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tedstryk
Here is a combination of all of Galileo's global color views of the Galileans. I have left out the large Europa mosaic because much of its color data is pulled from other orbits. I have also left out colorized views. Due to inconsistent filter selection, there some variation between images. I posted the Europa set in another thread, but I figured I would add the views of Ganymede and Callisto.

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ElkGroveDan
Galileo imagery?

APOD August 30 1996



Great work Ted, thanks for the new wallpaper.
nprev
ohmy.gif ...wow, Ted! Thank you; that's an incredible montage. In particular, Ganymede looks more interesting then I've ever seen it before.

Watch out, though; you forgot to include Io among the Galilean moons, so VP's gonna be torqued... wink.gif
ugordan
QUOTE (nprev @ Dec 9 2007, 10:59 PM) *
Watch out, though; you forgot to include Io among the Galilean moons, so VP's gonna be torqued... wink.gif

Well, he did label the collage "Icy Galileans" tongue.gif
tedstryk
Actually, I didn't forget....There are so many Io images that I haven't gotten to all of them yet. Here are a few I have processed. (I should mention that the third image is two color (violet/IR), which is why it looks a little off compared to the other images. I am working on trying to formulate a better "synthetic green."

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tedstryk
This one is actually from Voyager, showing Europa's night side.

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Tom Tamlyn
This seems like the right place to mention that Emily has posted an excellent write-up of Ted's work on her blog, to mark the inclusion of his wonderful Gallileo images of the Galileans on the Planetary Society's web site.

A question for Emily: When you refer to your "image database," I think you mean something more voluminous than the "space topic" write-ups for each planet, but I'm not sure where on the site to find these images.

TTT
nprev
Congrats, Ted; Emily's made you an international star! smile.gif Well done & well deserved.
elakdawalla
TTT -- I probably shouldn't refer to my image database in blog entries -- I mean the internal planetary.org image database that is used to populate our website with pictures. I'm proud of it because when we redesigned our website late in 2005 it's one of the things I demanded -- an image library where we can upload one copy of an image, with caption and credit, and it auomatically produces the three browse sizes we use, and spits out the formatted html code for our pages, and we never lose the files or have to rewrite captions, something we used to do regularly before the redesign. I suppose in a future redesign we ought to make this publicly searchable but, I'm very sorry to say, the idea didn't occur to me when we were doing the redesign.

--Emily
tedstryk
That is a really cool feature. By the way Emily, I really like the description of the kind of work I do (the explanation of the difference between what I do and what scientists do - at least most of the time (you will understand in a month or two)). In trying to portray what an object in space looks like, there are often trade-offs. Planetary objects don't have big gores in the side of them and discolored sections where one or two filters didn't cover. So, for the sake of producing a nice picture, creating convincing gapfill is important. However, if such images were used for science, such methods could lead some unfortunate person to think that they had discovered a truly different region. I will admit that I am MUCH more pliable with what I am willing to do with Galileo images than with other probes, as its coverage is so spotty. Where I draw the line is cloning over gaps with fictional features or features from another region - I always use actual images of the missing region or a gray fill that is roughly keyed to the surrounding albedo features. I realize, however, that those folks who produce maps for renderings to be viewed at any angle really don't have a choice but to clone missing regions.

For Galileo, I have even tried to play around with some of the better Opnavs. Sometimes there is a rotation sequence as Galileo approached a moon (usually Ganymede) which allows one to build up. Here is Ganymede on orbit J0 (after insertion and approaching the G1 encounter).

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Here is Europa on orbit G2 using the same technique.

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For the most part, these are tiny images (there are closer opnavs, but due to the compression formula, the data is so skeletal that recovery is impossible). The reason I bothered to figure out a recovery technique is that there are a handful of shots that would have been great "Kodak Moments" had the High Gain Antenna worked, but Galileo didn't have the luxury of taking such pictures. I wanted to test the technique before I bothered with some more difficult images. Here is one from orbit E4. On the left side, the only change I have made is to de-interlace Ganymede, which only has every third row (every fourth row near the top). I reconstructed the missing parts of Io using high phase data from other orbits and the hole in Ganymede from other shots in the sequence of opnavs. I colorized the images based on other orbits.

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tedstryk
I have re-reworked the closer I32 global view, and in the process I noticed something - you can see the planetshine - lit hemisphere. I know there are plenty of images showing this in much more detail, but I was mainly taken by the fact that I had worked with this dataset so much and never noticed this. The reason is probably that I was focused on making the image black in all areas off the limb except for the faint plume on the upper right. However, due to glow from the daylit hemisphere, the background is actually brighter than the planetshine on the right side of the image, so I probably destroyed it in earlier versions. I wiped out color in the planetshine area because it was not picked up in all filters, making for a very odd appearance. The first image is my new "regular" version, the second is with the planetshine area enhanced.

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PhilCo126
Here's a special image of the Jovian moons:
http://sohowww.nascom.nasa.gov/pickoftheweek/old/27mar2009/

Why did you think that this fit in a Galileo imagery thread?
DrShank

nice!
but Galileo image compression almost always wiped out any subtle details in any jupiter-shine imaging. wahhh!
Bjorn Jonsson
Having seen what Cassini has done at Saturn I'm becoming surprised there aren't any really nice Jupitershine images of the Galileans (especially Io's Jupiter facing hemisphere). This shouldn't have been very difficult since Jupiter is much brighter than Saturn. Of course the downlink was severely limited but despite this I'm a bit surprised.
stevesliva
QUOTE (Bjorn Jonsson @ Apr 23 2009, 08:25 PM) *
Having seen what Cassini has done at Saturn I'm becoming surprised there aren't any really nice Jupitershine images of the Galileans (especially Io's Jupiter facing hemisphere). This shouldn't have been very difficult since Jupiter is much brighter than Saturn. Of course the downlink was severely limited but despite this I'm a bit surprised.


Given the bandwidth limitations where they probably couldn't return every sunlit Io image they had, would Galileo have been focused on IR images of the volcanically active areas when Io was in eclipse and nearby? I'd think bandwidth coupled with Io looking interesting in non-visible wavelengths would but the nails in the coffin of visible Jupitershine images.
Sunspot
It's a shame its going to be at least 30 odd years before we ever get a good look at Jupiter again.
Phil Stooke
I expect the other things visible in sunlight were much higher priority than any potential earthshine images.
DrShank
QUOTE (stevesliva @ Apr 24 2009, 09:12 AM) *
Given the bandwidth limitations where they probably couldn't return every sunlit Io image they had, would Galileo have been focused on IR images of the volcanically active areas when Io was in eclipse and nearby? I'd think bandwidth coupled with Io looking interesting in non-visible wavelengths would but the nails in the coffin of visible Jupitershine images.


it would have been nice indeed. several things made it unlikely. The ccd on galileo was 8-bit, on cassini it is 16-bit (or is it 12, i can never remember). In any case, the cassini ccd has a significantly broader dynamic range and can capture low light images. even so, if the exposure isnt long enough even for cassini, compression artifacting begins to kick in. ive used quite a few of these and have seen a wide range of quality. given the lower sensitivity, and the severe restrictions on downlink and tape recorder, either you expose for the lit side or the dark side. galileo could usually do only one or the other, not both because it was not a high priority to take the same image twice. they were lucky to get 150 images of ALL targets during any given orbit. so nite side imaging took it in the teeth.
ugordan
Yes, Cassini has 12 bit A/D converters and although it typically encodes images using an 8 bit lookup table, it's still able to capture the greater dynamic range 12 bit images produce, albeit with only 256 discrete levels.

I don't think Galileo having an 8 bit dynamic range to begin with gives you much to work with if the exposures are set for sunlit surfaces. Maybe some detail could be pulled out from higher phase sunlit surfaces since those inherently use longer exposures for rocky surfaces, otherwise the brightness difference is too great.
Bjorn Jonsson
This is true and even long exposures might have been a problem due to scattered light unless the phase was relatively high. What I had in mind was something similar to Cassini's images of Iapetus (these are the best known Saturnshine images) of Io's subjovian hemisphere. The reason is that Galileo only obtained relatively low resolution images of this hemisphere. But possibly the flyby geometry was never suitable for this - it's probably time to get some SPICE kernels and start digesting them.
Phil Stooke
Cassini at Iapetus was moving very slowly, but Galileo at Io was moving very fast, so motion blur was a problem and compensation more difficult. And the long exposure would result in really bad radiation effects on the image.

Phil
ugordan
True, but Io also receives much more jupitershine being much closer to Jupiter (which in turn receives more sunlight) than Iapetus is to Saturn so that tends to cancel out greater flyby speeds somewhat.
tedstryk
In these images, compression was not the worst problem. It was a horrible amount of noise.
john_s
Actually there are a few low-resolution, global, Galileo images of Io's nightside in Jupiter shine, taken to look for condensing frosts. See Simonelli et al. 1998, Galileo Search for SO2-Frost Condensation on Io's Nightside, Icarus 135, 166-174. These are from that paper:

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John.
tedstryk
QUOTE (Sunspot @ Apr 24 2009, 10:09 PM) *
It's a shame its going to be at least 30 odd years before we ever get a good look at Jupiter again.


Sunspot, actually less than 20. The new mission is supposed to end in 2029, which is 20 years from now. smile.gif
tedstryk
Here is another nice view from Galileo, taken during the E15 orbit.

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DrShank
QUOTE (tedstryk @ May 1 2009, 01:24 PM) *
Here is another nice view from Galileo, taken during the E15 orbit.

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yes, this view is upside down with north at bottom. the clutch of mountains near the bright patch of Masubi (top)
is Hiiaki Montes, Shamshu Mons, plus a few others. Zal and Mongibello Mons are at bottom!
machi
Beautiful images! Io is really very photogenic object.
Here are some images from beginning of Galileo mission.
machi
Asteroid Ida in false color.
djellison
False colour? really? I've stretched the saturation to the max in Photoshop on that image, and there's no colour at all, just a slight orange tinge across the entire image.
machi
QUOTE (djellison @ Dec 1 2009, 12:34 PM) *
False colour? really? I've stretched the saturation to the max in Photoshop on that image, and there's no colour at all, just a slight orange tinge across the entire image.


It's slightly colored (aproximately brown color). But this is a problem with adjusting colors on different monitors. On my old CRT it looks fine, but on LCD it looks completely different.
I tested this image on LCD and it's colored (try adjusting contrast).
Phil Stooke
Since the original mosaic was monochrome, any colour is false! Looks good, though - probably fairly realistic.

Phil
paxdan
I believe machi is using false colour to mean artifical colour, not spectral imaging that uses combinations of wavelengths that do not approximate what is seen by the human eye.
machi
Full inline quote removed - ADMIN

Right. This is maybe little terminological problem. Color is entirely artificial. How Phil said, for this mosaic multispectral images don't exist.

For comparison, this is multispectral image maked from violet, green and IR images.
djellison
A more appropriate phrase would have been 'colourised' rather than 'false colour'. 'false colour' infers that you made the image from multiple filters.
jekbradbury
As Jason Perry pointed out a couple months back over at the Gish Bar Times, we have recently passed the tenth anniversary of Galileo's I24 flyby, that probe's first close-up look at Io. However, many of the images collected during the flyby had at least one of two anomalies, which the team later characterized here. They were able to create an algorithm to correct the first and simpler of the two anomalies, but were unable to correct the second anomaly. Thus, about a dozen close-in images of Io have been lost. I made an initial attempt at correcting the second anomaly for the example image used in the characterization document, but, although it makes for an interesting exercise in image processing, it's completely useless in its current form for anything resembling scientific analysis...
original:
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attempted restoration:
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The images themselves are here, with those containing an anomaly in the "garbled" directory and corrected versions of those with just the first anomaly in the "repaired" directory.
tedstryk
Impressive!

By the way, I don't think I ever have seen the documentation for the second anomaly. Very interesting!
tedstryk
I posted a short Europa-related blog entry yesterday.

http://planetimages.blogspot.com/2009/12/n...-of-europa.html
ugordan
Here are two rough color views from Galileo. Valhalla impact basin on Callisto:


Ganymede mosaic consisting of 4 footprints:


That's the Enki Catena crater chain at lower right. There exists a fifth footprint that I *think* fits to the lower left one, but there's no overlap to match them and I omitted it here.
volcanopele
What a difference rotating an image can make:

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From my blog post: The mosaic above shows a portion of the northeastern margin of Chaac Patera, a volcanic depression on the anti-Jupiter hemisphere of Io. Click the image for a full-resolution version. The terrain to the upper left is the hummocky plains that make up the upper level of the depression Chaac sits in. The terrain to the lower right is the floor of Chaac Patera, consisting of overlapping, thin silicate flows. The margin itself is quite steep, with slopes approach 70 degrees on the right hand side. On the left hand side, mass wasting has produced a two-tone talus apron at the base of the slope. This mass wasting seems to be the result of more extensive slope failure (see the broken off section of massive lava on the far left edge of the image).

These images were taken during the Galileo spacecraft's February 2000 flyby of Io. The pixel scale is 7 meters per pixel.

See PIA02551 to see how these images are normally shown... Rotate the image 90 degrees and suddenly the geologist part of my brain starts saying, "Oh now this makes A LOT more sense!"
machi
Amazing! I'm not geologist, but I have seen this image many times (in raw form) and now it looks really more understandable to me. Fantastic cliff!
Let's Look at Io from a Different Angle!
DrShank
or a slightly different take, simulating the view one might have out of a porthole on passing space cruiser . . .

DrShank
QUOTE (DrShank @ Jan 21 2010, 08:53 AM) *
and a different scene . . .
this is the eroded plains shot north of the equator, for which we have no context imaging. it shows a dark smooth plataeu in the foreground
and complex plains surrounding it. these palins are probably overlapping flows and erosional debris slides of some sort.



Explorer1
On a related note, look at what made it onto Wikipedia's front page today!
http://en.wikipedia.org/wiki/Callisto_%28moon%29
Rather a coincidence considering the recent blog post by Emily.....
volcanopele
I had this on my blog a few days ago, but I've gotten around to putting together a few mosaics of Europa from 1998 and 1999 by Galileo:

Click to view attachmentClick to view attachment

15ESREGMAP01
15ESREGMAP02
Description at http://www.gishbartimes.org/2010/03/two-mo...pa-mosaics.html

17ESREGMAP01
17ESAGENOR03
17ESSOUTHP01
17ESREGMAP02
Description at http://www.gishbartimes.org/2010/03/and-no...completely.html

19ESRHADAM01
Description at http://www.gishbartimes.org/2010/03/19esrh...-of-europa.html
stevesliva
QUOTE (volcanopele @ Mar 11 2010, 06:39 PM) *


Paging nirgal...
nprev
Those are just mind-blowing, Jason.

I never knew that there were features like that on Io...(sorry, couldn't resist! tongue.gif)
ugordan
Shamelessly stealing volcanopele's 10ISIOGLOC03 Io image and running it through CIE XYZ color calculation code based on Galileo's filter wavelengths (R 665, G 559 and V 413 nm):



It's also gamma-corrected (assuming the original composite is straight-up RGB substitution, judging by contrast and terminator line). Io's one of the few moons that doesn't really look bland this way.

Decepticon
Oh wow Gold!
JohnVV
I thought that this one was the correct color and gamma
and have been planing on redoing the color on my map ( i white balanced it )
{ http://celestiamotherlode.net/catalog/show...p?addon_id=1110 }
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http://pirlwww.lpl.arizona.edu/~perry/io_images/c21.htm
http://pirlwww.lpl.arizona.edu/~perry/io_i...1ISCOLOR_01.png
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