Comments on: Closest Flyby (So Far) of Enceladus http://joshuacolwell.com/blog/index.php/2008/closest-flyby-so-far-of-enceladus/ Science, astronomy, politics, movies, and various minutiae. Fri, 10 Feb 2012 09:56:37 +0000 http://wordpress.org/?v=2.7.1 hourly 1 By: JC http://joshuacolwell.com/blog/index.php/2008/closest-flyby-so-far-of-enceladus/comment-page-1/#comment-61691 JC Thu, 27 Mar 2008 14:31:04 +0000 http://joshuacolwell.com/blog/index.php/2008/closest-flyby-so-far-of-enceladus/#comment-61691 A paper by Colin Mitchell, Mihaly Horanyi, and myself a couple of years ago predicted that CDA would detect retrograde particles orbiting Saturn due to magnetospheric capture of interplanetary dust. We had previously seen this at Jupiter with the Galileo dust detector. It seems that the predicted particles may in fact have been detected. A paper by Colin Mitchell, Mihaly Horanyi, and myself a couple of years ago predicted that CDA would detect retrograde particles orbiting Saturn due to magnetospheric capture of interplanetary dust. We had previously seen this at Jupiter with the Galileo dust detector. It seems that the predicted particles may in fact have been detected.

]]> By: Bruce Moomaw http://joshuacolwell.com/blog/index.php/2008/closest-flyby-so-far-of-enceladus/comment-page-1/#comment-60963 Bruce Moomaw Mon, 24 Mar 2008 06:22:17 +0000 http://joshuacolwell.com/blog/index.php/2008/closest-flyby-so-far-of-enceladus/#comment-60963 Two articles by Frank Postberg on the goop that Cassini's Cosmic Dust Analyzer had already found mixed into the E-Ring particles' water ice: http://lasp.colorado.edu/~horanyi/FTP/Cassini_book_chapter/recent_publications/Kempf_E-ring2_2007.pdf http://archiv.ub.uni-heidelberg.de/volltextserver/volltexte/2008/7979/pdf/thesis_postberg_final.pdf This is the one measurement that Cassini blew on its recent very low Enceladus flyby, because they had misprogrammed the Cosmic Dust Analyzer. Postberg, however, makes it clear that the CDA has already turned out some very interesting results where the composition of E Ring particles is concerned: Specifically, some -- but only some -- of the E Ring particles contain other substances besides water and its derivatives, with AMUs all the way up to at least 65. Postberg goes through a number of candidate for them, both organic and silicate. And he concludes that their logical source -- unlike the other E Ring particles, which are made up only of water ice and its derivatives, and which are probably kicked off the surface of Enceladus and the other icy moons by micrometeoroids -- is the plumes. (As an interesting sidenote: his thesis notes that the CDA also found some totally dry dust particles orbiting Saturn, which seem to be iron-rich -- and it started finding those when it was still a long way from Saturn. They seem to be in orbits that are "retrograde or unbound". Obviously these could be blasted by micrometeoroids off the little outer satellites -- that is, Cassini may also have directly tasted the infall of rock dust that's colored the leading face of Iapetus.) Two articles by Frank Postberg on the goop that Cassini’s Cosmic Dust Analyzer had already found mixed into the E-Ring particles’ water ice:

http://lasp.colorado.edu/~horanyi/FTP/Cassini_book_chapter/recent_publications/Kempf_E-ring2_2007.pdf

http://archiv.ub.uni-heidelberg.de/volltextserver/volltexte/2008/7979/pdf/thesis_postberg_final.pdf

This is the one measurement that Cassini blew on its recent very low Enceladus flyby, because they had misprogrammed the Cosmic Dust Analyzer. Postberg, however, makes it clear that the CDA has already turned out some very interesting results where the composition of E Ring particles is concerned:

Specifically, some — but only some — of the E Ring particles contain other substances besides water and its derivatives, with AMUs all the way up to at least 65. Postberg goes through a number of candidate for them, both organic and silicate. And he concludes that their logical source — unlike the other E Ring particles, which are made up only of water ice and its derivatives, and which are probably kicked off the surface of Enceladus and the other icy moons by micrometeoroids — is the plumes.

(As an interesting sidenote: his thesis notes that the CDA also found some totally dry dust particles orbiting Saturn, which seem to be iron-rich — and it started finding those when it was still a long way from Saturn. They seem to be in orbits that are “retrograde or unbound”. Obviously these could be blasted by micrometeoroids off the little outer satellites — that is, Cassini may also have directly tasted the infall of rock dust that’s colored the leading face of Iapetus.)

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