TY - JOUR A1 - Ye, S. -Y. A1 - Kurth, William S. A1 - Hospodarsky, George B. A1 - Persoon, Ann M. A1 - Gurnett, Don A. A1 - Morooka, Michiko A1 - Wahlund, Jan-Erik A1 - Hsu, Hsiang-Wen A1 - Seiss, Martin A1 - Srama, Ralf T1 - Cassini RPWS dust observation near the Janus/Epimetheus orbit JF - Journal of geophysical research : Space physics N2 - During the Ring Grazing orbits near the end of Cassini mission, the spacecraft crossed the equatorial plane near the orbit of Janus/Epimetheus (similar to 2.5 Rs). This region is populated with dust particles that can be detected by the Radio and Plasma Wave Science (RPWS) instrument via an electric field antenna signal. Analysis of the voltage waveforms recorded on the RPWS antennas provides estimations of the density and size distribution of the dust particles. Measured RPWS profiles, fitted with Lorentzian functions, are shown to be mostly consistent with the Cosmic Dust Analyzer, the dedicated dust instrument on board Cassini. The thickness of the dusty ring varies between 600 and 1,000 km. The peak location shifts north and south within 100 km of the ring plane, likely a function of the precession phase of Janus orbit. KW - Saturn KW - dust KW - ring Y1 - 2018 U6 - https://doi.org/10.1029/2017JA025112 SN - 2169-9380 SN - 2169-9402 VL - 123 IS - 6 SP - 4952 EP - 4960 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Hsu, Hsiang-Wen A1 - Schmidt, Jürgen A1 - Kempf, Sascha A1 - Postberg, Frank A1 - Moragas-Klostermeyer, Georg A1 - Seiss, Martin A1 - Hoffmann, Holger A1 - Burton, Marcia A1 - Ye, ShengYi A1 - Kurth, William S. A1 - Horanyi, Mihaly A1 - Khawaja, Nozair A1 - Spahn, Frank A1 - Schirdewahn, Daniel A1 - Moore, Luke A1 - Cuzzi, Jeff A1 - Jones, Geraint H. A1 - Srama, Ralf T1 - In situ collection of dust grains falling from Saturn’s rings into its atmosphere JF - Science N2 - Saturn’s main rings are composed of >95% water ice, and the nature of the remaining few percent has remained unclear. The Cassini spacecraft’s traversals between Saturn and its innermost D ring allowed its cosmic dust analyzer (CDA) to collect material released from the main rings and to characterize the ring material infall into Saturn. We report the direct in situ detection of material from Saturn’s dense rings by the CDA impact mass spectrometer. Most detected grains are a few tens of nanometers in size and dynamically associated with the previously inferred “ring rain.” Silicate and water-ice grains were identified, in proportions that vary with latitude. Silicate grains constitute up to 30% of infalling grains, a higher percentage than the bulk silicate content of the rings. Y1 - 2018 U6 - https://doi.org/10.1126/science.aat3185 SN - 0036-8075 SN - 1095-9203 VL - 362 IS - 6410 SP - 49 EP - + PB - American Assoc. for the Advancement of Science CY - Washington ER - TY - JOUR A1 - Ye, Shengyi A1 - Kurth, William S. A1 - Hospodarsky, George B. A1 - Persoon, Ann M. A1 - Sulaiman, Ali H. A1 - Gurnett, Don A. A1 - Morooka, Michiko A1 - Wahlund, Jan-Erik A1 - Hsu, Hsiang-Wen A1 - Sternovsky, Zoltan A1 - Wang, Xu A1 - Horanyi, M. A1 - Seiss, Martin A1 - Srama, Ralf T1 - Dust Observations by the Radio and Plasma Wave Science Instrument During JF - Geophysical research letters N2 - Plain Language Summary Cassini flew through the gap between Saturn and its rings for 22 times before plunging into the atmosphere of Saturn, ending its 20-year mission. The radio and plasma waves instrument on board Cassini helped quantify the dust hazard in this previously unexplored region. The measured density of large dust particles was much lower than expected, allowing high-value science observations during the subsequent Grand Finale orbits. Y1 - 2018 U6 - https://doi.org/10.1029/2018GL078059 SN - 0094-8276 SN - 1944-8007 VL - 45 IS - 19 SP - 10101 EP - 10109 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Buratti, Bonnie J. A1 - Thomas, P. C. A1 - Roussos, E. A1 - Howett, Carly A1 - Seiss, Martin A1 - Hendrix, A. R. A1 - Helfenstein, Paul A1 - Brown, R. H. A1 - Clark, R. N. A1 - Denk, Tilmann A1 - Filacchione, Gianrico A1 - Hoffmann, Holger A1 - Jones, Geraint H. A1 - Khawaja, N. A1 - Kollmann, Peter A1 - Krupp, Norbert A1 - Lunine, Jonathan A1 - Momary, T. W. A1 - Paranicas, Christopher A1 - Postberg, Frank A1 - Sachse, Manuel A1 - Spahn, Frank A1 - Spencer, John A1 - Srama, Ralf A1 - Albin, T. A1 - Baines, K. H. A1 - Ciarniello, Mauro A1 - Economou, Thanasis A1 - Hsu, Hsiang-Wen A1 - Kempf, Sascha A1 - Krimigis, Stamatios M. A1 - Mitchell, Donald A1 - Moragas-Klostermeyer, Georg A1 - Nicholson, Philip D. A1 - Porco, C. C. A1 - Rosenberg, Heike A1 - Simolka, Jonas A1 - Soderblom, Laurence A. T1 - Close Cassini flybys of Saturn’s ring moons Pan, Daphnis, Atlas, Pandora, and Epimetheus JF - Science N2 - Saturn’s main ring system is associated with a set of small moons that either are embedded within it or interact with the rings to alter their shape and composition. Five close flybys of the moons Pan, Daphnis, Atlas, Pandora, and Epimetheus were performed between December 2016 and April 2017 during the ring-grazing orbits of the Cassini mission. Data on the moons’ morphology, structure, particle environment, and composition were returned, along with images in the ultraviolet and thermal infrared. We find that the optical properties of the moons’ surfaces are determined by two competing processes: contamination by a red material formed in Saturn’s main ring system and accretion of bright icy particles or water vapor from volcanic plumes originating on the moon Enceladus. Y1 - 2019 U6 - https://doi.org/10.1126/science.aat2349 SN - 0036-8075 SN - 1095-9203 VL - 364 IS - 6445 SP - 1053 PB - American Assoc. for the Advancement of Science CY - Washington ER -