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Detection of a strongly negative surface potential at Saturn's moon Hyperion
Author(s) -
Nordheim T. A.,
Jones G. H.,
Roussos E.,
Leisner J. S.,
Coates A. J.,
Kurth W. S.,
Khurana K. K.,
Krupp N.,
Dougherty M. K.,
Waite J. H.
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl061127
Subject(s) - saturn , astrobiology , geology , new moon , environmental science , meteorology , remote sensing , astronomy , planet , physics
Abstract On 26 September 2005, Cassini conducted its only close targeted flyby of Saturn's small, irregularly shaped moon Hyperion. Approximately 6 min before the closest approach, the electron spectrometer (ELS), part of the Cassini Plasma Spectrometer (CAPS) detected a field‐aligned electron population originating from the direction of the moon's surface. Plasma wave activity detected by the Radio and Plasma Wave instrument suggests electron beam activity. A dropout in energetic electrons was observed by both CAPS‐ELS and the Magnetospheric Imaging Instrument Low‐Energy Magnetospheric Measurement System, indicating that the moon and the spacecraft were magnetically connected when the field‐aligned electron population was observed. We show that this constitutes a remote detection of a strongly negative (~ −200 V) surface potential on Hyperion, consistent with the predicted surface potential in regions near the solar terminator.