Energetic particles at Venus - Galileo results

At Venus the Energetic Particles Detector (EPD) on the Galileo spacecraft measured the differential energy spectra and angular distributions of ions above about 22 keV and electrons above about 15 keV in energy. The only time particles were observed by EPD was in a series of episodic events near closest approach (0559:03 UT). Angular distributions were highly anisotropic, ordered by the magnetic field, and showed ions arriving from the hemisphere containing Venus and its bow shock. The spectra showed a power law form with intensities observed into the 120- to 280-keV range. Comparisons with model bow shock calculations show that these energetic ions are associated with the Venusian foreshock-bow shock region. Shock-drift acceleration in the Venusian bow shock seems the most likely process responsible for the observed ions.