[X] My Assistant

[Decepticon]

Nov. 2005 - 416,000 km - 2.5 km/pixel - eastern and central Cassini Region, northern bright terrain

http://space.jpl.nasa.gov/cgi-bin/wspace?t...porbs=1&brite=1

Buy this weekend (Nov 4,05) we will be getting some great views of Iapetus. Comparable to these images. http://ciclops.org/view.php?id=624

And buy Nov 11 will be within 417,000 km

I can't wait to see these images. 

I hope we get some approch images soon.

[Rob Pinnegar]

I hope we get some approch images soon.

It will be nice, but as has been pointed out elsewhere in this forum, for the most part we're going to be seeing parts of Iapetus that we've already seen at closer range (during the New Year's flyby).

[Decepticon]

Raw Images have started. http://saturn1.jpl.nasa.gov/multimedia/ima...5/N00042490.jpg

[tedstryk]

Raw Images have started. http://saturn1.jpl.nasa.gov/multimedia/ima...5/N00042490.jpg

Yes, but the angles and illumination are a bit different. Which, as far as making nice pictures to look at, is very exciting.

[Decepticon]

Oddly I can't find the name of that crater right hand side. Does anyone know if its been named?

That the central peak looks very prominent from this distance.

[tfisher]

Raw Images have started. http://saturn1.jpl.nasa.gov/multimedia/ima...5/N00042490.jpg

Here's an attempt at a color merge using two IR images, green, and UV. I pulled up the contrast a bit to try to bring out detail in the dark areas, but it is mostly JPEG artifacts in the raw data there.

[jmknapp]

The IR images show the dark area to be a bit hotter compared to UV:



If you take the ratio of the brightness of the dark to light areas, the ratio is almost 2x greater in the IR image.

To be expected I guess... like asphalt on a sunny day.

[jmknapp]

Oddly I can't find the name of that crater right hand side. Does anyone know if its been named?

That the central peak looks very prominent from this distance.

It's not listed at the USGS site. Maybe it's unnamed as yet?

Here's a mercator map showing its location as about 6N 324W:

Iapetus map

The size looks to be about 180km across (15 pixels at ~2,000,000 km).

There's nothing in the USGS list that matches that lat/lon:

USGS Iapetus nomenclature

Reportedly most of the features are named after characters in Chanson de Roland, or rather the British translation by Dorothy Sayers, Song of Roland.

[tedstryk]

The IR images show the dark area to be a bit hotter compared to UV:



If you take the ratio of the brightness of the dark to light areas, the ratio is almost 2x greater in the IR image.

To be expected I guess... like asphalt on a sunny day.

I was wondering wonder if you are right in an absolute sense. In other words, I wonder if the dark area is actually brighter causing the contrast to be less, or if the bright area is dimmer. With autostretch, there is no way to tell. I am not that confident with my Cassini color skills, but I decided to see if the trend showed up in Voyager OGV data. I took the highest resolution (and also least smeared) set, and carefully reprocessed them (the images I posted before had been cosmetically toyed with a bit, and I wanted to make sure I wasn't enhancing my own foolings with the channel mixer). Sure enough, when I enhanced the color, and overlayed it on a high-pass filtered image, the redness of the area was clear (well, orangeness, but based on what we are seeing, it seem that this trend continues further into the red and infrared).

[um3k]

Just take a look at this image and you will see the browness of Cassini Regio. http://photojournal.jpl.nasa.gov/catalog/PIA06167

[tasp]

Just take a look at this image and you will see the browness of Cassini Regio. http://photojournal.jpl.nasa.gov/catalog/PIA06167

Would you characterize the color of the dark bottoms of the craters of Hyperion to be brown also?

[um3k]

Would you characterize the color of the dark bottoms of the craters of Hyperion to be brown also?

I haven't seen a color image, so I can't answer that question.

[scalbers]

Yes, but the angles and illumination are a bit different.  Which, as far as making nice pictures to look at, is very exciting.

Nice to see the entire eastern edge of Cassini Regio in context. This is higher in resolution (~75%) than some of the previous imagery that I've used (e.g. PIA06100) and thus ought to be able to add some addtional details into my map. It also has a higher phase angle with more shadows to give contrast.

For comparison, my map with the previous imagery is at http://laps.fsl.noaa.gov/albers/sos/sos.html#IAPETUS

[JRehling]

Nice to see the entire eastern edge of Cassini Regio in context. This is higher in resolution (~75%) than some of the previous imagery that I've used (e.g. PIA06100) and thus ought to be able to add some addtional details into my map. It also has a higher phase angle with more shadows to give contrast.

For comparison, my map with the previous imagery is at http://laps.fsl.noaa.gov/albers/sos/sos.html#IAPETUS

It is interesting to see the white, vaguely peninsular, intrusion into eastern Cassini Regio. It is possibly similar to the white mountains that stick up out of western Cassini Regio. In both cases, it seems to be a continuation of the equatorial ridge, but broken in the western case, and at both ends of Cassini, bright instead of dark. Getting a better look at the "black eye" crater east of Cassini is also turning up some clues -- the identification of a central peak is new. More significant, it seems as though the darkening is, to the west of that crater, on the OUTSIDE of the rim, not the inside. If the dark stuff was blasted ballistically, this is a key distinction: was it landing on eastern Cassini Regio from the east, or from the west? If it came from the east, then likely all of Cassini Regio was laid out from east to west. If it came from the west, then likely all of Cassini Regio was emplaced from the inside (and/or above) OUT. What we don't get to see on this encounter are the craters to the east of that one, which are smaller and also have darkened rims. Whether the three rims were darkened west to east or vice versa, then we have a new significant clue regarding the creation of Cassini Regio. But we don't find out anything more until later.

[scalbers]

It is suggestive indeed to look at the white peninsular region on the eastern edge of Cassini Regio. It does appear somewhat continuous with the white peaks on the western side. The trick though is that a close look suggests that the white peninsular region is slightly inclined to the equator, assuming I have the night-side image navigated properly. The new imagery should also help me to get the navigation of various images to fit better.

Is there any chance the 2007 encounter will show us a close-up of the white portion of the equator?