Tuesday, April 26, 2005

Press Release: Cassini Finds Particles Near Saturn's Moon Enceladus

According to a press release put out today, the High Rate Detector on the Cosmic Dust Analyzer detected a high rate of hits from particles, about the width of a human hair, during Cassini's two recent close passes of Enceladus, first on February 17 at an altitude of 1,167 km and again on March 9 at 500 km. Presently, the CDA team can't distinguish in their data the source of these particles, whether they come from the E-Ring, which is densest near Enceladus, or from Enceladus itself, which would be further evidence for an active Enceladus. During the same encounter, the MAG instrument found evidence for water ions near Enceladus, perhaps part of an atmosphere. Such an atmosphere would require constant refreshment to persist, due to Enceladus' low gravity.

One bit of news that I think is being publically released for the first time, though I could always be wrong, I am a bit tired... The Enceladus flyby on July 14 has been lowered to 175 kilometers, which should allow for further understanding of Enceladus' active nature.

6 Comments:

Anonymous Gsnorgathon said...

Do you know if there are any plans to sample the E-ring when Enceladus isn't near? It seems to me you could at least get better circumstantial evidence for Enceladus being the E-ring source if the E-ring was densest near Enceladus, and least dense far away. (Suddenly I'm picturing Enceladus as Pigpen from Peanuts.)

I wish there were a word other than "atmosphere" to describe gaseous envelopes that aren't gravitationally bound to their parent bodies. IIRC, the atoms in Mercury's "atmosphere" don't even interact with each other! You call that an atmosphere? (Grumble, grumble.)

4/27/2005 12:04:00 AM  
Anonymous Pioneer said...

I wish there were a word other than "atmosphere" to describe gaseous envelopes that aren't gravitationally bound to their parent bodies. IIRC, the atoms in Mercury's "atmosphere" don't even interact with each other! You call that an atmosphere? (Grumble, grumble.)

I know what you mean. I read articles that say even the moon has a sodium "atmosphere" and asteroids in a sense have them! I think the term should apply only to cases where the gases cause pressure at the surface to be greater than in space. I still consider Mars to have an atmosphere - even though it's thin.

4/27/2005 08:31:00 AM  
Anonymous Anonymous said...

Re: "I wish there were a word other than 'atmosphere'..."

What about "coma", or if you want a new word, "comasphere"?

centsworth_II

4/27/2005 09:13:00 AM  
Anonymous Gsnorgathon said...

Yes! Thank you. "Coma" will do nicely.

4/27/2005 12:38:00 PM  
Blogger Jason said...

The usual term for such an "atmosphere" is exosphere, where the gasous envelope around a body is not collisional.

4/27/2005 04:06:00 PM  
Anonymous Gsnorgathon said...

Exosphere is good too.

4/28/2005 09:53:00 AM  

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