2012/01/18 by R. L. Tokar, R. E. Johnson, M. F. Thomsen +6 · 1 citation
Physics and Astronomy · Chemistry · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Mass Spectrometry Techniques and Applications #Exosphere #Saturn #Physics #Ion #Astrobiology #Plasma #Astronomy #Energetic neutral atom #Planet
paper · doi:10.1029/2011gl050452
openalex publication_date 2012/01/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/26
During a close pass of Cassini through the plasma wake of Saturn's moon Dione on April 7, 2010 the Cassini Plasma Spectrometer (CAPS) detected molecular oxygen ions (O 2 + ) on pick up ring velocity distributions, thus providing the first in situ detection of a neutral exosphere surrounding the icy moon. The density of O 2 + determined from the CAPS data ranges from 0.01 to 0.09 /cm 3 and is used to estimate the exosphere O 2 radial column density, obtaining the range 0.9 to 7 × 10 11 /cm 2 . CAPS was unable to directly detect pick up H 2 O + from the exosphere but the observations can be used to set an upper limit to their density of ∼10 times the O 2 + density.