 Mission operations are t
Page 132 and 133: PLANETARY MISSION OPERATIONS Functi
Page 134 and 135: two low-gain antennas 1 and will pr
Page 136 and 137: During much of Cassini’s orbital
Page 138 and 139: articulation control subsystem’s
Page 140 and 141: AFTERWORD It has been said that in
Page 142 and 143: Developments tied to the Cassini-Hu
Page 144 and 145: APPENDIX A Command. A data transact
Page 146 and 147: APPENDIX A 138 PASSAGE TO A RINGED
Page 148 and 149: APPENDIX A Plasma wave. A wave char
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Page 152 and 153: APPENDIX B H O 2 + Water molecule w
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Page 156 and 157: APPENDIX D 148 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
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National Aeronautics and Space Admi
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