Rev 49 - Aug 9-Sep 14, 2007 - Iapetus I1, The only close flyby of Iapetus Options

[elakdawalla]

[Moderator's note: This thread contains images from the Iapetus 2007-09-10 flyby and discussion of them. It was created by splitting this thread which contains pre-flyby discussion]


Another CL-UV3-GRN-IR1 set was posted today, though Iapetus seems to have been hiding from the green and IR filters...here's my best effort at making something from the CL and UV3 images. Lots of topography on the limb!

--Emily

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[Guest_AlexBlackwell_*]

...though Iapetus seems to have been hiding fromt he [sic] green and IR filters...

TED!!!!!! Should I or shouldn't I??

[ugordan]

I actually like the color in this one best. The stretched color views tend to oversaturate Cassini Regio.

Here's a quick collage of some of the lowest and some of the highest resolution color imagery we got of Iapetus in the past 3 years:


To think that in less than 4 days we'll have images with resolutions up to 1000 times better than the best shown here is exciting to say the least.

[volcanopele]

ISS_049IA_IAPETUS002_CIRS is now on the ground:

Clear Filter Frame: http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=125907

This was supposed to include a true color filter set (BL1, GRN, and RED), but it looks like the shutter times were a tad off and the RED and IR2 images were taken after CIRS pointed away from Iapetus (it points away from its target at the start and end of observations for calibration purposes). However, there is a UV3-GRN-IR1 filter set available from some industrious individual. The auto stretch feature appears to be working now so you guys should be able to do something with this data set.

Some interesting topography is visible in the crescent seen here, including the impact basin in south-central Cassini Regio, a pair of ridges to the northwest of the impact basin in north-central Cassini Regio (these things need names!!), and the equatorial ridge.

You know what, that's it, I am instituting a system of nicknames for the impact basins on Iapetus. These are just nicknames. In keeping with the official naming scheme for Iapetus, characters and places from the Song of Roland, all the nicknames will be predominately French. Map upcoming.

[CAP-Team]

Here's an IR3/GRN/BLU combination image from 7 september:

[volcanopele]

Here is a map of official names (in green) and nicknames (in red):

[TritonAntares]

Frosty, Sam, Yukon, Cornellis - doesn't sound french at all...
Anxious about calling the whole crater triplet Snowman - or say better in french:
bonhomme de neige...

I think IAU will get in trouble creating names from 'The Song of Roland', simply because of a limited number of characters there!

Nomenclatura in french seems to be one solution.
I personally would prefer naming surface structures after their appearance, like the Snowman for instance.

Bye.

[scalbers]

Nice to have CAP-Team's image and VP's names for reference. I think I can see Lionel on the terminator of the 9/7 image and maybe Jeanne near the limb. The NNE edge of Henri may be a spot where the bellyband diminishes eastward (into a flat area) and we thus would be seeing a shadowed slope along the bellyband in the image. If we can make out as far as the SW edge of Henri that could fill in a blank sliver on the map.



I'll go ahead and opine that we might eventually want a "Claudette" just to the east of "Claude"

[CAP-Team]

this is a simulated view, using VP's map with nicknames in Xplanet:

[tasp]

May I propose refering to the large elongated crater S of Joan on the edge of Casini Regio as Papillion ??

thanx for the consideration

[volcanopele]

Frosty, Sam, Yukon, Cornellis - doesn't sound french at all...
Anxious about calling the whole crater triplet Snowman - or say better in french:
bonhomme de neige...

Nomenclatura in french seems to be one solution.
I personally would prefer naming surface structures after their appearance, like the Snowman for instance.

It's Frosty, Sam, and Yukon Cornelius, btw... All the names have a French theme, except those. They are named after famous (in the US) snowmen. Frosty is obviously from Frosty the Snowman, and Sam and Yukon Cornelius are from the annual TV holiday special, Rudolph, the Red-Nosed Reindeer.

[Decepticon]

ugordan Your image is amazing! I appreciate the effort to make that montage.

[Decepticon]

Great News! New pics!
WOW! http://saturn1.jpl.nasa.gov/multimedia/ima...3/N00091644.jpg


My sad attempt at stacking.

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[elakdawalla]

Great stuff! Sadly the sole long-wavelength image seems to have missed, so I had to fudge for the red channel. The version below consists of clear for red, a stack of four green images for the green (clear plus 3 polarizers), and, for blue, the UV3 channel with cosmic ray hits erased or corrected for by copying bits from the polarized channels where cosmic rays hit the sunlit part of Iapetus. Then I converted to Lab, replaced the lightness with the clear image, and went back to RGB.

That's some pretty rumply looking topography in the southern hemisphere basin! The "belly band" seems to look sorta segmented, with little north-south notches cut into it.

--Emily

[volcanopele]

The South-central Cassini Regio impact basin ("Henri") appears to have a central massif, which matches with the morphology of similar basins in north-central Cassini Regio ("Aimee") and northeastern Cassini Regio ("Joan").

Not sure what is up with the equatorial ridge.

[Bjorn Jonsson]

I tried stacking 6 of the most recent images in RegiStax. They were obtained at a range of ~490,000 km. I omitted the polarized UV images as they looked too noisy and fuzzy.

This version has been sharpened with wavelet processing followed by postprocessing in Photoshop (mainly brightening it slightly). Probably overprocessed, doesn't look as nice as Deception's version above:



The following version has been processed to reveal the nightside. As these are not long-exposure images and the JPG compression destroys dark, low contrast details not even large scale features are visible on the nightside. However, Iapetus' entire limb is apparent and the irregular terminator looks nice:

[Michael Capobian...]

It sure looks like the Belly Band postdates Henri and is superimposed on top of it, which has some interesting implications. I guess we'll be able to tell for sure in the next set of images.

[Rob Pinnegar]

If the degraded basin that is right next to Henri is going to be visible on this flyby, maybe it should get a name too.

[volcanopele]

Which degraded basin? Henri is rather degraded.

Michael Capobianco, that's my sense too, that the equatorial ridge here is built-up on top of Henri's ejecta.

[Stu]

Hey, how's this for a "family portrait"..? Pioneer 11 and Voyager 1 - with New Horizons - all in the same field of view as Iapetus during tomorrow's encounter?



I know we won't actually see them, but kinda cool to think they'll be "in the area"...

[volcanopele]

Just a little update. This evening, we can expect to get three observations down from the spacecraft: ISS_049SA_SATSYSFIA001_PRIME, ISS_049IA_M33HRS001_PRIME, and ISS_049IA_GLOBMAPG001_PRIME . The first two is meant as a family portrait image set. SATSYSFIA001 can be thought of as a Kodak moment-type observation as Cassini images the entire Saturnian system from near-Iapetus using both the WAC and NAC cameras. Expect lots of ring NAC images and distant images of all the major moons of Saturn, plus a Wide-angle camera overview. M33HRS001 is an Iapetus observation immediately following SATSYSFIA001. Iapetus will almost fill the view in this observation. Hopefully, the targeting will be spot-on and I can use this image for controlling the other crescent/Saturn-shine images that come down later tonight and tomorrow. This view will have a pixel scale of 1.7 km/pixel. Finally, ISS_049IA_GLOBMAPG001_PRIME will also come down. This observation is a two-frame mosaic of the crescent at 1.3 km/pixel. CLR and UV3/GRN/IR1, as well as GRN polarized, images are expected for each footprint. These images are expected between 9 and 10pm tonight (though they could show up as early as 8:30pm, depending on how the Raw images page ingests images).

Tomorrow morning images from the ISS_049IA_LIMBTOPOG001_PRIME and ISS_049IA_SATUSHINE001_PRIME observations will come down. LIMBTOPOG001 is a two-frame mosaic of the crescent at 800 m/pixel. CLR and UV3/GRN/IR1, as well as GRN polarized, images are expected for each footprint. Saturn-shine observations over both poles are also expected with this observation. Expect anywhere from 0.82 to 1 pixel of smear in these Saturn-shine images. ISS_049IA_SATUSHINE001_PRIME is also expected. This sequence includes a four frame mosaic over the the crescent, 2 three-frame mosaics in saturn-shine over the polar regions, a frame over the ridge, and a frame over the south-western part of the impact basin in northeastern Cassini Region ("Joan"). These images are expected to be on the raw images page sometime between 7:15 and 8:15 am tomorrow morning.

[volcanopele]

Emily, those features along the ridge are superimposed impact craters:

[mgrodzki]

also made with infrared, GRN and ultraviolet

[elakdawalla]

Ah. Of course. It's obvious, now that you've explained it to me. I didn't recognize them because of the foreshortening. If it were less of a crescent view, there would have been craters along the ridge to compare them to, like in the image you showed; but with just the crescent illuminated it was quite mysterious.

Nice map!

--Emily

[Decepticon]

Here we go again!

http://saturn1.jpl.nasa.gov/multimedia/ima...iImageID=126174

[Rob Pinnegar]

Which degraded basin? Henri is rather degraded.

There's another one just to the southeast of Henri that is about the same size but is even harder to see. There isn't much left of it, but you can see it when it is close to the terminator.

Somebody pointed it out a year or two ago -- I can't remember who noticed it first.

[Edit: If you look at the collage of Iapetus images from the first page of this thread, it's visible in the images from the 7 o'clock and 8 o'clock positions on the "wheel".]

I hope we get the chance to see the Iapetus shots within the next couple of days after the close encounter. Good job this is happening on a Monday morning -- it would've been torture if it had been on a Friday.

[elakdawalla]

The latest set looks like ISS_049IA_M33HRS001_PRIME and appears to be perfectly targeted. Well done team!

EDIT: and here's my composite of that one. It's got stacked IR and Red for red, stacked green and clear for green, and just blue for blue (the UV3 one was a bit JPEGGy and cosmic-ray-hit to do much with)

I was busily erasing cosmic ray hits from the short-wavelength channels when I noticed that there seemed to be a "hit" in the same place on two of the channels. Three light spots, actually, repeated from channel to channel, which means they weren't hits, they were features; they were the pole-facing southern rims of three craters north of the equator. Neat! There was also one longer-exposure clear image in this observation, and you can see the outline of the limb -- with a hint of some interesting topography -- and maybe one mid-sized crater in the north polar area by Saturnshine, but not much else.

Also a few images from ISS_049IA_GLOBMAPG001_PRIME seem to be up, but not all of them.

Bedtime for me; I'll have to wait until tomorrow to see what Santa has brought!

--Emily

[JRehling]

[...]

[Steve G]

This one is about 60,000 km closer, crudely enhanced and rotated for easier interpretation. Looks like a crater chain running parallel to the ridge.

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[Steve G]

Man must explore. And this is exploration at its greatest - Dave Scott

[David]

I just can't get over the strangeness of that mountain chain so abruptly interrupting the otherwise smooth curve of Iapetus' horizon. It is unnatural -- and yet wonderful, too.

And yes, there does seem to be a linear feature running parallel to the equator. Maybe more than one. That makes the phenomenon all the stranger.

[ugordan]

I was struck by how lumpy this body is as seen in this overexposed image. Another thing is the 3 stars visible aren't streaks at all despite longer exposure. Cassini was obviously tracking Iapetus and the stillness of the stars suggests Iapetus wasn't moving in Cassini's windshield much at the time - more or less just growing bigger and bigger.

[Stu]

Thought I'd have a go, everyone else is going to!

[ugordan]

Wow!!! http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=126214
This is it, at 62 000 km it's already twice the resolution we ever got!

Just look at that rigde, like some alien spine creeping around the moon!

Where's that swear bucket when you need it?

[akuo]

Amazing views and it's only going to get better.

I don't actually remember, how high are the peaks in the mountain ridge?

[Bjorn Jonsson]

The highest ones are about 20 km high.

Not unexpectedly, that ridge looks ancient. At a quick glance it seems just as heavily cratered as the terrain near the ridge.

I noticed several 'black' images. I hope these are Saturnshine shots that the automatic contrast stretch didn't handle well and not images where Iapetus got missed. The fact that they are all CL1/CL2 suggests the former may be the case.

[TritonAntares]

I noticed several 'black' images. I hope these are Saturnshine shots that the automatic contrast stretch didn't handle well and not images where Iapetus got missed. The fact that they are all CL1/CL2 suggests the former may be the case.

Looks like saturnshine pics:


Much noise in there...

Till later...

[Stu]

Am I seeing things that aren't actually there, or is there a parallel feature running alongside the main ridge on both sides..?

[ugordan]

I believe the 10 consecutive "black" images are part of ISS_049IA_SATUSHINE001_PRIME:

Saturnshine (landslide crater):
- Eight long exp. 32s (fullres., g=3); two 2sum (46s + 32s, g=3)

I suspect they're black because cosmic noise confused the histogram stretcher. Saturn is in a more favorable saturnshine phase now, ~35° (rev B/C was ~70°).

Funny how we're seeing WAC frames now similar in resolution to what NAC saw a couple of days ago:

- WAC clr 260ms (straylight test) + 120ms (both WACs in BOTSIMs)

Except WAC PSF makes everything look blurrier.

[Phil Stooke]

Here's the view with saturnshine on the limb. A composite of three frames.

Phil

[ugordan]

Phil, I don't know why, but that composite reminds me of Voyager 2 Triton encounter for some reason.

[Rob Pinnegar]

Phil, I don't know why, but that composite reminds me of Voyager 2 Triton encounter for some reason.

Probably 'cause Iapetus' black streaking resembles the wind-blown geyser plumes.

Also: Stu, that's an interesting observation about the attendant linear features paralleling the main bellyband. The one on the right looks like it might be just a fortuitous arrangement of craters -- but it does seem that there might be something there.

[Bill Harris]

Today's the day and I'm absolutely a-bubble with excitement. Dreamt last night that the dark material on Iapetus was billions and billions of 2x3x5 (or 4x9x25) meter-tall black monoliths...

And Oppy is getting ready for the entry into Victoria. Can life get much better?

--Bill

[volcanopele]

Well, I guess you guys get the real-time feed... interesting.

Stu, the ridges parallel to the main ridge were seen during the New Year's 2005 encounter. According to Giese et al. (in press in Icarus), these are caused by flexure as the heavy load of the ridge is supported by the thick lithosphere.

[ugordan]

Well, I guess you guys get the real-time feed... interesting.

What do you mean by this?

P.S. Bill, it can always be even better!

[volcanopele]

Usually, we get the images several hours after the end of the downlink. That's how I calculated the 7:15-8:15am PDT arrival times for the images on the JPL raw images page. During the Iapetus encounter, however, we get the images in a "real-time" feed, meaning we see the images shortly after (within 15-30 minutes) they hit the ground, during the downlink. However, I expected the JPL raw images page to load the images several hours after the downlink, on the "Non-real-time" feed. But the fact that people were already looking at the images at 4:20am PDT tells me that you guys are getting them as soon as we are seeing them.

[Rob Pinnegar]

Well, we're past C/A now. Hope we get some images soon!

BTW, I assume that the scale of the "bellyband flexure" probably tells us something about the rigidity of the Iapetan lithosphere (and perhaps its thickness, at least thickness-at-the-time)?

[ugordan]

@VP: Well, if it's any consolation to you, the last downlink (yesterday, starting 14:15 UTC) certainly didn't feal "real time" to us. Unless the imaging data was downlinked at the very end of the pass, there was an obvious delay because no new images were posted on the raw page as of 21:30 UTC. I'm inclined to think the raw posting mechanism isn't totally automated, rather it is triggered by someone after the DL is complete. Who knows...

Rob, the way I see in Emily's table, we might not see any new images until tomorrow's huge 14 hour, partly redundant downlink. The next downlink (2 hrs duration) might only contain RADAR SAR data. That huge downlink is scheduled to begin something like 07:00 UTC September 11th.

[Mariner9]

I know there are a couple downloads scheduled during the flyby. Anyone know approximately how often and when the Raw Images site is going to updated today?

And may I add along with everyone else, Oh my f***ing g**d!!!


(no, no, that was "feeling good". You people think I would really swear like that on a public forum?)

[Mariner9]

Oops. Sorry. I didn't refresh my browser for a few minutes, and the "how often are we getting downloads" discussion has already happened.

But I'm still feeling good. This is great stuff. Flyby of a lifetime.

[Stu]

VP: thanks for the info on the parallel ridges, there was a bell ringing at the back of my mind about that but I'd forgotten the details.

Seriously guys, how amazing is this? Front row seats for almost real-time exploration of one of the solar system's most fascinating bodies?! I've managed to see Iapetus in my humble 4.5" telescope a few times... on very clear, still nights, through the light pollution above Kendal... and now I'm looking at images of a dinosaur spine crater-pocked mountain ridge on its surface, almost as soon as they reach Earth! What a fantastic example of what Doug was talking about in his recent presentation - the sheer joy and genuine excitement of "joining in" with a mission and feeling part of it. Many, many thanks to whoever (deliberately or accidentally!) is allowing us to drool over these pictures so quickly.

A true "THIS is how it should be done!" lesson to other space agencies, mentioning no names of course, haha...

[JRehling]

[...]

[Ant103]

Hi

Impressive flyby now And some images to produce .

These are my tries :
Narrow angle camera, today.


RVB wide angle cam

And an oversaturate pic to view more clearly color differences


I'm waiting for narrow RVB images...

[volcanopele]

Here is what I could glean from the playback schedule. Please take time values with a grain of salt. They can be off by a few hours (usually on the plus side). So if ORSHIRES001 doesn't show up at 1:06am PDT, don't come here screaming that something has gone wrong. BTW, all times are in Pacific Daylight Time (this is just copied from my personal notes):

FP1NITMAP001_CIRS - Monday, September 10 - between 2:43 and 3:49 pm
CASSREG001_PRIME - Tuesday, September 11 - between 12:13 and 12:16 am
ICYMAP003_UVIS - Tuesday, September 11 - between 12:16 and 12:31 am
ICYEXO009_UVIS - Tuesday, September 11 - between 12:31 and 12:45 am
ORSHIRES001_VIMS - Tuesday, September 11 - between 12:49 and 1:06 am
FP1DAYMAP001_CIRS - Tuesday, September 11 - between 7:19 and 8:00 am
IAPETUS013_VIMS - Tuesday, September 11 - between 12:51 and 1:00 pm
REGMAPTRL001_PRIME - Tuesday, September 11 - between 2:59 and 4:07 am
REGCOLTRL001_PRIME - Tuesday, September 11 - between 4:22 and 4:42 am
IAPETUS010_VIMS - Wednesday, September 12 - between 8:05 and 9:05 pm
LIMBTOPOI001_PRIME - Wednesday, September 12 - between 8:05 and 9:05 pm
IAPETUS004_CIRS - Thursday, September 13 - between 7:50 and 8:50 pm

[belleraphon1]

Thanks indeed to all those who have made this possible!!!!

Any one else out there old enough to remember the JPL "Blue Room" broadcasts during the Voyager mission? Our local PBS station aired those, and I will never forget watching the commentary of Hal Masursky and, I believe it was Larry Soderblom, as the first Voyager close encounter Io images were being downlinked. The sheer JOY of major discovery happening before our eyes!!!!!

Now here we are 28 years later watching Iapetus reveal itself to us all with data we can save and play with.
Another world develping before our eyes... are there really words that can express the emotions here????

Yes, indeed Stu.... this is how it should be done.

Craig

[elakdawalla]

Since Iapetus is tidally-locked and Cassini has spent most of the mission much closer to Saturn than to Iapetus, the saturnshine imagery is always the same hemisphere -- the one we've already seen over and over. This time around, we get a daylit look at the other side.

Of course, Saturnshine imagery will always only show one hemisphere, the sub-Saturnian hemisphere, regardless of where Cassini is, because that's the only hemisphere that'll get sunlight from Saturn. I think you know this, it just wasn't clear from your post, and in fact I always forget this fact -- you'll never get any Saturnshine images of the anti-Saturnian hemisphere, because that hemisphere never sees Saturn! The point you're making about getting a daylit view primarily of the anti-Saturnian hemisphere is a good one and one I keep forgetting to make.

I was struck by how lumpy this body is as seen in this overexposed image. Another thing is the 3 stars visible aren't streaks at all despite longer exposure. Cassini was obviously tracking Iapetus and the stillness of the stars suggests Iapetus wasn't moving in Cassini's windshield much at the time - more or less just growing bigger and bigger.

When I was talking with Tilmann at the satellites conference about this, he expressed concerns about the quality of the Saturnshine images because of this very geometry; that Cassini would not be able to use its vaunted tracking capabilities to keep long-exposure images from getting blurry. If it's flying by, from a distance, excellent tracking can keep the same points on the surface precisely in the same pixels on the detector. But if the moon is simply growing in the field of view as you approach it directly, the points on the surface are spreading out, and there's no way to prevent some of them from moving from one pixel to the next, introducing a spreading sort of blur. So they had to keep exposures short enough that this radial smear would be less than one pixel, meaning for the LIMTOPOG001 observation, the exposure was forced to be shorter than 56 seconds. I notice that on Tilmann's website, the detailed information for each observation includes a "Radial Smear Table" for the saturnshine observations.

I noticed several 'black' images. I hope these are Saturnshine shots that the automatic contrast stretch didn't handle well and not images where Iapetus got missed. The fact that they are all CL1/CL2 suggests the former may be the case.

Tilmann said something to me about this, which I don't remember perfectly, but it had something to do with avoiding every-other-line-truncation issues with these images by forcing them to occupy a smaller part of the histogram than they otherwise might, so he predicted that many of them would show up on the raw page as black images, annoying people.

--Emily

[ugordan]

Here's my stab at the mosaic, click for full-res:


I took care of varying distances between footprints and they match pretty nicely. The dynamic range on this thing is so big I had to overexpose the northern section a bit even while reducing contrast to make Cassini Regio better visible. I'll try a color one next, but the UV frames are smeared pretty badly.

[elakdawalla]

Nice work!

The UV images are really blurry. Just putting them together in an RGB doesn't work very well (first image). However I found that you can get rid of a lot of the blur and still preserve a little bit of the color information by stacking it with the clear-filter image first. Not ideal, but much better looking.


--Emily

[Stu]

Excellent work on the images sent back so far, well done everyone! Anyone else just want to go to bed right now and wake up when the close-ups are in?

Speaking of which, based on what we've seen today, and the detail we've seen on this part of the Great Wall (HATE "Belly Band", sorry!) has anyone out there an idea just what the images of the Voyager Mountains will actually show? Will we see peaks glinting in the sunlight? More avalanche features? Just curious because I'm giving a talk to an astro society in Carlisle on Thursday night, and although it was meant to be just about Titan I'm making space to feature Iapetus fly-by images too...



Even if no-one has any actual predictions, what would you like to see on those images of the mountains?

[ugordan]

Here's the best I could do to get some color out of the lower resolution filters. The UV filter proved most problematic (particularly in the right half of the mosaic), with its high noise and blur. I'm not too keen on the blue ice to the north, but its for keeping with the spirit of previous composites.

[Steve G]

In the old days, (Mariner 69 was the first instance for me) I remember watching all the US and Canadian news casts hoping they'd cover a flyby. If lucky, they did. Then I went through the newspapers, then rushing to the stores on the following Wednesday to pick up Time and Newsweek. Finally, about 6 weeks later, Sky & Telescope (and briefly Star & Sky - remember that one?) would have the best pictures.

How times have changed! Having them almost live, and then having you guys doing absolute amazing stuff has given me a front seat. Life doesn't get much better. Thanks!

[tedstryk]

In the old days, (Mariner 69 was the first instance for me) I remember watching all the US and Canadian news casts hoping they'd cover a flyby. If lucky, they did. Then I went through the newspapers, then rushing to the stores on the following Wednesday to pick up Time and Newsweek. Finally, about 6 weeks later, Sky & Telescope (and briefly Star & Sky - remember that one?) would have the best pictures.

How times have changed! Having them almost live, and then having you guys doing absolute amazing stuff has given me a front seat. Life doesn't get much better. Thanks!

I remember during Voyager's approach to Neptune, I would ride my bike to a local newstand and check every paper for news. If I found anthing substantial, I would buy it (on the days I had any money). I would also make trips by the library to see what was in Science and Science News.

[Steve G]

Yes, and Aviation Week as well. I'd hate to admit how much pilfering of library magazine pages adorned my scrapbooks! National Geographic was about a 5 month delay. I did manage to buy some amazing books at the book store at JPL during my one and only visit during my honeymoon in 1980. It was closed to the public, and I pleaded that I had come all the way from Montreal and they actually gave my wife and I a pass and we got a bit of a grand tour.

[JRehling]

[...]

[tedstryk]

Yes, and Aviation Week as well. I'd hate to admit how much pilfering of library magazine pages adorned my scrapbooks! National Geographic was about a 5 month delay. I did manage to buy some amazing books at the book store at JPL during my one and only visit during my honeymoon in 1980. It was closed to the public, and I pleaded that I had come all the way from Montreal and they actually gave my wife and I a pass and we got a bit of a grand tour.

I used photocopies, but I used to have boxloads. NG was a delay, but the quality was phenominal. I only had rare access to Aviation Week when I would get to go to a larger college library in another town.

[volcanopele]

I still have the three giant binders full of Io info from when I would go to the public library in my hometown of Leavenworth, KS and print off page after page of info on Io that I could find on the internet or copy from a book.

[elakdawalla]

Here's the best I could do to get some color out of the lower resolution filters...

Beat me to it, Gordan! Here's my effort. (Details will be posted shortly on the blog.)


--Emily

[ugordan]

Nice one! Looks like your color is more consistent through the footprints than mine, except for the leftmost part where a touch of green is noticeable.

[elakdawalla]

That leftmost one was tough, because it was both dark and dark -- both dimly lit and dark-colored. I really had to sink the levels down low to make it sort of match.

Blog entry now posted here.

Now I gotta go prepare for a $*(#^ dinner party...why can't my relatives check the space calendars before they try to schedule family events?

--Emily

[ugordan]

That leftmost one was tough, because it was both dark and dark -- both dimly lit and dark-colored. I really had to sink the levels down low to make it sort of match.

You can often alleviate this problem a bit if your footprints overlap. After you adjust color for each filter, you flip through overlapping layer portions through each RGB filter in Photoshop and take note if brightness appears to change in the overlapping region. You can match colors better this way as you're looking for difference, something the eye's good at picking out.

[ElkGroveDan]

...why can't my relatives check the space calendars before they try to schedule family events?

My wife has a solution for such schedule conflicts when she's working against a deadline.

[ngunn]

RVB wide angle cam

And an oversaturate pic to view more clearly color differences

OK just to stop me thinking about it what is that poorly registered red/green spot in the sky quite near the equatorial ridge in your middle image? A star? I don't see it on other processed versions.

[CAP-Team]

it's these days, same as the day the huygens lander landed on Titan, you'd want to sit and check every tv station and/or website covering the event, hoping to see the new incoming images the first.

Can's wait to see the new high-resolution images from the bright side of Iapetus. Emily did a really nice job with the image posted above!

[volcanopele]

OK just to stop me thinking about it what is that poorly registered red/green spot in the sky quite near the equatorial ridge in your middle image? A star? I don't see it on other processed versions.

Yeah, that's a star. There are a few that show up in the sky in the Iapetus images.

[TritonAntares]

FP1NITMAP001_CIRS - Monday, September 10 - between 2:43 and 3:49 pm

Should include the next transmitted image - Iapetus crescent at low southern latitudes, distance 39013 km, resolution 235 m/pxl:


The next dowlink:

2007-253T20:05:00 (SCET) 000T02:15:00 (duration) Intermed. downlink Canberra + Goldstone

That's 14 hours 5 minutes after the last transmission, whose images we already enjoyed.
So maybe earliest in 4 or 5 hours - time to have some sleep...

[elakdawalla]

Here's an attempt at stereo on the ridge. Did I do this right? I'm never really sure if I've assembled stereo images correctly; my eyes always give me topo-from-shading and I have trouble looking past that unless things REALLY leap out. The two images I used were
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=126188
and
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=126214


--Emily

[volcanopele]

You may need to rotate them so that they are both pointed north up. However, I am not sure there is enough difference between the geometry of the two images. I am assuming you used the two frames from SATUSHINE001? The sub-s/c longitude changed by 1/2 of a degree between the two. I would wait until the WAC from ORSHIRES001 - trigger number 2901 comes down. That would make a much better stereo pair.

[elakdawalla]

Yes, they're the two from SATUSHINE001; the second of them was described as "ridge stereo" so I assumed that's what they were for. But after more fiddling I'm giving up, as it seems that there just isn't enough difference between them to make the point of view any different between "left" and "right." One's 10% closer to Iapetus than the other but Cassini didn't move around the limb enough to make any difference.

--Emily

[Bjorn Jonsson]

WOW!!!!!!!!!!!!!!!!!!!!!!! :

http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=126229
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=126228

Less than 1500 km from Iapetus! Still trying to figure out what I'm seeing, for some reason my brain/eyes combination wants to see cones where I think I should be seeing craters.

[Bjorn Jonsson]

Weird, the links to the images no longer work. Here is one of them that I managed to save before this happened:

[Bjorn Jonsson]

Direct links to the JPGs apparently work:

http://saturn.jpl.nasa.gov/multimedia/imag...3/N00091840.jpg
http://saturn.jpl.nasa.gov/multimedia/imag...3/N00091841.jpg
http://saturn.jpl.nasa.gov/multimedia/imag...3/N00091842.jpg

(as should be obvious from this string of messages I'm rather excited about this )

[tedstryk]

Those really are amazing!

[mgrodzki]

where did emily and ugordan get the hires of each filter for that crescent image? the only IR1, GRE and UV files i saw were pretty lo-res.

[ElkGroveDan]

Just stunning. The words "very old" keep coming to mind.

Whatever is making it black must be something akin to electrostatic molecular coating. Even the finest dust or other particles after all these eons would show some kind of accumulation. All we see are raw untouched ancient crater fields.

[mchan]

Reminds me of the closeups of the similarly battered limb of Dione, where as Dione's surface looked like ice, Iapetus's surface looks like rock.

[volcanopele]

where did emily and ugordan get the hires of each filter for that crescent image? the only IR1, GRE and UV files i saw were pretty lo-res.

They probably did what I did, combined each color filter image with the full-res, clear filter image.

[edstrick]

N00091839.jpg is also accessible by a direct link.

The limb here is MUCH smoother than in 91840, to the "right" of the bellyband and near the start of the high latitude light terrain.

Attached thumbnail(s)

 

[mgrodzki]

combined them?… that is probably where any abilty i have to do this stuff drops off. i am only combining the IR, GRE and UV into the R, G, B channels in photoshop.

< place embarrassed emoticon here >

[volcanopele]

ed, where did that image come from...

[edstrick]

Because I cannot now open the mid-sized image for the most recent narrow angle frames (as noted above), and then get to their full-rez raw frames, I opened the raw for

http://saturn.jpl.nasa.gov/multimedia/imag...3/N00091828.jpg

and changed the last digits in the address bar to 39 and hit "enter".

Voila.

I just tried looking for the next WA frame after W00035137 and get "The Page You Requested Is Not Available", so we can work around bugs or whatever in the software but not "cheat" and get files that aren't there yet.

[Ian R]

Here's my contribution to the Iapetus party:



*Yawn* I'm off to bed then!

[TritonAntares]

Only six new images have been transmitted so far - probably prior to a large RADAR data downlink.
I think these images are connected with those CIRS observation mentioned above - but actually I'm not sure and I can't appreciate the numbers of NACs and WACs we see there now...

EDIT: Info from Tilmann - 2 are the only ISS-shots of ISS_049IA_FP1NITMAP001_CIRS prior to a large RADAR SAR data set from the dark side.

[volcanopele]

ICYEXO003_UVIS
=========
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=126232
(I presume the bright spot near the center of the image is Nunki or Sigma Sagittari)

ICYMAP003_UVIS
=========
http://saturn.jpl.nasa.gov/multimedia/imag...3/N00091840.jpg
http://saturn.jpl.nasa.gov/multimedia/imag...3/N00091841.jpg
http://saturn.jpl.nasa.gov/multimedia/imag...3/N00091842.jpg

FP1NITMAP001_CIRS
=========
http://saturn.jpl.nasa.gov/multimedia/imag...3/N00091839.jpg
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=126231

So we got a little bit more than we expected.

[antipode]

This surface makes most of Earth's moon look young....



P

[nprev]

Yeah... ...doesn't look like it ever had anything in the way of a major resurfacing event like the lunar maria, ever, at least the terrain we've seen. Think that exogenic origin of the splotch is looking more likely now...

Anyone else find these close-ups oddly evocative of Phoebe?

[CosmicRocker]

Good catch, antipode. I was so caught up in the wonder of the encounter that I somehow managed to miss that.

[dvandorn]

I don't know about anyone else, but in some of these images I'm seeing very definite evidence of material flow, in a direction that, if the shadows aren't playing tricks on me, seems parallel to Iapetus' orbital motion.

In other words, it looks a lot to me like most of the larger craters have debris on opposite sides, filling in both inner walls to some degree but piled up a bit more on the far sides (in relation to their orientation towards the direction of orbital motion). The debris patterns seem to consistently apply themselves 180 degrees apart on the larger crater rims (i.e., the thickest or most obvious sections of the debris accumulations lie approximately 180 degrees apart along the rims), and the vector through these points in the crater walls seem to align with direction of orbital motion.

I'm getting my concept of the direction of orbital motion from the shadow angles and from my (admittedly extremely rough) concept of where these regions lie in relation to the equatorial ridge. In any event, to make it a little simpler, it looks like the vector defined by the 180-degree-seperated rim distortions points back toward the center of Cassini Regio, i.e., towards the center of the region Iapetus that faces into its direction of orbital motion.

It will be more instructive, and prove more, when I can see exactly where these images are located and where those vectors actually point. After all, you *could* (and, on many Solar System bodies, do) see the same kind of phenomenah emanating from basins. But while some of this looks like ejecta, more of it looks like, well -- duning. To me.

This debris accumulation looks less obvious in the inter-crater "plains" (as rare as they seem to be) than on the rims and floors of the larger craters. But I really do think I see very specific patterns of debris accumulation here. It would seem to support the belief that material is, or has been at some point in the past, very slowly "flowing" from the midpoint of Cassini Regio out in vectors away from the leading face's central point. What's harder to tell is whether the "flow" is more radial to the center of the leading face, or more parallel to the equatorial ridge. It may well be a combination of the two...

I'd have to say it looks like the surface is very ancient, but that that the debris accumulations (which you don't see in such abundance on the other icy moons), while relatively thin in most places, seem to definitely overlay almost all of the craters to the same extent. In other words, this material is younger than the underlying ancient surface, but thin enough that it doesn't resurface the ancient terrain, it just piles dunes and sprays of debris on top of it. It's not enough material to resurface, but it does seem to be enough material to "paint" the cratered terrain a very dark brown.

-the other Doug

[volcanopele]

dvandorn, I'll have to look at these images again to see what you are talking about. Any chance you can draw up something in Paint or Photoshop to illustrate what you are talking about?

To me, these images tell the tale of a very ancient world. The surface is very heavily cratered. We do do see some relatively young craters (don't ask me for an age estimate) with flat floors, central peaks, and mild to major slumping along crater walls. We also see some very ancient craters that have been eroded by later impacts, which have ruggidized the crater floors and space weathering, which has smoothed out many of the earlier hummocks produced from slumping.

From the images that have been returned so far, expect the highest resolution images to show a relatively smooth surface with impact craters down to the limit of resolution, though it maybe interesting to see if the dark material deposition has buried some of the smallest impact craters. This would be evidenced of course by a lower limit to impact crater size. Could be interesting to see. I don't expect the kind of bouldery surface we saw at Enceladus.

[mchan]

The distribution (size and number) of smaller craters (if that's what they are) in the inter-crater "plains" appear odd. There appears to be some number of craters of one narrow size range, with very few or none that are, say, twice as large and larger, or half as large and smaller. At first glance, they appeared to be a smattering of huge boulders.

[edstrick]

<beats his head on the keyboard in frustration>

When, did somebody say, is the next batch of pictures likely to be posted?