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Enceladus PDS image products
djellison
post Oct 6 2011, 12:41 AM
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QUOTE (Stu @ Oct 5 2011, 04:21 PM) *
and on NASA's own websites


Yeah, someone should do something about that.


ph34r.gif

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eoincampbell
post Oct 6 2011, 02:09 AM
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Wondrous !


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ugordan
post Oct 10 2011, 08:33 PM
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Subject: Enceladus plume temporal variance. 3 NAC clear frames taken roughly at 50 second intervals, unsharped and contrast enhanced:

Attached Image


Can you pick up material from a couple of vents going up in "puffs"? I don't think this can be explained by parallax/rotation, the observed rotation of Enceladus is too small for that. I strongly believe this is a genuine variation in output flux on a timescale of a minute.


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ugordan
post Oct 10 2011, 08:43 PM
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Here's a ratio flicker gif. First frame is frame #2 divided by #1, second frame is frame #3 divided by #2. Shows subtle change in plume appearance from one frame to another better.

Attached Image


Notice alternating dark/bright clouds in the plume to the left and to the right. At least two distinct puffs seem to be present in each plume. There's a hint of variation in a third plume at around 12 o'clock but it's much less convincing than these two.

I tried to do a (very) rough measurement of the displacement in the right hand plume during the 50-ish seconds between snapshots and I got a radial velocity of ~250 m/s. I haven't double-checked this. In reality the flow is not in the viewing plane so any number would probably underestimate the real speed.

I've been looking to see if anything like this could be noticed in past plume images and I don't recall seeing anything convincing before.


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ngunn
post Oct 10 2011, 09:01 PM
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I'm not sure if it's two variable vents or just one that is changing direction, but yes, I agree there is real variation there. A nice obsevation! It's easy to believe - there's no reason why they shouldn't be variable. Perhaps the vent has an ice boulder stuck in its throat. Even in the absence of a mobile obstruction rapid flow is often accompanied by instability/turbulence. I wonder if it has a regular periodicity? Maybe it's singing a low lunar note.
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machi
post Oct 10 2011, 10:08 PM
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QUOTE (ugordan @ Oct 10 2011, 10:33 PM) *
Subject: Enceladus plume temporal variance. ....
Can you pick up material from a couple of vents going up in "puffs"? I don't think this can be explained by parallax/rotation, the observed rotation of Enceladus is too small for that. I strongly believe this is a genuine variation in output flux on a timescale of a minute.


It's very interesting, but I think, that it's game of shadows.


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eoincampbell
post Oct 11 2011, 02:49 AM
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Has the long shadow been explained?


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john_s
post Oct 12 2011, 02:34 AM
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QUOTE (ugordan @ Oct 10 2011, 02:33 PM) *
Subject: Enceladus plume temporal variance.


Awesome find! It looks pretty convincing to me.

Congratulations Gordan!
John
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nprev
post Oct 12 2011, 10:22 PM
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Re the long shadow: Looks to me like that's probably an effect of the shadow of Enceladus itself; parts of the plumes are in sunlight, some aren't. There are other plumes in the foreground of the shadowed region, which makes it look a little weird but that's a perspective effect.


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hendric
post Oct 13 2011, 06:24 PM
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Isn't that mostly Saturnshine lighting up the surface? It looks like the rightmost pixels are blown out, so that's where the sunlight terminator is located. The multiple shadow-lines are caused by the mostly-linear nature of the plumes; the further ones are more "down" I guess.


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Bjorn Jonsson
post Nov 15 2011, 09:54 PM
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This is a 21 frame mosaic of images obtained during Cassini's targeted flyby of Enceladus back in March 2005:

Attached Image


North is up and the resolution of the images I used ranges from ~35 m/pixel to ~350 m/pixel. This image is actually a by-product from a different image processing project; I should soon have a shape from shading DEM of most of this terrain.

The images were reprojected to simple cylindrical projection. The resulting map was then rendered with subspacecraft latitude=-1.4 and longitude=203.8 without applying any illumination.

Processed using mainly a 'mix' of ISIS, Photoshop and software written by myself.
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Juramike
post Nov 16 2011, 01:02 AM
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blink.gif Wow! The detail in that image is fantastic! Bravo!


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tedstryk
post Nov 16 2011, 05:59 PM
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QUOTE (Bjorn Jonsson @ Nov 15 2011, 09:54 PM) *
This is a 21 frame mosaic of images obtained during Cassini's targeted flyby of Enceladus back in March 2005:


I saw it and thought, "Oh, that's pretty." Then I zoomed in- AMAZING!!!


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Guillermo Abrams...
post Nov 17 2011, 01:37 AM
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Amazing. Thanks for sharing it.
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dilo
post Feb 8 2012, 09:19 AM
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Congratulations to Gordan for today's APOD mosaic, it is really stunning!
http://apod.nasa.gov/apod/ap120208.html
(I would like to see more in the plume region but I guess wasn't photographed).



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