Wednesday, September 30, 2009

Japan's First Lunar Mission

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

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.

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

Saturday, September 26, 2009

Jovian Moons

The four Galilean moons from Galileo:  A montage.

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

Wednesday, September 23, 2009

Enceladus from the Voyagers

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

Tuesday, September 22, 2009

DS-1 Part III: Borrelly

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

Monday, September 21, 2009

DS-1 Part II - Cruise and Braille

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

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

Mariner 10 at Mercury

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

Friday, September 18, 2009

Mars from Viking 2 - May, 1979

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

Wednesday, September 16, 2009

Some REALLY Old Images of Mars

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

Tuesday, September 15, 2009

Meridiani in 1969

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

Friday, September 11, 2009

Global views of Jupiter from Galileo's ninth orbit

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

Wednesday, September 09, 2009

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

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

Voyager 2

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

Tuesday, September 08, 2009

A Thirty Year Old View of Saturn

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

Friday, September 04, 2009

A Sad But Memorable Image

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

Thursday, September 03, 2009

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

Wednesday, September 02, 2009

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

Tuesday, September 01, 2009

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