The http://www.ciclops.org/view/6638/Rev141 has been up a few days, and goodies include a doppler-tracking pass over Enceladus' northern hemisphere, a search for Rhea co-orbitals, and the first reasonable-range imaging of Hyperion for five years.
The article doesn't state whether a different hemisphere will be on view than that imaged during the targeted flyby in '05, but I suppose it would be very unlucky if this was the case.
Images from the Hyperion encounter should be comparable to this:
The rotation of Hyperion is chaotic, so it may not be possible to predict how it will be oriented very far in advance.
Thank you, Hungry. Always good to see new views of our favorite celestial sponge!
Speaking of new views, has Hyperion's spin state been decisively resolved yet? I remember some buzz a few years back that it may be chaotic, but have heard nothing further for quite some time now.
Any time .
Hyperion's rotation axis was found to be chaotic from ground-based photometry after the Voyager encounters. Something to do with Titan being nearby?
Yeah, it does get pretty close to The Big Guy, and that'd do it!
So, Cassini planners aren't completely sure what they're going to see during each of these encounters. Interesting. I wonder if there's any attempt to see if the spin-axis precession might be "stochastic" instead of straight-up chaotic (if you know what I mean) given that we can now resolve & record the relative positions of small-scale surface features during these encounters.
I was wondering the same thing and did some digging earlier and came across this paper, which seemed to rule that out.
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WGF-47313KS-YY&_user=10&_coverDate=05%2F31%2F1984&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1559193430&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=5cbfa048e1c4e743422a85639c8bc69c&searchtype=a
Hyperion's rotation has also been modelled as a slow long axis rotation with large precession, like the nucleus of Halley's comet and asteroid Toutatis:
Hyperion: Rotation, Shape, and Geology from Voyager Images
Icarus, Volume 117, Issue 1, September 1995, Pages 128-148
P. C. Thomas, G. J. Black and P. D. Nicholson
This would be complex but predictable, not chaotic.
Phil
Glad to see Cassini back at work. These images of Hyperion are phenomenal!
Here's an early morning crack at a GRN/IR/UV colour composite:
it is looking like i am going to need to add some new images to my map of Hyperion
Thanks - I hadn't seen that abstract.
Phil
Looks like the remaining Hyperion images have been dumped onto the raw pages.
Did a little bit of processing on some of the new data and came up with this:
Re: john's post about the distinction between predictability and chaos:
I'm reminded of one reason I'm so fascinated with astronomy and the science of not-yet-fully-understood objects like the Saturnian moons. As a music student, I found the concept of ''constrained random fields'' in orchestral instructions very interesting and it became a tool I continue to use in my compositions. A piece of music can progress along a ''predictable'' course, then have moments of chaos.
An educated ear might be able to ascertain the method employed in a chaotic passage of music, and thus find it ''predictable''.
Similarly, thanks to Cassini and their wonderful team, we might ascertain the chaotic aspects of Hyperion's orbit.
However, I doubt we'll ever be able to predict Earth's weather.
Here's a 'tweened' flyby movie of this encounter:
http://www.youtube.com/watch?v=il1igwWjPds&fmt=22
I keep getting an error.
http://www.youtube.com/watch?v=il1igwWjPds works, however.
Its a little rough but I like it just as well . Thanks for animating this. I was really curious how it would look.
These Hyperion pics are awesome! The movie's very cool too.
A surprisingly strong and well defined jets. Especially this stream to the right.
http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS65/N00165288.jpg
Quick false color image (filters IR2, GRN, UV3) of Enceladus jets from yesterday's flyby.
Superb! It's amazing how adding the colour dimension, even if it's not real as-you-would-see-it colour, still adds 'reality' to the picture. (I think you've also cleverly smoothed out the greyscale steps a bit, but I'm not sure, and I don't need to know anyway.)
EDIT: Oh, and the dark limb of Enceladus is clearly visible all the way round to the bottom left of your version. Well picked out.
Aesthetically speaking at least, this is a particularly gorgeous image IMO:
http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=230048
There's about 25 of those plume images on the latest raw images index, I wonder if they'd be animatable so we can see changes in the plumes?
Also, were the Hyperion images the result of a targeted flyby of that moon, or was this a non-targeted flyby in which Cassini opportunistically imaged it because the geometry happened to be good at the time? (I'm suspecting it was targeted, since there's rather a lot of Hyperion images on the site!).
Ah! That's a stupendously handy reference - thanks!
(BTW, what's up with the UV1 filter on wheel 2? The images of Hyperion taken through that have lots of white speckles on them)
Could be that it's a very 'dark' filter (i.e. it's bandpass is either narrow, or well outside the best efficiency of the ccd, or both) and thus requires long exposure times and thus the raw unprocessed imagery is prone to noise.
I've put together a sequence of images of Hyperion (false colour, from the IR/Green/UV images) from the November 2010 sequence that you guys might appreciate .
I've also written an article about the images and Hyperion on my http://evildrganymede.net/2010/12/02/behold-hyperion/!
The Enceladan horizon from 51 kilometres above the surface:
Nice new one of Enceladus over the rings (or maybe the shadow of the rings on Saturn?):
http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=230086
I think something weird going on here (taken with CL1 and CL2):
http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=230114
Compare that with this (same filters):
http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=230116
It looks to me like the first image has more specular reflection (and contrast) in it? Is that just down to different exposure lengths, or is something else going on? Or is it just an illusion?
It is just a different stretch used by the JPL raw images page. The first image has fewer pixels on Enceladus' night side so the black level is set at a higher I/F than in the second image.
Very serious case of deja vu with this image:
http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS65/N00165320.jpg
Doesn't the terminator region look like the well-known corona on Miranda? I think so.
Phil
Here's a IR/UV/GRN combo, with the saturation increased, and the gamma decreased:
Gordan,
I stand corrected! It was the differing visibility of this feature in the individual filters that threw me: a quick check of several different UV-filtered images confirm that it is indeed an artefact.
In the meantime, here's a four-frame clear filter mosaic:
Nice!
Ian, that's a great composite! thanks for posting it
just some fun
a few shots from the rev 141
I have been fixing my spice kernels - things got a bit messed up .
http://www.imagebam.com/image/cb2f4c109495236 http://www.imagebam.com/image/7b88fa109495244 http://www.imagebam.com/image/e80bec109495250 http://www.imagebam.com/image/59cb30109495254 http://www.imagebam.com/image/3af4b6109495263
oops i need to move the post
There is a long series of images of a Tethys-Dione mutual event on the Cassini raw images pages. These images are just begging for an animation. (No, sorry, I can't do it myself now, I've got work to do .)
http://www.youtube.com/watch?v=Hm955AJ_yJ4
I made no effort to re-centre Dione (seemed a lot of effort for so many images).
Here's my version, making full use of the R/G/B filtered images:
http://www.youtube.com/watch?v=gN62-at3Xm4
I've re-compiled the video linked in my previous post based on a very good suggestion from Emily.
So gracious, love watching that, thanks
Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)