1991/09/27 by D. J. Williams, R. W. McEntire, S. M. Krimigis +9 · 1 citation
Physics and Astronomy · #Solar and Space Plasma Dynamics #Astro and Planetary Science #Planetary Science and Exploration
paper · doi:10.1126/science.253.5027.1525
openalex publication_date 1991/09/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/23
At Venus the Energetic Particles Detector (EPD) on the Galileo spacecraft measured the differential energy spectra and angular distributions of ions >22 kiloelectron volts (keV) and electrons > 15 keV in energy. The only time particles were observed by EPD was in a series of episodic events [0546 to 0638 universal time (UT)] 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.