A Distant View of Triton

My interest in planetary exploration was born in the 1988-1989 school year.  As a bored fourth-grader, I was paging through my science book when I came across this image .  I refuse to soil my blog with it.  My thought was that there was no way something in nature could be that ugly.   I began to go to local libraries, looking up anything I could find on the planets, trying to figure out what they looked like.  Saturn, it turns out, was a beautiful world, nothing like the picture.  I even talked my parents into getting me a telescope for my birthday.   I spent two hours looking before I finally found Saturn.  It was a beautiful yellow world, encircled by rings, as I had seen in some of the better books I had found.

I began to search libraries for more planetary images, joined the local astronomy club, and began connecting to BBS boards online to see more images and to find out what was going on in planetary exploration.   What I found was quite exciting.   Voyager 2 was approaching Neptune, Magellan was getting ready to head to Venus, Phobos-2 was about to swing into orbit around Mars, and Galileo was about to head to Jupiter.

Phobos-2 would send back some incredible images but then fail.   Next up was Voyager at Neptune.  I would ride my bike at least once a week to all the local libraries to see if a new image was released in a magazine or newspaper.  I would search BBS boards for any new information.   As I read predictions for the Neptune encounter, its large, quirky moon Triton captivated me.   Was it active?  Would we see through its atmosphere? 

As the encounter approached, I would buy a newspaper every day in case there was an update.   A few days before the August 25 encounter, there was an image of Triton published.  It was taken on August 21, and was blocky and fuzzy.   Still, it was the first image of I had ever seen that showed actual surface features on Triton.

I clipped that image and probably still have it somewhere, although I'm not sure where.   I haven't seen it published anywhere else.  I decided to dig up the data set and produce a view of Triton as seen by Voyager that day.   It was this encounter, along with the images from the Phobos-2 images, that crystalized my interest in both planetary science and in image processing, transforming it from a passing fancy of childhood to a lifelong passion.

Processed Image Copyright Ted Stryk, Raw Data Courtesy NASA/JPL

Io from Voyager 2

I have never worked much with Voyager 2 Io images.  Voyager 1 flew much closer to Io, and Galileo of course imaged it from even closer and monitored its volcanoes over a period of years.  The Voyager 2 images are relatively distant.  Still, some of them are quite sharp and show Io from angles not seen by other spacecraft.  This image is made from some of the closest Voyager 2 images, taken on July 9, 1979 from about 1.1 million kilometers.   One can see a multitude of high mountains casting shadows near the terminator.   One can also faintly see the night side of Io illuminated by reflected light from Jupiter.

 This is an alternative version.  It improves the view of the day side at the expense of suppressing the night side.

 In this image, I worked to compensate for the fact that the filter coverage is different on different parts of the disk and several color filters are badly underexposed by the terminator.  I think it is the best looking version.

Here is an enhancement of the night side.  Because it is very faint, this image appears very noisy.

Processed Images Copyright Ted Stryk, Raw Data Courtesy NASA/JPL

Some projects don't work out...

When I do work with limited and/or poor quality datasets, the failure rate is high.   Such was a recent attempt to make a perspective view from images of the surface of Venus taken in 1975 by Venera-9, the first spacecraft to take pictures from another planet.   Below is my enhanced version of the panorama it took.

 

Given that the spacecraft was only expected to last around an hour on the surface and its  slow transmission rate (by modern earthly standards), the view was only 128 pixels high and about 512 pixels wide.  In order to sample both the horizon and nearby areas with good enough resolution to distinguish what was being seen, the camera scanned a 180 degree panorama that started out looking at the horizon, dipped down in the center to the foot of the lander, and then went back up to the horizon on the other side.   My goal, following work that Don Mitchell has done with the much better datasets from Veneras 13 and 14, was to make a picture that would show Venera 9's surroundings from a more normal perspective.  I had reprojected the corner images before, as seen below.

These views, while from a somewhat more human perspective, are still awkward to look at.  My goal was to sample features at different distances in order to create something resembling an ordinary photograph.  The problem was that unlike Veneras 13 and 14, which took similar scans on both sides of the lander, Venera 9 only took one, and at significantly lower resolution.  In fact, the compilation is so obvious that some blurring was necessary to disguise the fact that the scan lines and pixels were going in different directions in different places.   Also, while I intended the image to be 480x640 pixels, the largest presentation it could sustain and still look half way presentable was 275x360.  Still, at about 99,000 pixels, it is still oversampled (the original data comes to about 65,500 pixels).  In other words, the best that could be managed was an image slightly less than 0.1 megapixels.   It also took some inventiveness.  One side of the panorama shows a ridge in the distance,  the other side does not.  The transition had to be guessed at.  Also, filtering was done to reduce the effects of differing illumination angles, improving the believability factor but at the expense of yet more resolution.

This is the finished product.  It turns out that there was not enough data in the Venera-9 set to make this work.

 

Finally, for fun I made a colorized version based on the Venera 13 and 14 color images.

Data courtesy the Russian Academy of Sciences.   Processed images Copyright Ted Stryk.

A close shot from Pioneer 10

This rarely seen image, badly damaged by the effects of radiation on Pioneer 10's imager, is from dataset A4.  It was taken 726,000 km from Jupiter.  A hint of the red spot can be seen on the terminator.   This image is still a work in progress.

 Here is an alternate processing with some cosmetic improvements and scaled closer to the original pixel size.

Processed image Copyright Ted Stryk.   Original prints scanned to create this image courtesy NASA/Ames.

Jupiter from Pioneer 11.

This exquisite image of Jupiter is from Pioneer 11, the last (and the closest - 760,000 km) image to show the planet's full disk before closest approach. The image, C5 in the pioneer catalog, is a combination of a red and a blue light scan with a synthesized green.  Images like this present a processing dilemma.   Pioneer got an unusually good view during approach of the south polar region during approach and an even better view of the north polar region as it left.  In my attempts to process these images, there appears to be a blue glow around the polar regions, perhaps due to a haze.  However, since I am working from scans and not digital data and the scanned prints are of varying quality (the yellowing of the individual sheets of paper was surprisingly inconsistent) and this is near the limit of what can be discerned.  Thus, figuring out if it is real is difficult.  The limitations of the medium, plus the 6-bit nature of Pioneer images, makes interpreting faint features very difficult.

While this dataset is very limited, it provides some of the best views we have of Jupiter's poles, so I intend to do more work with it in the near future.

While I'm at it, here is image C25, taken from 2.3 million kilometers.   It shows a higher phase angle than can be seen from earth.  It does not one of the polar region images, but it is a pretty picture nonetheless.

Processed image Copyright Ted Stryk.   Original prints scanned to create this image courtesy NASA/Ames.

NASA's DAWN spacecraft is approaching Vesta, the second most massive object in the asteroid belt.  It is now about 200,000 km out, and the view is getting very interesting.  Here is a stack of several frames taken on June 20, 2011, and released as part of an approach movie on June 23, 2011.

Data Courtesy approach sequence/movie released by NASA/JPL-Caltech/UCLA/MPS/DLR/PSI.    Much thanks to Emily Lakdawalla of the Planetary Society for breaking up the individual images in the movie.  Processed Image Copyright Ted Stryk