Astronomy [MISSION COVERAGE] Cassini

Discussion in 'Astronomy' started by Mizar, Nov 11, 2004.

  1. Mizar

    Mizar Premium Member

    the pourpose of this thread is to ad information on the cassini mission each time something intresting is heard about. Please post all findings of the mission here on this thread instead of starting a new one

    and ill start it off


    full story and a recap of happenings in the mission are avaible here More Science Findings From Cassini - Sky & Telescope

    Edited Title - JCMinJapan
     
  2. Mizar

    Mizar Premium Member

    I get a Weekly New letter from NASA on the cassini mission sometimes they give links soemtimes thy just send info when i find intresting things ill post them here

    ALL INFORMATION BELOW IS COURTESY OF NASA

     
  3. JcMinJapan

    JcMinJapan Premium Member

    updated title so we can cover events for this missionin one thread
     
  4. Mizar

    Mizar Premium Member

    IMMAGE UPDATE

    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 Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras, were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.
     
  5. Mizar

    Mizar Premium Member

    Tethys and 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 Cassini-Huygens 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 team is based at the Space Science Institute, Boulder, Colo.
     
  6. Mizar

    Mizar Premium Member

    Cassini Significant Events
    for 11/18/04 - 11/22/04

    Cassini spacecraft is in an excellent state of health and is operating
    normally. Information on the present position and speed of the Cassini
    spacecraft may be found on the "Present Position" web page located at
    http://saturn.jpl.nasa.gov/operations/present-position.cfm .

    On Friday, November 19, Deep Space Mission Systems (DSMS) held a
    successful
    Cassini-Huygens probe release, relay, and data playback Mission Event
    Readiness Review. The review board unanimously agreed that the DSMS is
    ready to support the Huygens Probe release and data playback.

    A program internal science talk was given this week by one of the
    Visual and
    Infrared Mapping Spectrometer (VIMS) team members on The Latest VIMS
    Results
    on Titan and the Icy Satellites.

    Cassini Outreach conducted a Cassini workshop for ten members of the
    Natural
    History Museum of Los Angeles education and outreach staff this week.
    Activities included talks by Cassini scientists, demonstration of
    hands-on
    educational activities from the Cassini education webpage, and a
    mission
    overview and science update.

    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
    Cassini-Huygens mission for NASA's Science Mission Directorate,
    Washington,
    D.C. JPL designed, developed and assembled the Cassini orbiter.
     
  7. JcMinJapan

    JcMinJapan Premium Member

    Here is the basic information on the Mission.

    Primary Mission: Four-year tour to study Saturn, its rings, moons and magnetosphere

    Launch: October 15, 1997 from Cape Canaveral Air Force Station, Florida

    Arrival at Saturn: July 1, 2004 (Eastern time)

    Distance Traveled: 2.2 billion miles (3.5 billion km)

    Huygens probe Titan descent: January 14, 2005
     
  8. helenheaven

    helenheaven Premium Member

    can you explain what a magnetosphere is ?
     
  9. JcMinJapan

    JcMinJapan Premium Member

    The simple answer:

    The area of space that is controlled by the earth magnetic field.
    We have the North and South Poles. The created the magnetic field around the earth. This actually protects the earth from many of the suns particles. It is extends to about 60,000 km from the earth.

    Do you want a more detailed answer? If ya do, just let me know and I will create a report on it for ya to give mroe details.
     
  10. Mizar

    Mizar Premium Member

     
  11. JcMinJapan

    JcMinJapan Premium Member

    This is an awesome pic! I love it so much, I really makes me wish that I could be there in person to observe that!
     
  12. Mizar

    Mizar Premium Member

    immage link-- http://ciclops.lpl.arizona.edu/media/dr/2004/547_1021_1.jpg
     
  13. Mizar

    Mizar Premium Member

    Immages-
    http://www.nasa.gov/images/content/103926main_pia06160-516.jpg
    http://www.nasa.gov/images/content/103923main_pia06155-516.jpg
     
  14. Mizar

    Mizar Premium Member

    Carolina Martinez (818) 354-9382

    Jet Propulsion Laboratory, Pasadena, Calif.



    Status Report: 2004-297 December 28, 2004


    Cassini Mission Status Report



    NASA's Cassini spacecraft successfully performed a getaway maneuver on Monday, Dec. 27, to keep it from following the European Space Agency's Huygens probe into the atmosphere of Saturn's moon Titan. This maneuver established the required geometry between the probe and the orbiter for radio communications during the probe descent on Jan. 14. The probe has no navigating capability, so the Cassini orbiter had been placed on a deliberate collision course with Titan to ensure the accurate delivery of the probe to Titan.



    The Huygens probe successfully detached from the Cassini orbiter on Dec. 24. All systems performed as expected.



    The European Space Agency's Huygens probe will be the first human-made object to explore on-site the unique environment of Titan, whose chemistry is thought to be very similar to that of early Earth before life arose.



    Next for Cassini is a flyby of Saturn's icy moon Iapetus on Dec. 31. Iapetus is Saturn's two-faced moon -- one side is very bright, and the other is very dark. One scenario for this striking difference is that the moon's surface is being resurfaced by some material spewing from within.



    The Cassini spacecraft has been in orbit around Saturn since June 30, 2004, and has returned stunning pictures of Saturn, its rings and many moons. Titan has already been the subject of two close flybys by Cassini. With 43 more flybys planned and the in-situ measurements made by the probe, it is likely only a matter of time before Titan's secrets begin to unfold.



    More information on the Cassini-Huygens mission is available at: http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini .
     
  15. Mizar

    Mizar Premium Member

    arolina Martinez (818) 354-9382

    Jet Propulsion Laboratory, Pasadena, Calif.



    News Release: 2004-300 December 30, 2004



    Cassini Caps off 2004 With Flyby of Icy Moon Iapetus



    NASA's Cassini spacecraft is set to cap off 2004 with an encounter of Saturn's ying-yang moon Iapetus (eye-APP-eh-tuss) on New Year's Eve.



    This is Cassini's closest pass yet by one of Saturn’s smaller icy satellites since its arrival around the ringed giant on June 30 of this year. The next close flyby of Iapetus is not until 2007.



    Iapetus is a world of sharp contrasts. The leading hemisphere is as dark as a freshly-tarred street, and the white, trailing hemisphere resembles freshly-fallen snow.



    Cassini will fly by the two-toned moon at a distance of approximately 123,400 kilometers (76,700 miles) on Friday, Dec. 31. This flyby brings to an end a year of major accomplishments and rings in what promises to be a year filled with new discoveries about Saturn and its moons.



    "I can think of no better way than this to wrap up what has been a whirlwind year," said Robert T. Mitchell, program manager for the Cassini mission at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The new year offers new opportunities, and 2005 will be the year of the icy satellites."



    In 2005 Cassini will have 13 targeted encounters with five of Saturn's moons. "We have 43 close flybys of Titan still ahead of us during the four-year tour. Next year, eight of our 13 close flybys will be of Titan. We will also have a number of more distant flybys of the icy satellites, and let's not forget Saturn and the rings each time we come around," said Mitchell.

    With a diameter of about 1,400 kilometers (890 miles), Iapetus is Saturn's third largest moon. It was discovered by Jean-Dominique Cassini in 1672. It was Cassini, for whom the Cassini-Huygens mission is named, who correctly deduced that one side of Iapetus was dark, while the other was white.

    Scientists still do not agree on whether the dark material originated from an outside source or was created from Iapetus' own interior. One scenario for the outside deposit of material would involve dark particles being ejected from Saturn’s little moon Phoebe and drifting inward to coat Iapetus. The major problem with this model is that the dark material on Iapetus is redder than Phoebe, although the material could have undergone chemical changes that made it redder after its expulsion from Phoebe. One observation lending credence to the theory of an internal origin is the concentration of material on crater floors, which implies that something is filling in the craters. In one model proposed by scientists, methane could erupt from the interior and then become darkened by ultraviolet radiation.

    Iapetus is odd in other respects. It is the only large Saturn moon in a highly inclined orbit, one that takes it far above and below the plane in which the rings and most of the moons orbit. It is less dense than objects of similar brightness, which implies it has a higher fraction of ice or possibly methane or ammonia in its interior.

    The last look at Iapetus was by NASA's Voyager 1 and 2 spacecraft in 1980 and 1981. The Cassini images will be the highest resolution images yet of this mysterious moon.

    The Iapetus flyby by Cassini follows the successful release of the Huygens probe on December 24.

    More information on the Cassini-Huygens mission is available at: http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini .

    The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Science Mission Directorate, Washington, D.C. JPL designed, developed and assembled the Cassini orbiter. The European Space Agency built and managed the development of the Huygens probe and is in charge of the probe operations. The Italian Space Agency provided the high-gain antenna, much of the radio system and elements of several of Cassini's science instruments.

    Cassini spacecraft targeted satellite encounters for 2005:



    Titan: January 14, 2005

    Titan: February 15, 2005

    Enceladus: March 9, 2005

    Titan: March 31, 2005

    Titan: April 16, 2005

    Enceladus: July 14, 2005

    Titan: August 22, 2005

    Titan: September 7, 2005

    Hyperion: September 26, 2005

    Dione: October 11, 2005

    Titan: October 28, 2005

    Rhea: November 26, 2005

    Titan: December 26, 2005
     
  16. Mizar

    Mizar Premium Member

    Carolina Martinez (818) 354-9382

    Jet Propulsion Laboratory, Pasadena, Calif.



    Status Report: 2005-002 January 3, 2005



    Cassini Mission Status Report



    NASA's Cassini spacecraft successfully flew by Saturn's moon Iapetus at a distance of 123,400 kilometers (76,700 miles) on Friday, Dec. 31. NASA's Deep Space Network tracking station in Goldstone, Calif., received the signal and science data that day beginning at 11:47 p.m. Pacific Standard Time.



    Iapetus is a world of sharp contrasts. The leading hemisphere is as dark as a freshly-tarred street, and the white, trailing hemisphere resembles freshly-fallen snow.



    Friday's flyby was the first close encounter of Iapetus during the four-year Cassini tour. The second and final close flyby of Iapetus is scheduled for 2007. Next up for Cassini is communications support for the European Space Agency's Huygens probe during its descent to Titan on Jan. 14.



    The Huygens probe successfully detached from the Cassini orbiter on Dec. 24. The data gathered during the descent through Titan's atmosphere will be transmitted from the probe to the Cassini orbiter. Afterward, Cassini will point its antenna to Earth and relay the data through NASA's Deep Space Network to NASA's Jet Propulsion Laboratory, Pasadena, Calif., and on to the European Space Agency's Space Operations Center in Darmstadt, Germany, which serves as the operations center for the Huygens probe mission. Two of the instruments on the probe -- the camera system and the gas chromatograph/mass spectrometer -- were provided by NASA.



    Raw images from the Iapetus flyby are available at: http://saturn.jpl.nasa.gov/multimedia/images/raw .

    More information on the Cassini-Huygens mission is available at: http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini .
     
  17. Mizar

    Mizar Premium Member

    Carolina Martinez (818) 354-9382

    Jet Propulsion Laboratory, Pasadena, Calif.



    Preston Dyches (720) 974-5823

    Cassini Imaging Central Laboratory for Operations

    Space Science Institute, Boulder, Colo.



    Press Release: 2005-005 January 7, 2005


    Saturn's Moon Iapetus Shows a Bulging Waistline



    Images returned by NASA's Cassini spacecraft cameras during a New Year's Eve flyby of Saturn’s moon Iapetus (eye-APP-eh-tuss) show startling surface features that are fueling heated scientific discussions about their origin.



    One of these features is a long narrow ridge that lies almost exactly on the equator of Iapetus, bisects its entire dark hemisphere and reaches 20 kilometers high (12 miles). It extends over 1,300 kilometers (808 miles) from side to side, along its midsection. No other moon in the solar system has such a striking geological feature. In places, the ridge is comprised of mountains. In height, they rival Olympus Mons on Mars, approximately three times the height of Mt. Everest, which is surprising for such a small body as Iapetus. Mars is nearly five times the size of Iapetus.



    Images from the flyby are available at http://saturn.jpl.nasa.gov, http://www.nasa.gov/cassini and http://ciclops.org .



    Iapetus is a two-toned moon. The leading hemisphere is as dark as a freshly-tarred street, and the white, trailing hemisphere resembles freshly-fallen snow.



    The flyby images, which revealed a region of Iapetus never before seen, show feathery-looking black streaks at the boundary between dark and bright hemispheres that indicate dark material has fallen onto Iapetus. Opinions differ as to whether this dark material originated from within or outside Iapetus. The images also show craters near this boundary with bright walls facing towards the pole and dark walls facing towards the equator.



    Cassini's next close encounter with Iapetus will occur in September 2007. The resolution of images from that flyby should be 100 times better than the ones currently being analyzed. The hope is that the increased detail may shed light on Iapetus’ amazing features and the question of whether it has been volcanically active in the past.



    With a diameter of about 1,400 kilometers (890 miles), Iapetus is Saturn's third largest moon. It was discovered by Jean-Dominique Cassini in 1672. It was Cassini, for whom the Cassini-Huygens mission is named, who correctly deduced that one side of Iapetus was dark, while the other was white.
     
  18. Mizar

    Mizar Premium Member

    Carolina Martinez (818) 354-9382

    Jet Propulsion Laboratory, Pasadena, Calif.



    Laura K. Kraft (808) 885-7887

    W. M. Keck Observatory, Mauna Kea, Hawaii



    Press Release: 2005-020 February 3, 2005


    Saturn's Bull's-Eye Marks its Hot Spot



    NASA astronomers using the Keck I telescope in Hawaii are learning much more about a strange, thermal "hot spot" on the tip of Saturn's south pole.



    In the most precise reading of Saturn's temperatures ever taken from Earth, a new set of infrared images suggests a warm "polar vortex" at Saturn's south pole - the first warm polar cap ever to be discovered in the solar system. The vortex is punctuated by a compact spot that is the warmest place on the planet. The researchers report their findings in the Feb. 4 issue of the journal Science.



    The images can be viewed at: http://www.nasa.gov/multimedia/imagegallery/ .



    A polar vortex is a persistent, large-scale weather pattern, likened to a jet stream on Earth in the upper atmosphere. On Earth, the Arctic Polar Vortex is typically located over eastern Canada and plunges arctic air to the northern plains in the United States. Earth's cold Antarctic Polar Vortex, centered over Antarctica, traps air and creates unusual chemistry, such as the effects that create the "ozone hole".



    Polar vortices on Earth, Jupiter, Mars and Venus are colder than their surroundings. But new images from the W. M. Keck Observatory show the first evidence of such a polar vortex at much warmer temperatures than their surroundings. And the even warmer, compact region at the pole itself is quite unusual.



    "There is nothing like this compact warm 'cap' in the Earth's atmosphere," said Dr. Glenn S. Orton, senior research scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., and lead author of the paper. "Meteorologists have detected sudden warming of the pole, but on Earth this effect is very short-term. This phenomenon on Saturn is longer-lived because we've been seeing hints of it in our data for at least two years."



    Data for these observations were taken in the imaging mode of the Keck facility instrument, the Long Wavelength Spectrometer, on Feb. 4, 2004, by Orton and Dr. Padma Yanamandra-Fisher, the paper's co-author, also a research scientist at JPL.



    The puzzle isn't that Saturn's south pole is warm; after all, it has been exposed to 15 years of continuous sunlight, having just reached its summer Solstice late in 2002. But both the distinct boundary of a warm polar vortex some 30 degrees latitude from the southern pole and a very hot "tip" right at the pole were completely unexpected. If the increased southern temperatures are the result of the seasonal variations of sunlight, then temperatures should increase gradually with increasing latitude. But they don't – the tropospheric temperature increases toward the pole abruptly near 70 degrees latitude from 88 to 89 Kelvin (-301 to -299 degrees Fahrenheit) and then to 91 Kelvin (-296 degrees Fahrenheit) right at the pole. Near 70 degrees latitude, the stratospheric temperature increases even more abruptly from 146 to 150 Kelvin (-197 to -189 degrees Fahrenheit) and then again to 151 Kelvin (-188 degrees Fahrenheit) right at the pole.



    The abrupt temperature changes may be caused by a concentration of sunlight-absorbing particulates trapping heat in Saturn's upper atmosphere. This theory would explain why the hot spot appears dark in visible light and contains the highest measured temperatures on Saturn. However, this alone would not explain why the particles themselves are constrained to a compact area at Saturn's south pole. One possible explanation would be downwelling of dry air, which is also consistent with deeper clouds observed at the southern pole. Researchers plan more observations to check that possibility.



    More detail about the temperatures and possible chemical changes in these regions may be available from an infrared spectrometer on the Cassini spacecraft, in orbit around Saturn. The discovery of the hot spot at Saturn's south pole has prompted Cassini's composite infrared spectrometer science team, including Orton, to redirect some future observations to this area.



    "One of the obvious questions is whether Saturn's north pole is abnormally cold and whether a cold polar vortex has been established there. That's something we can't see from Earth, and Cassini's instruments will be in a unique position to observe it," said Orton.



    Funding for this research was provided by NASA's Office of Space Sciences and

    Applications, Planetary Astronomy Discipline, and the NASA Cassini project. 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 Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C.



    The W.M. Keck Observatory is operated by the California Association for Research in Astronomy, a non-profit scientific partnership of the California Institute of Technology, the University of California, and NASA. On the Web at www.keckobservatory.org .
     
  19. JcMinJapan

    JcMinJapan Premium Member

    17.jpg

    NASA's Cassini spacecraft has had a busy week, snapping stunning new images of two of Saturn's moons -- smoggy Titan on Feb. 15 and wrinkled Enceladus on Feb. 16.

    Visible in radar images released today are a crater, channels, and terrain similar to the area where the European Space Agency's Huygens probe landed on Jan. 14.

    The crater is approximately 60 kilometers (37 miles) in diameter. Earlier this week, the radar team released an image of a giant impact crater dubbed "Circus Maximus," about 440 kilometers wide (273 miles).

    "The appearance of the small crater and the extremely bright, hence rough, blanket of material surrounding it is indicative of an origin by impact," said Dr. Jonathan Lunine, Cassini interdisciplinary scientist from the University of Arizona, Tucson.

    From the crater's size, scientists estimate that it was created when a comet or asteroid roughly 5 to 10 kilometers (3 to 6 miles) in size slammed into the surface of Titan. The feature lacks a central peak, suggesting that it has been eroded or otherwise modified since formation. Rainfall, wind erosion, and softening of the solid material in which the crater formed are all possible processes that might have altered this impact feature.

    Also visible in the radar images are channels located just east of Circus Maximus, the large impact crater. The longest channel is approximately 200 kilometers long (124 miles). The channels appear to flow from the slopes of the crater. The fluid was most likely liquid methane, given the extremely cold ambient conditions at the surface of Titan. The area somewhat resembles the rubble-strewn plains in the region where the Huygens probe landed.

    Just one day after the Titan flyby, Cassini turned its sights on Saturn's moon Enceladus, revealing a fascinating, tortured world of ice. The spacecraft swept within 1,180 kilometers (730 miles) of the moon's wrinkled surface, providing the first-ever high resolution images of this world with the brightest, most reflective surface in the solar system.

    Since NASA's Voyager spacecraft flew past Enceladus in 1980 and 1981, planetary scientists have been intrigued by the moon's wrinkled terrain and smooth plains, some of which appeared to be relatively free of impact craters. Smooth, crater-free surfaces on moons and planets indicate geologically young ages, while wrinkles may indicate tectonic activity or volcanism.

    "Cassini has now viewed these terrains at almost 10 times better resolution than Voyager," said Dr. Carolyn Porco, Cassini imaging team leader based at the Space Science Institute in Boulder, Colo. "Interestingly, the icy surface of Enceladus appears to have similarities to both Europa and Ganymede -- two prominent icy satellites of Jupiter -- and topographic relief of about 1 kilometer [.6 mile]. Both Europa and Ganymede are thought to have subsurface water layers, or 'oceans,' so the similarities with Enceladus are intriguing."

    One view released today is a high-resolution mosaic showing complex systems of fractures and resurfaced terrain. Among the most intriguing features in the images are a series of small, dark spots, which in many places seem to be aligned in chains parallel to narrow fractures.

    A false-color view shows some linear features on Enceladus with a slightly different color from their surroundings. Different colors of ice may be caused by varying compositions or varying ice crystal sizes. Either one can indicate different formation mechanisms or different ages. Another early highlight from the flyby is a high-resolution stereo view of Enceladus. Stereo views are helpful in interpreting the moon's complex topography.

    Other preliminary results from the visual and infrared mapping spectrometer show a surface composed of only pure water ice, with no other compounds detected. Ammonia or ammonium compounds and carbon dioxide were expected, but not seen in the data. Further analysis may find trace amounts. "The spectra look like laboratory fabricated water ice, indicating the ice is quite pure," said Dr. Roger N. Clark, Cassini science team member at the U.S. Geological Survey in Denver.

    During the latest flybys, Cassini was 1,577 kilometers (980 miles) above Titan, and 1,180 kilometers (730 miles) above Enceladus. Cassini will conduct an even closer flyby of Enceladus on March 9, coming within approximately 500 kilometers (310 miles) of its surface. More than 40 additional Titan flybys are planned.

    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 Cassini-Huygens 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 team is based at the Space Science Institute, Boulder, Colo
     
  20. mscbkc070904

    mscbkc070904 Premium Member

    CASSINI IMAGES DISCOVER A WINDY, WAVY TITAN ATMOSPHERE

    The dynamic atmosphere of Saturn’s haze-enshrouded moon Titan is revealed in the first Cassini Imaging Team report on Titan, to appear in the March 10 issue of Nature.

    Imaging scientists, analyzing images of Titan designed to allow views of the surface and lower atmosphere, have discovered that the winds on Titan blow a lot faster than the moon rotates. In contrast, the jet stream of Earth blows a lot slower than the surface of our planet moves.

    Titan is a particularly slow rotator, taking 16 Earth days to make one full rotation. Yet, despite its slow period, model simulations made a decade ago predicted that winds in its atmosphere should blow faster than its surface rotates, making it, like its slowly rotating cousin Venus, one of the solar system’s ‘super-rotators’.

    “It has long been known that winds in Venus’s atmosphere blow many times faster than the solid planet itself rotates,” said imaging team member Dr. Tony DelGenio of NASA’s Goddard Institute for Space Studies, or GISS, in New York, who made the first computer simulation predicting Titan super-rotation a decade ago. “Models of Titan’s atmosphere have indicated that it too should super-rotate just like Venus, but until now there have been no direct wind measurements to test the prediction,” he said.

    Titan’s winds are measured by watching its clouds move. Clouds are a rare occurrence on Titan, and those whose motions can be tracked are often small (about 100 kilometers or 60 miles across) and faint; in other words, the clouds are too inconspicuous to be seen from Earth. The discovery of moving clouds required careful manipulation of Cassini images in which cloud features are hard to distinguish through the moon’s ubiquitous haze and against the backdrop of Titan’s complex bright and dark surface. DelGenio and his associate John Barbara, also of GISS, used Cassini images that had been taken through special filters designed to see through the haze to detect surface features as well as clouds. "To discriminate clouds from surface features, I took images of the same region at different times and subtracted them from each other,” said Barbara. “When I did this, time-variable clouds stood out as regions of changing brightness.”

    Ten such clouds have been tracked, giving wind speeds as high as 34 meters per second (about 75 miles per hour) to the east – hurricane strength – at an altitude somewhere in Titan's middle and lower troposphere. "This result is consistent with the predictions of Titan weather models, and it suggests that we now understand the basic features of how meteorology works on slowly rotating planets," said Del Genio.

    Cassini images also reveal much larger cloud streaks – 1,000 kilometers (620 miles) long – elongated generally east-west. These clouds occur at preferred locations and move at only a few meters per second. Apparently these streak clouds originate closer to Titan’s surface, perhaps from places where methane is released to the atmosphere from below Titan’s surface, or places where wind blows over topography.

    In Titan’s hazy stratosphere, it looks as though modelers may have to go back to the drawing board. Voyager images of Titan detected a faint detached haze layer above Titan’s main stratospheric haze, at altitudes of 300-350 kilometers (190 to 220 miles). Cassini ultraviolet images, which are sensitive to scattering of sunlight by small particles, detect a similar detached haze layer, but at an altitude of 500 kilometers (310 miles) instead.

    “The change we see in the detached haze over the 25 years since Voyager suggests that either the photochemical process that produce the hydrocarbon haze particles, or the atmospheric circulation that distributes them around the planet, may change with the seasons,” said imaging team member Dr. Bob West of the Jet Propulsion Laboratory, who designed all the Titan atmosphere imaging sequences for the Cassini mission. “It will be a challenge for models to be able to predict how and where these detached hazes occur,” he said.

    Images of Titan’s night side, in which high haze layers are backlit by the Sun, surprised scientists by showing evidence of an entire series of haze layers. These may be evidence of gravity waves, the atmospheric equivalent of ripples on a pond, propagating up to Titan’s upper stratosphere by disturbances that originate at lower levels. If so, then analysis of the properties of these waves may yield insights into the temperature and wind profiles of Titan’s stratosphere and how they change over the course of the mission.

    Images associated with this release, and information about the Cassini-Huygens mission, are available at http://ciclops.org
    http://saturn.jpl.nasa.gov
    http://www.nasa.gov/cassini.