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New Cassini Data From Titan indicate A Rigid, Weathered Ice Shell

August 28, 2013 Leave a comment

An analysis of gravity and topography data from Saturn’s largest moon, Titan, has revealed unexpected features of the moon’s outer ice shell. The best explanation for the findings, the authors said, is that Titan’s ice shell is rigid and that relatively small topographic features on the surface are associated with large roots extending into the underlying ocean. The study is published in the August 29 issue of the journal Nature.

Led by planetary scientists Douglas Hemingway and Francis Nimmo at the University of California, Santa Cruz, the study used new data from NASA’s Cassini spacecraft. The researchers were surprised to find a negative correlation between the gravity and topography signals on Titan.

“Normally, if you fly over a mountain, you expect to see an increase in gravity due to the extra mass of the mountain. On Titan, when you fly over a mountain the gravity gets lower. That’s a very odd observation,” said Nimmo, a professor of Earth and planetary sciences at UC Santa Cruz.

Full Story: http://news.ucsc.edu/2013/08/titan-ice-shell.html

NASA Interplanetary Probes To Take Pictures Of Earth


Two NASA spacecraft, one studying the Saturn system, the other observing Mercury, are maneuvering into place to take pictures of Earth on July 19 and 20.

The image taken from the Saturn system by NASA’s Cassini spacecraft will occur between 2:27 and 2:42 PDT (5:27 and 5:42 p.m. EDT, or 21:27 and 21:47 UTC) Friday, July 19. Cassini will be nearly 900 million miles (nearly 1.5 billion kilometers) away from Earth. NASA is encouraging the public to look and wave in the direction of Saturn at the time of the portrait and share their pictures via the Internet.

The Cassini Earth portrait is part of a more extensive mosaic — or multi-image picture — of the Saturn system as it is backlit by the sun. The viewing geometry highlights the tiniest of ring particles and will allow scientists to see patterns within Saturn’s dusty rings. Processing of the Earth images is expected to take a few days, and processing of the full Saturn system mosaic will likely take several weeks.

Full Story and Links: http://www.jpl.nasa.gov/news/news.php?release=2013-225

Revealed The Mystery Of The Gigantic Storm On Saturn


We now understand the nature of the giant storms on Saturn. Through the analysis of images sent from the Cassini space probe belonging to the North American and European space agencies (NASA and ESA respectively), as well as the computer models of the storms and the examination of the clouds therein, the Planetary Sciences Group of the University of the Basque Country has managed to explain the behaviour of these storms for the very first time. The article explaining the discovery, the lead author being Enrique García Melendo, researcher at the Fundació Observatori Esteve Duran – Institut de Ciències de l’Espai, of Catalonia, was published in Nature Geosciences.

Approximately once every Saturnian year – equivalent to 30 Earth years – an enormous storm is produced on the ringed planet and which affects the aspect of its atmosphere on a global scale. These gigantic storms are known as Great White Spots, due to the appearance they have on the atmosphere of the planet. The first observation of one of these was made in 1876; the Great White Spot of 2010 was the sixth one to be observed. On this occasion the Cassini space vehicle was able to obtain very high resolution images of this great meteorological structure.

Full Story: http://www.ehu.es/p200-hmencont/en/contenidos/noticia/20130623_tormenta_saturno/en_info/tormenta_saturno.html

Cassini Finds Hints Of Activity At Saturn Moon Dione


Image credit: NASA/JPL/Space Science Institute

Image credit: NASA/JPL/Space Science Institute

From a distance, most of the Saturnian moon Dione resembles a bland cueball. Thanks to close-up images of a 500-mile-long (800-kilometer-long) mountain on the moon from NASA’s Cassini spacecraft, scientists have found more evidence for the idea that Dione was likely active in the past. It could still be active now.

“A picture is emerging that suggests Dione could be a fossil of the wondrous activity Cassini discovered spraying from Saturn’s geyser moon Enceladus or perhaps a weaker copycat Enceladus,” said Bonnie Buratti of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who leads the Cassini science team that studies icy satellites. “There may turn out to be many more active worlds with water out there than we previously thought.”

Other bodies in the solar system thought to have a subsurface ocean – including Saturn’s moons Enceladus and Titan and Jupiter’s moon Europa – are among the most geologically active worlds in our solar system. They have been intriguing targets for geologists and scientists looking for the building blocks of life elsewhere in the solar system. The presence of a subsurface ocean at Dione would boost the astrobiological potential of this once-boring iceball.

Full Story: http://www.jpl.nasa.gov/news/news.php?release=2013-178

Forecast For Titan: Wild Weather Could Be Ahead


Ligeia Mare, the second largest known body of liquid on Saturn's moon Titan. Image credit: NASA/JPL-Caltech/ASI/Cornell

Ligeia Mare, the second largest known body of liquid on Saturn’s moon Titan. Image credit: NASA/JPL-Caltech/ASI/Cornell

Saturn’s moon Titan might be in for some wild weather as it heads into its spring and summer, if two new models are correct. Scientists think that as the seasons change in Titan’s northern hemisphere, waves could ripple across the moon’s hydrocarbon seas, and hurricanes could begin to swirl over these areas, too. The model predicting waves tries to explain data from the moon obtained so far by NASA’s Cassini spacecraft. Both models help mission team members plan when and where to look for unusual atmospheric disturbances as Titan summer approaches.

“If you think being a weather forecaster on Earth is difficult, it can be even more challenging at Titan,” said Scott Edgington, Cassini’s deputy project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “We know there are weather processes similar to Earth’s at work on this strange world, but differences arise due to the presence of unfamiliar liquids like methane. We can’t wait for Cassini to tell us whether our forecasts are right as it continues its tour through Titan spring into the start of northern summer.”

Full Story: http://www.jpl.nasa.gov/news/news.php?release=2013-170&cid=release_2013-170

Cassini Shapes First Global Topographic Map Of Titan


Image credit: NASA/JPL-Caltech / ASI / JHUAPL / Cornell/Weizmann

Image credit: NASA/JPL-Caltech / ASI / JHUAPL / Cornell/Weizmann

Scientists have created the first global topographic map of Saturn’s moon Titan, giving researchers a valuable tool for learning more about one of the most Earth-like and interesting worlds in the solar system. The map was just published as part of a paper in the journal Icarus.

Titan is Saturn’s largest moon – with a radius of about 1,600 miles (2,574 kilometers), it’s bigger than planet Mercury – and is the second-largest moon in the solar system. Scientists care about Titan because it’s the only moon in the solar system known to have clouds, surface liquids and a mysterious, thick atmosphere. The cold atmosphere is mostly nitrogen, like Earth’s, but the organic compound methane on Titan acts the way water vapor does on Earth, forming clouds and falling as rain and carving the surface with rivers. Organic chemicals, derived from methane, are present in Titan’s atmosphere, lakes and rivers and may offer clues about the origins of life.

“Titan has so much interesting activity – like flowing liquids and moving sand dunes – but to understand these processes it’s useful to know how the terrain slopes,” said Ralph Lorenz, a member of the Cassini radar team based at the Johns Hopkins University Applied Physics Laboratory, Laurel, Md., who led the map-design team. “It’s especially helpful to those studying hydrology and modeling Titan’s climate and weather, who need to know whether there is high ground or low ground driving their models.”

Full Story: http://www.jpl.nasa.gov/news/news.php?release=2013-161

Telling Time On Saturn


Image courtesy of NASA

Image courtesy of NASA

A University of Iowa undergraduate student has discovered that a process occurring in Saturn’s magnetosphere is linked to the planet’s seasons and changes with them, a finding that helps clarify the length of a Saturn day and could alter our understanding of the Earth’s magnetosphere.

Saturn’s magnetosphere is the third largest structure in the solar system, eclipsed only by the magnetic fields of the sun and Jupiter. Unlike Earth, which has a visible rocky surface and rotates once every 24 hours, Saturn is composed mostly of clouds and liquid gas layers, each rotating about the planet at its own rate of speed. This variation in rotation made it difficult for scientists to pin down time for the planet.

Now, using data from NASA’s Cassini spacecraft, which entered orbit around Saturn in 2004, UI space physicist Donald Gurnett and other scientists showed that the north and south poles have their own SKR “days” that vary over periods of weeks and years. How these different periods arise and are driven through the magnetosphere has become a central question of the Cassini mission, according to NASA officials.

Full Story: http://now.uiowa.edu/2013/03/telling-time-saturn

NASA Probe Gets Close-Up Views Of Large Hurricane On Saturn


Image Credit: NASA/JPL-Caltech/SSI

Image Credit: NASA/JPL-Caltech/SSI

NASA’s Cassini spacecraft has provided scientists the first close-up, visible-light views of a behemoth hurricane swirling around Saturn’s north pole.

In high-resolution pictures and video, scientists see the hurricane’s eye is about 1,250 miles (2,000 kilometers) wide, 20 times larger than the average hurricane eye on Earth. Thin, bright clouds at the outer edge of the hurricane are traveling 330 mph(150 meters per second). The hurricane swirls inside a large, mysterious, six-sided weather pattern known as the hexagon.

“We did a double take when we saw this vortex because it looks so much like a hurricane on Earth,” said Andrew Ingersoll, a Cassini imaging team member at the California Institute of Technology in Pasadena. “But there it is at Saturn, on a much larger scale, and it is somehow getting by on the small amounts of water vapor in Saturn’s hydrogen atmosphere.”

Scientists will be studying the hurricane to gain insight into hurricanes on Earth, which feed off warm ocean water. Although there is no body of water close to these clouds high in Saturn’s atmosphere, learning how these Saturnian storms use water vapor could tell scientists more about how terrestrial hurricanes are generated and sustained.

Full Story and Images: http://www.jpl.nasa.gov/news/news.php?release=2013-149#

NASA Probe Observes Meteors Colliding With Saturn’s Rings


Image Credit: NASA/JPL-Caltech/Space Science Institute/Cornell

Image Credit: NASA/JPL-Caltech/Space Science Institute/Cornell

NASA’s Cassini spacecraft has provided the first direct evidence of small meteoroids breaking into streams of rubble and crashing into Saturn’s rings.

These observations make Saturn’s rings the only location besides Earth, the moon and Jupiter where scientists and amateur astronomers have been able to observe impacts as they occur. Studying the impact rate of meteoroids from outside the Saturnian system helps scientists understand how different planet systems in our solar system formed.

The solar system is full of small, speeding objects. These objects frequently pummel planetary bodies. The meteoroids at Saturn are estimated to range from about one-half inch to several yards (1 centimeter to several meters) in size. It took scientists years to distinguish tracks left by nine meteoroids in 2005, 2009 and 2012.

Results from Cassini have already shown Saturn’s rings act as very effective detectors of many kinds of surrounding phenomena, including the interior structure of the planet and the orbits of its moons. For example, a subtle but extensive corrugation that ripples 12,000 miles (19,000 kilometers) across the innermost rings tells of a very large meteoroid impact in 1983.

Full Story: http://www.jpl.nasa.gov/news/news.php?release=2013-147

Ice Cloud Heralds Fall At Titan’s South Pole


 

Credit: NASA/JPL-Caltech/Space Science Institute/GSFC

Credit: NASA/JPL-Caltech/Space Science Institute/GSFC

An ice cloud taking shape over Titan’s south pole is the latest sign that the change of seasons is setting off a cascade of radical changes in the atmosphere of Saturn’s largest moon. Made from an unknown ice, this type of cloud has long hung over Titan’s north pole, where it is now fading, according to observations made by the Composite Infrared Spectrometer (CIRS) on NASA’s Cassini spacecraft.

“We associate this particular kind of ice cloud with winter weather on Titan, and this is the first time we have detected it anywhere but the north pole,” said the study’s lead author, Donald E. Jennings, a CIRS Co-Investigator at NASA’s Goddard Space Flight Center in Greenbelt, Md.

The southern ice cloud, which shows up in the far infrared part of the light spectrum, is evidence that an important pattern of global air circulation on Titan has reversed direction. When Cassini first observed the circulation pattern, warm air from the southern hemisphere was rising high in the atmosphere and got transported to the cold north pole. There, the air cooled and sank down to lower layers of the atmosphere, where it formed ice clouds. A similar pattern, called a Hadley cell, carries warm, moist air from Earth’s tropics to the cooler middle latitudes.

Full Story: http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20130411.html