Planetary Images From Then and Now

Mars from Rosetta, 2007

2012-01-23T19:51:00.000-08:00

Here is an image from ESA's Rosetta spacecraft, en route to a comet, as it flew by Mars in 2007. The raw data finally hit the PDS this year, so I am posting this to celebrate.

Processed Image Copyright Ted Stryk, Raw Data Courtesy OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

Crescent Triton

2012-01-18T21:12:00.000-08:00

I have posted some views from Voyager 2 of a crescent Triton before. This is a version that is processed to appear as it might actually look if one were viewing it, instead of focusing on bringing out faint details.

Additionally, here is an even higher phase crescent, taken with the wide angle camera (the above image is from the narrow angle camera).

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

A final post for 2011

2011-12-31T12:31:00.000-08:00

The year 2011 has been a busy one for me, and I am resolving to make 2012 a more productive year in terms of image processing. In the meantime, here is an improved version of the last Voyager 2 image of Ariel prior to near encounter in January 1986.

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

A Crescent Callisto

2011-12-07T13:23:00.000-08:00

This is a crescent view of Jupiter's moon Callisto taken by Voyager 1 on March 6, 1979. Many of the pictures that were taken in this dataset smeared or missed Callisto, and all of the images are underexposed. The smoothness of the day/night terminator is a reminder that for all its craters, Callisto is a very flat world.

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

A new version of an earlier Triton mosaic.

2011-11-28T04:56:00.000-08:00

A few years ago, I posted this massive installment of Triton images. This is the large, high resolution mosaic seen through a high pass filter to cut down on the effects of illumination differences - such filtering helps to focus on smaller features across the image.

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

A (nearly) full Callisto from Voyager 2

2011-11-21T06:09:00.000-08:00

This is one of the best full-phased images of Callisto available. It was taken by Voyager 2 during its 1979 flyby of Jupiter just before Callisto fully filled the field of view of its narrow angle camera.

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

In Honor of Phobos-Grunt, a View of Halley's Comet from Vega 1

2011-11-10T19:04:00.000-08:00

The Russian Space Agency attempted to return to planetary exploration this month with November 8th's launch of Phobos-Grunt. It would be only the second planetary mission launched by Russia since the demise of the Soviet Union (the first was the ill-fated Mars '96). It is currently stuck in earth orbit, and whether or not it can be salvaged will be known in the coming day or two at the latest.

This image is a stack of three images taken of the nucleus of Halley's Comet by the Soviet Vega-1 spacecraft as it flew by on March 6, 1986. The images were badly blurred by optical problems in the camera, so a lot of deconvolution had to be applied. Bright gets can be seen emanating out of the long, skinny nucleus.

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

Update: Phobos-Grunt Status - this does not look good.

Experts assure that "Phobos-Grunt" will not crash on Moscow

http://www.rosbalt.ru/moscow/2011/11/11/911410.html

MOSCOW, November 11. In the case of a uncontrolled re-entry, Phobos-Grunt’s inclination allows it to crash into half of Eurasia, but in Moscow is not in the area in which it could crash crash. This is according to RAI Navosti magazine News of Cosmonautics editor and columnist Igor Lisov.

"Barring a miracle, and experts fail to establish communications with the mission, it will remain out of control. If it is out of control, then there is the option to shoot down with a missile. We know that China and the U.S. have facilities, which can bring down the spacecraft" - said Lisov.

Recall that the launch of the Phobos-Grunt" took place on 9 November 2011. After separation from the booster, the spacecraft went into a parking orbit around the Earth. It then experience a problem, because of what tits propulsion system did not operate and so it did not end up in a transfer orbit to Mars, but remained in near space.

Now ground control is trying to establish communications with the spacecraft; however, it did not respond to commands from Earth. According to specialists, if the spacecraft cannot be saved, then it may fall to Earth on November 26.

A Distant View of Triton

2011-09-16T20:59:00.000-07:00

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

2011-09-08T14:34:00.000-07:00

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...

2011-08-26T12:40:00.000-07:00

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

2011-08-23T20:54:00.000-07:00

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.

2011-08-21T09:25:00.000-07:00

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.

2011-06-23T16:52:00.000-07:00

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

Goodbye, Spirit

2011-05-25T09:27:00.000-07:00

Spirit, the first of the two Mars Exploration Rovers (MERs) to land on Mars, was officially declared dead this week. It had been silent for about a year, but there were hopes that improving seasonal conditions might lead to its reawakening. Sadly, that did not happen. As a small tribute, here is a small panorama, taken in early 2004, looking at Grissom Hill. Spirit traveled in the opposite direction, so it got its best views early on. In order to combine images taken from slightly different positions, I had to cut out the foreground, as it would not match up. Until we meet again!

Additionally, here is a reworked version of Spirit's view of its own heat shield from the 82nd sol (Martian day) of the mission).

Until we meet again, Spirit!

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

A View of the Martian Sufrace From Viking 1

2011-04-07T09:21:00.000-07:00

This view is a super-resolution view of some the area behind Viking lander 1. It uses images taken between 1976 and 1978. A large pile of rocks can be seen, as well as a small crater on the horizon. I did this work in 2004. One of my goals is to rework some of these images again. At the time, I stacked the images in an 8-bit format. By using a 16-bit format, I can minimize data loss as the image goes from through various stages of processing (given the size of the images and the limited memory/speed of the computer I was using at the time, working with 16-bit data was prohibitive).

The second image is a vertically stretched version of the above image. The stretching makes recognition of the crater rim easier.

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

A Storm on Saturn

2011-03-24T20:35:00.000-07:00

For the past few months, a storm has been raging on Saturn. Over time, the storm has been stretched into the white band seen in the mid northern (upper) latitudes. This view, taken on March 12, 2011, shows the late stages of the storm. It was taken using the Advanced Camera for Surveys (ACS) wide field camera on the Hubble Space Telescope, with color data taken from earlier images of a previous storm by Wide Field Planetary Camera 2 (WFPC2), a camera since replaced by the Wide Field Camera 3 (WFC3).

Raw Data Courtesy NASA STScI, Processed image Copyright Ted Stryk

Reality and the "Supermoon"

2011-03-20T05:39:00.000-07:00

I don't usually post images from my own telescope on this blog, but I will break with tradition tonight. You have likely heard all the fuss about the "Supermoon." The reality is is that it is a whopping fifteen kilometers closer to earth than its closest approach last year (four one-thousandth of one percent!). That's it. Other than a bit of trivia that provides a great excuse to go out and look at the oft-neglected moon, there is nothing more to it. The end.

Below is a view of the moon on the evening of March 19, 2011 ("Supermoon" night), with a 10-inch telescope through a thin layer of clouds.

Image Copyright Ted Stryk

Wanted: In Digital Format...and my 2011 LPSC poster presentation...

2011-03-07T13:14:00.000-08:00

I am posting this in hopes that someone will see it and know where I might find the dataset I am looking for. The image of Titan seen here is image G14. It is the best of a sequence that included G15 and G16 (for each number, there are two images, a red channel image and a blue channel image). If any of you have or know where I could find these (or any other Pioneer images) images in their native digital format (probably in the form of a printed out matrix), please let me know.

While I'm at it, here is how the image looks with both channels separated and without any processing. Again, what I am looking for is the digital data, not a better source to scan.

While I'm on the subject of Pioneer 10 and 11, here is the abstract I submitted for the Lunar and Planetary Science Conference (which I will be attending this week). http://www.lpi.usra.edu/meetings/lpsc2011/pdf/1267.pdf It was written before my visit to Ames Research Center in January. I did find some better material to scan and some fragments, but I did not find the digital data I had hoped to. The most useful projects will likely be a high resolution mosaic using the closeup data from Pioneer 11 as it passed over Jupiter's North Pole and a sequence (perhaps to be made into a movie) of Jupiter rotating from above the North Pole as Pioneer 11 receded. Here is the poster I am presenting, which is a combination of older work and very preliminary processing.

Each image is designated by a letter. Here is a guide to the images based on those letters:

A. Pioneer 11 image C5 (Jupiter) Scans

B. Pioneer 11 image C7 (Jupiter) Scans

C. Pioneer 11 images C1 and C2 (Jupiter) Scans

D. Pioneer 11 images D1 and C2 (Jupiter) Scans

E. Pioneer 11 image D16 (Jupiter) Scans

F. Pioneer 11 image D19 (Jupiter) Scans

G. Pioneer 11 image D7 (Io) Digital.

H. Pioneer 10 image A24 (Ganymede) Digital

I. Pioneer 11 image D3 (Jupiter) Scans

J. Pioneer 11 image F7 (Mimas transiting Saturn) Scans

K. Pioneer 11 image F12 (Saturnian Rings) Digital

L. Pioneer 10 image B38 (Jupiter with “Little Red Spot”) Scans

M. Pioneer 10 image B39 (Jupiter with “Little Red Spot”) Scans

N. Pioneer 11 mosaic using data from images F33, F19, and F12-F5 (Saturn) Mix of digital data and scans.

O. Pioneer 10 image A2 (Jupiter – Great Red Spot) Scan

This is only the tip of the iceberg...

Scanned material and raw data courtesy NASA/Ames Research Center. Processed images Copyright Ted Stryk.

2010-12-21T11:20:00.000-08:00

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

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

2010-12-18T10:23:00.000-08:00

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!

Raw Voyager Data Courtesy NASA/JPL
Raw Pioneer Data Courtesy NASA/Ames
Raw Hubble Data Courtesy NASA/STScI

Ganymede from Galileo

2010-10-20T12:57:00.000-07:00

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

Io over Jupiter's terminator

2010-08-29T11:24:00.000-07:00

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

Proteus

2010-07-31T10:09:00.000-07:00

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

Phobos 2 over Mars

2010-07-29T21:00:00.000-07:00

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

I'm Still Here...

2010-07-18T10:13:00.000-07:00

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

2010-03-18T20:53:00.001-07:00

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

Luna 20

2010-03-16T19:17:00.000-07:00

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

Tyre Macula

2010-03-12T13:45:00.000-08:00

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

Europa from Voyager 2

2010-03-11T20:38:00.000-08:00

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

Dione from Voyager

2010-02-15T19:02:00.000-08:00

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

Phobos-2 Images

2010-01-19T06:10:00.000-08:00

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

Three Years at Saturn

2009-12-31T15:25:00.000-08:00

Presently, the Cassini orbiter is still circling Saturn. The Saturnian season is now nearly the same as it was in when Voyager 1 flew through the Saturnian system. In fact, the three spacecraft that flew by each other did so roughly once a year, one after the other. Pioneer 11 flew by in September, 1979, just before a ring plane crossing (and looking at the unlit side of the rings). Voyager 1 flew by in November 1980. Voyager 2 flew by in August, 1981. Thanks to the greater tilt of the rings relative to the sun, they appear noticeably brighter than they did for Voyager 1. Here is a sequence, showing the planet as it appeared to each spacecraft on approach to the planet.

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

Io from Galileo's 32nd Orbit

2009-12-30T20:47:00.001-08:00

This is one of the the last views of Io taken during the Galileo mission. It is nominally one of the highest resolution global views, although noise and an increasingly unsteady spacecraft conspired to degrade it considerably. The plume, visible in the upper right, is artificially brightened.

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

A "New" Galileo View of Io

2009-12-28T15:19:00.001-08:00

This view of Io is a combination of three images taken over a span of about 40 minutes at around 16 hours on March 31, 1997 (orbit G7). While taken only for the purpose of optical navigation, when combined, these images show a significant amount of Io's limb (both in Jupiter shine and in sunlight). At the very bottom, the sampling is so poor that nothing reliable could be brought out. I also removed any "plume" that was based on only one image or that was based on one pixel (due to interpolation, such a feature might appear as big as three pixels across and therefore be deceptive). After doing so, only one plume-like feature remained, corresponding to Io's Pele volcano. It is exaggerated for visibility in the following image. Please note that the processing to bring out the plume also brought out a few spurious 1-pixel features. Missing areas of the image were never transmitted.

Since a view like this is hard to interpret, I combined this dataset with reprojected images, mainly from this orbit but a few from neighboring orbits, some adjusted to the nightside brightness where appropriate, in order to fill in the gaps. Please note that not all the data in the above image is as overexposed on the dayside as it appears here (I stretched the contrast to aid visibility of the plume). I also created a color overlay from this and other orbits. Both images in this post are shown at 2.5x original size to aid visibility.

While the above image is mostly the fill in data from G7 and other orbits described above, data from this OPNAV set was used where available. The purpose of this image is to show Pele's plume in context.

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

A Nice Little View of Europa

2009-12-27T21:35:00.000-08:00

This is a mosaic of Europa from Galileo's sixth orbit, taken on February 20, 1997. Color data is taken from other orbits. It shows a wide variety of terrain types found on this mysterious moon.

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

Hubble's First View of Saturn

2009-12-22T22:10:00.000-08:00

This image, taken on August 26, 1990, was Hubble's first image of the planet. Obtained using the wide field channel of the original Wide Field and Planetary Camera, it was still sharper than groundbased observations at the time (this is no longer true).

Processed Image Copyright Ted Stryk. Raw Data Courtesy NASA/STScI

2009-12-20T20:35:00.000-08:00

Here is a close-up of the Jovian cloud tops from Galileo. It was taken on January 1, 2001. This was during the same time as Cassini was making its distant flyby. It isn't that significant an image, but considering it is the first time I have had time to work on an image in two months, I figure I should post it.

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

2009-12-04T01:22:00.000-08:00

This view, taken on October 26, 1996, during Galileo's second orbit of Jupiter, shows a crescent Ganymede and Io. Missing pieces of Ganymede and Io are filled in from other orbits (the tips of Io's red crescent and a small portion of Ganymede's center). The color is taken from other orbits. This image was taken for the purpose of optical navigation, but it is still a pretty view.

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

2009-12-03T20:16:00.000-08:00

This is the crater Khittu on Ganymede. It was imaged in color by Galileo in 1996. Although this image has undergone extensive processing to improve clarity, the compression of the original data does limit its quality.

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

2009-11-30T20:44:00.001-08:00

Enceladus from Voyager 1. Voyager 1, unlike Voyager 2, looked at the young southern terrain, but was so distant that little of it could be interpreted.

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

Mathilde from NEAR

2009-11-29T19:12:00.000-08:00

This is an image of Mathilde, a battered main belt asteroid encountered by NASA's Near Earth Asteroid Rendezvous (NEAR) spacecraft on its way to orbit the near earth asteroid Eros. At 52 km across, it is the largest asteroid yet visited by a spacecraft.

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

2009-11-16T07:27:00.000-08:00

This image is a reprojected portion of Galileo's highest resolution view of Loki, one of the major active volcano's on this fascinating moon. It was taken on Galileo's 31st orbit. While it usually appears dark compared with its surroundings, in this version it appears to have bright areas due to the extremely high phase angle. Loki is on the feature seen on the terminator just above the middle.

Here is another version, which utilizes high pass filtering to better show features within the caldera.

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

Murky Views of Umbriel

2009-10-27T19:27:00.000-07:00

When Voyager 2 flew by Uranus in 1986, the extreme tilt of Uranus, the "planet on its side," and the need to continue on to Neptune meant that it would not be able to fly close to all of the planet's major moons, because it would make its closest approach to all of them at about the same time. Additionally, the best images of Umbriel are smeared.

While Umbriel is black as a lump of coal, a bright spot can be seen in a large basin near the terminator in this distant view.

In this view, Umbriel has rotated significantly, but because the south pole is pointed almost straight at the spacecraft, it appears to rotate like a pinwheel. More features can been, including the fact that the basin seen earlier is a double basin. A large lineament can be seen just to the lower right of the center of the disk.

This view is the closest color view of Umbriel (the closest view is colorized based on this image). Thank to spacecraft motion, the phase angle is growing, and the heavily cratered, dark moon can be seen to have several bright spots, most notably the extremely bright crater rim near the top of the disk, Wunda.

This is Voyager's best view of Umbriel and its cratered surface. It appears that their is a degraded tectonic feature near the bottom of the terminator. Wunda sits prominently at the top of the disk, and another crater, Skynd, on the upper terminator lacks a bright rim but has a bright central peak.

This view of Wunda, produced using the last two images shown here and reprojected to be seen as if viewed from above, shows the doughnut-like shape (with a tiny segment missing pointing diagonally down and left).

While of very limited quality, this crescent image, taken as Voyager receded, speaks to the rugged surface of this battered moon via its lumpiness. A bright spot can be seen toward the bottom of the crescent, possibly another bright spot.

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

Thebe from Galileo

2009-10-23T14:48:00.000-07:00

Thebe, with a mean diameter of about 100 kilometers, is the second largest of Jupiter's small inner moons. It was discovered by Voyager 1 during its approach to the planet in 1979. The image below contains all the images Galileo obtained. The closest view (third column, middle row) as a resolution of 2 km/pixel, nominally better than the best view of the largest inner moon, Amalthea, although this image is incredibly noisy, rendering an effective resolution somewhat poorer.

Galileo obtained a color view on its fourth orbit, showing Thebe to have a reddish color.

Here is a combination of the color data with the closest image.

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

Spirit's Heat Shield

2009-10-13T20:15:00.000-07:00

This is an super-resolution image of Spirit's Heat Shield taken in 2004 on sol 82. It has been combined with color data from Sol 80.

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

Ganymede and Io

2009-10-07T19:34:00.000-07:00

This image shows a crescent of the Jovian moons Ganymede (larger) and Io (smaller) from the Galileo spacecraft. The color is an overlay using data from other orbits.

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

A Collection of Lunar Images From Planetary Missions

2009-10-02T12:08:00.000-07:00

This is a collection of lunar images taken by spacecraft not normally associated with the moon. It is far from comprehensive, but provides an intersting sampling.

First is an image taken by Deep Impact in February of 2005, showing Mare Orientale on the terminator. It has been deconvolved to reduce the effects of Deep Impact's camera being out of focus.

This is another view showing Mare Orientale and taken in 2005. It was taken by the Messenger spacecraft on its way to study Mercury.

This image is a distant view from January of 1998. It was taken by the Near Earth Ateroid Rendezvous (NEAR) spacecraft during a flyby of the earth. NEAR was looking down on the south pole.

The final image was taken by the Stardust spacecraft during its earth flyby in January 200l, looking down on the north side. Unfortunately, Stardust suffered from a foggy camera (a problem that was largely resolved before its comet flyby. Here is the version of the image on the Stardust website http://stardust.jpl.nasa.gov/photo/lunar.jpg

Here is amy version of the image, with the fog removed.

Processed images Copyright Ted Stryk, Raw Data For Stardust and Deep Impact Courtesy NASA/JPL, Raw Data for Messenger and NEAR Courtesy NASA/JHU/APL

Japan's First Lunar Mission

2009-09-30T07:00:00.000-07:00

Hiten was launched by Japan on January 24, 1990. The spacecraft, intended as a technology demonstration mission, entered a circumlunar orbit and released a small orbiter, Hagoromo, into lunar orbit (Hagoromo was also a technology demonstration mission). The transmiter on Hagoromo failed rendering it scientifically useless, but the orbit insertion burn was verified optically. The only scientific instrument on Hiten was the Munich Dust Counter (MDC). The MDC provided data on the dust environment between the earth and the moon until April 10, 1993 when Hiten was intentionally crashed into the lunar surface between the craters Stevenius and Furnerius.
Hiten carried an optical navigation camera called the Optical Navigation System (ONS). The ONS consisted of a 384 by 490 pixel array. Since Hiten was spin stablized, the ONS shifted the charge from pixel to pixel to compensate for smear. The images were converted into a 4-bit digital signal that was relayed to earth. The resolution of the camera was about one arc minute.
Due to the limits of its spin compensation, small chip size, and 4-bit imagery, the images the ONS obtained were useful only for navigation. However, the ONS was used during the final plunge to the lunar surface, making for a Ranger-esque kamikaze sequence, although the quality is much poorer. The white dot marks the impact point. The view has been colorized. Below is an animation of the made from the sequence.

Hiten/ONS Data Courtesy JAXA. Processed Version Copyright Ted Stryk

2009-09-28T07:43:00.000-07:00

Adding to my earlier Mariner 10 at Mercury post. Here is a sequence showing the view as the spacecrat approached and receeded from the planet. Comparing the images will show a small amount of planetary rotation.

In Mariner 10's last glimpses as it receeded from Mercury, the planet had rotate enough so that Mozart, the large crater near the center of the terminator, could clearly be seen (it was in darkness during closes approach) and the deep crater near the center of Caloris (and clearly seen in Messenger images) has rotated into view. The image on the right has been processed using a high pass filter to emphasize topography.

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

Jovian Moons

2009-09-26T14:24:00.000-07:00

The four Galilean moons from Galileo: A montage.

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

Enceladus from the Voyagers

2009-09-23T18:12:00.000-07:00

I don't have much time for a post today, but I thought I would add some Voyager images of Enceladus. I have posted versions of these before, but I have made some improvements. Voyager 1 imaged the active southern hemisphere of this Saturnian moon, but was so distant that not can be seen (although it might be possible to look for albedo changes).

Voyager 2 passed much closer, but it viewed the older, cratered northern hemisphere. The Saturnian equinox just having past, Cassini will finally get a good look at these areas over the next year or two. The first view shows the best color view obtained by Voyager, in that it is made from orange (the closest thing Voyager had to a red filter), green, and violet filtered images.

The highest resolution image set does not include an orange image, meaning that to generate a color view, one has to use green for red, making a very unsatisfactory result if one is trying to replicate what the eye might see. Voyager 2 was supposed to obtain slightly better images, but its scan platform problem prevented this.

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

DS-1 Part III: Borrelly

2009-09-22T20:58:00.000-07:00

After the Braille flyby, the DS-1 primary mission was finished. It was to go on to encounter Comet Wilson-Harrington, a nearly inactive comet, and then Comet Borrelly, a more active comet. However, what seemed like disaster struck when the star tracker failed, leaving DS-1 unable to navigate. Amazingly, the flight team managed to program the spacecraft to use the MICAS camera, despite its narrow field of view, to be the navigation camera for the spacecraft. By the time this was accomplished, it was too late to reach Wilson-Harrington, but DS-1 could still make it to Borrelly. However, given that the spacecraft would not have a star tracker during the flyby since MICAS was being used to image the comet, there were fears that the imaging portion of the flyby would fail.

Amazingly, in September of 2001, as DS-1 approached Comet Borrelly, it successfully acquired the comet. I have marked the comet with an arrow. Everything else in the frame is due to a horrendous light leak. Keep in mind that the approach was made at a very moderate phase angle, so the stray light problems are not due to being pointed near the sun. The approach to Braille was looking very close to the sun, making the stray light problem much worse, and Braille was a much fainter target - no wonder DS-1 had problems aiming at it!

On September 22, 2001, while it's parent country was reeling from the September 11th attacks, DS-1 made its close approach to Comet Borrelly. This image is a long exposure to show features in Borrelly's coma.

The next view is a closer view, showing features on the nucleus.

The final view is a the best view of Borrelly. It shows numerous topographic features as well as faintly visible jests coming out of the nucleus. The image quality is far better than was expected for DS-1, and this image was by far the highest resolution view of a comet obtained to date (~45 meters/pixel in its original form - it has since been surpassed). DS-1's solar wind monitor also studied the comet.

There was talk about sending the probe on a six month "hyperextended" mission to an asteroid, but with the spacecraft being nearly out of fuel, this idea was rejected. Two months later, contact was lost, indicating that it had indeed run out of fuel, meaning that this extension would not have been possible.
Despite not being classified a science mission, DS-1 filled that role successfully, studing Braille, an asteroid which it confirmed to be related to Vesta, taking important spectra of Mars, and giving mankind what is still one of its best looks at a comet. Although it had many difficulties, the DS-1 was truly the little spacecraft that could!

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

DS-1 Part II - Cruise and Braille

2009-09-21T20:44:00.000-07:00

DS-1 missed its original launch window. Because of this, Its Mars flyby was canceled, and it had to find a new asteroid. The asteroid, 9969 Braille, was only 2 km in length at its longest, much smaller than the original target. Still, the mission was sufficient to test the technologies DS-1 carried.

During the cruise phase, DS-1 made observations of Jupiter and its moons.

More importantly, it observed Mars. Although it was distant and the imagery wasn't that good, the infrared spectr

At last, on July 29, 1998, DS-1 flew by the Asteroid 9969 Braille. Unfortunately, it went in to safe mode just before the encounter, leaving it without needed navigation imagery. That , coupled with Braille being much fainter than expected, caused the imaging sequence to miss the asteroid (it didn't entirely miss, but the automated features mistakenly edited out the wrong parts of the few images that contained the asteroid). Most of the images were taken using a sensor known as the "Active Pixel Sensor" (APS) in order to test the technology and beause of the limited amount of memory.

The infrared spectrometer caught the asteroid, showing it to be a fragment of Vesta. Two sets of two images were obtained during the outbound phase of the encounter, showing the asteroid to be an elogated rubble pile. The first pair, taken with the CCD, is the best.

The second, taken via the APS, shows a somewhat different angle. It is shown here with the CCD image for comparison.

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

The Journey of DS-1 Part I: Background

2009-09-21T09:00:00.000-07:00

In the mid-1990s, NASA was basking in the heyday of "Faster, Cheaper, Better." This philosophy, while it had been promoted earlier, really took hold after the loss of Mars Observer in 1993. The idea was that instead of only launching a few large, expensive missions designed to conduct a cornucopia of investigations, NASA would launch a plethora, of small, inexpensive spacecraft designed to accomplish a few narrowly defined exploration goals. The success of Lunar Prospector, Mars Pathfinder, Mars Global Surveyor, and the Near Earth Asteroid Rendezvous (usually just referred to as "NEAR") missions buoyed those who believed that this approach, along with an occasional "flagship" mission, such as the Cassini/Huygens mission to the Saturnian system, allowed a robust program of planetary exploration on a relatively low budget. Looking back, there is some truth to this - NASA had a tendency of focusing only on "Blockbuster" missions and ignoring smaller, cheaper opportunities. Still, the giddy administrators of the day greatly underestimated the cost of operating a successful mission, often blindsiding those who actually worked on the missions.

The chickens came home to roost in 1998-1999. NASA launched three planetary missions within a short period. One, Stardust, succeeded in returning samples from a comet and is now headed for a rendezvous with Comet Tempel-1. The other two, the Mars Polar Lander and the Mars Climate Orbiter, failed for embarrassing reasons that were the direct result of insufficient testing and operating budgets.

This is a slightly enhanced version of the

Mars Climate Orbiter's lone view of Mars

Also aboard the Mars 1998 lander were two hard-landing penatrators, which were primarily there as part of the Deep Space 2 (DS-2) mission, part of NASA's New Millenium program. They vanished without a trace.

The New Millennium Program was designed to test new technology for planetary and earth orbiting missions. The idea was straightforward. No mission planners want to risk their mission to try out unproven technology. Still, new technology often requires tests that simply cannot be done on the ground. The New Millennium were designed to test these technologies using cheap, dedicated missions that were not bound by science goals (all science was considered a "bonus") and thus could validate technologies to be used on scientific missions. DS-2 was designed to test hard-landing technology, and, as a "bonus," was to look for subsurface ice on Mars. It's total failure to return any information, engineering or otherwise, coupled with problems that plagued the earth orbiting side of the program, lead to the scaling back of the program to simply testing technologies in earth orbit and not using its meager resources to send spacecraft into deep space. The program was canceled in the 2009 budget.

Before the 1998 Mars failures signaled a rethinking of the approach to planetary missions, an ambitious test mission left the ground. It was the New Millenium Program's Deep Space-1 (DS-1), designed to test solar electric propulsion, a miniature imager/spectrometer, and a small solar wind instrument. It was also designed to test automated navigation software. This mission made a productive (though problem plagued) journey through the inner solar system, sending back "bonus science" along the way. In my next two posts, I will chronicle this journey.

Mariner 10 at Mercury

2009-09-20T05:49:00.000-07:00

On March 29, 1974, Mariner 10 became the first (and only until 2008) spacecraft to encounter the solar system's innermost planet. Given its odd combination of filters and calibration issues, the images were often only seen in their black and white form. I have created mosaics from the inbound and outbound imagery and used more distant views to create a color overlay.

Here is the inbound view.

And the outbound view:

On Mariner 10's second and third encounters, the approaching and receding views were quit similar. For a diferent perspective, here is a wide angle view of Mercury taken during the second flyby (September 21, 1974), looking down on Mercury's south pole.

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

Mars from Viking 2 - May, 1979

2009-09-18T09:04:00.000-07:00

This image of frost on Mars has become iconic. Unfortunately, it is tiny, because it was obtained using Viking's low resolution mode and there was no high resolution image taken along with it. Using a different high resolution image and simply using the color as an overlay would not work, because the frost would be absent or the patterns wouldn't match. Other image sets of the frost exist, but they have more serious problems with over/under exposure due to the high contrast of the scene and the limitations of the Viking imaging system. Therefore, I used super-resolution processing, a technique pioneered by Tim Parker of JPL, in order to get the best resolution I could out of the existing dataset. The result is quite pleasing.

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

Some REALLY Old Images of Mars

2009-09-16T08:57:00.000-07:00

Mars holds a special place in the history of planetary science. It is the only solid planet for which we have a long baseline of study that can be usefully compared with current observations. Venus is shrouded in clouds, meaning that the closest thing to actually seeing something prior to the use of ultraviolet photography consisted of faint, often illusory and always uninterpretable hints and dusky markings. Mercury is so close to the sun that most data obtained prior to the space age is of poor quality, and on an airless world like Mercury, there are no temporal phenomenon that visual observers could track. The Galilean satellites of Jupiter often show hints at detail in the eyepiece, but nothing more (at least nothing that could be understood without the aid of closeup data).

Then there is Mars. Clouds, dust storms, and surface changes have been watched by visual observers for over 300 years. At one time, the dark markings were thought to be oceans. White ice caps mark the poles. From the very beginning of the twentieth century through the present, there has been a consistent photographic and visual record which can be used to study the changing albedo patterns, the seasonal deposition and evaporation of material at the poles, dust storms, and clouds. In fact, we have a longer baseline of global imagery of Mars than we do of earth (although at very low resolution), since it wasn't until the 1960s that satellite imagery was available.

The 19th century was a transitional time. Telescopes were coming of age, and quality instruments were becoming more commonplace. Many quality drawings were made. These, along with more sporadic work from the previous centuries, have been used to try to reconstruct the history of regional and global dust storms (if many reliable observers recorded the same features being absent at the same time, and especially if they recorded an absence of detail while Mars was close, it is reasonable to assume a dust storm is the culprit). However, monitoring ordinary meteorological phenomena, the rate of expansion/evaporation of the polar caps, and changes in albedo features is nearly impossible from drawings, given the subjectivity involved. During the later part of the 19th century, some tracking of the polar caps was done using micrometers, but beyond that, visual observations are very difficult to use.

Mars was first photographed in 1877. I have never seen the images, but I am told they do not show any detail. The first quality images were taken by E. S. Holden using the 36-inch telescope at Lick Observatory between 1888 and 1892. He was never happy with the results, but they are impressive for the time. By 1890, he seemed to have some good results. However, in 1892, Mars had a declination far to the south, and as a result, the low position in the sky combined with the long exposures needed wrecked havoc, rendering most exposures useless. Additionally, film in those days was primarily sensitive to blue light. You will notice that clouds seem exaggerated as a result of this. Holden was angry at William Pickering, the director of Harvard Observatory (Lick Observatory was a part of Harvard Observatory), for using the images, which he felt were too poor to present when compared with the drawings of the day. For this and other reasons, Holden left Lick observatory and the project stopped. Pickering continued to use the images, and in many publications they are incorrectly attributed to him.

I applied some modern processing techniques to clean up some of the images. Because the film available to Pickering was highly sensitive to blue light and totally blind to red light, atmospheric features such as clouds appear exaggerated. Still, many familiar features can be seen. These images are especially remarkable given that the slow film speed required twenty minute exposures!

These images, obtained by Harvard Observatory/E.S. Holden, were processed and restored by Ted Stryk

Meridiani in 1969

2009-09-15T20:32:00.000-07:00

In 1969, Mariner 6 and 7 flew by Mars. The wide angle camera on each spacecraft carried red, green, and blue filters (actually two green filters). Such combinations would be used for color imagery on later missions. However, on Mariner 6 and 7, the image return was limited by data storage and transmission limitations, constraining the number of images returned and meaning that not all the data could be returned in a digital format. The filters were mainly included to better understand the photographic properties of Mars for future missions. This mission was more concerned with coverage. Hence, in most of the images taken, the color filters don't overlap, and hence color views cannot be reconstructed. However, prior to the near encounter phase, Mariner 7 took a color approach sequence in real time. Since only one in every 7 columns was transmitted, missing sections have been interpolated and the images have been stacked to improve sampling

After these images were taken, Mariner 7 began its Near Encounter phase. It took the lone closeup color mosaic of the mission, covering the Meridiani region, featured prominently in the approach images and now home to the Opportunity rover. Part of this image is made from Red-Green-Blue data, with the missing filter reconstructed for any areas with only two colors available. Areas with only one filter available are not included.

Finally, here is a narrow angle shot showing the area in the dark region with resolution of a few hundred meters. I used the wide angle image above to color it.

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

Global views of Jupiter from Galileo's ninth orbit

2009-09-11T20:23:00.000-07:00

Despite its antenna problems, Galileo accomplished some remarkable science. However, a major loss was the lack of global views during the orbital mission. Ignoring the resurrected OPNAV image I posted recently, this is largely true. However, in between Galileo's 9th and 10th orbit, it obtained some highly compressed, high phase global imagery. The images are reduced to 75% of the original resolution because of the damage from interlacing and compression.

This image, obtained September 3, 1997, shows an extremely thin crescent. Some band structure can be seen, but not much else.

The next mosaic, obtained on September 10, 1997, is taken from a slightly lower phase angle, and shows a lot of atmospheric features. I am really surprised this image was not processed for a press release or at least the Galileo website.

The final image, a crop of the image above, has been put through a high pass filter to show some of the "spots," storms in the Jovian atmosphere, that are visible in this dataset.

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

2009-09-09T17:54:00.000-07:00

Below I have posted some global mosaics of Callisto, the Jupiter's second largest moon. In all cases, missing data is filled in by lower resolution images or by reprojecting other images to fill the gaps. In the final image the color is entirely derived from other data. All images are from NASA's Galileo spacecraft. The color variations between images are due to the fact that they are made using differing color filter combination.

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

Ganymede Mosaics

2009-09-09T09:03:00.000-07:00

Below I have posted some global mosaics of Ganymede, the solar system's largest moon. In some cases, missing data is filled in by lower resolution images or by reprojecting other images to fill the gaps. On the second and third Galileo images, the color is derived from other datasets. The color variations between images are due to the fact that they are made using differing color filter combinations..

Voyager 1

Voyager 2

Galileo

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

A Thirty Year Old View of Saturn

2009-09-08T19:48:00.000-07:00

In the near future, I plan to make some larger posts of reprocessed Pioneer Images. For now, here is a view of Saturn from Pioneer 11. It was taken on September 1, 1979, as the spacecraft approached the unlit side of the rings.

Processed image Copyright Ted Stryk, Raw Data Courtesy NASA/AMES

A Sad But Memorable Image

2009-09-04T08:05:00.000-07:00

This image of Mars is something I worked on a long time ago...the late 1990s! It uses ground-based color to colorize a cleaned-up version of the first of two images that NASA's Mars Observer took in August 1993, 28 days before it was to enter orbit. It was lost just prior to entering orbit (likely a fuel line rupture), so it would never send back any more data. This image is the better looking of the two (just a nicer angle). Despite its small size and many imperfections, it is still a neat shot.

Processed image Copyright Ted Stryk, Raw Data Courtesy NASA/JPL/MSSS

2009-09-03T14:43:00.000-07:00

This image, taken by the Hubble Space Telescope on December 14th, 1990, is enhanced to show cloud activity in the martian atmosphere. This is also the best image of Mars that the Hubble took during that apparition.

Below is the full set, taken just after opposition, with Mars subtending about 18 arc seconds. The series began on December 13th and followed the planet as it rotated. The first set was a disaster - the image bounced all over the place from frame to frame, and all of the shots partially missed and some totally missed the planet. This is the image farthest to the right in the set below (given this half image, I went from right to left for aesthetic reasons). The middle image, most familiar in oft-copied scans of an over-processed press release image, shows the Syrtis Major hemisphere. However, there still seems to be a lot of jitter, and the frames do not seem sharp. I at first blamed spherical aberration, but since after deconvolution it still didn't look as good as later pre-repair images, I think that there are other problems. In the left-hand shot, which is the same as the image above, the image quality is excellent.

One reason I posted these images that enhance the hazes is that the original Wide Field/Planetary Camera took much more time between frames than WF/PC2 and later cameras, so planetary rotation is a serious problem. I reprojected the images to compensate, but the edges aren't perfect - the enhanced hazes help to mask that. Another version of these images will eventually be posted.

Processed images Copyright Ted Stryk, Raw Data Courtesy NASA/STSCI

2009-09-02T03:39:00.000-07:00

This is a view of Saturn from the high resolution channel of the Advanced Camera for Surveys aboard Hubble. Taken in July, 2003, it gives a preview of what Cassini would begin to study the next year.

Processed image Copyright Ted Stryk, Raw Data Courtesy NASA/STSCI

2009-09-01T19:42:00.000-07:00

Since Voyager departed Neptune, no spacecraft has made a followup visit, and no future missions to Neptune have made it out of the follow-up stages. Our best views have come from the Hubble Space Telescope. Hubble first viewed Neptune, using the original Wide Field / Planetary Camera on July 10, 1991, less than two years after Voyager. Triton can be seen to the right.

The dark south polar band was still visible, but not the Great Dark Spot. In fact, the Great Dark Spot seen by Voyager has disappeared, though it has been replaced by other large transient spots.

One of the best images of Neptune taken by Hubble was taken using the now-defunct high resolution channel of the Advanced Camera for Surveys (ACS). Many cloud features on Neptune are seen, and hints at albedo variations can be seen on the disk of Triton.

Here are cropped images from the one above.

Mark Showalter recently completed a set of observations using the newly installed Wide Field Camera-3, which should be able to identify Neptunian rings and moons too faint to be seen by Voyager. Even though we haven't been able to visit, exploration of the Neptunian system continues!

Note: The fact that Triton appears larger relative to Neptune in the first image compared to the second is a result of the fact that the pre-repair 1991 image is a bit blurry, even after processing.

Processed images Copyright Ted Stryk, Raw Data Courtesy NASA/STSCI

Processing an image versus reconstructing a view: An example from Galileo

2009-08-27T13:33:00.000-07:00

Anyone familiar with my image processing works knows my love of working with the worst of datasets in order to try to create something presentable. In some cases, the images can be cleaned to the point that the image resembles images that were created from much better data. In some cases, missing data is found or callibration problems are solved. In these cases, the data really can be brought up to a higher standard. At other times, the image, while still limited, looks fine to the eye but has clear limitations under closer inspection - certain areas damaged by smearing or perhaps certain areas missing color data which has to be filled in.

However, there are times when an image is simply a cool or unique view that has such serious shortcomings that any product made from it isn't going to be pretty or even interpretable without using extreme and unreliable techniques to fill in gaps and then tweeking it based on other images of the target. The result is useless scientifically (the raw image might have some basic value, but with heavy reconstruction it would be dangerous to try to base any interpretations on the reconstruction). The sole purpose of such images is to get an idea of what the camera was "seeing" when it took the picture in a remote corner of the solar system.

An extreme example of this is a dataset from September 13, 2000, when Galileo was millions of kilometers from Jupiter in its long 28th orbit that would send it to the heart of the Jovian system during the Cassini spacecraft's distant flyby in order to do some synchonized studies and pass close to the Jovian moon Ganymede. Just before Cassini started its far encounter imaging of Jupiter, Galileo snapped some images of Jupiter and Ganymede. Galileo, its main antenna having never opened, was forced to spend its entire mission communicating through a small antenna that was only there for emergency situations and for the early days of the mission before the planned antenna opening. It communicated at a paltry rate of 10 bits/second (up to 100/bits per second when antennae were arrayed). For comparison, the infamously slow 2400 "baud" modems had an effective data rate of 2400/bits per second (although there are some technical differences between baud and bits per second that are irrelevant here). In other words, it was ssslllooowww. A compression algorithm wsa developed so that each navigation image, or "OPNAV," would contain just enough data to locate, for example, the position of a moon or the planet versus a star, for example, and nothing more, although two images had a small "truth window" near the center of the disk just to the left of the terminator. Here is one of the images in its raw form (please note that to see anything but the "truth window," you will need to click on the image and view it at full size):

Not much there. Using "maximum" filtering one som of the existing pixels on the terminator and limb, and them patching them based on changing solar illumination to fill in the area inbetween, most of the disk could be reconstructed.

The missing lower tip was filled in based on the upper part of the disk and a transitional area between that and the nearest available data. Ganymede's tiny disk was only missing a few pixels, which could be interpolated (they were not in the same field of view, so it doesn't appear in the above images). In the example below, it has also been brightened.

Back to Jupiter, I removed the artifacts that stretched off the disk, making a smooth limb, and smoothed it to get rid of the blocky look. The banded appearance looked remarkably good considering the source (it was produced using a combination of all the images, not just the one shown above) and combined with color data from a telescopic photo taken around the same time. I independently process the the "truth windows" and it fit in nicely in its proper place on the reconstructed disk before adding the color data. Here is the "truth window" mosaic, shown at 2.5x its actual size to aid visibility and showing some banded structure. The original data was noisy and only 50x50 pixels per image.

When finished, I added some artificial noise in order to make the reconstructed image look less cartoonish. I also reduced the entire image to 22 percent of its original size (that was the largest size at which it looked somewhat decent). However, Ganymede suffered, as you can tell by comparing it to the image I posted of Ganymede alone. The image is extremely limited, but if one put together a photo-essay on the Galileo-Cassini "Millenium Flyby" of Jupiter, it would be nice to give an idea of the how Galileo appraoched the planet as Cassini approached the daylit hemisphere. There are similar OPNAVS showing Callisto at about the same size as the disk of Jupiter in this dataset, but since its surface has no convenient banded structure and is covered with discrete craters, the only thing one could do is to fill in the entire image was data from other images, which could be done just as well without even incorporating the OPNAV image. Jupiter has cloud bands running east and west, meaning that data along the edges of the disk could be used to fill in the gaps to some degree. So, here it is, the final version, The "truth window" is impossible to spot because each "window" is only 11x11 pixels at this size.

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

Flotsam and Jetsam

2009-08-26T09:21:00.000-07:00

In addition to Triton, Neptune has many smaller moons. In the compilation below, the image on the upper left depicts the moon Larissa and the rest of the images depict Proteus, Neptune's second largest moon. Proteus is one of the largest worlds in the solar system to not be fairly round, despite the fact that it is similar in size to Saturn's volcanically active moon Enceladus.

The image to the right depicts Nereid, Neptune's third largest moon, which orbits very far from Neptune and therefore was not seen close up. On the right is tiny Despina, a moon that orbits close to Neptune and is only about 150 km across.

Finally, here is Despina, transiting the disk of Neptune. This is a montage showing Despina and its shadow at four positions, each taken nine minutes apart. The last one shows Despina itself against the clouds of Neptune.

Finally, here is a version of the transit image with Despina artificially brightened to aid visibility.

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

More Triton Images

2009-08-26T08:15:00.000-07:00

Below I have posted the closest images from the Voyager flyby. The first image shows where they are located on the disk. Please excuse the "halo" around the top of the image - by mistake I used a very early version of the crescent image to chart out where the images were located. The images range from about 700 to about 450 km/pixel, although in many cases the smearing due low light levels and spacecraft motion significantly limits what can be seen.

I will finish with a close-up shot from the outbound leg of Voyager's Triton encounter. While this set is of much poorer quality than the set above, it provides a glipse at a new region of a largely unexplored world.

It will receive a dedicated post of its own.

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

2009-08-26T07:56:00.000-07:00

So it has been several years since I abandoned this blog. Today is a major day in the history of space exploration, the twentieth anniversary of the Voyager Neptune flyby. While the planet itself was fascination, perhaps the most fascinating part of the flyby was Voyager's visit to Neptune's largest moon, Triton. It was an exhilarating feeling seeing the Neptunian system come to life, a feeling that will perhaps be replicated when New Horizons completes the initial reconnaissance of the solar system at Pluto (regardless of what you think of Pluto's status, when we set out to explore the solar system it was considered a planet, so to claim that our initial reconnaissance is complete because of its demotion feels hollow). I will post some views of Triton today, and will be posting more material today and in the coming days.

This is a sequence showing the changing view as Voyager flew by Triton. The upper tip of the last view is reconstructed from other images because all the images were cut off.

This is a mosaic using some of the imagery obtained during the closest portion of the encounter.

A wide angle shot showing one of Triton's geysers in the upper left.

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

Dione Over Saturn...From Voyager

2005-10-02T18:31:00.000-07:00

Cassini is now routinely sending back images of Saturnian satellites in with the rings, as well as passing in front of the planet. The Voyagers only got one good set of such images, a set by Voyager 1 of Dione. Unfortunately, the only filters used were orange, blue, violet, and ultraviolet. Without a green image, a red Saturn always ended up being in the background, along with a bluish Dione, as seen in the planetary photojournal.

The view below was constructed with O-V color with 25% import on the O-V synthetic green image from the blue data. It was overlayed on top of an O-G-V-UV super-resolution black and white image. Although Cassini has taken better pictures of Dione, this stands as a pretty picture of an icy world hanging over its parent.

Rhea's Tirawa Basin

2005-09-27T18:49:00.000-07:00

As Voyager 1 receded from its close flyby of Rhea, it snapped this view of Rhea's Tirawa basin, a large impact structure seen on the terminator in this crescent view. It is on of the worst-imaged parts of this world, and this Voyager view is still the best. Rhea is a moon that shows some similar features to more active Dione and Tethys, but seems to have been inactive for longer, as evidenced by the fact that all of its surface is extremely worn from impacts and the evidences of internal activity are much more subtle.

Voyager's Hyperion

2005-09-27T11:40:00.000-07:00

Today Cassini is returning images from its flyby of Saturn's moon Hyperion. I have reprocessed some Voyager 1 images. This is a sequence from they flyby:

Here is a super-resolution color view. It is amazing to see the intricate patterns of bright
and dark areas. Cassini is now revealing this peculiar world.

Cassini Approaching Tethys (And Hyperion Too!)

2005-09-27T11:39:00.000-07:00

This orbit by the Cassini orbiter will include flybys of both Hyperion and Tethys. The Tethys flyby was added a few months ago due to increasing interest in this moon as a contributor of ring material. Here are the best Voyager views of this moon.

This view, from Voyager 1, clearly shows a dark band across the center of the disk. The existance of this has been seen in Cassini's images too, but the orgin is not yet known.

This is a color view of Tethys from Voyager 2's approach to the moon. It shows on the terminator the degraded Ithaca Chasma, a huge canyon bisecting this moon.

This is the last Voyager 2 view, showing Ithaca Chasma in the center and to the left. Within the next view days, Cassini should supercede this view. This was the best view (5 km/pixel) that either Voyager obtained before pointing errors and scan platform problems ruined imaging sequences.

With the scan platform sticking and the spacecraft off target, this is the only frame from the highest resolution mosaic of Tethys, taken at 2.2 km/pixel, to catch a corner of the moon. For years, this stood as the mysterious best view of this world. Cassini has already doubled this resolution, and at last the weekend has arrived where Tethys receives true closeup treatment! Stay tooned!

A Craggy Rock On Venus

2005-09-27T11:35:00.000-07:00

I have watched with great excitement how the Mars Exploration Rovers have explored the red planet. However, Venus, while it has had more successful landers on its surface, was the subject of much less capable spacecraft. There are four color image sets of the surface, all with blank or nearly blank blue channels. Venera 13 sent back one full pan in color, which is the best set we have, and another partial one (complete in black and white) that hs much poorer color data. Venera 14, which landed in a much rockier area, took a pretty good partial color pan (again, complete in black and white), but while the other pan was complete in both black and white and through color filters (althoug again the blue was almost useless), the color data in this set was horribly underexposed. Below is the Venera 14 partial pan, my favorite of the set because of the cool rock right near the lander. It seems to be sitting on the rocky plain...it makes one wonder how it got there. I don't see anything else like it in the Venera pans, although given their limited coverage, it doesnt mean there aren't perhaps a few more rocks like it around. But still , it is lucky it was so close to the lander and in a color zone.

Here is the other Venera 14 pan. The color data is OK on the sides, but in the center, all color data is nearly blank, making any color variations dubious in that part of the image.

Here is a composite of Venera 13 images, looking towards a ridge on the horizon.

New Color Views of Europa

2005-09-27T11:34:00.000-07:00

Below is a mosaic of color versions I have processed of all the Galileo global color views of Europa. The large mosaic on the bottom is partially from color from the dataset used to make the greyscale data and partially from the G1 orbit. Despite Galileo's limitations, these are some real gems. (Please note that the large mosaic on the bottom is at greatly reduced resolution, and the image in the upper left hand corner is reduced somewhat from the super-resolution product size, although it is larger than the original image size.

Remnants of a Lost Approach

2005-09-27T11:33:00.000-07:00

When Galileo approached Jupiter in the 1990s, the antenna problem, as well as a tape recorder problem in fall of 1995 that cost the images from the arrival orbit pretty much wiped out the return of images from this part of the mission, other than the Ida encounter, from which the images were piddled back over many months. In 1990, before even the Gaspra encounter, Galileo took some images for calibration that could be returned more easily while it was still in the inner solar system. Here is a color view of Jupiter and some of its moons generated from this data. It has the appearance of being taken through a small telescope.

Galileo would next image Jupiter during the SL9 imacts, a year and a half before arrival. It used a technique known as an "on chip mosaic," taking multiple images on the same frame so it could be returned as one picture. There were several techniques used that involved smearing the image to look for flareups from the impact. For the last impact, Galileo took multiple unsmeared images, providing a neat perspective, as its images are the only ones to see the impacts directly, and not coming over the limb. Perhaps another entry will be dedicated to these images. But here is one showing the impact and Jupiter, produced from several images on the on-chip mosaic.

The tape recorder problem caused the end of imaging until the G1 orbit in the summer of 1996. However, as Galileo approached in 1995, it took optical navigation frames showing Ganymede slowly looming larger to help plan for the G1 orbit. It is a little taste of the sights Galileo saw that fall but could not show us.

Galileo Mosaic of Ganymede

2005-09-27T11:32:00.000-07:00

This is a galileo mosaic of Ganymede taken on the G8 orbit. It both reminds me of Cassini mosaics of the Saturnian moons and reminds me of what the Galileo mission might have been like without the antenna problem. It does suffer from compression artifacts and a few data dropouts, and is not mutispectral. Also, there are a few missing spots I filled in with a blank disk. But all in all, it is a nice mosaic. I am surprised it was never released on the planetary photojournal. But then, I am always surprised at the gems that never get released to the public.

Here is a link to a full resolution jpeg version.

Reconstructed Pioneer View of Io

2005-09-27T11:31:00.001-07:00

I have updated my website with my newly reprocessed version of Io from Pioneer 11. I also have the raw images in lossless format there. Below is a version of the Pioneer image from a print copy I enhanced (I removed the terminator area because it was too problematic, which gives the appearance of a different phase), and to the right, a version made frmo the original data. My hope is that someone can use this to look for albedo changes over the years. These days HST and groundbased telescopes take images routinely that are better than this, if not from this angle, above the north pole. And of course there is Galileo and Voyager. But this is by far the best pre-Voyager view we have of this rapidly changing world. Here is a link to the page on my site.

Update On Mimas: A Record of Impacts

2005-09-27T11:31:00.000-07:00

Cassini flew by Mimas on August 2, 2005, and showed what had been expected: A battered world, with few if any signs of internal activity.

This leaves us with a mystery. Mimas is about 400 km in diameter. But moons of its size vary greatly. In the image below, from left to right, there is Neptune's moon Proteus, which could not even pull itself into a somewhat round shape, battered Mimas, the Uranian moon Miranda, which shows signs of intense internal activity that has now ceased (note the large grooved features), and Enceladus, which is still active today. It is indeed a complex solar system!

Sedna...Once A Big Discovery

2005-09-27T11:30:00.000-07:00

A few years ago, the discovery of Kuiper Belt object about 1000 km in diameter was heralded as a major find. This HST image was taken soon after it was found to pin down its size. Now, with several rivaling or possible a good deal larger than Pluto, it is just one of the zoo. So many worlds to explore!

The View Trapped In Low Earth Orbit

2005-09-27T11:29:00.000-07:00

In 1972, astronauts walked on the moon for the last time. Since
then, the Space Shuttle Program and the Space Station program, in its
various incarnations that would eventually materialize into the
International Space Station, have drained manned spaceflight, keeping
it trapped in low earth orbit. Hopefully, with the Shuttle
nearing the end of its life and the new Moon-Mars initiative, manned
spaceflight will soon join our wonderfully successful unmanned
planetary exploration program. While scientifically not very
productive, the ISS astronauts have gotten some nice photographs,
including many showing the moon, a bittersweet reminder of the heights
our space program once reached. Here are some of the best images.

One can only hope that soon the manned spaceflight program is back at the moon and looking at earth in this fashion!

Triton...A Glimpse of a Changing World

2005-09-27T11:28:00.001-07:00

Voyager flew by Triton in 1989, showing us an active world with an atmosphere, clouds, and erupting geysers. However, since then, we have only been able to study Triton from afar, and that situation will continue for the forseeable future. Only one data set, from the Hubble Space Telescope's Faint Object Camera in 1995, shows the resolved disk, barely. Below is the best I could get out of the HST views, which show one full rotation.

Bryan Flynn, the scientist behind this imagery, produced maps from the data, showing that the polar cap had enlarged since Voyager and hinting at variations between visible and ultraviolet images. Below are Flynn's maps:

Finally, here is a composite of Neptune and Triton I made from HST images from the mid 1990s. I hope that soon another telescope (or HST again) can image Triton at least at this resolution. Other data (light curves, spectra) have indicated increasing change, making continuing the baseline of coverage all the more important. With the discovery of planet size objects in the Kuiper belt, of which Triton is a captured member, understanding of this world is made all the more important. It is, after all, the only one we have seen closeup.

Iapetus from Cassini's Approach

2005-09-27T11:28:00.000-07:00

I have been working with some Cassini approach images from Saturn. I can't wait until the releases of raw data from the time in Saturn orbit. Here is the best approach view of Iapetus I could make.

Despite being pre-orbit, it is comparable to Voyagers best views:

Exciting times are ahead!

The Galilean Satellites and Titan: A View From The Pioneers

2005-09-27T11:27:00.000-07:00

Paving the way for the Voyager encounters, Pioneer 10 and 11 flew through the Jovian system in 1973 and 1974, respectively. They carried extensive particle and fields instruments, but due to the fact that they were spin stabilized, they did not carry cameras. However, one instrument, the Imaging Photopolarimeter, was capable of producing crude, 6-bit images in red and blue channels by scanning pixel by pixel, line by line as the spacecraft spun, slowly buiding an image. This worked pretty well for producing images of Jupiter's cloudtops, but the ability to image the moons of Jupiter was very limited. However, the Pioneers were able to produce the best images to date of these worlds, showing mottled albedo features that tantalized scientists. Pioneer 10 would have gotten a pretty good shot of Io, but unfortunately radiation effects prevented this. It did detect an ionosphere around Io, but this was detected through radio occultation. Pioneer 11 headed to Saturn, where it had a very successful encounter. However, when it reached Titan, a lot of data was lost due to the fact that Saturn was rapidly heading into solar conjunction. The images show the hemispheric brightness difference, the orange cloudtops, and little else (Titan alternately is brighter in its northern and southern hemispheres). It was a surprise that no other features in the clouds showed up, for we didn't know just how thick the clouds would prove.

Above are the best views of the Galileans and Titan. From left to right are Io, Europa, Ganymede, Callisto, and Titan. Some research was done using Pioneer images in the 1980s due to the fact that they had a red channel (the closest thing Voyager has is an orange filter). I would like to track down the original digital data for the Io image - if it were cleaned up, perhaps it could be used to look for change in albedo features compared to the Voyager 1979 images. This view shows it looking down on the north pole.
These views show these planet-sized moons on the edge of becoming worlds to us - these images made us wonder, but yielded few secrets.

The View From Earth

2005-09-27T11:26:00.000-07:00

The image below appears to be a typical telescopic view of the moon from earth. It is not what this picture shows that makes it special, but what it was taken with. It was obtained my the context imager for NASA's Mars Reconnaisance Orbiter during a test last fall. It will launch on August 10th. This camera will provide context images for HIRISE, an extremely powerful camera capable of taking images of the martian surface at 25 cm/pixel. This should be an exciting mission. For now, here is the context imager's view of the moon.

I33 - Galileo's Last Snapshots

2005-09-27T11:25:00.001-07:00

In January of 2002, Galileo swooped down on the Jovian system, the last time it would do this with cameras on. There was a hard fought campaign to fund this, led by Jason Perry, due to the fact that it would allow photography of portions of Jupiter's moon Io that had never before been seen at close range.

However, this was not to be. Galileo would suffer a radiation-related glitch, common during the later portion of the mission, causing it to miss the entire Io imaging sequence. Largely this orbit was a loss, and it drove the final nail in the coffin of imaging on Galileo's final orbit, A34, during which it would fly by tiny Amalthea. In addition to funding problems, it was decided that turns for imaging would make it to likely that the spacecraft would shut down before the flyby.

A few views did get returned from the I33 orbit. They stand as a last testament to Galileo's camera. It brought us some unforgettable glimpses of the Jovian system. However, we only saw a small fraction of what we would have, had Galileo's main antenna opened properly.

This view shows the top of the red spot on the limb of the planet. It is amazing to see all the intricate paterns in the clouds.

This view, taken as the red spot rotated further onto the disk, is a false-color view, generated from various infrared views. It certainlys shows great contrast between the spot (which appears blue here), the cloud belts, and the thunderheads that can be seen on the lower left.

This final view shows the spot rotating across the terminator, into the Jovian night.

On its way in and out, Galileo took these two snapshots of Amalthea. The purpose was to improve navigation for the upcoming flyby of this little moonlet, but such images also help in the study of the shape of irregular worlds.

Galileo also took a series of views of the Jovian cloudtops much further into the infrared than its camera could see, trying to study the temperature and composition of the clouds. This one shows Io, the bright spot to the left of the disk, and its shadow on the cloudtops, just left-of-center. It would be Galileo's last look at Io, and a bittersweet one, considering what might have come from this flyby.

This final image is of Europa. Taken to study the way Europa reflects light when it is viewed at a "full moon" illumination angle - called opposition surge - it is Galileo's last view of a world where it discovered an ocean beneath the icy surface, and a world that Galileo turned into a top priority for future exploration.

Metis and Adrastea...Sources of the Jovian Rings

2005-09-27T11:25:00.000-07:00

Metis and Adrastea are the two inner innermost moons of Jupiter. Being deep within the radiation belts, they are difficult to study with a spacecraft. The problem is worsened by the fact that they are only 20 and 12 km in diameter, respectively. Metis was viewed several times during the Galileo mission. Here is a collection of all the angles the spacecraft got on this moonlet.

Using data from other orbits, I was able to colorize the lone image from Galileo's 26th orbit. It appears reddish, likely due to deposits from Io. It was taken from about 290,000 km at 3km/pixel.

Adrastea was the worst observed of the inner moons, the best galileo views simply show it as a tiny disk.

This image below, from NASA's planetary photojournal, shows how Metis and Adrastea fit into Galileo's ring scheme. They are different from Amalthea and Thebe, the sources of the Gossamer ring, in that they are more icy, less heavy in silicates. It is not know whether they are of different origins, or something caused these little moons in their inner orbits to lose their volatiles. It is possible that the rings and all four inner moons are pieces of the same parent body.

Perhaps NASA's upcomming Juno mission will be able to make some improvements. Its focus will be on studing Jupiter's internal structure, but it will orbit very close to Jupiter's cloudtops, likely allowing better study at least Amalthea but maybe, just maybe, some of these even less-known inner moons. Perhaps they are the leftovers of a collision - perhaps they were once as prominent as Saturn's rings. Here is a view of the rings from Galileo, with Europa in the background. This hard-to-explore area calls out for exploration.

Umbriel...A Shadowy World Gaurds Its Secrets

2005-09-27T11:24:00.000-07:00

Voyager 2 flew by the Uranian moon Umbriel in 1986. Umbriel, 1,200 km in diameter, was only seen from half a million kilometers away. It reflects only 16 percent of the light hitting it, making it significantly fainter than the other major Uraniam moons. Distance and darkness conspired to limit the quality of Umbriel imaging. These images, taken during approach, show a dark world, battered with craters. A few bright markings appear. On the left-hand image, there seems to be a huge crater with a bright central peak near the bottom. Fainter, large scale albedo features can be seen a the top of this image and others, as well as in the image on the right. Paul Helfenstein, Peter C. Thomas, and Joseph Veverka proposed in a 1989 letter to the journal Nature that polygonal paterns can be seen in these features and the at they are the remnants of an ancient tectonic system similar to those seen on other moons of similar size. This remains an intriguing possibility.

The surface of Umbriel is ncient one. A collection of impact craters of various sizes was found to saturate the landscape. As Voyager drew closer, became clear that most or all of the bright features are related to craters. On the terminator, one can see two interesting craters. One, Skynd, has a bright central peak. The others, Wunda, at the top of the image, has a bright rim and no apparent central peak. This is the best color image obtained by Voyager.

This is a composite of the best Voyager images, slightly better than the original 8 km/pixel resolution. It appears to be a battered world - no features appear to be generated by anything other than impacts, unless the bright areas are produced by internal activity.

Here is a closeup systhesis from all the closeups of Wunda. It is hard to tell if the craters dug up the bright material, or if they had something to do with the impacts. Maybe it was derived from eruptions or melting caused by imacts. Or maybe they are some sort of frost left over from impacts. This issue may not be resolved until another spacecraft observes Umbriel. Here (below, left) is the best view of Wunda that can be generated with the available data.

Voyager left Umbriel behind, but the study of this world using earth-based instruments continues. The right hand image above shows a crescent view taken as Voyager receded. Perhaps compositional studies will yield clues that help us resolve some of the secrets Umbriel holds. We are left to wonder at this faint, fleeting, and fuzzy glimpse of this intriguing world.

Mars in 1993

2005-09-27T11:23:00.001-07:00

In the Summer of 1993, it appeared a new era of space exploration was going to a major boost. After Pionneer Venus was launched in 1978, no U.S. planetary probes were launched until 1989. Magellan was sent off to Venus, and Galileo to Jupiter. It was now time for Mars Observer to enter Mars orbit, and begin advance studies of the planet. Unfortunately, this would have to wait until the 1997 arrival of Mars Pathfinder and Mars Global Surveyor. Mars Observer lost contact with earth (it seems now that a fuel line exploded) just before entering Mars orbit, never to be heard from again. Below are the only two resolved images it ever took of Mars. I colorized the image based roughly on somoe wide angle data, with a little editing to make it look a bit more realistic.

Mars Climate Orbiter also failed just before entering orbit too - in this case, due to a metric/English conversion error! This is its lone image - unfortunately, not nearly as detailed as the Mars Observer image.

Venus from Cassini

2005-09-27T11:23:00.000-07:00

Venus Through the Eyes of Cassini

On its way to its 2004 arrival at Saturn, the Cassini spacecraft made two flybys of Venus. However, due to the proximity of Venus to the sun (a big deal for a spacecraft designed for Saturn) combined with the fact that, due to budget constraints, much of its software was still in development, very little science data was taken. No imaging was done except for a sequence during which Venus serendipitously passed through the spacecraft's field of view. Since the Venusian clouds are nearly blank at visible wavelengths, this allowed it to be used to test Cassini's cameras. Most of the images look quite blank. However, one wide angle frame shows the terminator (the night/day boundary), and faint markings in the clouds can be seen. This false color image is a testament to the power of the Cassini camera - it was taken in red light, and most views of Venus in red light look blank. This little picture of the clouds of Venus makes me excited about the views to come with the arrival of the Europe's Venus Express mission in the spring.

2005-09-27T11:22:00.000-07:00

Well, I had a huge post for today, and accidentally deleted it before posting it. I will develop all large future posts in a safer way. So for today, I will post an image or two of Mimas, a moon of Saturn. At 400 km across, it is only slightly smaller than Enceladus, but it shows no sign of activity. A large crater visible in some of the images gave it an uncanny resemblance to the Death Star!

At 6:49 PM EDT August 1, the Cassini spacecraft will make its closest approach to Mimas, coming within 62,000 km of the moon (it was originally going to be 49,000km, but this was sacrificed to allow Cassini to fly closer to Tethys on a future orbit, a moon that may be contributing particles to Saturn's rings). This is not a superclose flyby by Cassini standards, but it should be spectacular none-the-less. In the mean time, here is a super-resolution version of the closest Voyager view, taken by Voyager 1 in 1980 from 127,000 km (these distances can't be directly compared, because Cassini's cameras are far superior to Voyager's). It is made from the best three images from a six image set taken by Voyager.

Saturn's Active Moon Enceladus From Voyager and Cassini

2005-09-27T11:12:00.000-07:00

Today it appears that the Cassini spacecraft has discovered evidence of active volcanism at the south pole of Enceladus. This is exciting! This is a world that is no wider than the state of Tennessee, yet it seems to have active volcanos at its south pole (based on infrared maps)

This has caused me to go back into my archives, and work on some old Voyager images of the place. Cassini has now imaged this world down to the size of a small desk. But up until now, we were dependent on a few Voyager images from 1981 to study this world. This is the view we usually saw, taken at closest approach (a little more than 100,000 km).

I have been working with the next best Voyager set, which show the North pole of Enceladus very well (Cassini won't be able to see it for a few more years because it is in winter - remember that a year in the Saturnian system is 26 earth years). This set, while somewhat poorer in resolution, has a distinct advantage - OGV color. Voyager could not see red light. Most color images of the outer solar system from Voyager 1 and 2 are therefore done in GVUV color, where a green light image us used for red, violet is used for green, and ultraviolet for blue. This set has an orange filtered image, allowing OGV (Orange Green Blue ) which is not as far off from RGB, which is traditionally used for color imaging (Red Green Blue). I have included the raw images underneath the color composite for perspective. They are shown at their orignial size, but the color composite is enlarged (due to a super-resolution image created from the grayscale data).

Edit: Here is a link to my sequence of Enceladus approach images. The above row is a sequence of color images taken as Voyager-2 approached (unfortunately, since various color combinations had to be used, it isn't very even). The lower row shows the same sequence, but resampled to be about the same size. It creates a strange appearance of snapping in to focus. While it is useful for comparison - you can really see Enceladus rotating better than when the different sizes are shown, it looks artifically smooth in the early images.
http://img78.imageshack.us/img78/3981/encapproach3qv.jpg

Ted's Planetary Images

2005-09-27T11:10:00.000-07:00

I have decided to end my Xanga planetary blog, and to move the posts here. Enjoy!