Thursday, December 31, 2009

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.

Wednesday, December 30, 2009

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.

Monday, December 28, 2009

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.

Tuesday, December 22, 2009

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).

Sunday, December 20, 2009

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.

Friday, December 04, 2009

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.

Thursday, December 03, 2009

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.

Sunday, November 29, 2009

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.

Monday, November 16, 2009

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.

Tuesday, October 27, 2009

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.

Friday, October 23, 2009

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.

Friday, October 02, 2009

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

Wednesday, September 30, 2009

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.

Monday, September 28, 2009

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.

Wednesday, September 23, 2009

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.

Tuesday, September 22, 2009

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!

Monday, September 21, 2009

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.

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.

Sunday, September 20, 2009

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.

Friday, September 18, 2009

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.

About Me

I am a philosophy professor at Roane State Community College in Oak Ridge, Tennessee. Planetary exploration has always been an interest of mine. You can follow me on twitter @tedstryk for the latest updates on my work.
Please note that since the processed images are copyrighted, they should not be reused without permission. If you are interested in using any of my work, please contact me at strykt(at)roanestate.edu or tedstryk(at)gmail.com (I avoided @ to make the addresses harder for spam bots to pick up).