Tuesday, December 21, 2010

During Galileo's 24th orbit of Jupiter in October of 1999, it flew by its innermost large moon, Io, snapping closeup photos.  However, many of those photos were scrambled by the effects of Jupiter's intense radiation belts. They were descrambled using ingenious software, but they still look rough compared with normal images.  I have been exploring ways to make cosmetic improvements to the images, but the results have been dissapointing.  Still, one mosaic is worth sharing, centered over Donar Fluctus (the wedge shaped feature).   The color and gaps in the data have been filled in from Galileo's 3rd and 21st orbit.

Here is another version.

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

Saturday, December 18, 2010

Updated: Io Over Jupiter's Terminator (and also a bit of historical perspective)

On March 4, 1979, Voyager 1 snapped an exquisite mosaic of Io as it completed a transit above the Jovian cloud tops. This is an improved version of a mosaic of images it took that I posted in August.

The next set is a comparison to show just how far planetary imaging has come.  The top row shows the best images of the Jovian moons Io and Ganymede from the Pioneer mission in the early 1970s as they flew by Jupiter.  The Pioneer probes were spin stabilized which (at least in those days) made it impossible for them to carry a true camera, so they had to scan line by line to build up an image. 
The bottom row also shows images of  Io and Ganymede, this time from the mid 2000s, taken by the Hubble Space Telescope.  For comparison, please keep in mind that they don't show the same parts of each  moon and the illumination angle is different, especially for Io.  Still, the Hubble images, taken from low earth orbit, are far superior.  How far we have come!

Processed Images Copyright Ted Stryk
Raw Voyager Data Courtesy NASA/JPL
Raw Pioneer Data Courtesy NASA/Ames
Raw Hubble Data Courtesy NASA/STScI

Wednesday, October 20, 2010

Ganymede from Galileo

The image below is Galileo's view of Jupiter's moon Ganymede. It was taken on February 27, 1997.   Missing areas were filled in with other data, and color was taken from other datasets as well.

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

Sunday, August 29, 2010

Io over Jupiter's terminator

On March 4, 1979, Voyager 1 snapped an exquisite mosaic of Io as it completed a transit above the Jovian cloud tops.  Unfortunately, the apparent motion of Io was so great with respect to Jupiter that it is very difficult to assemble.  I still plan to do further tweaking, so this is somewhat of a work in progress.  The bit of Jupiter visible is simply the last bit of haze that caught sunlight at the edge of the day side, so there isn't much detail to be seen.  The view of Io is quite sharp.

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

Saturday, July 31, 2010


I continue to toy with Voyager's underexposed but highest resolution image of Neptune's second largest moon, Proteus.  I think this version may be the best approximation of how it actually appears.  Be very careful with feature identification.  In once sense, the features visible are real.  However, the fainter features  are hard to interpret.   The image was so badly underexposed that Voyager only barely detected these features.  Hence, a crater might appear as a "u" shape" or even an ambiguous blip because the higher contrast areas (the side that was in shadow, for instance) but lower contrast features and craters under high solar illumination are lost or nearly totally lost.  However, some craters, including the large one in the upper right, and some grooves/fractures are visible.  Given that Proteus is in roughly the same size class as Mimas (moon of Saturn) and Miranda (moon of Uranus), it is remarkable how primitive and irregularly shaped it is.
 Here is the second best image, the lone color shot of Proteus. 

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

Thursday, July 29, 2010

Phobos 2 over Mars

Here is a view of Mars from thermoscan on Phobos 2 in 1989.  This shows some of the fractured terrain near the Valles Marineris canyon network on Mars.

  Data Courtesy the Russian Academy of Sciences.   Processed Image Copyright Ted Stryk

Sunday, July 18, 2010

I'm Still Here...

Things have been quite eventful, so I have had little time for image processing lately.  Eventually I do plan to resume regular posting.  In the mean time, here is a view of Io from Galileo, taken on August 12, 1999 during the spacecraft's 22nd orbit of Jupiter.

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

Thursday, March 18, 2010

On September 29, 2009, the Messenger spacecraft flew by the planet Mercury.  The approach data was successfully obtained, but thanks to a safe mode incident, the departure data was lost.  On October 3, the spacecraft finally recovered.  It took this image through its wide angle camera that day

Only albedo features can be seen.  Had the Narrow Angle Camera taken data that day, good imagery could have been obtained, but since it would have been of little value had closer data been taken, none were scheduled until October 10th.  In that view, shown below, a few large craters can still be seen on the terminator despite a distance of 2 million kilometers - it is still better than the image above. 

While the loss of departure imagery is disappointing, all in all the Messenger flybys proved very successful.  One can only look forward to the beginning of the orbital mission next year!

Raw Data Courtesy APL/JHU/NASA   Processed Images Copyright Ted Stryk

Tuesday, March 16, 2010

Luna 20

On February 21, 1972, Luna 20 landed in the Apollonius Highlands, a highlands region  located between Mare Crisium and Mare Fecunditatis.  It was the only Soviet sample return mission to land in the highlands, and also the only one to return imagery of its surroundings.  Due to difficulties with the sampling apparatus, the drill only penetrated 25 centimeters and returned 55 grams of lunar material. Despite the small size, given the unique regional setting, these samples proved extremely valuable.    Reports of how much image data it returned are conflicting, but only fragments have been published.  These images were assembled by piecing together the available fragments.   Because quality varied greatly, some areas are notably sharper.

The first pair shows the drilling arm as it moves while preparing to drill into the surface. Hills can be seen in the distance in the upper left-hand corner.  One of Luna 20's antennae can also be seen (the long, skinny pole to the left of the sampling arm).  It is much closer to the camera and higher above the surface than the sampling arm, which is why it casts no shadow within the field of the camera.

The next image shows more hills and some craters near the landing site. It is possible that this segment is a continuation of the panorama above, but I am not at all sure of this.  The left hand half of the image is made of much poorer data than the right hand side.  The lower right hand area is obstructed by part of the spacecraft.

Data Courtesy the Russian Academy of Sciences.  Processed Images Copyright Ted Stryk

Friday, March 12, 2010

Tyre Macula

Building on yesterday's post, here is another view of Europa.  It shows Tyre Macula, one of the few large impact structures identified on Europa.  This view shows it nestled among the Europan lineaments. 

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

Thursday, March 11, 2010

Europa from Voyager 2

When the Voyager Jupiter flybys were planned, very little was known about the Galilean moons.  Because it was impossible for both Voyagers to make a close flyby of each moon and still get to Saturn, planners were forced to be selective.  They gave the two largest moons, Ganymede and Callisto, a close flyby from each spacecraft.  Io, known to be an oddball, got an extremely close (by Voyager standards) flyby by Voyager 1.  Europa, the smallest of the Galileans, was given the lowest priority.  Voyager 2 made the only relatively close flyby, and it was relatively distant.  Still, it obtained some beautiful imagery.  There is a crescent image, which is the closest mosaic and has the best filter coverage, that has been reprocessed several times.  There is also a slightly more distant mosaic, taken from about 250,000 km.  It is limited in filter coverage, but shows Europa at a half phase, therefore showing significantly area.  The base color was created using orange filter data as red, blue as green, and a mix of violet and ultraviolet as blue. I have mixed the color data with OGV wide angle data taken later and reconstructed in the areas not covered by the later data.  The grayscale data is stacked and shown at 1.7x original size.  The result is one of the better global views of Europa presently available.

Here is a second version, leaning more heavily on the OGV data described above for color balance.

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

Monday, February 15, 2010

Dione from Voyager

Cassini continues to pour down imagery from the Saturnian system.  However, decades earlier, the Voyagers gave us our first close-up look at Saturn's moons.  As Voyager 1 approached, it took this view of Dione over Saturn's clouds.  I posted this years ago, but this version was done using improved techniques.
This is a color view taken of the wispy trailing hemisphere.
As Voyager 1 got closer, it got a much better view, as shown here, where the boundary between the wispy trailing hemisphere and leading hemisphere is clearly visible.

The mosaic below is Voyager's closest view of Dione.
 Voyager 2 did not come nearly as close to Dione, but it did get some interesting views. This is its closest view.  There is some overlap with Voyager 1's high resolution mosaic, but parts of this image show areas poorly seen in the first Voyager flyby.
Processed Images Copyright Ted Stryk, Raw Data Courtesy NASA/JPL

Tuesday, January 19, 2010

Phobos-2 Images

This pair of images, obtained by Phobos-2 in 1989, make a good example of what Phobos-2 images look like.  The aspect ratio has to be fixed, and extensive noise removal, calibration, and cleanup is needed.  Also, due to the significant time lag between images, Phobos and Mars have to be processed separately, because they have shifted relative to one another.  Color has to be filled in for areas of Mars obscured in one image but not the other.

Raw Data Courtesy the Russian Academy of Sciences, Processed Version Copyright Ted Stryk