Enceladus Plume Search, Nov. 27 Options

[jmknapp]

Interesting item in the science plan kernel (S16) just released to the NAIF website:

OBSERVATION_ID: S1629

SEQUENCE: S16

OBSERVATION_TITLE: Plume Search

SCIENCE_OBJECTIVE: Hope to detect/observe plumes, whether from volcanic activity or geysers.

OBS_DESCRIPTION: Point and stare.

SUBSYSTEM: ISS

PRIMARY_POINTING: ISS_NAC to Enceladus (0.0,5.0,0.0 deg. offset)

REQUEST_ID: ISS_018EN_PLUMES001_PRIME

REQUEST_TITLE: ENCELADUS Geyser/Plume Search

REQ_DESCRIPTION: 1;ENCELADUS Geyser/Plume Search 1x1xNPp -- 3 different exposures

BEGIN_TIME: 2005 NOV 27 19:00:00 UTC

END_TIME: 2005 NOV 27 20:00:00 UTC

[tasp]

Would solar UV ionize the gas? Then Saturn's magnetic field would 'sweep' gasses from Enceladus.

Although weak at Saturn's distance from sun, Poynting-Robertson effects (hope I spelled it right) would also be operative on small particles and would accelerate material from Enceladus.

Is the E-ring continuous around Saturn? Or does it 'parse' in the vicinity of Enceladus. (I'm thinking of horse shoe orbits for the E-ring particles)

[jmknapp]

Would solar UV ionize the gas?  Then Saturn's magnetic field would 'sweep' gasses from Enceladus.

Although weak at Saturn's distance from sun, Poynting-Robertson effects (hope I spelled it right) would also be operative on small particles and would accelerate material from Enceladus.

Is the E-ring continuous around Saturn? Or does it 'parse' in the vicinity of Enceladus.  (I'm thinking of horse shoe orbits for the E-ring particles)

I believe the thinking is that particles from the solar wind, or Saturn wind, would sweep away gas particles. But seems like macroscopic ice particles would be a bit more of a problem?

Jason recently posted two excellent links to Dr. Esposito's talk back on August 30. Here is one slide:



see: slides from Esposito talk (PDF)

The accompanying transcript says:

"I’m moving to my next slide, which is about the first clues that Cassini had of something more exciting happening on Enceladus. On the 17th of February 2005 we had a close fly-by of Enceladus, and Cassini’s magnetometer detected a bending of the magnetic field around Enceladus. Now, this may seem a minor or maybe even a negligible discovery, but the magnetic field, like an electromagnet, or the earth’s magnetic field, is excluded by conductors. It looks as though there was a conducting layer surrounding the moon Enceladus, which the investigators hypothesized may have been a result of ions formed by sunlight falling on the atmosphere of Enceladus, if it had one. So the idea was that there might be an atmosphere around Enceladus and light from the sun would be removing electrons from some of the atoms in the atmosphere, making them conductors, and those conductors would exclude the magnetic field from the region around Enceladus. This was a very exciting indirect indication that Enceladus might have an atmosphere, and the project decided to reinvest some of its resources and to re-plan a later fly-by of Enceladus, which was scheduled for July of this year, to fly very, very close to the moon, to fly within 175 kilometers of the surface of Enceladus."

...

"I’m moving to my next slide, which is a demonstration of the effect that was seen by the magnetometer, and what you’re seeing here are these yellow arrows and lines and all that yellow stuff is truly invisible, it’s a representation of the Van Allen belts of Saturn, which are trapped by the magnetic field. As the moon, Enceladus, which you can see on the right, moves around Saturn and moves through that magnetic environment, mostly without any trouble, except if there might be some cloud near Enceladus."

"Here are the artists’ drawings, and you can see on the diagram how the lines of magnetic force have changed their location. The lines of magnetic force are excluded by the neutrals in the cloud, which is shown here near the southern pole of Enceladus; that’s a point we didn’t know yet, so that already in February we had some indications that Enceladus was unusual and the project used some of its capability to readjust the mission to aim for a close fly-by of the moon in the month of July. So, Cassini was redirected to fly within 179 kilometers of Enceladus on the 14th of July 2005."