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Posted by: tedstryk Dec 8 2005, 03:49 AM

Well, the fall sequence of targeted encounters is over. But it appears the Christmas flyby includes a great encounter with Telesto (19,000 km) - I hope it is taken advantage of. Also, there is a pretty good Enceladus NT, which, although observations were not originally scheduled, there has been rumor that the last orbit's discoveries have changed that. Does anyone have any info on the Rev019 NTs?

Posted by: tedstryk Dec 10 2005, 10:11 PM

Does anyone know the status of these NT's?

Posted by: Bjorn Jonsson Dec 11 2005, 05:55 PM

The closest approach distances to some of the satellites:

Mimas 410,000 km - phase 151°
Enceladus 94,000 km - phase 131°
Tethys 175,000 km - phase 114°
Dione 150,000 km - phase 101°
Rhea 201,000 km, phase 104°
Hyperion 225,000 km - phase 60°
Epimetheus 205,000 km - phase 147°
Prometheus 137,000 km - phase 106°
Pandora 225,000 km - phase 161°
Telesto 20,000 km - phase 80°

I don't know which ones will be observed but there are lots of opportunities for NT-observations here.

Posted by: volcanopele Dec 12 2005, 09:13 PM

Quite a few opportunities indeed, including a ~1.5 km/pixel look at Odysseus on Tethys, ~1.5 km/pixel look at the anti-Saturnian and trailing hemispheres of Rhea, a ~2.5 km/pixel view of the leading hemisphere of Dione, another Telesto pass, and a ~4.5 km/pixel view of Hyperion.

Posted by: Decepticon Dec 12 2005, 11:20 PM

Nice stuff!

Posted by: jmknapp Dec 13 2005, 10:39 AM

I'm dreaming of a high-albedo Christmas.

Posted by: ugordan Dec 13 2005, 11:01 AM

High albedo is good, but high phase is even better!

Posted by: alan Dec 24 2005, 09:55 PM

new images are up
Dione
http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=58998
Rhea
http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=58997

Posted by: ugordan Dec 24 2005, 10:09 PM

Also, check out the neat mutual event between Mimas and Enceladus (I guess).
A bit http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=58932, though...

Posted by: nprev Dec 24 2005, 10:24 PM

Very nice, but as you say, a bit overexposed. I wonder if any of the image-savvy members can make this more better...?

Posted by: djellison Dec 24 2005, 10:43 PM

I had a look at it in Photoshop and it is actually bleached out there, there's nothing to be had.

Doug

Posted by: ugordan Dec 24 2005, 11:33 PM

Yeah, looks like a classic case of exposure being optimized for ring imaging and not the moons. Why they were using it and targetting Mimas at the same time is beyond me...

Posted by: Decepticon Dec 25 2005, 04:17 AM

WOW!

Update! http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-list.cfm?browseLatest=0&cacheQ=0&storedQ=0

Posted by: Decepticon Dec 25 2005, 02:15 PM

http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS17/N00047119.jpg

Talk about a great orbit. The pic compliments Last months Rhea flyby.

Posted by: djxatlanta Dec 26 2005, 12:47 AM

Anybody know what that other moon passing beneath Janus is in my animation? I tried identifying it with Celestia, but I was unable to... I'm guessing either Epimetheus, Prometheus, or Pandora.

Animation of Janus (and mystery moon)
 Cassini_2005_12_23_Janus_anim.mov ( 156.36K ) : 445


Exaggerated Color Image of Rhea (IR/G/UV)

Near True-Color Image of Dione (MT/G/B, magnified x2)

Posted by: BruceMoomaw Dec 26 2005, 09:51 AM

I'm reasonably sure it's Epimetheus. (See http://photojournal.jpl.nasa.gov/catalog/PIA07615 .) It certainly isn't Prometheus -- not elongated enough.

Posted by: Decepticon Dec 26 2005, 12:12 PM

A wonderful picture of Dione! http://saturn1.jpl.nasa.gov/multimedia/images/raw/casJPGFullS17/N00047223.jpg

Hope there is more cause I only see the one.

Posted by: JTN Dec 26 2005, 12:23 PM

At least in 1.3.2, Celestia seems too chicken to model Janus/Epimetheus properly; it appears to keep them about 180° apart all the time, which isn't accurate at the moment.

Posted by: Decepticon Dec 26 2005, 12:45 PM

http://saturn1.jpl.nasa.gov/multimedia/images/raw/casJPGFullS17/N00047283.jpg

EPIMETHEUS!


Tethys http://saturn1.jpl.nasa.gov/multimedia/images/raw/casJPGFullS17/N00047274.jpg

TELESTO http://saturn1.jpl.nasa.gov/multimedia/images/raw/casJPGFullS17/N00047271.jpg

ENCELADUS!!! http://saturn1.jpl.nasa.gov/multimedia/images/raw/casJPGFullS17/N00047262.jpg

BaBOOM! Tethys!!
http://saturn1.jpl.nasa.gov/multimedia/images/raw/casJPGFullS17/N00047246.jpg

Posted by: ugordan Dec 26 2005, 02:04 PM

Enceladus approximately true color composite (RED-GRN-BL1):

Tethys false color composite (IR3-GRN-UV3):

Note the familiar bluish band running across the disk...

Posted by: tedstryk Dec 26 2005, 02:06 PM

Decepticon, I am surprised at you... With your love of nigth side imagery, I am surprised you didn't post this image of http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS17/N00047275.jpg

Posted by: Decepticon Dec 26 2005, 02:14 PM

I did! I didn't notice until now the link is broken. If only the image was exposed a little longer. tedstryk could you do your magic on that image?


I was playing around with the light levels and it turned into Jpg Pixel Nightmare!

I hope to see some of you image experts adobeing away!

I hope Steve Albers finds this data flood helpful for his mapping.

Posted by: djxatlanta Dec 26 2005, 02:23 PM

Color Image of Crescent Dione (IR/G/UV) with Saturn-Shine Illumination

I've increased the contrast for the nightside by several levels to make the Saturn-shine more visible.

Posted by: tedstryk Dec 26 2005, 02:44 PM

Cool. And cool color work earlier.

Here is my result with Dione (Dayside)
http://img396.imageshack.us/my.php?image=dionerev192op.jpg

Decepticon: I will see what I can do.

Posted by: ugordan Dec 26 2005, 02:46 PM

Very nice! Surprisingly, JPEG compression didn't manage to destroy every bit of detail there. Here's my go at the Tethys nightside image, I stacked the 3 CL frames for better S/N ratio, but the results are poor anyway


Also, my quick-and-dirty stitch of 2 Dione footprints using IR1-GRN-UV3 filters, no enhancements for "natural" colors were done, just some unsharp masking:


EDIT: Argh, I see Ted already beat me to it! Ah well, nevermind... It's great though, this rev was probably one of the best ones yet in terms of NT observations. Maybe the best for some time to come also. As the old saying goes, there's no rev like rev 019

Posted by: tedstryk Dec 26 2005, 03:07 PM

Here is my take on the Tethys night images (I used 2x2 binning to reduce artifacts (I tried it at full size but got no more real detail)



http://img523.imageshack.us/img523/6410/nightful6nq.jpg

Posted by: Decepticon Dec 26 2005, 03:17 PM

What a amazing Christmas Gift JPL!

Thanks T!!

Posted by: ugordan Dec 26 2005, 04:40 PM

Last but not least, a Telesto false-color image from about 21 000 km away:

Now, onwards to the T9 imagery!

Posted by: tedstryk Dec 26 2005, 05:00 PM

Great one! The whole Telesto sequence is kind of neat this orbit. I made a super-res of the first shot to get it up to size, although it still suffers from overexposure or stretching (not sure which).

Posted by: pat Dec 26 2005, 07:06 PM

Thats Epimetheus

Posted by: Phil Stooke Dec 27 2005, 12:17 AM

This is my version of the first Telesto sequence from this very nice orbit. Five images stretched and stacked.

Phil

Posted by: tedstryk Dec 27 2005, 03:19 AM

Great work! I hadn't noticed that there was any detail in the washed out areas.

Posted by: ugordan Dec 27 2005, 06:50 PM

T-9 http://saturn.jpl.nasa.gov/multimedia/images/raw/ have just started to come in...

Posted by: tedstryk Dec 27 2005, 08:51 PM

Looks like a really cool sequence coming down...

http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS17/W00012696.jpg

Posted by: ugordan Dec 27 2005, 08:58 PM

Yeah, too bad the RGB frames can't be made to fit without some serious cheating.
Yet another feature brought to you by C.U.S.R.T. - or - Cassini's Ultra Slow Readout Times ™...

I know, I know, I'm just being unfair here

Posted by: jmknapp Dec 28 2005, 02:23 AM

Official Cassini color images in the past of Enceladus have shown how the tiger stripes are bluish, fresh ice surfaces tending towards blue. In that vein it's interesting that if the saturation is jacked up in your image, the south pole region comes out blue:

Posted by: ugordan Dec 28 2005, 11:45 AM

I noticed the blue hue also, but it's quite remarkable just how far you have to stretch the saturation to bring out any color differences.
In all its glory, Enceladus really is a pretty grayish place.

Posted by: djellison Dec 28 2005, 01:17 PM

Some two-frame mosaics from this rev



Doug

Posted by: elakdawalla Dec 28 2005, 01:31 PM

Lovely, Doug! You can really see how Dione has had soemthing very interesting going on in its past, whereas Rhea is just really really battered. I like the noticeably non-round edges to Rhea's disk.

--Emily

Posted by: Decepticon Dec 28 2005, 01:40 PM

I almost missed Dione's basin. Wonderful Pics!

Posted by: JRehling Dec 28 2005, 04:48 PM

Spot on, Doug!

Notice the partially-shaded crater with the well-defined central peak near the center of the Dione image... Shades of Mars -- that crater is on a pedestal, surrounded by impact melt. I haven't seen that anywhere else on ANY icy body, including craters of similar size on Dione! What's the difference with this one?

Posted by: silylene Dec 28 2005, 06:17 PM

The two large Dione craters to the SW of the one you mention with the central peak show a lot of wall slumping also, consistent with a softer icy surface. The bottom of those two has slumped to form a nice pentagonal shape.

Posted by: JTN Dec 31 2005, 09:35 PM

A nice triple "mutual event" sequence has recently appeared, e.g.:
http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS17/N00047440.jpg (http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=59491)
http://www.cassinicam.com/sp/S17/req/ISS_019JA_MUTUALEVE006_PRIME.html looks relevant; Janus, Epimetheus(?guess) and Dione?

Posted by: JTN Jan 2 2006, 01:14 AM

Here is a rough cropped animated GIF of this sequence. I've made no attempt to fix brightness, noise etc. (Hope this isn't too big for the site.)

Posted by: JTN Jan 2 2006, 01:17 AM

(Anyone know where I can simulate this view? As I've mentioned elsewhere, http://www.shatters.net/celestia/ doesn't model Janus and Epimetheus well -- anyone know of an add-on to fix this? -- and http://space.jpl.nasa.gov/ doesn't appear to include them at all, AFAICT.)

Posted by: elakdawalla Jan 2 2006, 03:20 AM

I like the Saturn Viewer at the PDS rings node:
http://pds-rings.seti.org/tools/viewer2_sat.html

Attached is a view generated for Cassini looking at Dione on 2005-12-30T09:10.
--Emily

Posted by: djellison Jan 2 2006, 11:40 AM

Ahh - fantastic, brilliant retro-renderings - that's quite usefull actually and I love those '60s style drawings

Doug

Posted by: Bob Shaw Jan 2 2006, 12:15 PM

I see *more* lobate flows, all extending out to about one crater radius...

Bob Shaw

Posted by: scalbers Jan 7 2006, 04:46 PM

Thanks Alan for pointing these out. I have updated my Rhea map and indeed a small portion of the above image does cover uncharted territory better than what I had mapped before. The web location is here:

http://laps.noaa.gov/albers/sos/sos.html#RHEA

Posted by: alan Jan 7 2006, 06:04 PM

I beleive this image will fill in the southern hole in the Dione map
http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=59013

Posted by: scalbers Jan 11 2006, 08:55 PM

Thanks again Alan for pointing that out as indeed it is a good gap filler...

http://laps.noaa.gov/albers/sos/sos.html#DIONE

Posted by: volcanopele Jan 11 2006, 09:01 PM

Don't forget this Tethys image: http://saturn1.jpl.nasa.gov/multimedia/images/raw/casJPGFullS17/N00047246.jpg , which provides higher resolution coverage over Odysseus.

Posted by: scalbers Jan 18 2006, 07:24 PM

Thanks VP for the timely reminder - I've included said image in an updated Tethys map here:

http://laps.noaa.gov/albers/sos/sos.html#TETHYS

Posted by: TritonAntares Jan 19 2006, 11:46 AM

What about Rhea, scalbers....

There has been a fly-by in a distance of roughly 184.000 km on January 17th.

http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-list.cfm?StartRow=1&cacheQ=1&browseLatest=0&storedQ=1166388

Any of those images usable for improving your map?

Posted by: scalbers Jan 21 2006, 05:15 PM

Good call TritonAntares. I added what looks like the image above (a raw image from about 245000km out, CL1/CL2 filters). I was able to blend this with color info from a previously released CICLOPS image as part of the map processing. This can still be tweaked a bit, though you should be able to see the initial version is a big help. This is really Rev 20 (or could be the Rhea Jan 17 thread) yet this thread appears to be a good one to reply to.

http://laps.noaa.gov/albers/sos/sos.html#RHEA

By the way, I'm still gradually working on the Iapetus Saturn-shine images. If I can navigate them a bit better then I may be able to post maps with just individual images on them that could be cropped for use in stereo viewing. I use a variety of methods to navigate images and I'm developing an enhancement that would let me specify three tiepoints of known lat/lon that should allow me to solve more completely for the spacecraft geometry (yet still tricky with bumpy Iapetus). This is helpful in cases like this when the ephemeris from Mark Showalter's page is inaccurate due to orbit adjustments. In contrast, Mark's page was right on track for the Rev019 Rhea flyby.

Posted by: TritonAntares Jan 21 2006, 09:56 PM

Wow, Steve...
What an emprovement...

Comparison between your map...

...and this NASA/JPL map from Dec.22.:


No words...

And good luck for your tricky work on those stereo Iapetus Saturn-shine images.
By the way, http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-list.cfm?StartRow=49&cacheQ=1&browseLatest=0&storedQ=1168580 have recently been released.

Bye.

Posted by: JRehling Jan 22 2006, 09:33 PM

No doubt -- Steve's work is outstanding again and again.

A certain baseline of coverage is now there for most of the icy satellite surfaces in the sense that most surfaces have been observed at least once at reasonable resolution. The hitch is that varying illumination and viewing geometry come into play -- what we would ultimately like is a high-phase and low-phase angle observation of all surfaces along with a stereo-derived DEM. The only way to make very polished maps of the moons is to have all of that data in the first place. Currently, mapmakers have to fuse imagery that is going to have rough borders where neighboring craters, for example, have greatly contrasting shadowing. Steve's work is a perfect ace in adjusting the albedo borders -- the JPL maps have not done that, but note that without the raw data to produce a phase-angle-adjusted map, the seamlessness in Steve's work is necessarily a bit on the cosmetic and even fictitious level, in that he controls for relative brightness, but with all those patchy inconsistencies in illumination. That is to say, we should love Steve's work, but realize that the blotches in the JPL maps are an honest portrayal of the lack of data.

Posted by: Phil Stooke Jan 22 2006, 10:02 PM

Good points, JRehling, though there are other reasons for the difference as well. Steve is using more images - the JPL version is from earlier. In fact if my eyes are not deceiving me, some of the JPL map is still using Voyager images... more than 'some' in fact. And the central meridians are 180 degrees different in these two maps, which makes comparison a bit confusing until you notice it.

Excellent maps, Steve!

Phil

Posted by: volcanopele Jan 22 2006, 10:44 PM

Yes, many of those maps do not include data from the most recent flybys. It takes time to get all those images into their proper place, and hopefully controlled basemaps of Rhea and Dione will soon reflect more recent coverage.

Posted by: ljk4-1 Feb 10 2006, 12:54 PM

A Closer Look at Telesto

Summary - (Thu, 09 Feb 2006) This false-colour view taken by NASA's Cassini spacecraft shows the surface features and color variation on the moon Telesto. Similar to Pandora, the smooth surface of this Trojan moon suggests that it's covered with a mantle of fine, dust-sized icy material. The small moon Telesto is about 24 kilometers (15 miles) wide. Cassini captured this image at a distance of approximately 20,000 kilometers (12,000 miles) with its narrow-angle camera on December 25, 2005.

http://www.universetoday.com/am/publish/closer_telesto.html?922006

Posted by: Phil Stooke Feb 13 2006, 04:13 AM

This is a slightly spiffed-up version of the latest Cassini release, the Janus-Epimetheus pair. I just stretched it a bit to show the saturnshine areas better. I like the way part of Epimetheus is silhouetted against the ring in the background.

Phil

Posted by: dilo Feb 14 2006, 06:36 AM

Look at this strange double portrait:
http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS18/N00050395.jpg
Which moon behind Mimas?

Posted by: BruceMoomaw Feb 14 2006, 07:33 AM

That's no two moons; that's one moon masquerading as a space station! Specifically, Mimas with its crater Herschel facing us.

Posted by: TritonAntares Feb 14 2006, 09:25 AM

Herschel?

Never...
Take a close look at the terminators.
And where is the dominant central peak of Herschel?

Mimas in front,
Rhea, Tethys or Dione behind.

Who knows the answer?

Bye.

Posted by: pat Feb 14 2006, 11:36 AM

Thats Mimas transiting Tethys. Look at the several tens of images before and after this one to get the complete mutual event.

Posted by: hendric Feb 14 2006, 04:40 PM

Finally figured out how to do animated GIFs with the GIMP....Here's a few frames of the encounter.

Posted by: BruceMoomaw Feb 14 2006, 10:03 PM

Well, it sure LOOKED like a space station...

Posted by: ljk4-1 Feb 16 2006, 12:42 PM

Telesto's Smooth Surface

Wed, 15 Feb 2006 - Cassini was only 14,500 km (9,000 miles) from Saturn's moon Telesto when it took this photograph. Telesto is tiny, only 24 km (15 miles across), and it appears to be covered in fine, icy material that obscures ancient meteor strikes. This is quite different from many of Saturn's other moons, which look quite pockmarked in comparison.

http://www.universetoday.com/am/publish/smooth_telesto_surface.html?1522006

Posted by: volcanopele Feb 26 2006, 05:33 PM

I've moved the posts for images from Rev21 to a more appropriate thread:

http://www.unmannedspaceflight.com/index.php?showtopic=2312