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(Astronomy) Saturn's Spongy Moon

 
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PostPosted: Mon Jan 02, 2006 8:39 am    Post subject: (Astronomy) Saturn's Spongy Moon Reply with quote






Saturn is one of the planets in our solar system. It is the planet known for its rings. Explore this planet starting with the article below and the numerous links provided at the end. These websites were specifically designed for children. There are numerous images provided as well as links to the missions that have been launched to explore the planet of rings.

Saturn's Spongy Moon
Oct. 12, 2005
Emily Sohn

Saturn has a lot going for it. The planet's spectacular rings are pretty cool. It has 31 moons, maybe more. Its largest moon, Titan, even has its own atmosphere. One of its smaller moons, Hyperion, looks like a potato and tumbles strangely as it orbits the planet.

Now, the Cassini spacecraft, which is in orbit around Saturn, has taken the first close-up pictures of Hyperion. And the view is surprising.

Hyperion is 266 kilometers (165 miles) across, and it has an irregular shape. Much of its inside is probably empty space. Scientists describe the moon as a "rubble pile."

On Sept. 26, Cassini swooped to within 500 kilometers (310 miles) of the icy moon. The close-up images showed that Hyperion's surface is unlike that of any of the planet's other moons. They revealed a reddish surface dotted with craters and changed by some unknown process to give it a spongy look.

Some Cassini researchers suspect that the spongelike appearance is a result of closely packed craters that were never filled in. Usually, when craters form, debris falls back into the holes. The gravity from nearby Titan, however, may have prevented that from happening.—E. Sohn


http://www.sciencenewsforkids....../Note3.asp

From Science News for Kids Oct. 12, 2005.

*************************************************************
Questions to explore further this topic:

What is Saturn?

http://www.frontiernet.net/~kidpower/saturn.html
http://kids.nineplanets.org/saturn.htm
http://www.esa.int/esaKIDSen/S.....rse_0.html
http://www.dustbunny.com/afk/planets/saturn/
http://saturn.jpl.nasa.gov/new...../index.cfm
http://saturn.jpl.nasa.gov/new.....planet.cfm

Images from Saturn and its moons:

http://saturn.jpl.nasa.gov/home/index.cfm

The Rings of Saturn:

http://saturn.jpl.nasa.gov/new...../rings.cfm

The Moons of Saturn:

http://saturn.jpl.nasa.gov/new...../moons.cfm
http://www.kidsastronomy.com/saturn/moons.htm
http://saturn.jpl.nasa.gov/kid.....-moons.cfm
http://www.enchantedlearning.c.....oons.shtml
http://www.sciencenewsforkids....../Note3.asp

Titan, One of Saturn's Moons:

http://www.esa.int/esaKIDSen/S.....rse_0.html
http://www.sciencenewsforkids......ature1.asp
http://www.sciencenewsforkids....../Note2.asp

Saturn's Moon Hyperion:

http://www.planetary.org/explo.....erion.html

Animations and Images from Saturn:

http://pds-rings.seti.org/saturn/#ANIMATIONS

History of Saturn observation:

http://soc.jpl.nasa.gov/history.cfm
http://saturn.jpl.nasa.gov/new.....istory.cfm
http://saturn.jpl.nasa.gov/new.....ed-obs.cfm

What is the Cassini-Huygens mission?

http://www.esa.int/SPECIALS/Kids_Comic/index.html
http://www.sciencenewsforkids......ature1.asp
http://www.esa.int/esaKIDSen/S.....rse_0.html
http://saturn.jpl.nasa.gov/kid.....tories.cfm
http://saturn.jpl.nasa.gov/new.....ecraft.cfm
http://saturn.jpl.nasa.gov/new.....cience.cfm

Getting Cassini to the Kennedy Space Center:

http://saturn.jpl.nasa.gov/kids/amazing-ksc.cfm

DVD with signatures on its way to Saturn:

http://saturn.jpl.nasa.gov/kids/amazing-ksc.cfm

Cassini members are singers too:

http://saturn.jpl.nasa.gov/kid.....ingers.cfm

Moments of Inspiration:

http://saturn.jpl.nasa.gov/kid.....ration.cfm

GAMES

http://www.surfnetkids.com/games/saturn-sc.htm
http://www.esa.int/esaKIDSen/SEMBM7XDE2E_q.html
http://www.esa.int/esaKIDSen/games.html
http://www.esa.int/esaKIDSen/games_1_a.html
http://www.esa.int/esaKIDSen/games_9_a.html
http://www.esa.int/esaKIDSen/games_17_a.html
http://www.esa.int/esaKIDSen/games_25_a.html


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PostPosted: Thu Mar 09, 2006 2:35 pm    Post subject: NASA's Cassini Discovers Potential Liquid Water on Enceladus Reply with quote

NASA's Cassini Discovers Potential Liquid Water on Enceladus
March 9, 2006
(Source: NASA/JPL)
http://saturn.jpl.nasa.gov/new.....newsID=639

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

NASA's Cassini spacecraft may have found evidence of liquid water reservoirs that erupt in Yellowstone-like geysers on Saturn's moon Enceladus. The rare occurrence of liquid water so near the surface raises many new questions about the mysterious moon.

"We realize that this is a radical conclusion -- that we may have evidence for liquid water within a body so small and so cold," said Dr. Carolyn Porco, Cassini imaging team leader at Space Science Institute, Boulder, Colo. "However, if we are right, we have significantly broadened the diversity of solar system environments where we might possibly have conditions suitable for living organisms."

High-resolution Cassini images show icy jets and towering plumes ejecting large quantities of particles at high speed. Scientists examined several models to explain the process. They ruled out the idea that the particles are produced by or blown off the moon's surface by vapor created when warm water ice converts to a gas. Instead, scientists have found evidence for a much more exciting possibility -- the jets might be erupting from near-surface pockets of liquid water above 0 degrees Celsius (32 degrees Fahrenheit), like cold versions of the Old Faithful geyser in Yellowstone.


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

Mission scientists report these and other Enceladus findings in this week's issue of Science.

"We previously knew of at most three places where active volcanism exists: Jupiter's moon Io, Earth, and possibly Neptune's moon Triton. Cassini changed all that, making Enceladus the latest member of this very exclusive club, and one of the most exciting places in the solar system," said Dr. John Spencer, Cassini scientist, Southwest Research Institute, Boulder, Colo.

"Other moons in the solar system have liquid-water oceans covered by kilometers of icy crust," said Dr. Andrew Ingersoll, imaging team member and atmospheric scientist at the California Institute of Technology, Pasadena, Calif. "What's different here is that pockets of liquid water may be no more than tens of meters below the surface."

Other unexplained oddities now make sense. "As Cassini approached Saturn, we discovered that the Saturnian system is filled with oxygen atoms. At the time we had no idea where the oxygen was coming from," said Dr. Candy Hansen, Cassini scientist at NASA's Jet Propulsion Laboratory in Pasadena. "Now we know that Enceladus is spewing out water molecules, which break down into oxygen and hydrogen."


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

Scientists are also seeing variability at Enceladus. "Even when Cassini is not flying close to Enceladus, we can detect that the plume's activity has been changing through its varying effects on the soup of electrically-charged particles that flow past the moon," said Dr. Geraint H. Jones, Cassini scientist, magnetospheric imaging instrument, Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany.

Scientists still have many questions. Why is Enceladus currently so active? Are other sites on Enceladus active? Might this activity have been continuous enough over the moon's history for life to have had a chance to take hold in the moon's interior?

"Our search for liquid water has taken a new turn. The type of evidence for liquid water on Enceladus is very different from what we've seen at Jupiter's moon Europa. On Europa the evidence from surface geological features points to an internal ocean. On Enceladus the evidence is direct observation of water vapor venting from sources close to the surface," said Dr. Peter Thomas, Cassini imaging scientist, Cornell University, Ithaca, N.Y.

In the spring of 2008, scientists will get another chance to look at Enceladus when Cassini flies within 350 kilometers (approximately 220 miles), but much work remains after Cassini¿s four-year prime mission is over.

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

"There's no question that, along with the moon Titan, Enceladus should be a very high priority for us. Saturn has given us two exciting worlds to explore," said Dr. Jonathan Lunine, Cassini interdisciplinary scientist, University of Arizona, Tucson, Ariz.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the 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 .
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PostPosted: Fri Apr 07, 2006 10:33 am    Post subject: New Cassini image Reply with quote

University of Colorado at Boulder
6 April 2006
New Cassini image shows "A" ring contains more debris than once thought

Views of Saturn's stunning ring system from above by the Cassini-Huygens spacecraft now orbiting the planet indicate the prominent A ring contains more debris than once thought, according to a new University of Colorado at Boulder study.
Previous observations with the Voyager spacecraft in the early 1980s found the ring was more transparent, indicating less material, said Joshua Colwell of CU-Boulder's Laboratory for Atmospheric and Space Physics. But new calculations based on May 2005 observations with Cassini's Ultraviolet Imaging Spectrograph, or UVIS, indicates the opacity of the ring is up to 35 percent higher than previously reported.

Because of the uneven distribution of the ring particles - which range in size from dust grains to school buses - the transparency of the rings depends on the angle from which they are viewed, he said. The particles are arranged essentially parallel in long stringy clumps as large as 60 feet across, 16 feet thick and 160 feet long, according to models produced from observation data, said Colwell.

A paper on the subject by Colwell, Larry Esposito and Miodrag Sremcevic of CU-Boulder's LASP appears in the April 1 issue of Geophysical Research Letters, or GRL. Esposito is science team leader for UVIS, a $12.5 million instrument designed and built at CU-Boulder by LASP that is riding on the Cassini spacecraft.

A new image released by the team in conjunction with the GRL paper shows the distribution of the ring material. The opaque B ring has more material than the A ring, located just outside it, and the A ring is densest near its inner edge, according to the team. The new clumps observed by Cassini mean a larger amount of material overall said Colwell, a LASP research associate and UVIS science team member.

The particles are trapped in ever-changing clusters of debris that are regularly torn apart and reassembled by gravitational forces from the planet, Colwell said. The size and behavior of the clusters were deduced by observing flickering light as the ring passed in front of a star in a process known as stellar occultation, he said.

"The flickers are like a time-lapse movie of a car's headlights taken from the other side of a picket fence," said Colwell. "The flickering would provide us details about the pickets."

The observations of the particle clusters indicate the A ring is primarily empty space. A close-up view of the rings would show as "short, flattened strands of spiral arms with very few particles between them," he said.


###
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 in Washington, D.C.

The Cassini orbiter was designed, developed and assembled at JPL. For more information about the Cassini-Huygens mission, visit

http://saturn.jpl.nasa.gov

The ultraviolet imaging spectrograph team home page is at

http://lasp.colorado.edu/cassini
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PostPosted: Sun Aug 06, 2006 7:36 am    Post subject: Titan's Lakes: Evidence of liquid on Saturn's largest moon Reply with quote

Science News Online
Week of Aug. 5, 2006; Vol. 170, No. 6

Titan's Lakes: Evidence of liquid on Saturn's largest moon
Ron Cowen

New radar images indicate that Saturn's giant moon Titan contains lakes of liquid hydrocarbons. The finding provides the first compelling evidence for bodies of liquid on the surface of any object besides Earth, say the researchers who analyzed the images.


For the full article:

http://sciencenews.org/articles/20060805/fob1.asp
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PostPosted: Thu Oct 05, 2006 9:15 am    Post subject: Through Saturn’s atmosphere Reply with quote

Through Saturn’s atmosphere
Basque Research
October 5, 2006

Saturn is famous for its rings. Nevertheless, it does have other, characteristic if not unique, features – its atmosphere, for example. The prime aim of the Planetary Science Group at the University of the Basque Country (EHU-UPV) is, in fact, to study the atmospheres of the planets: their cloud formations and fogs, how these are distributed vertically in the atmosphere, their movement and their meteorology in general.

To study Saturn’s atmosphere, images from the Hubble space telescope were used. There were numerous photographs – more than 200 were taken over the ten-year period from 1994 to 2004. These are pictures that enabled us to find out what the planet is like and what it looks like, observed in different wavelengths. This is the observational part of the study.

But, a numerical simulation can also be undertaken. This is based on the use of numerical codes, which reproduce the manner in which photons enter the atmosphere, and how they are emitted in different directions until some of them are absorbed and others emitted once again into space, i.e. reflected by the atmosphere.

These numerical codes have been developed over the past few years by a team from the EHU-UPV who, on analysing this light reflected by the atmosphere, were able to infer what particles are behind this reflection, i.e. by observing the reflected light, they could determine the number of cloud layers, their depth, the optical properties thereof, and so on. In this way, Saturn’s clouds and their evolution were studied over ten years, a relatively long time for a study of this nature.

Wind variation

Once the structural characteristics of the atmosphere were determined, other members of the team were able to evaluate the altitude at which these winds were located on the giant planet. This is of great importance in understanding the meteorology of the planet, given that it provides a three-dimensional image of its atmosphere.

In 2003, the Planetary Science Group, with images from the Hubble space telescope, observed an intense variation of the winds in Saturn’s atmosphere at its equator - in comparison to the previous measurements by the Voyager space probe. This was something that nobody really expected.

The winds at the equator of Saturn, measured by the Voyager space probe at the beginning of the 80s, blew with an enormous force - about 1700 km/h. Nevertheless, in 2003, a drop of 40% in this value was observed, as if a brake had been applied to the winds. Subsequently, when the Cassini probe arrived in 2004, it was observed that, at certain wavelengths, there were slower winds and, at others, more rapid winds. Thus, the hypothesis was put forward that the winds slackened according to altitude – the winds blowing at higher altitudes were less intense than those at lower altitudes. This, in principle, would have been expected, given that atmospheric winds generally vary with height. The EHU-UPV team quantified this hypothesis in such a way as to make it a valid one, based on measurements of the variation of the wind as a function of altitude.

Nevertheless, compared with the winds measured in the Voyager period, it was shown, effectively, that there had been an important variation. The fact is that, in 1990, there was an enormous storm at the equator of Saturn. On Saturn there is a phenomenon that repeats itself every 30 years approximately – a huge storm that disturbs an enormous region of the planet, a storm several times bigger than our own planet. The Planetary Science Group at EHU-UPV are currently trying, amongst other endeavours, to analyse how this type of phenomena might affect an atmosphere like that on planet Saturn.


Notes


Research team:
A. Sanchez-Lavega, J. Arregi, S. Baeza, R. Hueso, E. Garcia-Melendo, J. Legarreta, S. Perez-Hoyos, J.F. Rojas, N. Barrado and J. Peralta.

Department:
Applied Physics I

Faculty:
Engineering High School (Bilbao)

Photography:
NASA/ESA/HST

Internet reference
www.ajax.ehu.es/index.eusk.html
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PostPosted: Thu Oct 12, 2006 7:01 am    Post subject: Cassini finds more rings highlighted by telltale small parti Reply with quote

Cassini Imaging Central Laboratory for Operations (CICLOPS)
11 October 2006

Cassini finds more rings highlighted by telltale small particles

Images taken by NASA's Cassini spacecraft, looking in the direction of the Sun, have provided scientists fresh insights into the dynamic nature of the rings and, in particular, the creation of new rings made from tiny particles released from larger bodies.

Cassini findings being presented this week at the Division for Planetary Sciences Meeting of the American Astronomical Society held in Pasadena, Calif. include several new faint ring structures formed by processes acting on and within Saturn's moons and main rings.

A series of unique observations gathered in mid-September by NASA's Saturn-orbiting Cassini spacecraft as it drifted slowly through Saturn's shadow, allowed the entire ring system to be seen from a perspective that highlights microscopic ring particles: in many cases, particles only recently released into Saturn orbit. While observing from this locale, Cassini spotted, a single faint new ring, announced previously, in the shared orbit of the moons Janus and Epimetheus.

Scientists are now ecstatic to find even more rings. A second new diffuse but narrow ring is coincident with the orbit of the tiny moon Pallene, also discovered by Cassini's imaging cameras and only 4 kilometers (2.5 miles) across. Curiously, another similar-sized moon called Methone, discovered earlier in the mission in roughly the same region, does not seem to sport a ring.

A third diffuse ring--the brightest seen in the Cassini Division between the main A and B rings--was also spotted on Sept. 15 from Saturn's shadow.

Finally, a faint, very narrow, and seemingly discontinuous ringlet was also found between the broad bands of ring material in the Cassini Division. Though too small to be resolved during the September observations, it too was first seen in images taken in a geometry that enhances the visibility of small particles.

"Cassini's superior cameras and close orbits around Saturn allow us to spot fainter and narrower rings than Voyager was able to see", said Dr. Joseph Spitale, an imaging team associate working with team leader Dr. Carolyn Porco. "I wouldn't be surprised if we find more as time goes on."

All of these new rings are likely formed and maintained by impacts onto larger bodies, whether moons or large ring particles. These impacts blast material off their surfaces, creating diffuse rings in the same orbit as the parent body.

Saturn's diffuse rings are a subset that includes the E, G, and newly discovered rings. Scientists suspect that the G ring is created by impacts into bodies trapped in a remarkably bright arc in the ring. Unlike the other diffuse rings, however, Cassini observations have confirmed that the E ring is created by tiny ice particles spewing from surface jets on the geologically active moon Enceladus.

No matter how they are released, small grains are pushed about by sunlight and by electrical forces; hence their distribution tells much about the local space environment.

Imaging scientists have also noticed color variations across the diffuse rings that imply active processes sort the particles along the ring according to their sizes. Looking at the faint rings on one side of Saturn, the E ring appears to have a red core with a bluish halo, but the appearance is reversed on the right side--where there is a blue ring interior to a red ring.

According to Dr. Matt Hedman, an imaging team associate working at Cornell University in Ithaca, NY, this color variation may imply particles are being sorted by some process according to their sizes.

"These tiny grains are like spices--even a little bit of material can alter the ring's character," Hedman said.

Additionally, Cassini acquired a movie sequence and other images showing the narrowly confined G ring and its faint arc of material, which is likely held in place by a gravitational resonance with one of Saturn's moons.

Imaging Team member Joe Burns, also of Cornell University remarks, "We've been stunned by the rings' variability. Who would have thought, even a few years ago, that we'd see so many new features as the Cassini mission progressed?"


###
Images accompanying this release, including the G ring movie and a full color panoramic view of Saturn, are available at http://ciclops.org
http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team consists of scientists from the U.S., England, France, and Germany. The imaging operations center and team leader (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.
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PostPosted: Tue Nov 07, 2006 7:17 am    Post subject: Earth’s Origin’s a Gas Reply with quote

Earth’s Origin’s a Gas

By Sara Goudarzi
LiveScience Staff Writer
posted: 06 November 2006
05:00 pm ET

Life on Earth emerged out of thin air, scientists now say.

By mimicking in a lab the gases that could have been present on early Earth, researchers have concluded that a layer of haze blanketing our planet produced organic material that helped living organisms develop.

The haze, they found, resembles that of Saturn’s moon Titan, demonstrating for the first time a long-held notion that early Earth and this mysterious moon supported similar atmospheric conditions.


For the full article:

http://www.livescience.com/env....._haze.html
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PostPosted: Sat Nov 11, 2006 11:01 am    Post subject: NASA Sees Into the Eye of a Monster Storm on Saturn Reply with quote

Erica Hupp/Dwayne Brown
Headquarters, Washington

Carolina Martinez
Jet Propulsion Laboratory, Pasadena, Calif.

Nov. 9, 2006
RELEASE: 06-344


NASA Sees Into the Eye of a Monster Storm on Saturn

NASA's Cassini spacecraft has seen something never before seen on another planet -- a hurricane-like storm at Saturn's South Pole with a well-developed eye, ringed by towering clouds.

The "hurricane" spans a dark area inside a thick, brighter ring of clouds. It is approximately 5,000 miles across, or two thirds the diameter of Earth.

"It looks like a hurricane, but it doesn't behave like a hurricane," said Andrew Ingersoll, a member of Cassini's imaging team at the California Institute of Technology, Pasadena. "Whatever it is, we're going to focus on the eye of this storm and find out why it's there."

A movie taken by Cassini's camera over a three-hour period reveals winds around Saturn's South Pole blowing clockwise at 350 miles per hour. The camera also saw the shadow cast by a ring of towering clouds surrounding the pole, and two spiral arms of clouds extending from the central ring. These ring clouds, 20 to 45 miles above those in the center of the storm, are two to five times taller than the clouds of thunderstorms and hurricanes on Earth.

Eye-wall clouds are a distinguishing feature of hurricanes on Earth. They form where moist air flows inward across the ocean's surface, rising vertically and releasing a heavy rain around an interior circle of descending air that is the eye of the storm itself. Though it is uncertain whether such moist convection is driving Saturn's storm, the dark "eye" at the pole, the eye-wall clouds and the spiral arms together indicate a hurricane-like system.

Distinctive eye-wall clouds have not been seen on any planet other than Earth. Even Jupiter's Great Red Spot, much larger than Saturn's polar storm, has no eye or eye-wall, and is relatively calm at the center.

This giant Saturnian storm is apparently different than hurricanes on Earth because it is locked to the pole and does not drift around like terrestrial hurricanes. Also, since Saturn is a gaseous planet, the storm forms without an ocean at its base.

In the Cassini imagery the eye looks dark at light wavelengths where methane gas absorbs the light and only the highest clouds are visible.

"The clear skies over the eye appear to extend down to a level about twice as deep as the usual cloud level observed on Saturn," said Kevin H. Baines, of Cassini's visual and infrared mapping spectrometer team at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "This gives us the deepest view yet into Saturn over a wide range of wavelengths, and reveals a mysterious set of dark clouds at the bottom of the eye."

Infrared images taken by the Keck I telescope in Mauna Kea, Hawaii, had previously shown Saturn's South Pole to be warm. Cassini's composite infrared spectrometer has confirmed this with higher resolution temperature maps of the area. The spectrometer observed a temperature increase of about 4 degrees Fahrenheit at the pole. The instrument measured high temperatures in the upper troposphere and stratosphere, regions higher in the atmosphere than the clouds seen by the Cassini imaging instruments.

"The winds decrease with height, and the atmosphere is sinking, compressing and heating over the South Pole," said Richard Achterberg, a member of Cassini's composite infrared spectrometer team at NASA's Goddard Spaceflight Center, Greenbelt, Md.

Observations taken over the next few years, as the South Pole season changes from summer to fall, will help scientists understand the role seasons play in driving the dramatic meteorology at the south pole of Saturn.

The Cassini-Huygens mission is a cooperative project of 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.

For a movie, high-resolution images, infrared images and Saturn temperature maps, visit:


http://www.nasa.gov/cassini
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PostPosted: Mon Jan 01, 2007 12:08 pm    Post subject: Titan's Massive Mountains Reply with quote

Titan's Massive Mountains
Emily Sohn

Jan. 3, 2007

Saturn's moon Titan has long fascinated scientists with its thick atmosphere, liquid-filled lakes, textured landscape, and other Earth-like qualities.
New images now reveal the largest mountains yet discovered on Titan. The peaks are 1.5 kilometers (nearly a mile) high. The range is about 100 miles long. Titan itself has a diameter of 5,150 kilometers.

For the full article:

http://www.sciencenewsforkids....../Note2.asp
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PostPosted: Thu Jan 25, 2007 3:34 pm    Post subject: Unexpected cooling effect in Saturn's upper atmosphere Reply with quote

Particle Physics & Astronomy Research Council
25 January 2007

Unexpected cooling effect in Saturn's upper atmosphere

UK researchers from University College London (UCL), along with colleagues from Boston University, have found that the hotter than expected temperature of Saturn's upper atmosphere – and that of the other giant planets – is not due to the same mechanism that heats the atmosphere around the Earth's Northern Lights. Reporting in Nature (25th January) the researchers findings thus rule out a long held theory.

A simple calculation to give the expected temperature of a planet's upper atmosphere balances the amount of sunlight absorbed by the energy lost to the lower atmosphere. But the calculated values don't tally with the actual observations of the Gas Giants: they are consistently much hotter.

It has long been thought that the culprit behind the heating process was the ionosphere, being driven by the planet's magnetic field, or magnetosphere. By using numerical models of Saturn's atmosphere the researchers found that the net effects of the winds driven by polar energy inputs is not to heat the atmosphere but to actually cool it.

Professor Alan Aylward, of the UCL Department of Physics & Astronomy, and an author of the study, explains: "The aurora has been studied for over a hundred years, yet our discovery takes us back to first principles. We need to re-examine our basic assumptions about planetary atmospheres and what causes the observed heating."

"Studying what happens on planets such as Saturn gives us an insight into what happens closer to home. Planets can lose their atmospheres as we see with Mars. Do we completely understand how this happens? Are there mechanisms heating the gas and causing it to escape that we do not yet fully understand? By studying what happens in other atmospheres we may find clues to Earth's future."


###
The study was funded by the UK Particle Physics and Astronomy Research Council (PPARC) and Sun Microsystems Ltd and carried out using the HiPerSPACE facility at University College London.
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PostPosted: Tue May 22, 2007 9:48 am    Post subject: Cassini 'CAT Scan' maps clumps in Saturn's rings, says UCF r Reply with quote

University of Central Florida
22 May 2007

Cassini 'CAT Scan' maps clumps in Saturn's rings, says UCF researcher, team

Results may help explain origin of rings
Saturn's largest and most densely packed ring is composed of dense clumps of particles separated by nearly empty gaps, according to new findings from NASA's Cassini spacecraft.

These clumps in Saturn's B ring are neatly organized and constantly colliding, which surprised scientists.

Previous interpretations assumed the ring particles were distributed uniformly and so scientists underestimated the total mass of Saturn's rings. The mass may actually be two or more times previous estimates.

"These results will help us understand the overall question of the age and hence the origin of Saturn's rings," said Josh Colwell, assistant professor of physics at the University of Central Florida and a member of the Cassini ultraviolet imaging spectrograph team publishing its results in the journal Icarus this month.

Principal investigator Larry Esposito at the University of Colorado, Boulder is fascinated with the findings.

"The rings are different from the picture we had in our minds," Esposito said. "We originally thought we would see a uniform cloud of particles. Instead we find that the particles are clumped together with empty spaces in between. If you were flying under Saturn's rings in an airplane, you would see these flashes of sunlight come through the gaps, followed by dark and so forth. This is different from flying under a uniform cloud of particles."

The observations were made using the spectrograph aboard the Cassini spacecraft, which left earth in 1997 on a mission to collect detailed data about Saturn, its rings and moons. Cassini -- the largest interplanetary spacecraft launched from earth -- entered Saturn's orbit in July 2004, and scientists have been using sophisticated equipment on board to view and analyze images.

Boulder and UCF scientists observed the brightness of a star as the rings passed in front of the star on multiple occasions. This provides a measurement of the amount of ring material between the spacecraft and the star.

"Combining many of these occultations at different viewing geometries is like doing a CAT scan of the rings," said Colwell. "By studying the brightness of stars as the rings pass in front of them, we are able to map the ring structure in 3-D and learn more about the shape, spacing and orientation of clusters of particles."

The observations confirm that the gravitational attraction of ring particles to each other creates clumps, or "self-gravity wakes." If the clumps were farther from Saturn, they might continue to grow into a moon. But because these clumps are so close to Saturn, their different speeds around Saturn counteract this gravitational attraction so that the clumps get stretched like taffy and pulled apart. The clumps are constantly forming and coming apart once they get to be about 30 to 50 meters (about 100 to 150 feet) across.

"At any given time, most particles are going to be in one of the clumps, but the particles keep moving from clump to clump as clumps are destroyed and new ones are formed," added Colwell.

Colwell is a professor in UCF's growing program in planetary sciences. He joined the faculty because of the "opportunity to be involved in growing a new planetary sciences program."


###
He is a DeLand native and earned his bachelor's degree at Stetson University before doing advanced study at the University of Colorado, where he met Esposito. Colwell's area of expertise is planetary dynamics and his research focus is determining the origins of the solar system.

A picture of the rings based on the team's results is available at: http://www.nasa.gov/cassini, http://saturn.jpl.nasa.gov and http://lasp.colorado.edu/cassini.

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, Calif., manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter was designed, developed and assembled at JPL. The ultraviolet imaging spectrograph was built at the University of Colorado, Boulder, where the team is based.
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PostPosted: Wed May 23, 2007 7:44 am    Post subject: Constantly Colliding Clumps Found in Saturn's Rings Reply with quote

Constantly Colliding Clumps Found in Saturn's Rings
By SPACE.com Staff

posted: 22 May 2007 03:00 pm ET

Saturn's largest ring might appear solid when viewed from Earth, but closer inspection by NASA's Cassini spacecraft reveals it is composed of tightly packed clumps of particles in constant collision with one another.

The research also suggests scientists have underestimated the total mass of Saturn's rings, which might actually be two or more times as massive than previously thought.

"The rings are different from the picture we had in our minds," said study leader Larry Esposito of the University of Colorado, Boulder. "If you were flying under Saturn's rings in an airplane, you would see these flashes of sunlight come through the gaps, followed by dark and so forth."

The findings, to be detailed in an upcoming issue of the journal Icarus, show Saturn's B ring particles are not uniformly distributed as previously thought.

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http://www.livescience.com/spa.....rings.html
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PostPosted: Tue Jun 12, 2007 9:25 am    Post subject: Earth's Future Glimpsed on Titan Reply with quote

Earth's Future Glimpsed on Titan
By Charles Q. Choi, Special to SPACE.com

posted: 12 June 2007 06:52 am ET

The enigmatic Saturnian moon Titan is still yielding surprising new details years after scientists first pierced its thick haze veil. The vision now emerging of Saturn's largest moon, with its giant dunes and oceanless surface, is perhaps a glimpse of Earth's desert future.

"Titan may be very different from Earth today, but maybe not Earth tomorrow," Jonathan Lunine, Cassini-Huygens interdisciplinary scientist at the University of Arizona, told SPACE.com.

The surface of Titan was a total mystery before the Huygens probe infiltrated past its dense hazy atmosphere in 2005. After a seven-year voyage aboard the Cassini spacecraft, Huygens spent roughly two-and-a-half hours parachuting down and then sent transmissions from Titan's surface for another 70 minutes before Cassini moved out of range. The mission was a joint project of NASA, the European Space Agency and the Italian Space Agency.

"Even though we have only four hours of data, it is so rich that after two years of work we have yet to retrieve all the information it contains," says François Raulin, Huygens interdisciplinary scientist at the Laboratory of Environmental Physics and Chemistry in Paris.

Lunine explained that "a number of instruments aboard Huygens simply require quite a lot of calibration and cross-checking to get a sensible result."

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http://www.livescience.com/spa.....titan.html
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PostPosted: Thu Jul 05, 2007 11:52 am    Post subject: Key to Giant Space Sponge Revealed Reply with quote

Key to Giant Space Sponge Revealed
By Ker Than, Staff Writer

posted: 04 July 2007 01:01 pm ET

One of the strangest moons in our solar system is Hyperion, a Saturnian satellite so pockmarked by deep craters that it looks like a giant, rotating bath sponge adrift in space.

New image analyses suggest the moon's odd appearance is the result of a highly porous surface that preserves craters, allowing them to remain nearly as pristine as the day they were created.

The finding is just one of several new details about the quirky moon revealed in two studies published in the July 5 issue of the journal Nature. Scientists determined that Hyperion is composed mostly of water ice and that the bottoms of its craters are covered in a dark red gunk that could be the key to resolving some of the moon's other strange properties.

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http://www.livescience.com/spa....._moon.html
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PostPosted: Fri Jul 20, 2007 8:03 am    Post subject: New 60th Moon of Saturn Discovered Reply with quote

New 60th Moon of Saturn Discovered
By SPACE.com staff

posted: 19 July 2007 12:13 pm ET

A new moon of Saturn has been discovered, bringing the planet's satellite tally to 60.

Initial measurements suggest the new moon, which is still unnamed, is about 1.2 miles (2 kilometers) wide, and lies between the orbits of Mehone and Pallene, two Saturnian moons discovered by NASA's Cassini spacecraft in 2004. The newfound moon is about 1.09 million miles (1.76 million kilometers) from Saturn and could be part of a larger group of still undiscovered moons around the ringed planet.

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PostPosted: Mon Jul 23, 2007 9:44 am    Post subject: Walnut-Shaped Moon's Mystery Solved Reply with quote

Walnut-Shaped Moon's Mystery Solved
By Dave Mosher, Staff Writer

posted: 23 July 2007 06:46 am ET

There's a strange moon whizzing around Saturn that's shaped, oddly, like a walnut.

Now astronomers find that Iapetus got its nutty shape from a super-fast spin that was frozen into place early in the solar system's formation.

When the Cassini spacecraft snapped close-ups of Saturn's moons in 2005, it revealed a bulging waistline of rock along the equator of the now slowly spinning Iapetus. Astronomers think this characteristic shape persists because Iapetus was cryogenically frozen in time about 3 billion years ago, during the moon's "teen" years.

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PostPosted: Thu Aug 02, 2007 2:53 pm    Post subject: Saturn's Mysterious G-ring Explained Reply with quote

Saturn's Mysterious G-ring Explained
By Ker Than, Staff Writer

posted: 02 August 2007 02:00 pm ET

A loosely knit band of roving ice boulders in orbit around Saturn could be providing the raw material for one of the planet's rings, scientists say.

The finding, detailed in the Aug. 3 issue of the journal Science, could solve the puzzle of what sustains Saturn's "G-ring" and might be evidence that a Saturnian moonlet was destroyed during an ancient collision.

The formation of Saturn's rings is a general mystery, but theorists figure they're the result of one or more breakups of icy objects in the past. In particular though, the G-ring has really puzzled scientists since its discovery in the late 1970s by the Voyager mission.

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http://www.livescience.com/spa.....gring.html
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PostPosted: Sat Aug 04, 2007 10:36 am    Post subject: G Whiz! Craft identifies source of faint Saturnian ring Reply with quote

Week of Aug. 4, 2007; Vol. 172, No. 5 , p. 68

G Whiz! Craft identifies source of faint Saturnian ring
Ron Cowen

Among Saturn's shimmering ice belts, the planet's G ring has proved the most puzzling. The very location of this faint, narrow ring, well beyond the planet's main ring system, has been a riddle ever since the two Voyager spacecraft spied it in 1980. The G ring lies more than 15,000 kilometers from any Saturnian moon. It's neither flanked by bodies that might corral its particles, as the moons Pandora and Prometheus do for the F ring, nor close to an object that could shed particles to populate the ring, as Enceladus does for the E ring.

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http://sciencenews.org/articles/20070804/fob4.asp
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PostPosted: Thu Sep 13, 2007 5:27 pm    Post subject: Saturn’s moon Iapetus is the Yin-Yang of the Solar System Reply with quote

Saturn’s moon Iapetus is the Yin-Yang of the Solar System

13 September 2007
ESA

Cassini scientists are poring through hundreds of images returned from the 10 September fly-by of Saturn's two-toned moon Iapetus.

The pictures show the moon's yin and yang - a white hemisphere resembling snow, and the other as black as tar.
Images returned late Tuesday and early Wednesday show a surface that is heavily cratered, along with the mountain ridge that runs along the moon's equator. Many of the close-up observations focused on studying the strange 20-km high mountain ridge that gives the moon a walnut-shaped appearance.

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http://www.esa.int/esaSC/SEM5E613J6F_index_0.html
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PostPosted: Tue Oct 02, 2007 12:52 pm    Post subject: Titan's icy climate mimics Earth's tropics Reply with quote

University of Chicago
2 October 2007

Titan's icy climate mimics Earth's tropics


If space travelers ever visit Saturn's largest moon, they will find a tropical world where temperatures plunge to minus 274 degrees Fahrenheit, methane rains from the sky and dunes of ice or tar cover the planet's most arid regions. These conditions reflect a cold mirror image of Earth's tropical climate, according to scientists at the University of Chicago.

"You have all these things that are analogous to Earth. At the same time, it's foreign and unfamiliar," said Ray Pierrehumbert, the Louis Block Professor in Geophysical Sciences at Chicago.

Titan, one of Saturn's 60 moons, is the only moon in the solar system large enough to support an atmosphere. Pierrehumbert and Jonathan Mitchell, who recently completed his Ph.D. in Astronomy & Astrophysics at Chicago, have been comparing observations of Titan collected by the Cassini space probe and the Hubble Space Telescope with their own computer simulations of the moon's atmosphere.

Their study of the dynamics behind Titan's methane clouds have appeared in the Proceedings of the National Academy of Sciences. Their continuing research on Titan's climate focuses on the moon's deserts.

"One of the things that attracts me about Titan is that it has a lot of the same circulation features as Earth, but done with completely different substances that work at different temperatures," Pierrehumbert said. On Earth, for example, water forms liquid and is relatively active as a vapor in the atmosphere. But on Titan, water is a rock.

"It's not more volatile on Titan than sand is on Earth."

Methane-natural gas-assumes an Earthlike role of water on Titan. It exists in enough abundance to condense into rain and form puddles on the surface within the range of temperatures that occur on Titan.

"The ironic thing on Titan is that although it's much colder than Earth, it actually acts like a super-hot Earth rather than a snowball Earth, because at Titan temperatures, methane is more volatile than water vapor is at Earth temperatures," Pierrehumbert said.

Pierrehumbert and Mitchell even go so far as to call Titan's climate tropical, even though it sounds odd for a moon that orbits Saturn more than nine times farther from the sun than Earth. Along with the behavior of methane, Titan's slow rotation rate also contributes to its tropical nature. Earth's tropical weather systems extend only to plus or minus 30 degrees of latitude from the equator. But on Titan, which rotates only once every 16 days, "the tropical weather system extends to the entire planet," Pierrehumbert said.

Titan's tropical nature means that scientists can observe the behavior of its clouds using theories they've relied upon to understand Earth's tropics, Mitchell noted.Titan's atmosphere produces an updraft where surface winds converge. This updraft lifts evaporated methane up to cooler temperatures and lower pressures, where much of it condenses and forms clouds.

"This is a well-known feature on Earth called an ITCZ, the inter-tropical convergence zone," Mitchell said. Earth's oceans help confine the ITCZ to the lowest latitudes. But in some scenarios for oceanless Titan, the ITCZ in Mitchell's computer simulations wanders in latitude almost from one pole to the other. Titan's clouds should also follow the ITCZ.

Titan's orange atmospheric haze complicates efforts to observe the moon's clouds. "This haze shrouds the entire surface," Mitchell said. "It pretty much blocks all visible light from reaching us from the surface or from the lower atmosphere."

Nevertheless, infrared observations via two narrow frequency bands have recently revealed that clouds are currently confined to the moon's southern hemisphere, which is just now emerging from its summer season.

"There should be a very large seasonality in these cloud features," Mitchell said. "Cassini and other instruments might be able to tell us about that in the next seven to 10 years or so, as the seasons progress."

Mitchell and Pierrehumbert's next paper will describe how oscillations in Titan's atmospheric circulation dry out the moon's midsection. Over the course of a year, Mitchell explained, "this oscillation in the atmosphere tends to transport moisture, or evaporated methane, out of the low latitudes and then deposit it at mid and high latitude in the form of rainfall. This is interesting, because recent Cassini observations of the surface suggest that the low latitudes are very dry."

Cassini images show dunes of ice or tar covering these low-latitude regions that correspond to the tropics on Earth. When ultraviolet light from the sun interacts with methane high in Titan's atmosphere, it creates byproducts such as ethane and hydrogen.

These byproducts become linked to chains of hydrocarbon molecules that create Titan's orange haze. When these molecules coalesce into large particles, they settle out as a tar-like rain.

"Titan is like a big petrochemical plant," Pierrehumbert said. "Although this is all happening at a much lower temperature than in a petroleum refinery, the basic processes going on there are very closely allied to what people do when they make fuel."
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PostPosted: Wed Oct 10, 2007 2:17 pm    Post subject: Geysers Gush from Cracks in Saturn's Moon Reply with quote

Geysers Gush from Cracks in Saturn's Moon
By Ker Than, Staff Writer

posted: 10 October 2007 01:00 pm ET

Slushy geysers on Saturn's moon Enceladus erupt from fractures clustered around a hot spot at the satellite's south pole, scientists have now confirmed.

Using NASA's Cassini spacecraft, researchers recorded the location of jet events on Enceladus for two years. They found that the most prominent jets emanated from hot spots along four cracks, or "tiger stripes," on the moon's surface called Alexandria, Cairo, Baghdad and Damascus.

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http://www.livescience.com/spa.....-jets.html
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PostPosted: Wed Nov 28, 2007 1:34 pm    Post subject: Organic 'building blocks' discovered in Titan's atmosphere Reply with quote

University College London

Organic 'building blocks' discovered in Titan's atmosphere

28 November 2007

Scientists analysing data gathered by the Cassini spacecraft have confirmed the presence of heavy negative ions in the upper regions of Titan’s atmosphere. These particles may act as organic building blocks for even more complicated molecules and their discovery was completely unexpected because of the chemical composition of the atmosphere (which lacks oxygen and mainly consists of nitrogen and methane). The observation has now been verified on 16 different encounters and findings will be published in Geophysical Research Letters on November 28.

Professor Andrew Coates, researcher at UCL’s Mullard Space Science Laboratory and lead author of the paper, says: “Cassini’s electron spectrometer has enabled us to detect negative ions which have 10,000 times the mass of hydrogen. Additional rings of carbon can build up on these ions, forming molecules called polycyclic aromatic hydrocarbons, which may act as a basis for the earliest forms of life.

“Their existence poses questions about the processes involved in atmospheric chemistry and aerosol formation and we now think it most likely that these negative ions form in the upper atmosphere before moving closer to the surface, where they probably form the mist which shrouds the planet and which has hidden its secrets from us in the past. It was this mist which stopped the Voyager mission from examining Titan more closely in 1980 and was one of the reasons that Cassini was launched.”

The new paper builds on work published in Science (May 11) where the team found smaller tholins, up to 8,000 times the mass of hydrogen, forming away from the surface of Titan.

Dr Hunter Waite of the South West Research Institute in Texas and author of the earlier study, said: “Tholins are very large, complex, organic molecules thought to include chemical precursors to life. Understanding how they form could provide valuable insight into the origin of life in the solar system."


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

Notes to editors:

More information about the mission is available at http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini
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PostPosted: Thu Dec 06, 2007 6:22 pm    Post subject: 'Flying Saucers' Around Saturn Explained Reply with quote

'Flying Saucers' Around Saturn Explained
By Charles Q. Choi, Special to SPACE.com

posted: 06 December 2007 02:01 pm ET

The formation of strange flying-saucer-shaped moons embedded in Saturn's rings have baffled scientists. New findings suggest they're born largely from clumps of icy particles in the rings themselves, an insight that could shed light on how Earth and other planets coalesced from the disk of matter that once surrounded our newborn sun.

Saturn's rings orbit the planet in a flat disk that corresponds to the planet's equator. Likewise, Earth and the other planets orbit the sun in a fairly flat plane that relates to the sun's equator. The planets, at least the rocky ones, are thought to have formed when bits of material orbiting the newborn sun stuck together, forming larger and larger objects that collided and coalesced.

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http://www.livescience.com/spa.....moons.html
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PostPosted: Sat Dec 15, 2007 1:40 pm    Post subject: Saturn's rings may be as old as solar system, says CU-Boulde Reply with quote

University of Colorado at Boulder
13 December 2007

Saturn's rings may be as old as solar system, says CU-Boulder planetary scientist

Rings may last for billions of years, according to new research

New observations by NASA's Cassini spacecraft indicate the rings of Saturn, once thought to have formed during the age of the dinosaurs, instead may have been created roughly 4.5 billion years ago when the solar system was still under construction.

Professor Larry Esposito, principal investigator for Cassini's Ultraviolet Imaging Spectrograph at CU-Boulder, said data from NASA's Voyager spacecraft in the 1970s and later NASA's Hubble Space Telescope had led scientists to believe Saturn's rings were relatively youthful and likely created by a comet that shattered a large moon, perhaps 100 million years ago.

But ring features seen by instruments on Cassini -- which arrived at Saturn in 2004 -- indicate the rings were not formed by a single cataclysmic event, he said. The ages of the different rings appear to vary significantly and the ring material is continually being recycled, Esposito said.

"The evidence is consistent with the picture that Saturn has had rings all through its history," said Esposito of CU-Boulder's Laboratory for Atmospheric and Space Physics. "We see extensive, rapid recycling of ring material, in which moons are continually shattered into ring particles, which then gather together and re-form moons."

Esposito and CU-Boulder colleague Miodrag Sremcevic presented their findings today in a news briefing at the fall meeting of the American Geophysical Union held Dec. 10 to Dec. 14 in San Francisco.

"We have discovered that the rings were probably not created just yesterday in cosmic time, and in this scenario it is not just luck that we are seeing planetary rings now," said Esposito. "They probably were always around but continually changing, and they will be around for many billions of years."

Scientists had previously believed rings as old as Saturn itself should be darker due to ongoing pollution by the "infall" of meteoric dust, leaving telltale spectral signatures, Esposito said. But the new Cassini observations indicate the churning mass of ice and rock within Saturn's gigantic ring system is likely much larger than previously estimated, helping to explain why the rings appear relatively bright to ground-based telescopes and spacecraft.

"The more mass there is in the rings, the more raw material there is for recycling, which essentially spreads this cosmic pollution around," he said. "If this pollution is being shared by a much larger volume of ring material, it becomes diluted and helps explain why the rings appear brighter and more pristine than we would have expected."

Esposito, who discovered Saturn's faint F ring in 1979 using data from NASA's Pioneer 11 spacecraft, said an upcoming paper by him and colleagues in the journal Icarus supports the theory that Saturn's ring material is being continually recycled. Observing the flickering of starlight passing through the rings in a process known as stellar occultation, the researchers discovered 13 objects in the F ring ranging in size from 30 yards to six miles across.

Since most of the objects were translucent -- indicating at least some starlight was passing through them -- the researchers concluded they probably are temporary clumps of icy boulders that are continually collecting and disbanding due to the competing processes of shattering and coming together again. The team tagged the clumpy moonlets with cat names like "Mittens" and "Fluffy" because they appear to come and go unexpectedly over time and have multiple lives, said Esposito.

Esposito stressed that in the future Saturn's rings won't be the same we see today, likening them to great cities around the world like San Francisco, Berlin or Beijing. "While the cities themselves will go on for centuries or millennia, the faces of people on the streets will always be changing due to continual birth and aging of new citizens."


###
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 in Washington, D.C.

For more information about the NASA Cassini-Huygens mission visit the Web at http://saturn.jpl.nasa.gov. To listen to a podcast of Esposito and view a short video animation of objects in Saturn's F ring shattering and re-forming, visit the Web at http://www.colorado.edu/news/reports/space/
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PostPosted: Mon Dec 15, 2008 1:17 pm    Post subject: Reply with quote

TITAN – A MOON FULL OF ORGANIC LAKES AND SEAS?
It is always been a fascination to scientists to have deeper understanding of the heavenly bodies in our universe. The possibility of life in these bodies other than in Earth is a quest that even the Hollywood sci-fi movies explore on. It is generally assumed that if the body behaves more likely as the Earth, life may exist or had existed in it. One of the bodies most closely similar to Earth, as to possessing atmosphere, is Titan. In fact, astronomers suppose that this atmosphere may be similar to the one that the prehistoric Earth had.
Titan is the largest among the 31 known moons (and still counting) of the planet Saturn. It was discovered in March 25, 1655 by the novice Dutch astronomer Christiaan Huygens. It is second in size, roughly as large as the planet Mars, among the satellites in our Solar System, next to Juniper’s Ganymede. It rotates around Saturn over the period of 15.945 Earth days. It has a very low surface temperature (-178 ˚C) and higher atmospheric pressure (1.5 bars), as compared to Earth. Apart from the ground-based and space observatories, two notable space explorations that helped in establishing data about (Saturn and) Titan are the Voyagers in 1980s and the Cassini-Huygens which was launched in 1997 but only entered the Saturn’s orbit in July 2004. Each spacecraft is equipped with various spectroscopic instruments for the data collection and analysis.
Astronomers generally use energy samples, rather than material ones, from the objects they study. Visible light, along with its invisible next of kin – ultraviolet (UV) and infrared (IR) radiations and radio waves, are the energy samples used in the analysis, with the right telescopes and instruments. Many of the substances in these heavenly bodies make permanent and unique fingerprints of the energy they emit. Digging out the chemical composition of these bodies from the beam of light they radiate away is achieved by spectroscopy. This technique is just like the disentangling a ball of threads, of different colors and lengths. Each thread is a radiation with a distinct energy, corresponding to a specific wavelength and intensity – color and length of thread, respectively. In a scientific inquiry, a spectrum is analyzed, a display of the rise and fall of the intensity with respect to the wavelength of the radiation. Each compound has its own and exclusive combination of threads resulting to a unique series of narrowly-spaced (or single broad) dips, the absorption band, in the spectrum.
The idea that Titan has atmosphere originated from José Comàs Sola, as published in Astromische Nachrichten in 1908. He used a 38-cm telescope at the Fabra Observatory in Barcelona, Spain, and observed that Titan had very darkened edges with a much brighter central part, where the “darkening of the edges demonstrates the existence of a strongly absorbing atmosphere around Titan”. His claims were considered as slightly doubtful because with seeing the edge darkening clearly by the eye with only a modest telescope is technically impossible. It was Gerald Kuiper of Chicago University that provided the first formal proof of existence of Titan’s atmosphere. In 1944, he observed Titan using a 2.08-m telescope at the McDonald Observatory in Texas, USA, and recorded its spectra in the both visible light and the near infrared. He discovered spectral signatures at wavelengths longer than 0.6 microns, where he identified two absorption bands of methane at 6190 Å and 7250 Å. The main composition, temperature and pressure were determined from the fly-bys of the Voyager spacecraft. Like Earth, nitrogen is the most abundant component as detected by the ultraviolet spectrometer. But instead of oxygen, the next abundant molecule is methane (CH4), followed by traces of hydrogen, moderately complex organic gases and simple oxygen compounds like carbon dioxide (CO2). The Titan’s atmosphere is also structured into regions, like that of Earth, of defined temperature variations with height or pressure. Interestingly, the haze layers that hide the surface of Titan very well is thought to function just like the ozone layer of Earth, blocking UV light. As with oxygen for ozone, this haze layer is made by the action of UV light on the methane in the atmosphere.
The concept that Titan has an atmosphere gave rise to the proposal of having liquid bodies on its surface. When it was proved that the satellite Titan has a dense atmosphere, the next set of questions to be answered is about how does Titan keep this. The origin and evolution of its components, particularly methane, are puzzles to astronomers. Logical explanations given came from the interplay of ultraviolet radiation from the Sun resulting to photochemical reactions. Lunine, Stevenson and Yung proposed that there should be oceans of ethane (C2H6) on Titan’s surface, as published in the journal Science (volume 222, pages 1229-30, year 1983). This ocean is the source and sink for the methane photolysis. When methane absorbs UV light, the energy of this light is enough to cause the decomposition of the said molecule producing CH2 and CH. The degraded particles from methane combine to form majority ethane, with minute amounts of acetylene (C2H2). Ethane is liquid at the surface temperature of Titan, hence, it will condense. Upon condensation, it will form bodies of liquid ethane on Titan’s surface.
Just recently, in the journal Science (volume 454, pages 587-9, 607-10, year 2008), it was reported that the data collected by the Huygen probe in the Cassini orbiter confirmed the presence of huge lake of hydrocarbons in Titan. This lake, the Ontario Lacus, is said to be composed of liquid ethane-methane mixture, with dissolved nitrogen and some organic compounds produced in the atmosphere. These findings demonstrated that there can be a complex methane cycle of cloud formation, rain, runoff and evaporation, similar to the hydrologic or water cycle in Earth. Apart from these lakes, it is said that methane may have been trapped as methane hydrates (clathrates), similar to the methane hydrates found in deep-sea and oceans in Earth, during the formation of the satellite. Then methane is released through volcanic action from these interior sources or from the evaporation of the ethane-methane lakes. Chemical reaction in the atmosphere, with the participation of UV light, converts it to ethane. Ethane, with some methane, condense forming clouds and precipitate replenishing the organic lakes.
Visual and Infrared Mapping Spectrometer (VIMS) is one of the main instruments aboard the Cassini orbiter, and it is based on imaging spectroscopy. Imaging spectroscopy is used to determine the chemical composition of the surfaces and atmospheres of planetary objects through sampling hundreds of narrow spectral bands throughout the visible to short wave infrared electromagnetic spectrum. Here, it is important that all the colors at each point in the image are separated to provide relevant information. Cassini’s VIMS is essentially composed of two cameras, one to measure the visible wavelengths, the other one is for IR. In IR, molecular vibrations (and sometimes rotations) have discrete energy levels as to where these will occur. These energies corresponds to certain frequencies in the IR region of electromagnetic radiation. Ethane in Ontario Lacus was detected by its distinct IR spectrum. The diagnostic feature of this spectrum was the absorption band centered at 2.11 µm. Upon comparison with a model spectrum of liquid ethane, this band matches up with the absorption band within the 2-µm window of the Titan’s atmosphere. In addition, they found out that there was a steep decline in reflectance beyond 4.8 µm, which is characteristic of ethane.
Discovery of such cold liquids in the lakes of Titan leads to a broader aspect of scientific research in the marvelous satellite of Saturn. Speculations that there might life in these types of environment is getting popular. But, the most prevalent is the potential of these organic lakes as chemical reactor. With these at hand, future explorations are being considered by National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA).

By Mae Joanne Aguila, Georgetown University, Washington D.C., 15 December 2008

References
Raulin, Francois, “Organic Lakes in Titan”, Science 454, 587-9 (2008).
Brown, R. H., L. A. Soderblom, J. M. Soderblom, R. N. Clark, R. Jaumann, J. W. Barnes, C. Sotin, B. Buratti, K. H. Baines and P. D. Nicholson, “The Identification of Liquid Ethane in Titan’s Ontario Lacus”, Science 454, 607-10 (2008).
Lunine, J. I., D. J. Stevenson and Y. L. Yung, “Ethane Ocean on Titan”, Science 222, 1229-30 (1983).
Coustenis, A. and F. Taylor, 1999. Titan: The Earth-Like Moon, World Scientific Publishers, Singapore.
Lorenz, R. and J. Mitton, 2002. Lifting Titan’s Veil: Exploring the Giant Moon of Saturn, Cambridge University Press, United Kingdom.
Coustenis, A. and F. Taylor, 2008. Titan:Exploroing the Earth-Like World, 2nd Ed., World Scientific Publishers, Singapore.

Questions to Explore Further This Topic:
What is the Solar System?
http://www.nineplanets.org/
http://www.kidsastronomy.com/solar_system.htm
http://solarsystem.nasa.gov/index.cfm
What is Saturn as a planet?
http://www.solarviews.com/eng/saturn.htm
What is Titan?
http://solar-system-astronomy......_of_saturn
http://www.solarviews.com/eng/titan.htm
http://www.planetary.org/explo.....titan.html
Who is Christiaan Huygens?
http://great-scientists.suite1.....an_huygens
What is spectroscopy?
http://loke.as.arizona.edu/~ck.....intro.html
http://www.chem.vt.edu/chem-ed/spec/spectros.html
What is light?
http://en.wikipedia.org/wiki/Light
http://www.tulane.edu/~sanelso.....plight.htm
Who is José Comàs Sola?
http://translate.google.com/tr.....26hs%3DNsw
Who is Gerald Kuiper?
http://en.wikipedia.org/wiki/Gerard_Kuiper
What is the Voyager Mission?
http://www.nasa.gov/mission_pa.....index.html
http://nssdc.gsfc.nasa.gov/planetary/voyager.html
http://voyager.jpl.nasa.gov/mission/mission.html
What is The Cassini-Huygen Mission?
http://www.esa.int/SPECIALS/Ca.....index.html
http://www.nasa.gov/mission_pa.....index.html
http://saturn.jpl.nasa.gov/home/index.cfm
What are hydrocarbons?
http://en.wikipedia.org/wiki/Hydrocarbon
What is the atmospheric stratification in Earth?
http://en.wikipedia.org/wiki/Earth%27s_atmosphere
What is a photochemical reaction?
http://en.wikipedia.org/wiki/P.....l_reaction
How does photolysis occur?
http://en.wikipedia.org/wiki/Photodissociation
What is the water cycle?
http://en.wikipedia.org/wiki/Water_cycle
http://earthguide.ucsd.edu/ear.....index.html
http://www.kidzone.ws/water/
What is the methane cycle in Titan?
http://www.astrobio.net/news/article2038.html
http://atoc.colorado.edu/~tfan.....ge0003.htm
What is methane hydrate?
http://en.wikipedia.org/wiki/Methane_hydrate
How are liquid bodies discovered in Titan?
http://www.sciencedaily.com/re.....080639.htm
http://www.sciencedaily.com/re.....125330.htm
What is imaging spectroscopy?
http://en.wikipedia.org/wiki/Imaging_spectroscopy
What is VIMS?
http://wwwvims.lpl.arizona.edu/index.html
http://saturn.jpl.nasa.gov/spa.....i-vims.cfm
http://www.planetary.org/explo....._vims.html
What is infrared spectroscopy?
http://en.wikipedia.org/wiki/Infrared_spectroscopy

Pictures of Saturn and Titan
http://saturn.jpl.nasa.gov/mul...../index.cfm
http://saturn.jpl.nasa.gov/new...../index.cfm
http://www.daviddarling.info/e.....Titan.html
http://nssdc.gsfc.nasa.gov/pho.....satellites
http://images.google.com/image.....urn,+titan
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