Electron density dropout near Enceladus in the context of water-vapor and water-ice
2009 (English)In: Geophysical Research Letters, ISSN 0094-8276, Vol. 36, no 10, L10203- p.Article in journal (Refereed) Published
On 12 March 2008, the Cassini spacecraft made a close encounter with the Saturnian moon Enceladus, passing within 52 km of the moon. The spacecraft trajectory was intentionally-oriented in a southerly direction to create a close alignment with the intense water-dominated plumes emitted from the south polar region. During the passage, the Cassini Radio and Plasma Wave System (RPWS) detected two distinct radio signatures: 1) Impulses associated with small water-ice dust grain impacts and 2) an upper hybrid (UH) resonance emission that both intensified and displayed a sharp frequency decrease in the near-vicinity of the moon. The frequency decrease of the UH emission is associated with an unexpectedly sharp decrease in electron density from similar to 90 cl/cm(3) to below 20 cl/cm(3) that occurs on a time scale of a minute near the closest encounter with the moon. In this work, we consider a number of scenarios to explain this sharp electron dropout, but surmise that electron absorption by ice grains is the most likely process.
Place, publisher, year, edition, pages
2009. Vol. 36, no 10, L10203- p.
IdentifiersURN: urn:nbn:se:uu:diva-148329DOI: 10.1029/2008GL037108ISI: 000266362900001OAI: oai:DiVA.org:uu-148329DiVA: diva2:402106