@article{discovery1452135, volume = {41}, month = {October}, note = {{\copyright}2014. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.}, pages = {7011 -- 7018}, year = {2014}, title = {Detection of a strongly negative surface potential at Saturn's moon Hyperion}, journal = {GEOPHYSICAL RESEARCH LETTERS}, number = {20}, keywords = {Saturn's moons, surface charging, Cassini, Hyperion}, url = {http://dx.doi.org/10.1002/2014GL061127}, 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 ({\texttt{\char126}} ?200 V) surface potential on Hyperion, consistent with the predicted surface potential in regions near the solar terminator.}, author = {Nordheim, TA and Jones, GH and Roussos, E and Leisner, JS and Coates, AJ and Kurth, WS and Khurana, KK and Krupp, N and Dougherty, MK and Waite, JH}, issn = {0094-8276} }