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Titan's Meteorology Over the Cassini Mission: Evidence for Extensive Subsurface Methane Reservoirs
DOI: 10.1029/2018GL078170 Bibcode: 2018GeoRL..45.5320T

Le Mouélic, S.; Rodriguez, S.; Sotin, C. +15 more

Cassini observations of Titan's weather patterns over >13 years, almost half a Saturnian year, provide insight into seasonal circulation patterns and the methane cycle. The Imaging Science Subsystem and the Visual and Infrared Mapping Spectrometer documented cloud locations, characteristics, morphologies, and behavior. Clouds were generally mor…

2018 Geophysical Research Letters
Cassini 59
Models of Saturn's Equatorial Ionosphere Based on In Situ Data From Cassini's Grand Finale
DOI: 10.1029/2018GL078162 Bibcode: 2018GeoRL..45.9398M

Wahlund, J. -E.; Waite, J. H.; Cravens, T. E. +8 more

We present new models of Saturn's equatorial ionosphere based on the first in situ measurements of its upper atmosphere. The neutral spectrum measured by Cassini's Ion and Neutral Mass Spectrometer, which includes substantial methane, ammonia, and organics in addition to the anticipated molecular hydrogen, helium, and water, serves as input for un…

2018 Geophysical Research Letters
Cassini 25
Thermal Structure and Composition of Saturn's Upper Atmosphere From Cassini/Ion Neutral Mass Spectrometer Measurements
DOI: 10.1029/2018GL078454 Bibcode: 2018GeoRL..4510951Y

Waite, J. Hunter; Hörst, S. M.; Perry, M. E. +4 more

Analysis of measurements of the H2 density in Saturn's equatorial thermosphere indicates temperatures from 340 to 370 K. The deepest measurements, obtained during Cassini's final plunge into the atmosphere, measure the thermospheric temperature profile. The measurements are well fit by a Bates profile with an exospheric temperature of 3…

2018 Geophysical Research Letters
Cassini 19
Heliospheric Conditions at Saturn During Cassini's Ring-Grazing and Proximal Orbits
DOI: 10.1029/2018GL078093 Bibcode: 2018GeoRL..4510812R

Krupp, N.; Jackman, C. M.; Roussos, E. +6 more

We surveyed energetic charged particle measurements by Cassini between 2016 and the end of the mission in order to identify transients of solar energetic particles and galactic cosmic rays. Such transients offer hints about the state of the heliosphere and valuable context for interpreting space weather phenomena in Saturn's magnetosphere. The per…

2018 Geophysical Research Letters
Cassini 12
Saturn's Innermost Radiation Belt Throughout and Inward of the D-Ring
DOI: 10.1029/2018GL077954 Bibcode: 2018GeoRL..4510912K

Krupp, N.; Roussos, E.; Mitchell, D. G. +6 more

Cassini discovered Saturn's innermost radiation belt during the end of its mission. The belt is populated with relativistic protons, probably up to the trapping limit of ≈20 GeV. It extends from Saturn's dense atmosphere into and throughout the D-ring. The A-C rings separate this belt entirely from the previously known radiation belts, suggesting …

2018 Geophysical Research Letters
Cassini 9
Photometric Modeling and VIS-IR Albedo Maps of Dione From Cassini-VIMS
DOI: 10.1002/2017GL076869 Bibcode: 2018GeoRL..45.2184F

Buratti, B. J.; Clark, R. N.; Stephan, K. +6 more

We report about visible and infrared albedo maps and spectral indicators of Dione's surface derived from the complete Visual and Infrared Mapping Spectrometer (VIMS) data set acquired between 2004 and 2017 during the Cassini tour in Saturn's system. Maps are derived by applying a photometric correction necessary to disentangle the intrinsic albedo…

2018 Geophysical Research Letters
Cassini 8
Energetic Neutral and Charged Particle Measurements in the Inner Saturnian Magnetosphere During the Grand Finale Orbits of Cassini 2016/2017
DOI: 10.1029/2018GL078096 Bibcode: 2018GeoRL..4510847K

Krupp, N.; Dougherty, M. K.; Roussos, E. +6 more

We give an overview of the charged and neutral particle measurements during the Grand Finale of Cassini performed by the Magnetosphere Imaging Instrument, MIMI, on board. The first in situ measurements of MeV particles between the D-ring and the atmosphere of the planet showed protons with energies above 300 MeV with higher count rates when magnet…

2018 Geophysical Research Letters
Cassini 8
Saturn's Planetary Period Oscillations During the Closest Approach of Cassini's Ring-Grazing Orbits
DOI: 10.1029/2018GL077925 Bibcode: 2018GeoRL..45.4692H

Dougherty, M. K.; Cowley, S. W. H.; Provan, G. +2 more

Saturn's planetary period oscillations (PPOs) are ubiquitous throughout its magnetosphere. We investigate the PPO's azimuthal magnetic field amplitude interior to the field-aligned currents, during the closest approaches of Cassini's ring-grazing orbits (October 2016 to April 2017), with periapses at 2.5 RS. The amplitudes of the northe…

2018 Geophysical Research Letters
Cassini 8
Cassini CAPS Identification of Pickup Ion Compositions at Rhea
DOI: 10.1002/2017GL076588 Bibcode: 2018GeoRL..45.1704D

Coates, A. J.; Thomsen, M. F.; Jones, G. H. +9 more

Saturn's largest icy moon, Rhea, hosts a tenuous surface-sputtered exosphere composed primarily of molecular oxygen and carbon dioxide. In this Letter, we examine Cassini Plasma Spectrometer velocity space distributions near Rhea and confirm that Cassini detected nongyrotropic fluxes of outflowing CO2+ during both the R1 and R1.5 encounters. Accou…

2018 Geophysical Research Letters
Cassini 8
Photometric Modeling and VIS-IR Albedo Maps of Tethys From Cassini-VIMS
DOI: 10.1029/2018GL078602 Bibcode: 2018GeoRL..45.6400F

Clark, R. N.; Stephan, K.; D'Aversa, E. +6 more

We report about the derivation of visible (VIS) and infrared (IR) albedo maps and spectral indicators of Saturn's satellite Tethys from the complete Cassini-Visual and Infrared Mapping Spectrometer (VIMS) data set. The application of a photometric correction is necessary to remove illumination and viewing effects from the I/F spectra, to compute s…

2018 Geophysical Research Letters
Cassini 7