This thread deals with Cassini-Huygens' exploration of Titan. Discoveries about Saturn's moon Enceladus can be found here: Saturn's Moon Enceladus & Its Geysers. Many of the images made using that spacecraft's optical cameras can be found in the Cassini - Images of Saturn & Its Moons thread. Infrared discoveries can be found in the Cassini - Infrared Images thread. Other major announcements and discoveries may be found in separate threads.

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Crescent Moon with Rings
April 14, 2006

This poetic scene shows the giant, smog-enshrouded moon Titan behind Saturn's nearly edge-on rings. Much smaller Epimetheus (116 kilometers, or 72 miles across) is just visible to the left of Titan (5,150 kilometers, or 3,200 miles across).
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on March 9, 2006, at a distance of approximately 4.1 million kilometers (2.5 million miles) from Titan. The image scale is 25 kilometers (16 miles) per pixel on Titan. The brightness of Epimetheus was enhanced for visibility.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

That picture is beautiful...Titan with the edge-on rings in front!

Titan (T13) Viewed by Cassini's Radar
April 27, 2006

This set of images shows the areas mapped so far on Saturn's moon Titan by the Cassini radar mapper using its synthetic aperture radar imaging mode.
Labels represent the approximate longitude of each globe. The radar swaths are superimposed on a false-color image made from observations by NASA's Hubble Space Telescope.

The swath shown in light green represents the area to be imaged in the upcoming April 30, 2006, flyby. It will go right across an optically bright region of Titan known as Xanadu. See Flat Map or Flat Map (annotated) for different views.

Cassini's radar has revealed a variety of geologic features, including impact craters, wind-blown deposits, channels and cryovolcanic features.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

Titan (T13) Viewed by Cassini's Radar Flat Map
April 27, 2006

This map of Saturn's moon Titan shows the location of the upcoming April 30, 2006, Titan flyby and the areas mapped so far by the Cassini radar mapper using its synthetic aperture radar imaging mode.
Longitudes are labeled at the bottom of the map. The radar swaths are superimposed on a false-color image made from observations by NASA's Hubble Space Telescope.

The swath shown in light green represents the area to be imaged in the upcoming April 30 flyby. It will go right across an optically bright region of Titan known as Xanadu. See Titan (T13) Viewed by Cassini's Radar for another view of this pass, or Flat Map (annotated) version.

The far left image shows the location of the radar swath for the Oct. 28, 2005, flyby. On the top right is the radar swath from the first Titan flyby, on Oct. 26, 2004. The second from the top image is from the second radar pass of Titan, on Feb. 15, 2005 (near-equatorial). The bottom right swath is from the Sept. 7, 2005, flyby. Cassini's radar has revealed a variety of geologic features, including impact craters, wind-blown deposits, channels and cryovolcanic features.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

Titan (T13) Viewed by Cassini's Radar Flat Map (Annotated)
April 27, 2006

This map of Saturn's moon Titan shows the location of the upcoming April 30, 2006, Titan flyby and the areas mapped so far by the Cassini radar mapper using its synthetic aperture radar imaging mode.
Longitudes are labeled at the bottom of the map. The radar swaths are superimposed on a false-color image made from observations by NASA's Hubble Space Telescope.

The swath shown in light green represents the area to be imaged in the upcoming April 30 flyby. It will go right across an optically bright region of Titan known as Xanadu. See Titan (T13) Viewed by Cassini's Radar for another view of this pass. See Titan (T13) Flat Map for a non-annotated version of this image.

The far left image shows the location of the radar swath for the Oct. 28, 2005, flyby. On the top right is the radar swath from the first Titan flyby, on Oct. 26, 2004. The second from the top image is from the second radar pass of Titan, on Feb. 15, 2005 (near-equatorial). The bottom right swath is from the Sept. 7, 2005, flyby. Cassini's radar has revealed a variety of geologic features, including impact craters, wind-blown deposits, channels and cryovolcanic features.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

May 3, 2006
(Source: Jet Propulsion Laboratory)


Saturn's moon Titan continued to surprise scientists during a flyby that took Cassini into regions previously unexplored by radar. Two very noticeable circular features, possible impact craters or calderas, appear in the latest radar images taken during the flyby on April 30, 2006.

The flyby targeted Xanadu, one of the most prominent features on Titan, visible even from telescopes on Earth. The origin of Xanadu is still unknown, but the radar images reveal details previously unseen, such as numerous curvy features that may indicate fluid flows. Scientists speculate that two prominent circular features are probably impact craters but they don't rule out the possibility that they might be calderas or volcanoes. Sand dunes, discovered in previous flybys, continue to crisscross Titan's surface.



Radar Images Shikoku -- "Great Britain"

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Communication from the spacecraft was temporarily interrupted for nearly five hours during the data playback following the flyby. The most important science data from the flyby were protected by a contingency plan put in place in advance of the flyby. The flight team believes the outage was likely due to a galactic cosmic-ray hit on a power switch in the spacecraft communications subsystem. The anomaly resulted in the loss of some science data. However, the spacecraft is now performing normally.



Radar Images the Margin of Xanadu

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This was the 14th Titan flyby for Cassini, with nine more remaining this year. The next will be May 20, 2006. During the nominal four-year mission Cassini will perform 45 Titan flybys.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of Caltech, manages the mission for NASA's Science Mission Directorate. The Cassini orbiter was designed, developed and assembled at JPL.

For images and more information, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.

Contacts:
Carolina Martinez (818) 354-9382
Jet Propulsion Laboratory, Pasadena, Calif.

Source: NASA/JPL - News

Radar Images the Margin of Xanadu
May 3, 2006

This image of Saturn's moon Titan from the Synthetic Aperture Radar instrument on the Cassini spacecraft shows the southwestern area of a feature called Xanadu (bottom right of the image). The area is bright because it reflects the radio wavelengths used to make this radar images. The image was taken on April 30, 2006.

Xanadu is one of the most prominent features on Titan and was first seen in ground-based observations. The origin of Xanadu is still unknown, but this radar image reveals details previously unseen, such as numerous curvy features that may indicate fluid flows. Linear dark streaks visible in radar-dark areas are dune fields, also seen in previous radar images (see Dunes Galore).

Near the center of the image is a prominent circular feature, named Guabonito, about 90 kilometers (56 miles) in diameter. It might be an impact crater or a cryovolcanic caldera. If this is an impact structure, the absence of an ejecta blanket suggests that the feature has been highly eroded, like some impact structures on Earth, or has been buried by the dune fields. Other radar-bright areas (top left and top right) appear to be topographically high and might act as obstacles, diverting the dunes around them.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: NASA/JPL

Source: NASA/JPL - Cassini

I have been wanting to know what the surface of titan looks like.

Radar Images Shikoku -- "Great Britain"
May 3, 2006

This image of Saturn's moon Titan from the Synthetic Aperture Radar instrument on the Cassini spacecraft shows Shikoku Facula, a region that is bright in both radar and visible wavelengths. This radar image was taken on April 30, 2006. For a visible-light image of Shikoku Facula see Naming New Lands.

A circular feature with a radar-dark interior, probably an impact crater, is seen near the top of the image and is about 35 kilometers (22 miles) in diameter. Numerous linear dark features are seen running across the image, mostly on the right-hand side. These features were seen on other radar images (see Radar Images the Margin of Xanadu and Dunes Galore) and interpreted as dune fields. Bright, ridge-like features mainly on the lower half of the image may be topographically high regions. Radar-dark, thin, sinuous features, which may be channels draining from the bright to the dark regions, are seen below the circular feature.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: NASA/JPL

Source: NASA/JPL - Cassini

My favortie planets bigest moon maped more! whopie!

Stereographic View of Titan's Surface
May 4, 2006

This poster shows a stereographic (fish-eye) view of Titan's surface from six different altitudes. The images taken by the European Space Agency's Huygens probe descent imager/spectral radiometer show the haze layer at 20 to 21 kilometers (12 to 13 miles). The images were taken on Jan. 14, 2005.
The Huygens probe was delivered to Saturn's moon Titan by the Cassini spacecraft, which is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. NASA supplied two instruments on the probe, the descent imager/spectral radiometer and the gas chromatograph mass spectrometer.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The descent imager/spectral radiometer team is based at the University of Arizona, Tucson.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: ESA/NASA/JPL/University of Arizona

Source: NASA/JPL - Cassini

Mercator Projection of Huygens's View
May 4, 2006

This poster shows a flattened (Mercator) projection of the Huygens probe's view from 10 kilometers altitude (6 miles). The images that make up this view were taken on Jan. 14, 2005, with the descent imager/spectral radiometer onboard the European Agency's Huygens probe.

The Huygens probe was delivered to Saturn's moon Titan by the Cassini spacecraft, which is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. NASA supplied two instruments on the probe, the descent imager/spectral radiometer and the gas chromatograph mass spectrometer.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The descent imager/spectral radiometer team is based at the University of Arizona, Tucson.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: ESA/NASA/JPL/University of Arizona

Source: NASA/JPL - Cassini

Fish-eye View of Titan's Surface
May 4, 2006

This poster is a stereographic (fish-eye) projection taken with the descent imager/spectral radiometer onboard the European Space Agency's Huygens probe, when the probe was about 5 kilometers (3 miles) above Titan's surface. The images were taken on Jan. 14, 2005.

The Huygens probe was delivered to Saturn's moon Titan by the Cassini spacecraft, which is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. NASA supplied two instruments on the probe, the descent imager/spectral radiometer and the gas chromatograph mass spectrometer.
ectral radiometer and the gas chromatograph mass spectrometer.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The descent imager/spectral radiometer team is based at the University of Arizona, Tucson.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: ESA/NASA/JPL/University of Arizona

Source: NASA/JPL - Cassini

Titan's Surface
May 4, 2006

This poster shows a composite view from the descent imager/spectral radiometer taken while the European Space Agency's Huygens probe was setting on Titan's surface, juxtaposed with a similarly scaled picture taken on the Moon's surface. Objects near the center of the picture are roughly the size of a man's foot. Objects at the horizon are a fraction of a man's height. The Huygens image was taken on Jan. 14, 2005.

The Huygens probe was delivered to Saturn's moon Titan by the Cassini spacecraft, which is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. NASA supplied two instruments on the probe, the descent imager/spectral radiometer and the gas chromatograph mass spectrometer.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The descent imager/spectral radiometer team is based at the University of Arizona, Tucson.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: ESA/NASA/JPL/University of Arizona

Source: NASA/JPL - Cassini

Titan's Pebbles
May 4, 2006

When printed on letter sized paper this poster shows the size of the 'rocks' on Titan's surface in their true size. The left image was taken with the descent imager/spectral radiometer onboard the European Space Agency's Huygens probe. The Huygens image was taken on Jan. 14, 2005.

The Huygens probe was delivered to Saturn's moon Titan by the Cassini spacecraft, which is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. NASA supplied two instruments on the probe, the descent imager/spectral radiometer and the gas chromatograph mass spectrometer.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The descent imager/spectral radiometer team is based at the University of Arizona, Tucson.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: ESA/NASA/JPL/University of Arizona

Source: NASA/JPL - Cassini

Views of Titan from Different Altitudes
May 4, 2006

This poster shows a set of images acquired by the European Space Agency's Huygens probe descent imager/spectral radiometer, in the four cardinal directions (north, south, east, west), at five different altitudes above Titan's surface. The images were taken on Jan. 14, 2005.

The Huygens probe was delivered to Saturn's moon Titan by the Cassini spacecraft, which is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. NASA supplied two instruments on the probe, the descent imager/spectral radiometer and the gas chromatograph mass spectrometer.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The descent imager/spectral radiometer team is based at the University of Arizona, Tucson.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: ESA/NASA/JPL/University of Arizona

Source: NASA/JPL - Cassini

Mercator projection of Huygens's view at different altitudes
May 4, 2006

This poster shows a flattened (Mercator) projection of the view from the descent imager/spectral radiometer on the European Space Agency's Huygens probe at four different altitudes. The images were taken on Jan. 14, 2005.

The Huygens probe was delivered to Saturn's moon Titan by the Cassini spacecraft, which is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. NASA supplied two instruments on the probe, the descent imager/spectral radiometer and the gas chromatograph mass spectrometer.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The descent imager/spectral radiometer team is based at the University of Arizona, Tucson.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: ESA/NASA/JPL/University of Arizona

Source: NASA/JPL - Cassini

stunning images great job thanks for posting

May 4, 2006
(Source: ESA/NASA/JPL/University of Arizona)


New views of the most distant touchdown ever made by a spacecraft are being released today by NASA, the European Space Agency and the University of Arizona. The movies show the dramatic descent of the Huygens probe to the surface of Saturn's moon Titan on Jan. 14, 2005.

The movies were put together with data collected by the Descent Imager/Spectral Radiometer instrument during the probe's 147-minute plunge through Titan's thick orange-brown atmosphere to a soft sandy riverbed. The Descent Imager/Spectral Radiometer was funded by NASA.



A View from Huygens
+ Play Movie -- no audio (10Mb)

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The data were analyzed for months after the landing and represent the best visual product obtained from the Huygens mission. It is the most realistic way yet to experience the Huygens probe landing. The movie "View from Huygens on Jan. 14, 2005," provides in 4 minutes and 40 seconds of what the probe actually "saw" during the 2.5 hours of the descent and touchdown.

"At first, the Huygens camera just saw fog over the distant surface," said Erich Karkoschka, team member at the University of Arizona, Tucson, and creator of the movies. "The fog started to clear only at about 60 kilometers [37 miles] altitude, making it possible to resolve surface features as large as 100 meters [328 feet]," he said. "But only after landing could the probe's camera resolve little grains of sand millions and millions of times smaller than Titan. A movie is a perfect medium to show such a huge change of scale."



Titan Descent Data Movie with Bells and Whistles
+ Play Movie (11Mb)

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For the second movie, scientists used artistic license and added sound to represent the different data sets collected. They re-created a scientifically accurate representation of the mission life in less than five minutes.

"These movies really demonstrate that the Huygens camera was very well designed for the job," said Jean-Pierre Lebreton, Huygens project scientist and mission manager at the European Space Agency. "They show so many different details of a landscape that covers only a tiny fraction -- one-thousandth -- of Titan's surface. This makes me dream of what a possible future mission to Titan may return of this wonderful and fascinating Earth-like world," he said.

The Huygens probe was delivered to Saturn's moon Titan by the Cassini spacecraft, which is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. NASA supplied two instruments on the probe, the Descent Imager/Spectral Radiometer and the Gas Chromatograph Mass Spectrometer.

The Cassini spacecraft continues orbiting Saturn in its second year of its four-year tour. Cassini's next Titan flyby is on May 20, 2006. Twenty-two flybys of Titan are planned this year by Cassini, with 45 total flybys of Titan in the full tour.

The new movies and images are available at: http://saturn.jpl.nasa.gov, http://www.nasa.gov/cassini, http://saturn.esa.int and http://www.lpl.arizona.edu/DISR/.

The Cassini-Huygens mission to Saturn and Titan is a joint mission of NASA, the European Space Agency and the Italian Space Agency. ESA supplied and manages the Huygens probe that descended to Titan's surface. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. NASA funded the Descent Imager/Spectral Radiometer, which was built by Lockheed Martin. University of Arizona Lunar and Planetary Laboratory scientist Martin Tomasko leads the Descent Imager/Spectral Radiometer team. Team members are based throughout the United States and Europe.

Contacts:
Carolina Martinez (818) 354-9382
Jet Propulsion Laboratory, Pasadena, Calif.

Lori Stiles (520) 621-1877
University of Arizona, Tucson

Monica Talevi (011) 31-71-565-3223
European Space Agency, Noordwijk, Netherlands

NEWS RELEASE: 2006-070

Source: NASA/JPL - News

The University of Arizona press release is reproduced below:


Cassini radar sees sand dunes on Saturn's giant moon Titan (upper
photo) that are sculpted like Namibian sand dunes on Earth (lower
photo). The bright features in the upper radar photo are not clouds
but topographic features among the dunes.
(Photo: NASA/JPL - upper photo; NASA - lower photo)

By Lori Stiles
May 04, 2006

Until a couple of years ago, scientists thought the dark equatorial regions of Titan might be liquid oceans.

New radar evidence shows they are seas -- but seas of sand dunes like those in the Arabian or Namibian Deserts, a University of Arizona member of the Cassini radar team and colleagues report in Science (May 5).

Radar images taken when the Cassini spacecraft flew by Titan last October show dunes 330 feet (100 meters) high that run parallel to each other for hundreds of miles at Titan's equator. One dune field runs more than 930 miles (1500 km) long, said Ralph Lorenz of UA's Lunar and Planetary Laboratory.

"It's bizarre," Lorenz said. "These images from a moon of Saturn look just like radar images of Namibia or Arabia. Titan's atmosphere is thicker than Earth's, its gravity is lower, its sand is certainly different -- everything is different except for the physical process that forms the dunes and resulting landscape."


Detail from a Cassini radar image of sand dunes on Titan.
(Photo: NASA/JPL)

Ten years ago, scientists believed that Saturn's moon Titan is too far from the sun to have solar-driven surface winds powerful enough to sculpt sand dunes. They also theorized that the dark regions at Titan's equator might be liquid ethane oceans that would trap sand.

But researchers have since learned that Saturn's powerful gravity creates significant tides in Titan's atmosphere. Saturn's tidal effect on Titan is roughly 400 times greater than our moon's tidal pull on Earth.

As first seen in circulation models a couple of years ago, Lorenz said, "Tides apparently dominate the near-surface winds because they're so strong throughout the atmosphere, top to bottom. Solar-driven winds are strong only high up."

The dunes seen by Cassini radar are a particular linear or longitudinal type that is characteristic of dunes formed by winds blowing from different directions. The tides cause wind to change direction as they drive winds toward the equator, Lorenz said.

And when the tidal wind combines with Titan's west-to-east zonal wind, as the radar images show, it creates dunes aligned nearly west-east except near mountains that influence local wind direction.

"When we saw these dunes in radar it started to make sense," he said. "If you look at the dunes, you see tidal winds might be blowing sand around the moon several times and working it into dunes at the equator. It's possible that tidal winds are carrying dark sediments from higher latitudes to the equator, forming Titan's dark belt."

The researchers' model of Titan suggests tides can create surface winds that reach about one mile per hour (a half-meter per second). "Even though this is a very gentle wind, this is enough to blow grains along the ground in Titan's thick atmosphere and low gravity," Lorenz said. Titan's sand is a little coarser but less dense than typical sand on Earth or Mars. "These grains might resemble coffee grounds."

The variable tidal wind combines with Titan's west-to-east zonal wind to create surface winds that average about one mile per hour (a half meter per second). Average wind speed is a bit deceptive, because sand dunes wouldn't form on Earth or Mars at their average wind speeds.

Whether the grains are made of organic solids, water ice, or a mixture of both is a mystery. Cassini's Visual and Infrared Mapping Spectrometer, led by UA's Robert Brown, may get results on sand dune composition.

How the sand formed is another peculiar story.

Sand may have formed when liquid methane rain eroded particles from ice bedrock. Researchers previously thought that it doesn't rain enough on Titan to erode much bedrock, but they thought in terms of average rainfall.

Observations and models of Titan show that clouds and rain are rare. That means that individual storms could be large and still yield a low average rainfall, Lorenz explained.

When the UA-led Descent Imager/Spectral Radiometer (DISR) team produced images taken during the Huygens probe landing on Titan in January 2005, the world saw gullies, streambeds and canyons in the landscape. These same features on Titan have been seen with radar.

These features show that when it does rain on Titan, it rains in very energetic events, just as it does in the Arizona desert, Lorenz said.

Energetic rain that triggers flash floods may be a mechanism for making sand, he added.

Alternatively, the sand may come from organic solids produced by photochemical reactions in Titan's atmosphere.

"It's exciting that the radar, which is mainly to study the surface of Titan, is telling us so much about how winds on Titan work," Lorenz said. "This will be important information for when we return to Titan in the future, perhaps with a balloon."

An international group of scientists are co-authors on the Science article, "The Sand Seas of Titan: Cassini Observations of Longitudinal Dunes." They are from the Jet Propulsion Laboratory, California Institute of Technology, U.S. Geological Survey - Flagstaff, Planetary Science Institute, Wheeling Jesuit College, Proxemy Research of Bowie, Md., Stanford University, Goddard Institute for Space Studies, Observatoire de Paris, International Research School of Planetary Sciences, Universita' d'Annunzio, Facolt di Ingegneria, Universit La Sapienza, Politecnico di Bari and Agenzia Spaziale Italiana. Jani Radebaugh and Jonathan Lunine of UA's Lunar and Planetary Laboratory are among the co-authors.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter was designed, developed and assembled at JPL.

Related Web site

http://www.lpl.arizona.edu/~rlorenz

http://www.nasa.gov/cassini

http://saturn.jpl.nasa.gov

Source: University of Arizona Press Release

That's disheartening in a way...

waspie, i love how you write a headline for all your threads.. its very convinient!

You like big, central and purple then?

most definitley

Xanadu: Rivers flowed onto a sunless sea
May 5, 2006

This image from the Synthetic Aperture Radar instrument on the Cassini spacecraft shows the radar-bright western margin of Xanadu, one of the most prominent features on Titan (see also Radar Images the Margin of Xanadu above). In radar images, bright regions indicate a rough or scattering material, while a dark region might be smoother or more absorbing. The image was taken during a flyby of Titan on April 30, 2006.

Narrow, sinuous, radar-bright channels, meandering like a maze, are seen on the right-hand-side of the image. These may be river networks that might have flowed onto the dark areas on the left of the image. Vast, dark areas covered by dunes are seen on the equatorial regions of Titan Dunes Galore) and have been referred to as Titan's "sand seas." Near the middle of the image is a radar-bright area that has a boundary with the dark sand seas. Because the radar illumination is coming from the top, this indicates that the bright region, Xanadu, is topographically higher than the sand seas.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: NASA/JPL

Source: NASA/JPL - Cassini

Impact craters on Xanadu
May 5, 2006

This image from the Synthetic Aperture Radar instrument on the Cassini spacecraft shows the radar-bright region Xanadu and two circular features interpreted to be degraded impact craters. In radar images, bright regions indicate a rough or scattering material, while a dark region might be smoother or more absorbing. The image was acquired during a flyby of Titan on April 30, 2006.

Near the top of the image is a 70-kilometer-wide (47-mile-wide) impact structure. In contrast to a similarly sized crater called Sinlap (see Impact Crater with Ejecta Blanket), this crater shows a prominent central peak, indicating that the interaction between the impact and the crust was different in this region.

Near the bottom of the image is another circular feature with a dark central region that does not show evidence of a central peak. Numerous radar-bright channels cut across the image, indicating that liquids have flowed in this region.


The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: NASA/JPL

Source: NASA/JPL - Cassini

Radar Flyby of Titan - April 30, 2006
May 5, 2006

This map of Saturn's moon Titan shows the location mapped with the Cassini radar mapper using its Synthetic Aperture Radar imaging mode on April 30, 2006.
The global map shows the areas mapped so far by radar. The top radar swath was mapped during a flyby on Oct. 26, 2004. The middle swath was taken during the Feb. 15, 2006, flyby.

Labels represent the approximate longitude. The radar swaths are superimposed on a false-color image made from observations by NASA's Hubble Space Telescope.

Cassini's radar has revealed a variety of geologic features, including impact craters, wind-blown deposits, channels and cryovolcanic features.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: NASA/JPL

Source: NASA/JPL - Cassini

Complex Terrain
May 8, 2006

This complex area of hilly terrain and erosional channels is located atop Xanadu, the continent-sized region on Saturn's moon Titan. The image was captured by the Cassini Titan Radar Mapper on April 30, 2006. It shows details as small as 350 meters (1148 feet). Each side of the picture covers 200 kilometers (124 miles).
Chains of hills or mountains are located near the bottom of the image, appearing bright on their north side (toward the top in this image). Extending further north is a drainage region where liquids flowed, eroding the presumably water-ice bedrock of Xanadu. Careful inspection reveals a series of faint drainage channels, some of which appear to empty into the dark region near the top of the image. Liquid methane might be fed from springs within Xanadu or by occasional rainfall suspected to occur on Titan. There is evidence for this rainfall in images taken by the Descent Imager/ Spectral Radiometer camera on the Huygens probe as it landed, well to the west of this area, on January 14, 2005 (see Water Ice and Methane Springs on Titan).

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: NASA/JPL

Source: NASA/JPL - Cassini

Titan's Land-o-Lakes
May 8, 2006

The Cassini spacecraft's Titan Radar Mapper instrument imaged this area atop Xanadu, the bright area of Titan, on April 30, 2006. The picture is roughly 150 kilometers (93 miles) wide by 400 kilometers (249 miles) long, and shows features as small as 350 meters (1148 feet). Chains of hills or mountains are revealed by the radar beam, which is illuminating their northern sides (in this image, north is up). Interspersed between the chains of hills are darker areas where topographic features are absent or partly buried. The darkest areas could contain liquids, which tend to reflect the radar beam away from Cassini in the absence of winds, making the area appear quite dark. At Titan's icy conditions, these liquids would be methane and/or ethane. Stubby drainage features can be see faintly between the chains of hills, suggesting flow of the liquid across parts of the region.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: NASA/JPL

Source: NASA/JPL - Cassini

Dunes and more dunes
May 12, 2006

This image was taken with the Cassini Synthetic Aperture Radar instrument on Oct. 28, 2005.
This was the fourth flyby of Titan during which radar images were obtained, and this pass considerably expanded the coverage of Titan's surface.

The swath is about 6,150 kilometers kilometers (3,821 miles) long, extending from 7 degrees north to 18 degrees south latitude and 179 west to 320 west longitude.

The spatial resolution of the radar images ranges from about 300 meters (984 feet) per pixel to about 1.5 kilometers (0.9 miles) per pixel. It covers the area where the Huygens probe landed (eastern end of the swath), giving geologic context for the landing site.

The most ubiquitous features in this swath are "cat scratches," which are interpreted as longitudinal dunes and were first seen in the February 2005 flyby, see Titan, a Geologically Dynamic World.

Also prominent are long, bright ridges, concentrated near the eastern end of the swath. These may be tectonic in origin, and are seen for the first time here. No impact craters are seen, indicating a young surface.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: NASA/JPL

Source: NASA/JPL - Cassini

agreed, kinda sad...

I was hoping for some kind of liquid...

It looks like there is liquid there, just not large oceans.

that's good...

Titan on the Side
May 30, 2006

Saturn's largest moon, Titan, peaks out from under the planet's rings of ice.
This view looks toward Titan (5,150 kilometers, or 3,200 miles across) from slightly beneath the ringplane. The dark Encke gap (325 kilometers, or 200 miles wide) is visible here, as is the narrow F ring.

Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were taken with the Cassini spacecraft narrow-angle camera on April 28, 2006 at a distance of approximately 1.8 million kilometers (1.1 million miles) from Titan. Image scale is 11 kilometers (7 miles) per pixel on Titan.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

Ring of Light
June 30, 2006

Dazzling Titan glows with a 360-degree sunset as light scatters through its very extended atmosphere. Some structure is visible in the hazes of the northern polar hood.
To the left is Janus (181 kilometers, or 113 miles across), far off on the opposite side of the ringplane. The rings show their unlit side to Cassini, as the spacecraft viewed them from slightly above the ringplane.

A world with strikingly Earth-like physical processes, frigid Titan is Saturn's largest natural satellite, at 5,150 kilometers (3,200 miles) across. Titan's image is saturated at the 5 o'clock position.

The view was acquired in visible light with the Cassini spacecraft narrow-angle camera on June 2, 2006 at a distance of approximately 2.3 million kilometers (1.5 million miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 163 degrees. Cassini was 3.7 million kilometers (2.3 million miles) from Janus. Image scale is 14 kilometers (9 miles) per pixel on Titan and 22 kilometers (14 miles) on Janus.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

That is an amazing picture

Amazing Hazes
July 5, 2006

Sunlight streams through the high-altitude haze layer that extends completely around the giant moon, Titan, in this view of the moon taken by the Cassini spacecraft. Some fine structure can be spotted in the ever-shifting hazes in Titan's northern polar reaches to the top.
The distant sky beyond Titan (5,150 kilometers, or 3,200 miles across) is not empty, but instead is filled in the lower half by the barely visible, immense bulk of Saturn 1.3 million kilometers (800,000 miles) beyond. The view is toward the night side of both worlds.

Titan's image is saturated, or over exposed, near the five o'clock position, obscuring the details in the atmosphere.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 2, 2006 at a distance of approximately 2.3 million kilometers (1.4 million miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 163 degrees. Image scale is 14 kilometers (9 miles) per pixel on Titan.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

The press release is reproduced below:

July 19, 2006

Dwayne Brown/Erica Hupp
Headquarters, Washington
202-358-1726/1237

Carolina Martinez
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-9382

RELEASE: 06-281

Cassini Reveals Titan's Xanadu Region To Be an Earth-like Land

New radar images from NASA's Cassini spacecraft revealed geological features similar to Earth on Xanadu, an Australia-sized, bright region on Saturn's moon Titan.

These radar images, from a strip more than 2,796 miles long, show Xanadu is surrounded by darker terrain, reminiscent of a free-standing landmass. At the region's western edge, dark sand dunes give way to land cut by river networks, hills and valleys. These narrow river networks flow onto darker areas, which may be lakes. A crater formed by the impact of an asteroid or by water volcanism is also visible. More channels snake through the eastern part of Xanadu, ending on a dark plain where dunes, abundant elsewhere, seem absent. Appalachian-sized mountains crisscross the region.

"We could only speculate about the nature of this mysterious bright country, too far from us for details to be revealed by Earth-based and space-based telescopes. Now, under Cassini's powerful radar eyes, facts are replacing speculation," said Jonathan Lunine, Cassini interdisciplinary scientist at the University of Arizona, Tucson. "Surprisingly, this cold, faraway region has geological features remarkably like Earth."

Titan is a place of twilight, dimmed by a haze of hydrocarbons surrounding it. Cassini's radar instrument can see through the haze by bouncing radio signals off the surface and timing their return. In the radar images bright regions indicate rough or scattering material, while a dark region might be smoother or more absorbing material, possibly liquid.

Xanadu was first discovered by NASA's Hubble Space Telescope in 1994 as a striking bright spot seen in infrared imaging. When Cassini's radar system viewed Xanadu on April 30, 2006, it found a surface modified by winds, rain, and the flow of liquids. At Titan's frigid temperatures, the liquid cannot be water; it is almost certainly methane or ethane.

"Although Titan gets far less sunlight and is much smaller and colder than Earth, Xanadu is no longer just a mere bright spot, but a land where rivers flow down to a sunless sea," Lunine said.

Observations by the European Space Agency's Huygens probe, that Cassini carried to Titan, and by NASA's Voyager spacecraft strongly hint that both methane rain and dark orange hydrocarbon solids fall like soot from the moon's dark skies.

On Xanadu, liquid methane might fall as rain or trickle from springs. Rivers of methane might carve the channels and carry off grains of material to accumulate as sand dunes elsewhere on Titan.

"This land is heavily tortured, convoluted and filled with hills and mountains," said Steve Wall, the Cassini radar team's deputy leader at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "There appear to be faults, deeply cut channels and valleys. Also, it appears to be the only vast area not covered by organic dirt. Xanadu has been washed clean. What is left underneath looks like very porous water ice, maybe filled with caverns.

"In the 1980s, it took the shuttle imaging radar to discover subsurface rivers in the Sahara. Similarly, if it hadn't been for the Cassini radar, we would have missed all of this. We have a newly discovered continent to explore," Wall said.

Cassini will view Titan again on Saturday, July 22, exploring the high northern latitudes. In the next two years the orbiter will fly by Titan 29 times, nearly twice as many encounters as in the first half of Cassini's four-year prime mission. Twelve of the planned flybys will use radar.

For Cassini images and information, visit:

http://www.nasa.gov/cassini

The Cassini-Huygens mission is a cooperative project between NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington.

- end -

--------------------------------------------------------------------------------

Source: NASA Press Release 06-281

Titan (T13) Viewed by Cassini's Radar - April 30, 2006

July 19, 2006

This image of Titan was acquired on April 30, 2006, by Cassini's radar instrument in synthetic-aperture mode over the continent-sized region called Xanadu.
Xanadu is one of the brightest areas on Titan, measuring about 4,000 kilometers (2,485 miles) east to west and 2,000 kilometers (1,243 miles) north to south. The radar coverage shown ranges from 220 to 490 kilometers (140 to 300 miles) from top to bottom, and is about 4,850 kilometers (3,013 miles) wide. Smallest details in this image are about 400 meters (1,310 feet) across.

On Xanadu, most of the geologic forces that modify Earth's surface can be found. Channels are seen crossing through plains and meandering through bright, hilly country. Chains of taller mountains appear in Xanadu's interior. Dunes traverse darker areas to the west of Xanadu itself. Circular features might have been formed by the impact of an asteroid or by cryovolcanism. More channels carve through the eastern (right) margin, ending on a dark plain where the dunes abundant elsewhere seem absent.


The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: NASA/JPL

Source: NASA/JPL - Cassini

Xanadu's Meandering Rivers
July 19, 2006

A network of river channels is located atop Xanadu, the continent-sized region on Saturn's moon Titan. This radar image was captured by the Cassini Radar Mapper on April 30, 2006.
These winding, meandering river channels start from the top of the image and run like a fork in the road, splitting to the right and left of the image. At Titan's chilly conditions, streams of methane and/or ethane might flow across parts of the region.

The picture is roughly 230 kilometers (143 miles) wide by 340 kilometers (211 miles) long, and shows features as small as 500 meters (1,640 feet).

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: NASA/JPL

Source: NASA/JPL - Cassini

Cassini's powerful radar eyes have uncovered a geologic goldmine in a region called Xanadu on Saturn's moon Titan. Panning west to east, the geologic features include river channels, mountains and hills, a crater and possible lakes.
The movie shows the location mapped with the Cassini Radar Mapper using its Synthetic Aperture Radar imaging mode on April 30, 2006. The global map shows the areas mapped so far by radar. The radar swaths are superimposed on a false-color image made from observations by NASA's Hubble Space Telescope.

Cassini's radar has revealed a variety of geologic features, including impact craters, wind-blown deposits, channels and cryovolcanic features.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.

Credit: NASA/JPL

Source: NASA/JPL - Cassini

Lakes on Titan
July 24, 2006

The Cassini spacecraft, using its radar system, has discovered very strong evidence for hydrocarbon lakes on Titan. Dark patches, which resemble terrestrial lakes, seem to be sprinkled all over the high latitudes surrounding Titan's north pole.
Scientists have speculated that liquid methane or ethane might form lakes on Titan, particularly near the somewhat colder polar regions. In the images, a variety of dark patches, some with channels leading in or out of them, appear. The channels have a shape that strongly implies they were carved by liquid. Some of the dark patches and connecting channels are completely black, that is, they reflect back essentially no radar signal, and hence must be extremely smooth. In some cases rims can be seen around the dark patches, suggesting deposits that might form as liquid evaporates. The abundant methane in Titan's atmosphere is stable as a liquid under Titan conditions, as is its abundant chemical product, ethane, but liquid water is not. For all these reasons, scientists interpret the dark areas as lakes of liquid methane or ethane, making Titan the only body in the solar system besides Earth known to possess lakes. Because such lakes may wax and wane over time, and winds may alter the roughness of their surfaces. Repeat coverage of these areas should test whether indeed these are bodies of liquid.

These two radar images were acquired by the Cassini radar instrument in synthetic aperture mode on July 21, 2006. The top image centered near 80 degrees north, 92 degrees west measures about 420 kilometers by 150 kilometers (260 miles by 93 miles). The lower image centered near 78 degrees north, 18 degrees west measures about 475 kilometers by 150 kilometers (295 miles by 93 miles). Smallest details in this image are about 500 meters (1,640 feet) across.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.


For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov .

Credit: NASA/JPL

Source: NASA/JPL - Cassini

An artist's interpretation of the area surrounding the Huygens landing site based on images and data returned on 14 January 2005.

Credits: ESA

25 July 2006
An unexpected radio reflection from the surface of Titan has allowed ESA scientists to deduce the average size of stones and pebbles close to the Huygens’ landing site. The technique could be used on other lander missions to analyse planetary surfaces for free.

When Huygens came to rest on the surface of Titan on 14 January 2005, it survived the impact and continued to transmit to the Cassini mothership, orbiting above. Part of that radio signal 'leaked' downwards and hit the surface of Titan before being reflected back up to Cassini. On its way up, it interfered with the direct beam.
As Miguel Pérez-Ayúcar, a member of the Huygens Team at ESA’s European Space Research and Technology Centre (ESTEC) in The Netherlands, and his colleagues watched the signal coming back, they were initially puzzled to see the power of the signal rising and falling in a repetitive manner.

“Huygens had not been designed to necessarily survive impact so we had never thought about what the signal would look like from the surface,” says Pérez. After making a joke that aliens must be dragging the craft along the surface, Pérez and the team began work at once to understand the signal.


This technical sketch illustrates the radio signals emitted by the Huygens probe from Titan's surface after touch down on 14 January 2005. The probe survived the impact and continued to transmit to the Cassini mothership, orbiting above. Part of that radio signal ‘leaked’ downwards and hit the surface of Titan before being reflected back up to Cassini. On its way up, it interfered with the direct beam. Thanks to this 'multipath' phenomena related to the Huygens radio signal, it has been possible to deduce that the surface swathe must be relatively flat and covered mostly in stones of around 5-10 centimetres in diameter.

Credits: M. Pérez-Ayúcar/ESA

The clue was the repetitive oscillation of the power. It made Pérez think about the interaction of the direct signal with that reflecting from the surface of Titan. As Cassini travelled away from the Huygens landing site, the angle between it and Huygens changed. This altered the way in which the interference between the reflected and direct beams was detected, perhaps causing the variation in power.

He began running computer models and saw that not only could he reproduce the received signal but also it was sensitive to the size of pebbles on the surface of Titan.

Cassini collected data for 71 minutes after Huygens landed. After that time, the spacecraft’s motion took it below the horizon as seen from Huygens' landing site. Until then, it soaked up radio signals that encoded information about a swathe of Titan’s surface from 1 metre to 2 kilometres to the west of the landed probe.

To accurately mirror the true signal, Pérez and his team discovered that the surface swathe must be relatively flat and covered mostly in stones of around 5-10 centimetres in diameter.


This image was returned 14 January 2005, by ESA's Huygens probe during its successful descent to land on Titan. This is the coloured view, following processing to add reflection spectra data, gives a better indication of the actual colour of the surface. Initially thought to be rocks or ice blocks, they are more pebble-sized. The two rock-like objects just below the middle of the image are about 15 centimetres (left) and 4 centimetres (centre) across respectively, at a distance of about 85 centimetres from Huygens. The surface is darker than originally expected, consisting of a mixture of water and hydrocarbon ice. There is also evidence of erosion at the base of these objects, indicating possible fluvial activity.

Credits: ESA/NASA/JPL/University of Arizona

This unique result complements the data taken by the Descent Imager and Spectral Radiometer (DISR) instrument. When Huygens came to rest on the surface of Titan, DISR was pointing due south. Its images show stones and terrain in good agreement with the newly deduced western facing radio data. "This is a real bonus to the mission. It requires no special equipment, just the usual communications subsystem," says Pérez.

Now that the scientists have understood the process using the unexpected Huygens data, the technique could be implemented on future lander missions. "This experience can be inherited by any future lander," says Pérez, "All that will be needed is a few refinements and it will become a powerful technique."

By subtly altering the properties of the radio beam for instance, the radio transmitter and receiver can be optimised to help deduce the chemical composition of the planetary surface.

Note:

The results appear in the 25 July 2006 issue of the Journal of Geophysical Research (Vol. 111. Doi: 10.1029/2005JE002613, 2006). The paper, titled 'Bistatic Observations of Titan’s Surface with the Huygens probe radio signal', is by M Pérez-Ayúcar, J.P.Lebreton, N.Floury and R.Prieto-Cerdeira (ESA-ESTEC, Noordwijk, The Netherlands), and R.D.Lorenz (Univ.of Arizona, Tucson, Arizona, USA).

Source: ESA - News

This image provides a comparison between the Huygens landing site on Titan as viewed by the Cassini Imaging Science Subsystem (ISS) and the NACO/SDI instrument mounted on the 8-metre Yepun telescope of the VLT (Very Large Telescope) station, in Chile.
From the two images it is possible to see a high consistency between the two measurements. The Cassini image - taken in the near-infrared (938 nanometres)- shows the Huygens landing site map wrapped around Titan, rotated to the same position as the January 2005 NACO/SDI observations.

The coloured lines outline the regions that were imaged by Cassini at different resolutions. The lower-resolution imaging sequences are outlined in blue. Other areas have been specifically targeted to build moderate and high resolution mosaics of surface features. These include the site where the Huygens probe has touched down on 14 January 2005, marked with the yellow X, and located at a latitude of 10.3° south and a longitude of 192.32° west (or 167.7° east).

The landing site is located on the boundary between the bright region called Adiri and the dark one called Shangri-la.

The red colour on the NACO/SDI image corresponds to an atmospheric filter at 1.625 micron, while the blue colour corresponds to a filter for the surface at 1.600 and 1.575 micron.

Credits: NASA/JPL/Cassini-ISS/Space Science Institute and ESO/NACO-SDI/VLT

27 July 2006
As Huygens parachuted to the surface of Titan in January 2005, a battery of telescopes around the world were watching or listening.

The results of those observations are now being collected together and published for the first time. The work gives valuable additional context within which to interpret the 'ground truth' returned by Huygens.
Hundreds of scientists, working at 25 radio and optical telescopes situated mainly around the Pacific, from where Titan would be visible at the time of Huygens descent, observed the moon before, during and after the Huygens descent. It was one of the largest ground-based observational campaigns ever to take place in support of a space mission.

The first observations began well over a year before Huygens entered the alien world's atmosphere, when scientists used the fact that Titan would pass directly in front of two distant stars. By watching the way the light faded from the stars, scientists analysed the density, wind and temperature of Titan’s atmosphere. It helped to build confidence by confirming that the atmosphere was similar to their expectations.

A year later, telescopes monitored Titan's atmosphere and its surface at infrared wavelengths for the days and weeks around the Huygens descent. Even now, those observations are of critical importance to the scientists as they continue to interpret the data returned by the probe. "We wanted to know whether the day of the descent was a special day or not on Titan, so that we can place the Huygens data in the correct context," says Olivier Witasse, a Huygens scientist at ESA's European Space Research and Technology Centre (ESTEC) in The Netherlands.

Radio telescopes were used to track Huygens. Both Single-Dish Doppler-tracking, and a Very Long Baseline Interferometry (VLBI) observation that included 17 telescopes, were planned. Doppler-tracking was expected to complement the radio experiment onboard Huygens that used the probe-orbiter link. The VLBI project was initiated about two years before the Huygens entry as a test experiment. No one could predict for certain that the Huygens signal would be detectable but, if it were detected, it would provide unique information.

"One goal of the VLBI observation was to reconstruct the probe's descent trajectory to an accuracy of ten kilometres. At Titan's distance of more than 1 billion kilometres, this is the equivalent of determining positions with an accuracy of just three metres on our own Moon. Another goal was to demonstrate this as a new technique for future missions," says Jean-Pierre Lebreton, Huygens Project Scientist.


The radio experiments worked beyond expectations and even proved to be a 'safety net' when the reception of Huygens' second communications channel failed during the descent. The data from several of Huygens’ six experiments was lost, including that required for the Huygens radio experiment to track the winds during the whole descent. The Doppler-tracking data from the Green Bank Telescope (West Virginia, America) and from Parkes (Australia) provided real-time information about the probe's drift in the winds. The processing of the VLBI data set is not yet completed but initial results look very promising.

The combined analysis of the Huygens data with that acquired by the Cassini orbiter in the past two years allowed scientists to reconstruct the movement of the probe precisely. They pinpointed its landing to 10.33 degrees south and 192.32 degrees west. The VLBI data set will provide an independent reconstruction of the trajectory. It should help to confirm and most likely refine the whole descent trajectory and the coordinates of the landing site.

Notes:

The results appeared on 27 July 2006 in the Journal of Geophysical Research, in the article "Overview of the coordinated ground-based observations of Titan during the Huygens mission", by O. Witasse, J-P. Lebreton et al. (111, doi: 10.1029/2005JE002640). This issue of JGR contains 12 companion papers on results about Titan.

Huygens will certainly not be the last mission to benefit from a coordinated ground-based observational campaign. Promoting such observations is one of the main activities of the EU-sponsored Europlanet project. Jean-Pierre Lebreton, initiated the Titan coordinated observation campaign before the birth of Europlanet. "The Huygens experience is directly injected into the Europlanet activities," says Lebreton.

Europlanet's objective is to draw together planetary science research activities in Europe. "Europlanet's long-term goal is to pull together European resources to capitalise on the investments made in space missions. We will do this by promoting complementary and coordinated activities such as ground based observations, laboratory work, modelling and theory. Access to relevant archived laboratory data and ground-based data should become as easy as access to archived space-based planetary mission data," added Lebreton.

There is already an ongoing effort associated with ESA's comet chaser, Rosetta, which was launched on 2 March 2004. Rosetta's target was chosen after a prolonged series of ground-based observations. Even now, telescopes continue to monitor comet Churyumov-Gerasimenko as Rosetta cruises towards its 2014 rendezvous. A major coordinated ground-based campaign is expected when Rosetta reaches the comet.

Source: ESA - News

Saturn's View of Titan
July 28, 2006

As it approached Titan for yet another revealing encounter, the Cassini spacecraft acquired this image showing terrain on the moon's Saturn-facing hemisphere.

Prominent dark areas found in the moon's equatorial region appear to contain vast and continuous dune fields, discovered by the Cassini Radar experiment and likely composed of particles that drop from Titan's unique, smoggy atmosphere. The dark regions seen here are provisionally named Aaru and Senkyo (at right), with parts of western Fensal and Aztlan showing at left, near the terminator.

Titan is 5,150 kilometers (3,200 miles) across.

The image was taken with the Cassini spacecraft wide-angle camera using a spectral filter sensitive to wavelengths of infrared light centered at 752 nanometers. The view was obtained on July 2, 2006 at a distance of approximately 163,000 kilometers (101,000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 62 degrees. Image scale is 19 kilometers (12 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

Source: NASA/JPL - Cassini

The NASA/Ames Research Center press release is reproduced below:

July 27, 2006

John Bluck
NASA Ames Research Center, Moffett Field, Calif.
Phone: (650) 604-5026/9000
E-mail: jbluck@mail.arc.nasa.gov

RELEASE: 06_57AR


NASA Reports That Methane Drizzles on Saturn's Moon, Titan

Liquid methane drizzles on the surface of Titan, a moon of Saturn, according to a paper by NASA and university scientists that appears in today's issue of the journal, Nature.

Data from the European Space Agency's Huygens probe indicates there is a lower, barely visible, liquid methane-nitrogen cloud that drops rain to the surface of Titan, reported a team of scientists from universities, an observatory and NASA. The probe collected the data on January 14, 2005, when it approached and landed on Titan.

"The rain on Titan is just a slight drizzle, but it rains all the time, day in, day out. It makes the ground wet and muddy with liquid methane. This is why the Huygens probe landed with a splat. It landed in methane mud," said Christopher McKay, a scientist at NASA Ames Research Center in California's Silicon Valley and second author of the study. The principal author is Tetsuya Tokano from the University of Cologne, Germany.

On Titan, the clouds and rain are formed of liquid methane. On Earth, methane is a flammable gas, but Titan has no oxygen in its atmosphere that could support combustion. Also, the temperatures on Titan are so cold -- minus 300 degrees Fahrenheit (minus 149 degrees Celsius) -- that the methane can form liquid. Titan's landscape includes fluvial, river-like features that may well be formed by methane rain, scientists noted.

A gap separates the liquid methane cloud -- the source of the rain -- from a higher, upper methane ice cloud, according to the scientific study. Scientists say the downward flow of methane due to the rain is balanced by upward transport of methane gas by large-scale atmospheric circulation.

According to scientists, the rain comes from thin clouds of methane. The upper clouds are methane ice, and the lower clouds are liquid and composed of a combination of methane and nitrogen. Computer models indicate these thin liquid methane clouds cover about half of Titan, even though methane abundance on the moon decreases with latitude, the team reported.

"We determined that the rain on Titan is equal to about two inches (about 5 centimeters) a year," McKay said. "This is about as much rain as Death Valley (receives). The difference is (that) on Titan, this rain is spread out evenly over the entire year."

The scientists reported that erosion potential from the very light methane drizzle may be quite limited, but at least would be sufficient to wet the surface material, and may explain its generally wet character.

In addition to McKay the other co-authors of the scientific paper include Fritz Neubauer, of the University of Cologne; Sushil Atreya, University of Michigan, Ann Arbor; Francesca Ferri, University of Padova, Italy; Marcello Fulchignoni, of both the Paris Observatory and the University of Denis Diderot, Paris; and Hasso Niemann, NASA Goddard Space Flight Center, Greenbelt, Md.

More information about the Huygens mission to Titan can be found at on the Internet at: