title: Oxygen ions observed near Saturn's A ring.
abstract: Ions were detected in the vicinity of Saturn's A ring by the Ion and Neutral Mass Spectrometer (INMS) instrument onboard the Cassini Orbiter during the spacecraft's passage over the rings. The INMS saw signatures of molecular and atomic oxygen ions and of protons, thus demonstrating the existence of an ionosphere associated with the A ring. A likely explanation for these ions is photoionization by solar ultraviolet radiation of neutral O2 molecules associated with a tenuous ring atmosphere. INMS neutral measurements made during the ring encounter are dominated by a background signal.
authors.affiliation: Department of Atmospheric, Oceanic, and Space Physics, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Waite
authors.forename: T E
authors.initials: TE
authors.lastname: Cravens
authors.forename: W-H
authors.initials: WH
authors.lastname: Ip
authors.forename: W T
authors.initials: WT
authors.lastname: Kasprzak
authors.forename: J G
authors.initials: JG
authors.lastname: Luhmann
authors.forename: R L
authors.initials: RL
authors.lastname: McNutt
authors.forename: H B
authors.initials: HB
authors.lastname: Niemann
authors.forename: R V
authors.initials: RV
authors.lastname: Yelle
authors.forename: I
authors.initials: I
authors.lastname: Mueller-Wodarg
authors.forename: S A
authors.initials: SA
authors.lastname: Ledvina
authors.forename: S
authors.initials: S
authors.lastname: Scherer
mesh_terms: D001272:Atmosphere; D005118:Extraterrestrial Environment; D007053:Ice; D007477:Ions; D013058:Mass Spectrometry; D010100:Oxygen; D011522:Protons; D018539:Saturn; D018531:Spacecraft
chemical_list: D007053:Ice; D007477:Ions; D011522:Protons; D010100:Oxygen