Spacecraft charging near Enceladus

In the vicinity of Enceladus, a geologically active moon of Saturn, the modeled spacecraft potential is significantly more negative than indicated by the Cassini Langmuir probe measurements. To understand this potential difference, we introduce two new dust-related charging currents: a) the dust ram current; and b) the dust impact-plasma current, in addition to the customary collection of electrons and ions, and photoemission. Our results show that these dust currents are important at high relative speeds between the spacecraft and the dust, or in regions with a low plasma-to-dust ratio, and can lead to reduced spacecraft charging. Citation: Hsu, H.-W., M. Horanyi, S. Kempf, and E. Grun (2012), Spacecraft charging near Enceladus, Geophys. Res. Lett., 39, L06108, doi:10.1029/2012GL050999.