Dust Detection System (DDS)

Description

The Galileo Dust Detector System (DDS) was used to determine individual particle impacts and measure their mass, impact velocity (speed and direction), and charge state. The primary objectives of the experiment were to: (1) investigate the interaction of the Galilean satellites with their dust environment, specifically to study the relationship between dust impact on the satellites and their surface properties and perform direct measurements of eject particles therefrom; (2) examine the interaction of dust particles with the ambient plasma and magnetic field so as to determine the relationship between concentrations of dust and the attenuation of trapped radiation and the effects of the Jovian magnetic field on charged dust particle trajectories; and, (3) to measure the influence of Jupiter's gravitational field on the interplanetary dust population and search for rings around Jupiter.

In order to achieve these goals, the instrument consisted of an impact ionization detector, identical to the one flown on Ulysses. Both instruments were direct descendants of the dust detector flown on HEOS 2, but differed in that the sensitive detector area was increased from ~0.01 sq m to 0.10 sq m, a measurement channel for determining the electric charge of a dust particle was added, and an electron multiplier, used to obtain an additional independent signal of dust impacts, was added. The detector provided a very sensitive measurement of small dust particles, massing from 0.1 fg to 1 microgram.