On Nov 15, 5:28 pm, Robert Clark wrote:
I remember reading about the study last year that failed to find
sodium in the Saturn E ring with Earth-bound telescopes, suggesting
Enceladus could not have a subsurface ocean:

Sodium issue clouds Enceladus.
By Molly Bentley
Sunday, 16 December 2007, 17:21 GMThttp://news.bbc.co.uk/2/hi/science/nature/7145530.stm

But I don't remember seeing this study this year using the Cosmic Dust
Analyzer on Cassini that did detect sodium in the E ring:

Saturn's moon may host an ocean.
By Ron Cowen
August 30th, 2008; Vol.174 #5
Enceladus' geysers could have delivered sodium from its underground
ocean and into Saturn's E ring.
"The Cassini spacecraft has found what may be the strongest evidence
yet that Saturn’s tiny moon Enceladus has an ocean beneath its icy
surface. If the liquid water finding is confirmed, it would suggest
that the moon may be one of the most promising places in the solar
system to search for signs of past or present extraterrestrial life."
...
"Cassini researcher Roger Yelle of the University of Arizona has a
different view. "The surface of Enceladus is not pure water ice. We
just don't have a good idea of what the other components are," he
notes. "There could be a small amount of sodium in the minerals in the
surface layer." The sodium detected in the E ring could have come from
that material on the moon's surface, rather than from its interior. "I
don’t believe that you can say that the detection of sodium [in the E
ring] implies that it came from a sub-surface ocean" on Enceladus,
Yelle says. "So, let’s not run around crazy-like claiming the likely
detection of life because sodium was found in dust particles in the
Saturn system.”
"Another complicating factor is that studies from Earth, using large
telescopes such as the Keck Observatory atop Hawaii’s Mauna Kea, have
not found any sign of sodium in the E ring. Nick Schneider of the
University of Colorado at Boulder reported the lack of sodium last
December in San Francisco during a meeting of the American Geophysical
Union.
"But such studies, notes Kempf, can only detect sodium in its gaseous
form, not the solid sodium in the frozen ice particles. He maintains
that the bulk of the sodium in the E ring lies in the solid phase
recorded by Cassini’s cosmic dust analyzer."http://sciencenews.org/view/generic/id/34109/title/Saturns_moon_may_h...

The Cassini sodium readings will also be presented at the upcoming
December AGU meeting:

Sodium Salts in Ice Grains from Enceladus' Plumes: Evidence for an
Ocean below the Moon's Surface.http://www.agu.org/cgi-bin/SFgate/SF...sh&verbose=0&l...

Bob Clark

Our Selene/moon is surrounded by a 9r surrounding cloud of sodium,
plus having a million km comet like tail of sodium that starts off at
9r (31,000 km diameter) by 1e6 km before fading away. Now that's a
lot of sodium.

~ Brad Guth Brad_Guth Brad.Guth BradGuth BG / “Guth Usenet”