GEOPHYSICAL MONOGRAPH SERIES, VOL. 53, PP. 31-40, 1989
Plasma wave observations at comets Giacobini-Zinner and Halley
TRW Space and Technology Group, Redondo Beach, California, USA 90278
The 1985–86 spacecraft encounters with Comets Giacobini-Zinner and Halley provided direct evidence that the solar wind interaction
with comets involves plasma physics phenomena that extend over distance scales that are measured in millions of kilometers.
The comet interaction phenomena that are dominated or controlled by plasma instabilities include pickup and energization of
newly-born cometary ions at great distances, solar-wind mass loading effects, formation of diffuse low-Mach number bow shocks,
development of intense plasma turbulence that provides scattering and heating, and onset of critical ionization. In this review
we describe and evaluate the cometary plasma wave measurements in the spectral range extending from the lower hybrid resonance
frequency (a few Hertz in the upstream regions for Giacobini-Zinner and Halley) to the electron plasma frequency (a few MegaHertz
during the Giacobini-Zinner tail crossing). We also discuss the difficulties of making plasma wave measurements in the presence
of large fluxes of dust particles that impact the spacecraft at high speeds.
Citation: Scarf, F. (1989), Plasma wave observations at comets Giacobini-Zinner and Halley, in Plasma Waves and Instabilities at Comets and in Magnetospheres, Geophys. Monogr. Ser., vol. 53, edited by