Giotto Ion Mass Spectrometer, High Energy Range Spectrometer Observations of Comet Halley

A wide range of ion species and velocity distributions are expected to be found as the Giotto spacecraft traverses the coma of Halley's Comet. The Giotto Ion Mass Spectrometer (IMS) therefore consists of two sensors: one optimized for the outer and the other for the inner coma. The prime objective of the High-Energy Range Spectrometer (HERS) is to measure the ion abundances and three-dimensional velocity distributions outside the cometary contact surface.