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Space Topics: SaturnCassini RADAR Images of the Surface of Titan
When the twin Voyager spacecraft passed
by Saturn in 1980 and 1981, there were high hopes for what they would reveal
of Titan, which was known
to possess a methane-rich atmosphere. Unfortunately, the Voyager camera
system proved unable to pierce Titan's haze to see the surface. Cassini was
sent to Saturn with a completely different type of imaging system capable
of penetrating the thickest atmosphere. The Cassini RADAR instrument broadcasts
radio signals at the surface and "listens"
for the reflected waves. Through hefty computer processing, the reflected
signals can be used to generate Synthetic Aperture Radar (SAR) images able
to resolve features as small as a few hundred meters across. Read
more about Cassini RADAR for further information on SAR images and how
they are different from optical images. Because Cassini's radio dish and optical instruments are pointed in perpendicular directions, it is not possible for SAR imaging and optical imaging to be performed simultaneously. SAR imaging can only be performed when Cassini is near its closest approach to Titan -- a time period that is much in demand from the other instruments. SAR images are therefore acquired only on a subset of Titan flybys. They come in "swaths," long, skinny images captured to one side of Cassini's ground track. After each SAR pass, the Cassini RADAR team releases selected pieces of the image to the public with captions. Then, 9 to 12 months after the completion of the pass, the full swath is released to the Planetary Data System (PDS). Flyby Ta (Oct 26, 2004) - Full swath from PDS Descriptions of each flyby can be downloaded in PDF format from the Cassini mission's multimedia products page. Flyby Ta (October 26, 2004)
This swath has been released to the Planetary Data System. For a better view of the features in this swath, it is divided below into three segments. The resolution of these segments is 128 pixels per degree, or 350 meters per pixel, roughly equivalent to the best resolution achievable by the RADAR instrument at the center of the swath. The version in the Planetary Data System is at 256 pixels per degree. A JPEG version at this maximum resolution can be downloaded from Jason Perry's website.
The following are links to captioned pieces from this swath on the Planetary
Photojournal:
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Cassini RADAR swath on Titan, flyby T3, February 15, 2005
This swath is about 4,500 kilometers (2,800 miles) long, subtending 120 degrees of longitude on Titan. It covers similar longitudes to the first RADAR swath -- from 133 to 12 degrees west longitude -- but is located closer to the equator. This was the second RADAR swath on Titan. It contains two probable impact structures, 400-kilometer-diameter Menrva near the center and 80-kilometer-diameter Sinlap near the eastern end, as well as numerous disconnected fields of "cat scratches," now thought to be longitudinal sand dunes. It is shown here at a resolution of 32 pixels per degree (1.4 kilometers or 4,600 feet per pixel), an eighth of the full resolution available in the Planetary Data System. Credit: NASA / JPL |
This swath has been released to the Planetary Data System. For a better view of the features in this swath, it is divided below into four segments. The resolution of these segments is 128 pixels per degree, or 350 meters per pixel, roughly equivalent to the best resolution achievable by the RADAR instrument at the center of the swath. The version in the Planetary Data System is at 256 pixels per degree. A JPEG version at this maximum resolution can be downloaded from Jason Perry's website.
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The following are links to captioned pieces from this swath on the Planetary
Photojournal:
PIA07009 -
PIA07365 - PIA07366 - PIA07367 - PIA07368 -
PIA03555
Flyby T7 (September 7, 2005)
Cassini RADAR swath on Titan, flyby T7, September 7, 2005
Cassini acquired about half of the planned RADAR swath on the September 7, 2005 flyby, covering a region from 30 to about 65 degrees south and from 30 through 0 to about 345 degrees west. It contains lots of apparently fluvial features, both incised channels and fanned delta-like structures. At the extreme right of the swath (nearest the summer pole), the mottled terrain suddenly gives way to a very low-backscatter plain. Credit: NASA / JPL |
This swath has been released to the Planetary Data System. For a better view of the features in this swath, it is divided below into two segments. The resolution of these segments is 128 pixels per degree, or 350 meters per pixel, roughly equivalent to the best resolution achievable by the RADAR instrument at the center of the swath. The version in the Planetary Data System is at 256 pixels per degree. A JPEG version at this maximum resolution can be downloaded from Jason Perry's website.
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The following are links to captioned pieces from this swath on the Planetary
Photojournal:
PIA03563 - PIA03564 - PIA03565
Flyby T8 (October 28, 2005)
Read an article about this data: "New RADAR Images of Titan: The Features Are Getting More Familiar, But Aren't Getting Less Mysterious," November 2, 2005
Cassini RADAR swath on Titan, flyby T8, October 28, 2005
The October 28, 2005 flyby covered a region just south of the equator from about 190 degrees through about 320 degrees west. The easternmost end of the swath covered the Huygens landing site. Longitudinal sand dunes (formerly called "cat scratches") abound, and completely fill the center section of this swath. The eastern part contains many linear ridges, not previously seen elsewhere on Titan. The swath is shown here at a resolution of 32 pixels per degree (1.4 kilometers or 4,600 feet per pixel), a quarter of the full resolution at which the image was released. Credit: NASA / JPL |
This swath has been released to the Planetary Data System. For a better view of the features in this swath, it is divided below into five segments. The resolution of these segments is 128 pixels per degree, or 350 meters per pixel, roughly equivalent to the best resolution achievable by the RADAR instrument at the center of the swath. The version in the Planetary Data System is at 256 pixels per degree. A JPEG version at this maximum resolution can be downloaded from Jason Perry's website.
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The following are links to captioned pieces from this swath on the Planetary
Photojournal:
PIA03566 - PIA03567 - PIA03568 - PIA03569 -
PIA08454
Flyby T12 (March 18, 2006)
This swath has not yet been released to the Planetary Data System (that should occur in January 2007) .
Flyby T13 (April 30, 2006)
Cassini RADAR swath on Titan, flyby T13, April 30, 2006
The April 30, 2006 RADAR swath on Titan covered a region just south of the equator, complementary to the region sampled in the previous flyby (T8, October 28, 2005). It subtends about 120 degrees of longitude, from about 40 to about 160 degrees west. The western end covers an area that has been studied in depth with the optical remote sensing instruments, including Shikoku Facula ("Great Britain"), part of Kerguelen Facula, and the doughnut-shaped Guabonito crater. The rest of the swath covers the bright region of Xanadu. Xanadu contains rough terrain dissected by channels, as well as some possible impact craters. Credit: NASA / JPL |
This swath has not yet been released to the Planetary Data System (that should occur in April 2007), but the entire swath was released to NASA's Planetary Photojournal in July 2006. For a better view of the features in this swath, it is divided below into four segments. The resolution of these segments is 128 pixels per degree, or 350 meters per pixel, roughly equivalent to the best resolution achievable by the RADAR instrument at the center of the swath.
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The following are links to captioned pieces from this swath on the Planetary
Photojournal:
PIA07785 - PIA08425 - PIA08426 - PIA08428 - PIA08429 - PIA08448 - PIA08449- PIA08552 - PIA08604 - PIA08605 (movie)
Flyby T16 (July 22, 2006)
Read an article about this data: "Cassini RADAR Reveals Lakes on Titan At Last," July 24, 2006.
Cassini RADAR swath on Titan, flyby T16, July 22, 2006
This swath is about 6,600 kilometers (4,129 miles) long, subtending over 200 degrees of longitude and 55 degrees of latitude on Titan. It begins at 20 degrees north, 142 west, with a 75-kilometer-diameter circular feature that could be an impact crater or a volcano. From there it swings northward. At about 70 degrees north, the black spots of the putative methane lakes begin to appear. The center of the swath is near the north pole. The extreme right end is at 13 degrees north, 347 degrees west, and covers some of the now-familiar longitudinal sand dunes. The swath is shown here at a resolution of 32 pixels per degree (1.4 kilometers or 4,600 feet per pixel), a quarter of the full resolution at which the image was released. Credit: NASA / JPL |
This swath has not yet been released to the Planetary Data System (that should occur in July 2007), but the entire swath was released to NASA's Planetary Photojournal in January 2007. For a better view of the features in this swath, it is divided below into five segments. The resolution of these segments is 128 pixels per degree, or 350 meters per pixel, roughly equivalent to the best resolution achievable by the RADAR instrument at the center of the swath.
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The following are links to captioned pieces from this swath on the Planetary
Photojournal:
PIA08630 -
PIA09102 - PIA09177 - PIA09183 (movie)
Flyby T17 (September 7, 2006)
The T17 flyby was the first of three at the end of 2006 that were conducted as "ride-along" observations, where the pointing of the spacecraft was controlled not by the RADAR instrument but rather by the Ion Neutral Mass Spectrometer.
Cassini RADAR swath on Titan, flyby T17, September 7, 2006
The September 7, 2006 flyby covered a region just north of the equator from about 70 to about 30 degrees west. The swath is short because the RADAR instrument was not in charge of pointing for the flyby's closest approach; that honor went instead to the INMSAs with other equatorial swaths, longitudinal sand dunes (formerly called "cat scratches") abound, keeping to a generally east-west orientation but diverting around apparent topographic highs. The west end of this swath overlaps one of only three unequivocal impact craters discovered in the RADAR data to date. The swath is shown here at a resolution of 64 pixels per degree (0.7 kilometers or 2,300 feet per pixel), a quarter of the full resolution at which the image was released. Credit: NASA / JPL-Caltech |
This swath has not yet been released to the Planetary Data System (that should occur in July 2007), but the entire swath was released to NASA's Planetary Photojournal in February 2007. The resolution of this image is segments is 128 pixels per degree, or 350 meters per pixel, roughly equivalent to the best resolution achievable by the RADAR instrument at the center of the swath, but only half the resolution at which it was released to Photojournal.
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The following are links to captioned pieces from this swath on the Planetary
Photojournal:
PIA08737 - PIA08738 - PIA09172
Flyby T18 (September 23, 2006)
The T18 flyby was the second of three at the end of 2006 that were conducted as "ride-along" observations, where the pointing of the spacecraft was controlled not by the RADAR instrument but rather by the Ion Neutral Mass Spectrometer.
Cassini RADAR swath on Titan, flyby T18, September 23, 2006
The September 23, 2006 flyby covered the north polar region beginning at about 63 degrees north latitude by 255 degrees west longitude. Like the T16 flyby, this one crosses radar-dark features that are probably fluid-filled lakes. The swath is shown here at a resolution of 32 pixels per degree (1.4 kilometers or 4,600 feet per pixel), a quarter of the full resolution at which the image was released. Credit: NASA / JPL-Caltech |
This swath has not yet been released to the Planetary Data System (that should occur in July 2007), but the entire swath was released to NASA's Planetary Photojournal in March 2007. For a better view of the features in this swath, it is divided below into two segments. The resolution of these segments is 128 pixels per degree, or 350 meters per pixel, roughly equivalent to the best resolution achievable by the RADAR instrument at the center of the swath, but only half the resolution at which it was released to Photojournal.
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The following are links to captioned pieces from this swath on the Planetary
Photojournal:
PIA08740 - PIA08741 - PIA09177 - PIA09179 - PIA09183 (movie)
Flyby T19 (October 9, 2006)
The following are links to captioned pieces from this swath on the Planetary
Photojournal:
PIA01942 - PIA01943 - PIA09177 - PIA09183 (movie)
Flyby T21 (December 12, 2006)
The T21 flyby was the last of three at the end of 2006 that were conducted as "ride-along" observations, where the pointing of the spacecraft was controlled not by the RADAR instrument but rather by the Ion Neutral Mass Spectrometer.
The following are links to captioned pieces from this swath on the Planetary
Photojournal:
PIA09111
Flyby T23 (January 13, 2007)
The following are links to captioned pieces from this swath on the Planetary
Photojournal:
PIA09175 - PIA09176
Flyby T25 (February 22, 2007)
Cassini RADAR swath on Titan, flyby T25, February 22, 2007
The T25 swath on Titan covers a wide variety of landforms. It begins south of the equator (32°S, 55°W), crossing wide fields of dunes in the equatorial regions. The narrowest portion of the swath is at 33°N, 28°W. As the swath continues northward, fluid-related features begin to appear: channels, canyons, and radar-bright depressions. Continuing north, the first radar-dark lakes appear. At the end of the swath, near the pole, is the largest lake yet seen in RADAR imagery. This lake covers at least 0.12 percent of the surface of Titan, larger in proportion to the globe than the Black Sea, the largest inland sea on Earth. The swath is shown here at a resolution of 32 pixels per degree (1.4 kilometers or 4,600 feet per pixel), a quarter of the full resolution at which the image was released. Credit: NASA / JPL-Caltech |
This swath has not yet been released to the Planetary Data System (that should occur in January 2008), but the entire swath was released to NASA's Planetary Photojournal in March 2007. For a better view of the features in this swath, it is divided below into five segments. The resolution of these segments is 128 pixels per degree, or 350 meters per pixel, roughly equivalent to the best resolution achievable by the RADAR instrument at the center of the swath.
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The
following are links to captioned pieces from this swath on the Planetary Photojournal:
PIA09180 - PIA09181 - PIA09182 - PIA09183 (movie)
- PIA09184
Flyby T28 (APRIL 10, 2007)
Cassini RADAR swath on Titan, flyby T28, April 10, 2007
The April 10, 2007 flyby tracked across Titan from south of the equator (beginning at about 20 degrees south, 37 degrees west), up to near the north pole at 80 degrees north, 300 degrees west before turning back south again, finishing at 51 degrees north, 213 degrees west. The swath is shown here at a resolution of 32 pixels per degree (1.4 kilometers or 4,600 feet per pixel), a quarter of the full resolution at which the image was released. The equatorial regions are covered with now-familiar longitudinal dunes streaking from west to east (top to bottom in this view), creating streamlined bright "islands" of highstanding material. In Titan's temperate regions, the dunes give way to various other kinds of features that could be cryovolcanic in origin. Near the north pole, the swath crosses extremely dark lakes with dendritic channels pouring in to them. One lake has a large island, whose mountainous terrain may stand 2,000 meters above the lake surface. The swath is shown here at a resolution of 32 pixels per degree (1.4 kilometers or 4,600 feet per pixel), a quarter of the full resolution at which the image was released. Credit: NASA / JPL |
This swath has not yet been released to the Planetary Data System (that should occur in April 2008), but the entire swath was released to NASA's Planetary Photojournal in July 2007. For a better view of the features in this swath, it is divided below into five segments. The resolution of these segments is 128 pixels per degree, or 350 meters per pixel, roughly equivalent to the best resolution achievable by the RADAR instrument at the center of the swath.
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The following are links to captioned pieces from this swath on the Planetary
Photojournal:
PIA09217
Flyby T29 (APRIL 26, 2007)
Nothing from this swath has been released yet.
Flyby T30 (May 12, 2007)
Cassini RADAR swath on Titan, flyby T30, May 12, 2007
This half-swath on Titan was acquired by the Cassini RADAR instrument on May 12, 2007. It begins near the north pole at 69 degrees north, 329 degrees west, and runs east and south to 33 degrees north, 227 degrees west. At the extreme north (left) enf is a very dark lake with a complex margin that was first spotted in ISS images. The swath is shown here at a resolution of 32 pixels per degree (1.4 kilometers or 4,600 feet per pixel), a quarter of the full resolution at which the image was released. Credit: NASA / JPL |
This swath has not yet been released to the Planetary Data System (that should occur in April 2008), but the entire swath was released to NASA's Planetary Photojournal in August 2007. For a better view of the features in this swath, it is divided below into two segments. The resolution of these segments is 128 pixels per degree, or 350 meters per pixel, roughly equivalent to the best resolution achievable by the RADAR instrument at the center of the swath.
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The following are links to captioned pieces from this swath on the Planetary
Photojournal:
PIA09211 - PIA09218
Future Flybys
Future flybys that are currently planned to include SAR imaging are:
T39 (December 20, 2007)
T41 (February 22, 2008)
T43 (May 12, 2008)
T44 (May 28, 2008) - maybe; the planners are carrying two options, one
of them SAR.
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