The Cosmic Dust Analyzer onboard Cassini: ten years of discoveries

TL;DR

Over ten years, the Cosmic Dust Analyzer onboard Cassini made groundbreaking discoveries about interplanetary, interstellar, and planetary dust, including the detection of interstellar dust, water-ice grains, and active geysers on Enceladus, significantly advancing our understanding of Saturn's environment.

Contribution

This paper presents a comprehensive summary of ten years of dust measurements and discoveries made by the CDA instrument, including new insights into Saturn's dust environment and moon Enceladus.

Findings

Detection of interstellar dust in the inner solar system

Discovery of water-ice grains and liquid water reservoirs on Enceladus

Measurement of over one million dust impacts at Saturn

Abstract

The interplanetary space probe Cassini/Huygens reached Saturn in July 2004 after seven years of cruise phase. The Cosmic Dust Analyzer (CDA) measures the interplanetary, interstellar and planetary dust in our solar system since 1999 and provided unique discoveries. In 1999, CDA detected interstellar dust in the inner solar system followed by the detection of electrical charges of interplanetary dust grains during the cruise phase between Earth and Jupiter. The instrument determined the composition of interplanetary dust and the nanometre sized dust streams originating from Jupiter's moon Io. During the approach to Saturn in 2004, similar streams of submicron grains with speeds in the order of 100 km/s were detected from Saturn's inner and outer ring system and are released to the interplanetary magnetic field. Since 2004 CDA measured more than one million dust impacts characterizing the dust environment of Saturn. The instrument is one of three experiments which discovered the active ice geysers located at the south pole of Saturn's moon Enceladus in 2005. Later, a detailed compositional analysis of the water ice grains in Saturn's E ring system lead to the discovery of large reservoirs of liquid water (oceans) below the icy crust of Enceladus. Finally, the determination of the dust- magnetosphere interaction and the discovery of the extended E ring (at least twice as large as predicted) allowed the definition of a dynamical dust model of Saturn's E ring describing the observed properties. This paper summarizes the discoveries of a ten year story of success based on reliable measurements with the most advanced dust detector flown in space until today. This paper focuses on cruise results and findings achieved at Saturn with a focus on flux and density measurements.