The composition of Saturn's E ring

• Published in: Monthly notices of the Royal Astronomical Society Vol. 377; no. 4; pp. 1588 - 1596
• Main Authors: Hillier, Jon K., Green, S. F., McBride, N., Schwanethal, J. P., Postberg, F., Srama, R., Kempf, S., Moragas-Klostermeyer, G., McDonnell, J. A. M., Grün, E.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-06-2007; Blackwell Science; Oxford University Press
• Subjects: Astronomy; Astrophysics; Earth, ocean, space; Exact sciences and technology; Geochemistry; Measurement; planets and satellites: individual: Enceladus; planets: rings; Saturn; Spectrum analysis; planets: rings; planets and satellites: individual: Enceladus; Measurement in situ; Saturn planet; Ammonia; Cosmic dust; Enceladus; Saturn satellite; Ice; Formation mechanism; Mass spectra
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2007.11710.x

We present the first in situ direct measurement of the composition of particles in Saturn's rings. The Cassini cosmic dust analyser (CDA) measured the mass spectra of nearly 300 impacting dust particles during the 2004 October E ring crossing. An initial interpretation of the data shows that the particles are predominantly water ice, with minor contributions from possible combinations of silicates, carbon dioxide, ammonia, molecular nitrogen, hydrocarbons and perhaps carbon monoxide. This places constraints on both the composition of Enceladus, the main source of the E ring, as well as the grain formation mechanisms.