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Pioneer 11 Saturn, Reprocessed Images
mchan
post Feb 16 2007, 06:07 AM
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My memories were of watchng raw images come down on a projection TV of the times at the Exploratorium in San Francisco. There was a decent crowd of 100-200 people. The images were of medium quality, but were nevertheless exciting as images from the first spacecraft flyby of Saturn.

Which reminds me I still have an old T-shirt from Ames of the flyby somewhere that I will have to find.
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4th rock from th...
post Feb 16 2007, 11:13 AM
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Ted,

Nice processing, I like your versions, very clean and soft, really natural looking.
Keep it up :-)


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tedstryk
post Feb 16 2007, 11:44 AM
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Thanks. 4th rock, your versions are very good as well.

The thing that one has to remember is that the Pioneers used 1960s technology. Because they were small, spin-stabilized spacecraft, they could not carry a proper camera. The imaging photopolarimeter, when in imaging mode, was essentially a two channel photometer. It usually took about 40 minutes to build up an image, which is why there is such a problem with distortion (spacecraft motion and planetary rotation became a factor). Add to that the fact that, at best, the Pioneers transmitted at 2048 bits per second (and, because Saturn was entering conjunction at the time of the encounter, the data rate was often lower than that - a lot of Titan data was lost, and most of the post-encounter imagery was compressed by returning only every-other scan). That small bandwith was split between all the instruments. To make matters worse, Pioneer carried no means to store data for later transmission - everything was in real time (with the exception of a device with very limited storage for keeping data obtained while the spacecraft was behind a planet). The data is coded in 6-bit format, a la Mariner-4. The imagery looks better at Jupiter because Jupiter is brighter, larger (so that its apparent diameter was bigger from farther away, giving time to build an image), and higher contrast, making 6-bit more tolerable. Still, the original images are tiny - check out 4th-rocks page for an idea of the real sizes of the images.

I have always liked the dark-ring perspective....then again, I have never viewed these images without the Voyager images being in existence. But I think the main thing that caused the Pioneer-11 Saturn imagery to dissapoint was that Voyager had just flown by Jupiter, and so going back to Pioneer-quality imagery was tough.


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edstrick
post Feb 17 2007, 08:53 AM
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The real problem with the Pioneer images at Saturn is that they don't show much. Data rates were low and dropping as Saturn was days from solar conjunction, so close-in pics were narrower than at Jupiter. Worse, light levels were much lower than at Jupiter and the Pioneer spin-scan camera couldn't take longer exposures, so the data's noisier. And Saturn is so much blander than Jupiter, almost no cloud features show other than the belts. What they show that's new is the high phase view and the unlit side of the rings, and that's about it.
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tedstryk
post Sep 4 2007, 11:21 AM
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Here is another mosaic. This one shows Mimas below the rings and its shadow above the rings.

Attached Image


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GregM
post Sep 7 2007, 04:26 PM
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.
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JRehling
post Sep 7 2007, 04:50 PM
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QUOTE (GregM @ Sep 7 2007, 09:26 AM) *
Very nice. It looks to be free of the geometric distortions from the spin-scan. Colour looks very "realistic" as well. I think that this is a definate improvement over the "old" P-11 Saturn images.


It really does look suddenly Voyagerish in quality.

Of course, like those audiophiles who claim to prefer vinyl, I have such nostalgia for Pioneer 11 that I *like* the grainy images. *grumble* *grumble*

Just kidding -- keep on truckin', Ted.
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tedstryk
post Sep 10 2007, 05:36 PM
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There are three reasons to collect and reprocess old planetary images. One is to pull out new scientific information and to create a baseline for studies of temporal phenomena. The other two are what most of us here are involved in.

One is what I spend most of my time on - compared to the billions of photographs from different time periods and places that we have of Earth, both from the ground and space, we have relatively few of other worlds - even Mars pales in comparison. We have earthbased telescopic views, but until webcams and adaptive optics came along, it was impossible to take a planetary picture that didn't look blury when reproduced at a decent size except with excellent equiptment on a rare night. Of the images we do have, we only tend to see a small selection, perhaps those pulled out of the pile for "instant science" during a flyby, or those selected for use in the post-mission articles in Science or Icarus. The Voyager and Viking missions, for example, captured a plethora of beautiful shots that rarely see the light of day. In addition, the views we see are often impacted by outdated processing techniques (which sometimes goes as far as mosaics made of prints glued or taped together) as well as generational loss from scans made from scans made from scans, etc. Then there is data that was not recorded and or stored in digital form, and that was taken by crude imaging systems. With the processing techniques available at the time, even if science data could be gleaned, pretty pictures were out of the question. With Pioneer 11, my goal is to get beyond the limits of the Imaging Photopolarimiter and create nice looking (if small) photographs showing what Saturn looked like in September 1979, or what Jupiter looked like in 1973 and 4.

However, that brings me to the third reason - the preservation of history. When images that I have processed, such as my Phobos-2 and Mars-3 work, as well as those of others (4th rock and Phil Stooke come to mind), we create far nicer views that the scientists were able to produce at the time of the mission. So even if I can make a Pioneer image look Voyager-ish in quality, while I might have created a better depiction of Saturn, it is no longer a record of what the scientists (as well as the public) were viewing at or around the time. Pre-Apollo, we didn't have views of the lunar surface as nice and unobstructed as Phil Stooke's panoramas - they were covered in mosaic lines and light and dark areas of the vidicon. Therefore, the earier versions of these images still hold great value - it is these images that show us our best view of neigboring worlds in the mid '60s (Surveyor) or 1979 (Pioneer). However, if we want an idea of what we might have seen standing near Tycho on the lunar surface or hurtling towards Saturn, the enhanced versions are better.

I share nostalgia for the old Surveyor, Mariner, Pioneer, Voyager, and Viking (I could make this list longer - you get the idea) - they were my initial tour of the solar system. Of course, I am not a techie - There is something organic about things that are not digital that I like.


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tedstryk
post Sep 16 2007, 09:29 PM
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Here is an approach sequence. The closest shot is actually a mosaic of the best images from close encounter.

Ted

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Dominik
post Sep 16 2007, 09:51 PM
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WOW ohmy.gif

A really great picture from such old data!


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ugordan
post Sep 16 2007, 10:25 PM
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Indeed. Outstanding work, Ted!


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GregM
post Sep 17 2007, 12:40 AM
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tedstryk
post Sep 17 2007, 02:54 AM
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I don't think they can stand much enlargement. I am not happy with the second closest, and the most distant is already at full resolution. Here are the other two.

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