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Titan (Saturn's Largest Moon)

Huygens Finds A Hostile World On Titan


Conditions on Saturn's moon Titan, with its dense atmosphere, are similar to those on Earth early in our solar system. Pictures and spectral analysis of Titan's surface, recorded by an international scientific team including researchers from the Max Planck Institute for Solar System Research (MPS), show a dried-out "river" landscape.
Evaluating the data has now shown that methane on Titan exists in solid, liquid, and gas states, and plays a similar role in Titan's atmosphere and on its surface that water plays on Earth. Water ice on Titan congeals to be similar to stone on Earth: it makes up a major component of the Titan's surface. "Stones" made presumably largely of water ice show signs of erosion and transport through a liquid. (Nature, Advanced Online Publication, November 30, 2005).

With a diameter of about 5,150 kilometres, Titan is the largest moon of Saturn. It has a dense atmosphere which we mostly cannot see through. Until recently, Titan was one of the few objects in the solar system whose surface was not researched. In 1997, the Cassini/Huygens mission to Saturn was launched.

The NASA spaceship Cassini reached Saturn's orbit in 2004 and since then has been investigating the ringed planet and its moons. The Huygens probe of the European Space Agency ESA separated from Cassini at the end of 2004 and landed on Titan on January 14, 2005, after a two-and-a-half hour descent through the atmosphere.

Among the scientific instruments aboard Huygens were the Descent Imager/Spectral Radiometer (DISR), plus a combination of 14 cameras, spectrometers for visible and infrared light, and photometers. The Max Planck Institute for Solar System Research developed the CCD detector, which received the signal from all the cameras and spectrometers in the visible wavelengths.

During descent, as well as after Huygens landed, the DISR investigated the atmosphere and surface of Titan. At first sight, it is similar to a landscape on Earth. We can see the courses of rivers, which lead from a higher-lying area to a lower, flat terrain, bordered by a kind of coastline (see image 1). Spectral analysis showed indeed that materials from the higher areas were transported down to a "sea".

Huygens landed in the low-lying, flat area. The pictures taken after landing (see image 2) show that there is currently no liquid in the "sea". There are, however, "stones", whose rounded shape, and size distribution, suggest they were transported in a liquid. Given the extremely low temperatures on Titan -- about 180 degrees below Celsius -- the liquid could not be water. The scientists guess rather that it is methane and/or another hydrocarbon, and that the "stones" are made of water ice.

Investigations of the atmosphere on Titan concentrated on its dust layer. Before landing, it was assumed that the dust is only located above 50 kilometres up in the atmosphere, and the area lying underneath it is clear. The DISR measurements have now shown that the dust layer reaches down to the surface. Spectral analysis shows that the dust particles are aggregates of some hundreds of very small particles, about 50 nanometers across. Original work:

http://www.spacedaily.com/news/saturn-titan-05zp.html
 
Cassini Significant Events 12/21/05 - 01/04/06


The most recent spacecraft telemetry was acquired Wednesday, January 4, from the Goldstone tracking stations. The 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/p ... sition.cfm .

Cassini Significant Events 12/21/05 - 01/04/06

Due to the holidays, no Significant Events report was generated last week. The report this week covers 15 days from December 21, 2005 through January 4, 2006. Hang on, it's gonna be a long report!

Wednesday, December 21 (DOY 355):

Uplink Operations personnel sent commands to the spacecraft today to perform an on-board live Inertial Vector Propagation (IVP) update. The update will execute on DOY 358/359 and will update vectors for Dione, Tethys, Enceladus, Saturn, and Telesto.

Science activities today included a distant observation of Hyperion involving all Optical Remote Sensing (ORS) instruments, and Imaging Science Subsystem (ISS) tracks of many small moons as part of the Satellite Orbit Determination Campaign.

Thursday, December 22 (DOY 356):

A preparation meeting was held today for Orbit Trim Maneuver (OTM) 047. The maneuver is scheduled to execute on December 29.

Friday, December 23 (DOY 357):

The RADAR instrument performed an engineering test that will address radiometer calibration issues using Saturn as a reference target.

Saturday, December 24 (DOY 358):

Today marked the start of the annual sequence development hiatus. The Aftermarket, Science Operations Plan Update (SOPU), and Science and Sequence Update Process will pause activities from today through January 2, 2006. The processes will begin again on January 3. Early on in the tour, program management identified the difficulty of trying to conduct this type of development over the Christmas and New Year's holidays due to varying vacation schedules and the different holiday schedules of our foreign partners. As a result, each year a pause is built in to the development schedules that lasts for about two weeks during this time. Operations work continues, OTMs, real time commanding, downlink, etc. It's just these three processes that pause. Well, OK, we do cancel a few meetings:)>)

Non-targeted flybys of Enceladus and Pallene occurred today. The Enceladus flyby was at an altitude of 93,984 km.

Whoa. It's been a year. Today is the one-year anniversary of the Huygens Probe release! For those of you who would like to remember where we were last year at this time, here is an extract from the Significant Events report for December 24, 2004, Christmas Eve:

Everything looks good and nominal.

JPL provided dinner for those of us who had to work. There was slight congestion at the dessert table, but everything else was nominal.

All Orbiter instruments reported in. Everyone is in the correct configuration and is ready for release.

The project set up a conference line so that Cassini flight team members who are not working the event but who came in anyway to show their support can listen in on events as they unfold.

The Huygens Probe was successfully deployed from the Cassini Orbiter! Navigation and Spacecraft Operations Office teams confirmed the nominal separation of the Probe at 7:24 Pacific time. The Probe is now in free flight at a spin rate of 7.5 rpm as detected by the Magnetometer Subsystem. All systems performed as expected, there were no problems reported with the Cassini spacecraft, no red alarms, no fault protection. Congratulations everyone!

After release, the Uplink Operations (ULO) sequence lead called for the start of planned Probe optical navigation imaging. This is a 4.5 hour process. Currently we are on schedule.

The head of the Huygens Spacecraft Operations Unit expressed his thanks to the team for a wonderful adventure in the exploration of Saturn. Huygens personnel are now waiting with great expectation for the Probe descent on January 14, 2005.

Sunday, December 25 (DOY 359):

Non-targeted flybys of Helene and Telesto occurred today.

Science activities today included a Composite Infrared Spectrometer (CIRS) Saturn Tethys F-Ring movie, and the first of three Radio Science Subsystem (RSS) Gravity Science Enhancement passes on and after Christmas - DOY 359, 361, and 362. These are additional downlink passes at Ka-band to obtain Titan gravity science.

Monday, December 26 (DOY 360):

On December 26, Cassini flew by Titan at an altitude of 10,409 kilometers. At this time, the Imaging Science Subsystem (ISS) acquired a mosaic of Titan's albedo features Aztlan and Quivira, Bazaruto and Elba Faculae, and Omacatl Macula, at low phase angles of approximately 25 degrees and pixel resolution scales of approximately 700 to 450 meters. This ISS observation also overlaps eastern portions of the Titan A and Titan 3 RADAR swaths. The Composite Infrared Spectrometer (CIRS) obtained information on trace constituents in Titan's stratosphere. An integration of the limb obtained information on CO, HCN, and CH4. The Ultraviolet Imaging Spectrograph (UVIS) used its Hydrogen-Deuterium Absorption Cell (HDAC) to conduct key measurements of the Titan atmosphere as well. Measurements of the D/H ratio in the Titan atmosphere will yield clues to the formation and history of Titan and the Saturnian system. The Visual and Infrared Mapping Spectrometer (VIMS) also obtained a medium resolution regional map using the same observing strategy as the previous Titan flyby.

Moreover, this Titan flyby presented an excellent diametric wake crossing at 5.04 Titan radii downstream for all of the Magnetospheric and Plasma Science (MAPS) instruments, which will be ideal for comparisons to the Voyager-1 Titan flyby data set. Cassini's encounter possessed similar observing geometry as the encounter of Voyager-1 in November 1980. Especially with the increased capability of Cassini, the MAPS instruments will finally be able to compare the Cassini and Voyager data sets to further study Titan's atmospheric loss and the structure of Titan's plasma wake. But more importantly, this flyby will represent the only crossing of Titan's magnetotail at an intermediate distance in the Cassini tour, which will be highly valuable for the study of the formation of Titan's magnetotail as a function of distance.

Tuesday, December 27 (DOY 361):

It was reported today at the weekly Operations Status and Coordination meeting that data from the Titan 9 flyby yesterday has been successfully downlinked. In particular UVIS reported that they had received the entire HDAC observation data set. There were several gaps of less than one minute due to some problems at DSS-14, but nothing that required the implementation of the contingency plans and procedures that had been developed and reported on last week.

Wednesday, December 28 (DOY 362):

An article was presented in the December 27 Aerospace Daily & Defense Report stating that NASA is considering a two-year extension to the Cassini mission that would extend the exploration of Saturn and its moons through 2010. "NASA has given us some additional funding to study what the options would be" for the extra two years, said Bob Mitchell, Cassini program manager at the Jet Propulsion Laboratory in Pasadena, Calif. The spacecraft's lifetime ultimately will be determined by what kind of follow-on mission, if any, is carried out. "If we put together a tour that would look very much like what we're doing now - a Titan flyby every month or so and an icy satellite flyby stuck in here and there - then another two years would probably about run us out of propellant. However, if the spacecraft is placed in a fairly uneventful orbit and dedicated to studying Saturn's ring system, for example, it could likely last years longer." he said.

Thursday, December 29 (DOY 363):

OTM-047 was successfully performed today. This was the cleanup maneuver from the Titan-9 flyby that occurred on December 26. The reaction control subsystem (RCS) burn began at 7:55 pm Pacific Time. Telemetry obtained immediately after the maneuver showed the burn duration was 198.9 seconds, giving a burn delta-V of 0.179 m/s. All subsystems reported nominal performance after the OTM.

Beginning today and running through January 4, science activities involve the entire suite of MAPS instruments simultaneously performing low-rate outer magnetospheric surveys to observe the variability of magnetospheric boundaries at a variety of radial distances. Optical remote sensing activities include ISS observations of a mutual event capturing Janus crossing Dione, many photometric calibrations done with a variety of stars, and narrow-angle camera lightning searches in Saturn's northern hemisphere. Finally, UVIS will obtain mosaics of Saturn's inner magnetosphere.

Friday, December 30 (DOY 364):

Today is the fifth anniversary of the Cassini flyby of Jupiter on December 30, 2000.

Saturday, December 31 (DOY 365):

Documenting a year at Saturn, Astronomy Picture of the Day selected for their picture today an image of Saturn's moon Dione in front of edge-on rings and the cloud tops of Saturn draped with broad ring shadows. It's very cool!

2006

Sunday, January 1 (DOY 001):

This feels more like a Christmas present than a report of what to expect in the New Year! In 2006 Cassini will execute all or part of 10 on-board sequences from S17 through S26, and all or part of 18 orbits of Saturn from Rev 19 through Rev 36 will occur. During this time there will be 13 targeted flybys of Titan including T10 through T22, 20 non-targeted flybys including Helene, Rhea, Polydeuces, Tethys, Telesto, Titan, Atlas, Calypso, Enceladus, Methone, and Dione, 39 opportunities for maneuvers from OTM-048 through OTM-086, the start of extended mission development will begin in January, one superior conjunction will occur in August, and finally a partridge in a pear tree will occur next December. :)>). Should be a busy year.

Monday, January 2 (DOY 002):

OTM-48, originally scheduled for today, was cancelled back in early November along with OTM-54 and OTM-60. This was done because there were only three DSN tracks between the cleanup and apoapsis maneuvers, delivery errors did not improve after the apoapsis maneuver, and the maneuvers would be difficult to cancel in real time. The delta-V cost was about 0.8 m/sec. The capability to execute a maneuver on the planned prime and backup passes was retained but proved unnecessary for OTM-048. Spacecraft Operations and Navigation will re-evaluate OTMs 54 and 60 as necessary.

Tuesday, January 3 (DOY 003):

Dark terrain on Iapetus was selected as Astronomy Picture of the Day today.

Flight software (FSW) normalization for CIRS and the Cassini Plasma Spectrometer (CAPS) was begun today and will continue through January 6. There are four copies of an instrument's FSW in partitions 0 through 3 on each SSR. When the instrument team has a new version of FSW, it is uploaded into 2 of the partitions, in this case partitions 2 and 3, leaving copies of the old software on 0 and 1. The old version is retained until the instrument team performs a flight software checkout and confirms the new version. After the confirmation, "normalization" is performed where the new version replaces the old version in the remaining partitions on both SSRs, in this case 0 and 1.

Wednesday, January 4 (DOY 004):

The Science Operations Plan Update process for S20 kicked off today. The process will run for five weeks and will conclude on February 10.

Wrap up:

Check out the Cassini web site at http://saturn.jpl.nasa.gov for the latest press releases and images.

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.

http://saturn.jpl.nasa.gov/news/sig-eve ... newsID=625
 
A return to the orangey world

It had this strange orange-yellow hue and the focussing was some way off pin-sharp, but the image returned from the surface of Titan by the Huygens probe was unquestionably one of the pictures of 2005.

Twelve months on, and you still look at it with wonder - what lies to the right or left, just out of view? What's behind?

All we got was the one shot; so, those questions will for ever be left hanging.

It seems remarkable - to this correspondent at least - that you can get any sort of picture from the surface of a moon that's more than a billion km from Earth.

Mind you, not everyone was impressed. A few newspapers remarked on the picture's mundaneness. "Is that all?" they asked; "It looks like a beach on Earth."

One columnist even suggested the public had become bored with fuzzy space images and jokingly suggested that only a Frisbee-catching dog running in the background could have piqued people's interest.

Not for John Zarnecki, the principal investigator on the science payload sent with Huygens to investigate Titan's surface. He continues to marvel at that picture and is staggered by the probe's achievements.

"It's still not long enough for me to be able to look back in a detached way," the Open University professor told the BBC News website.

"People tend to think that it happens, you do the analysis and that's it. Not so; we're still deep in it."

'Technology tallpoles'

Indeed, the data returned by the robot probe as it floated down through the moon's thick atmosphere to land on a pebble-strewn terrain will keep researchers busy for years.

Titan lived up to expectations; the photochemical haze that shrouds its surface was finally lifted.

Huygens showed us a frozen world that seemed to resemble a primitive Earth - it was somehow very familiar but also very alien.

The rocks are really ice and the rain that falls in a good breeze is made of liquid methane, not water.

The probe spied channels and basins that looked as though they had been cut by rivers, and the surface itself appeared to be covered in a "wet" sand that threw up a plume of methane as the warm robot touched down.

"We actually think we hit one of those pebbles as we landed," said Zarnecki. "If you look at that orangey picture, look at the bottom-left - one of the pebbles is broken. We'll never know for sure but that might have been the one we bashed and broke in two."

However big the data return, there are always going to be more questions than answers; and the desire to go back will get ever stronger.

It won't happen for another 10 years or so. The scientific community has its eye next on Europa, the icy moon of Jupiter; but that does not mean researchers have put aside thoughts of a follow-up - far from it.

The US space agency (Nasa), for example, has teams who conceptualise future missions.

"We try to understand what can and cannot be done; what are the technological tallpoles, and from these kind of studies we can see what needs to be developed and that feeds into our programmes," explains Dr Tibor Balint, from the Jet Propulsion Laboratory in Pasadena.

Power issue

Balint's team has recently worked through the engineering challenge of putting a rover on Titan. The group envisioned a vehicle that looked much like the robot explorers despatched to Mars.

Obvious comparisons include the mast-mounted camera system and the robotic arm that can reach out to take measurements or bring back samples to an instrument carousel.

Unlike the Mars rovers' six-wheel configuration, the Titan concept would use just four large wheels.

"When you get down to the surface, you fold the wheels out, inflate them and you can have a much larger surface coverage," Dr Balint told me. "These wheels are 1.5m in diameter and over a three-year operation you could cover up to 500km."

Perhaps the biggest difference to the Mars machines, though, is the power source.

The Mars rovers have a deck of solar cells to top their batteries. Being positioned so far from the Sun and hidden under a deep column of haze, the Titan rover would need a radioisotope thermoelectric generator (RTG).

This type of generator creates electricity from heat given off by the natural decay of plutonium. The US has long experience of using RTGs in space: the 1970s Viking landers on Mars were powered in this way, as is Huygens' mothership, Cassini.

The Titan explorer would trundle over those orange pebbles looking for "lakes" of methane, and studying the surface composition and chemistry.

It is an enticing prospect but it is not the only option being considered. Another JPL team has been looking into the idea of putting a 15m-long, helium or hydrogen-filled blimp on Titan.

In the dark

A balloon can cover far greater distances than a rover and the conditions on the Saturnian moon would be ideal: a dense atmosphere, low gravity and only gentle winds (walking pace) at the surface.

Current designs call for two larger propeller engines to drive the airship forward and two smaller props at the rear to control pitch and yaw.

A gondola could be slung beneath the envelope to carry the instrument suite and a RTG that would provide that all important power.

But there is a significant challenge in operating such a vehicle so far from Earth.

"The round trip light-time is 2.6 hours; that's a lot worse than talking to the rovers on Mars," explains team member Alberto Elfes.

"In addition to that, depending on the relative positions of Titan, Saturn and Earth, you may have situations where you have blackout periods of up to 16 days or so.

"Under those conditions, you need a vehicle that is substantially autonomous, that can take care of itself."

Elfes and colleagues have tested an artificial intelligence system on a small airship over a dry lake bed in El Mirage, California. The vehicle was able to navigate itself to designated waypoints, correcting its path to take account of the wind.

Take this sophistication to another level and an aerobot sent to Titan could be left to get on with scientific observations, safe in the knowledge that the vehicle would not crash into the first hill.

Alien waves

Dr Elfes sees a Titan blimp working close to the surface, possibly firing tethered, harpoon-like probes into the ground to grab samples for study.

"You collect a small amount of material, release the [harpoon] mechanism on the surface and haul up the small, thimble full of material to be analysed onboard," he said.

"We have looked at designs that would have 12 to 24 of these throwaway probes that would be used as you go from one interesting site to another."

John Zarnecki favours an aerial mission but he also rather likes the idea of combining it with a mini-rover. The airship would first survey the most interesting sites and then unleash a wheeled vehicle to get in amongst those pebbles.

"I definitely want to go back," he said. "I'd love to see the lakes that must be there some times - lakes of liquid hydrocarbons. I'd love to see a lake with some gentle waves lapping on the shore.

"These physical processes are so familiar on Earth but we've never seen them in a different parameter space - one-seventh gravity with liquid methane instead of water. It would be mind-blowing."

http://news.bbc.co.uk/1/hi/sci/tech/4610792.stm
 
Hmmm.. Titan always seemed one of the best candidates for life of some sort.

Earth could seed Titan with life
By Paul Rincon
BBC News science reporter, Houston , Texas




Terrestrial rocks blown into space by asteroid impacts on Earth could have taken life to Saturn's moon Titan, scientists have announced.
Earth microbes in these meteorites could have seeded the organic-rich world with life, scientists believe.

They think the impact on Earth that killed off the dinosaurs could have ejected enough material for some to reach far-off moons like Titan.

Details were unveiled at a major science conference in Houston, US.

The theory of panspermia holds that life on planets like Earth and Mars was seeded from space, perhaps hitching a ride on meteorites and comets.

To get terrestrial, life-bearing rocks to escape the Earth's atmosphere and reach space, an impact by an asteroid or comet between 10 and 50km is required. Only a handful of recorded strikes in geological history fit the bill.

Million-year journey

One of them is the asteroid strike 65 million years ago, which punched a crater between 160 and 240km wide in what is today the Yucatan peninsula, Mexico.


Brett Gladman from the University of British Columbia (UBC) in Vancouver and colleagues calculated that about 600 million fragments from such an impact would escape from Earth into an orbit around the Sun. Some of these would have escape velocities such that they could get to Jupiter and Saturn in roughly a million years.
Using computer models, they plotted the behaviour of these fragments once they were in orbit. From this, they calculated the expected number that would hit certain moons of Jupiter and Saturn.

The principal targets they chose, Titan and Europa, are of considerable interest to astrobiologists, the community of scientists who study the habitability of other planetary bodies.

Titan is rich in organic compounds, which provide a potential energy source for primitive life forms, Europa is thought to harbour a liquid water ocean under its thick crust of ice.

Hitting at speed

Dr Gladman's team calculated that up to 20 terrestrial rocks from a large impact on Earth would reach Titan. These would strike Titan's upper atmosphere at 10-15 km/s. At this velocity, the cruise down to the surface might be comfortable enough for microbes to survive the journey.


But the news was more bleak for Europa. By contrast with the handful that hit Titan, about 100 terrestrial meteoroids hit the icy moon.
But Jupiter's gravity boosts their speed such that they strike Europa's surface at an average 25 km/s, with some hitting at 40 km/s. Dr Gladman said other scientists had investigated the survival of amino acids hitting a planetary surface at this speed and they were "not good".

"It's frustrating if you're a microbe that's been wandering the Universe for a million years to then die striking the surface of Europa," Dr Gladman said.

Asked after his presentation by one scientist whether he thought microbes would be able to survive Titan's freezing temperatures, Dr Gladman answered: "That's for you people to decide, I'm just the pizza delivery boy."

The UBC researcher gave his presentation at the astrobiology session held at the Lunar and Planetary Science Conference in Houston, Texas.

Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/s ... 819370.stm

Published: 2006/03/18 09:04:43 GMT

© BBC MMVI
 
*bump* (again)



Cassini-Huygens Team Receives Space Award


The Cassini-Huygens mission team, which has captured the most detailed views ever of Saturn and its myriad of moons, was honored with an Aerospace Laurel award by the editors of Aviation Week & Space Technology magazine.

Aviation Week presented the award for the successful landing of the European Space Agency's Huygens probe on Saturn's moon Titan, and for the science return and inspiring images from NASA's Cassini orbiter, which will continue sending back data for many years.

According to the Aviation Week magazine citation, "Dennis Matson, the project scientist at NASA's Jet Propulsion Laboratory, and Jean-Pierre Lebreton, the European Space Agency's project scientist and mission manager, have strived since the beginning to create, protect and operate the Cassini-Huygens mission, and are good representatives of the larger team that made this two-decade international project possible." The award was presented on April 7 in Washington, D.C.

Cassini-Huygens was launched on Oct. 15, 1997. Cassini arrived at Saturn in July 2004, and embarked on a science-packed expedition of the ringed planet and its dozens of moons, including Titan. The Huygens probe hitched a ride on Cassini during the journey covering 3.5 billion kilometers (2.2 billion miles). The probe descended through Titan's dense, murky atmosphere to reveal a whole new world with Earth-like processes. Cassini recently made a remarkable discovery at another moon of Saturn, snowy Enceladus, discovering gigantic geysers of ice particles spewing into space from a warm interior.

The mission represents the best technical efforts of 260 scientists from the United States and 17 European nations. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of Caltech, manages the mission for NASA's Science Mission Directorate. The Cassini orbiter was designed, developed and assembled at JPL.

http://saturn.jpl.nasa.gov/news/press-r ... newsID=647
 
Xanadu: Rivers Flowed onto a Sunless Sea

Xanadu: Rivers Flowed onto a Sunless Sea

http://photojournal.jpl.nasa.gov/catalog/PIA08428

This image from the Synthetic Aperture Radar instrument on the Cassini spacecraft shows the radar-bright western margin of Xanadu, one of the most prominent features on Titan (see also PIA08425). In radar images, bright regions indicate a rough or scattering material, while a dark region might be smoother or more absorbing. The image was taken during a flyby of Titan on April 30, 2006.

Narrow, sinuous, radar-bright channels, meandering like a maze, are seen on the right-hand-side of the image. These may be river networks that might have flowed onto the dark areas on the left of the image. Vast, dark areas covered by dunes are seen on the equatorial regions of Titan (see PIA03567) and have been referred to as Titan's "sand seas." Near the middle of the image is a radar-bright area that has a boundary with the dark sand seas. Because the radar illumination is coming from the top, this indicates that the bright region, Xanadu, is topographically higher than the sand seas.
 
Titan's Land-o-Lakes

Titan's Land-o-Lakes

http://photojournal.jpl.nasa.gov/catalog/PIA08448

The Cassini spacecraft's Titan Radar Mapper instrument imaged this area atop Xanadu, the bright area of Titan, on April 30, 2006. The picture is roughly 150 kilometers (93 miles) wide by 400 kilometers (249 miles) long, and shows features as small as 350 meters (1148 feet). Chains of hills or mountains are revealed by the radar beam, which is illuminating their northern sides (in this image, north is up). Interspersed between the chains of hills are darker areas where topographic features are absent or partly buried. The darkest areas could contain liquids, which tend to reflect the radar beam away from Cassini in the absence of winds, making the area appear quite dark. At Titan's icy conditions, these liquids would be methane and/or ethane. Stubby drainage features can be see faintly between the chains of hills, suggesting flow of the liquid across parts of the region.
 
8)

Titan weather: Methane downpours and drizzle

ONLY two worlds in the solar system have rain that falls all the way to the ground. We live on one; the other is Saturn's giant moon Titan. Now findings from the Cassini mission and the Huygens probe that landed on Titan last year are starting to reveal the patterns of rainfall on the moon.

Unmistakable river channels cut into Titan's icy terrain. So there must be some kind of rainfall, almost certainly drops of liquid methane, to feed the rivers.

Some of this rain could come from fierce storms generated by clouds that cluster around Titan's south pole, according to Ricardo Hueso Alonso at the University of the Basque Country in Bilbao, Spain. Hueso and his colleague Agustín Sánchez-Lavega modelled Titan's atmosphere and then varied the methane "humidity" and temperature until their model recreated the moon's polar clouds, which sometimes reach as high as 25 kilometres. To climb so high, the clouds must be lifted by powerful convection currents driven by the heat energy that sudden condensation releases. Raindrops would condense around the aerosol particles that the Huygens lander detected in large quantities when it descended through Titan's atmosphere in January 2005.

In the model, cloudbursts over the south pole would dump about 150 millimetres of rain in just 2 hours - comparable to some of the fiercest storms on Earth (Nature, vol 442, p 428). Methane droplets, up to 5 millimetres across, could fall at more than 100 kilometres per hour.

Most of the moon does not see storm clouds like this, however; Titan's run-of-the-mill rainfall may be much less dramatic. A team led by Tetsuya Tokano of the University of Cologne in Germany has used Huygens data to work out the methane humidity in the atmosphere (Nature, vol 442, p 432). They calculate that the methane should condense into small ice crystals at altitudes of about 20 to 30 kilometres, forming the hazy layer of clouds that Huygens saw above Titan. The ice crystals should then drift down, melt and eventually drizzle to the surface.

Such drizzle and polar storms can't be the whole story, however. Most of Titan's river systems are far from the pole, and the drizzle is much too light to account for them - it only adds up to about 50 millimetres per year, less than the average rainfall in some deserts on Earth. "Maybe at middle latitudes there are storms in a different season," says Hueso.

http://www.newscientistspace.com/articl ... izzle.html
 
*BUMP*


Massive Mountain Range Imaged on Saturn's Moon Titan


The tallest mountains ever seen on Titan -- coated with layers of organic material and blanketed by clouds -- have been imaged on Saturn's moon Titan by NASA's Cassini spacecraft.

"We see a massive mountain range that kind of reminds me of the Sierra Nevada mountains in the western United States. This mountain range is continuous and is nearly 100 miles long," said Dr. Bob Brown, team leader of the Cassini visual and infrared mapping spectrometer at the University of Arizona, Tucson.

During an Oct. 25 flyby designed to obtain the highest resolution infrared views of Titan yet, Cassini resolved surface features as small as 400 meters (1,300 feet). The images reveal a large mountain range, dunes, and a deposit of material that resembles a volcanic flow. These data, together with radar data from previous flybys, provide new information on the height and composition of geologic features on Titan.

If Titan were Earth, these mountains would lie south of the equator, somewhere in New Zealand. The range is about 150 kilometers long (93 miles) and 30 kilometers (19 miles) wide and about 1.5 kilometers (nearly a mile) high. Deposits of bright, white material, which may be methane "snow" or exposures of some other organic material, lie at the top of the mountain ridges.

"These mountains are probably as hard as rock, made of icy materials, and are coated with different layers of organics," said Dr. Larry Soderblom, Cassini interdisciplinary scientist at the U.S. Geological Survey, Flagstaff, Ariz.

He added, "There seem to be layers and layers of various coats of organic 'paint' on top of each other on these mountain tops, almost like a painter laying the background on a canvas. Some of this organic gunk falls out of the atmosphere as rain, dust, or smog onto the valley floors and mountain tops, which are coated with dark spots that appear to be brushed, washed, scoured and moved around the surface."

The mountains probably formed when material welled up from below to fill the gaps opened when tectonic plates pull apart, similar to the way mid-ocean ridges are formed on Earth.

Separately, the radar and infrared data are difficult to interpret, but together they are a powerful combination. In the infrared images, one can see the shadows of the mountains, and in radar, one can see their shape. But when combined, scientists begin to see variations on the mountains, which is essential to unraveling the mysteries of the geologic processes on Titan.

A fan-shaped feature, possibly a remnant of a volcanic flow, is also visible in the infrared images. The radar instrument imaged this flow and a circular feature from which the flow seems to emanate on a previous flyby, but not in this level of detail.

"The evidence is mounting that this circular feature is a volcano," said Dr. Rosaly Lopes, Cassini radar team member at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "With radar data alone, we identified it as a possible volcano, but the combination of radar and infrared makes it much clearer."

Near the wrinkled, mountainous terrain are clouds in Titan's southern mid latitudes whose source continues to elude scientists. These clouds are probably methane droplets that may form when the atmosphere on Titan cools as it is pushed over the mountains by winds.

The composition of dunes that run across much of Titan is also much clearer. "The dunes seem to consist of sand grains made of organics, built on water-ice bedrock, and there may also be some snow and bright deposits," Brown said.

Titan is a complex place and scientists are uncovering the secrets of the surface, one flyby at a time. Scientists hope to get more clues from the next Titan flyby, on Dec. 12.

For the new infrared images of the mountains visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov and http://wwwvims.lpl.arizona.edu . Additional information on NASA news from the American Geophysical Union conference is at http://www.nasa.gov/agu .

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. The Cassini orbiter was designed, developed and assembled at JPL. The Visual and Infrared Mapping Spectrometer team is based at the University of Arizona where this image was produced. The radar instrument team is based at JPL, working with team members from the United States and several European countries.

http://saturn.jpl.nasa.gov/news/press-r ... newsID=709

See also the best images taken by Cassini. You can vote for your favourite as well. How's that eh?!

http://saturn.jpl.nasa.gov/multimedia/poll/index.cfm
 
'Proof' of methane lakes on Titan

The lakes should grow and shrink with Titan's seasons

The Cassini probe has spotted what scientists say is unequivocal evidence of lakes of liquid methane on Titan, Saturn's largest moon.

Radar images reveal dark, smooth patches that range in size from three to 70km across (two to 44 miles).

The team says the features, which were spied in the moon's far north, look like crater or caldera lakes on Earth. The researchers tell the journal Nature that everything about the patches points to them being pools of liquid.

"They look very similar to lakes on Earth," explained Dr Ellen Stofan, a Cassini radar team member from Proxemy Research in Washington DC, US.

"They have channels feeding into them just like you have rivers feeding into lakes on the Earth. Their shapes, their shorelines, all of those geologic aspects are actually very familiar."

The Cassini-Huygens mission is a cooperative project of the US space agency (Nasa), the European Space Agency (Esa) and the Italian Space Agency (Asi).

http://news.bbc.co.uk/1/hi/sci/tech/6230381.stm
 
Titan's largest lake rivals Earth's Caspian Sea

A lake the size of the Caspian Sea may have been spotted on Saturn's frigid moon, Titan. If it is indeed filled with liquid, the 1100-kilometre-long lake would be the largest yet found on the moon.

The dark feature appears in an image of Titan's north polar region taken by NASA's Cassini spacecraft on 25 February. It has a surface area slightly smaller than the Caspian Sea, which is the largest lake on Earth.

At -180° Celsius, Titan's surface is far too cold for liquid water. Instead, liquid methane, perhaps with some liquid ethane mixed in, is thought to fill the moon's apparent lakes.

The new image was obtained using Cassini's Imaging Science Subsystem (ISS), which is comprised of two cameras that can see in ultraviolet, visible and infrared light.

The instrument has previously spotted a small, kidney-shaped feature that is considered a likely lake (see Titan may boast methane lakes after all).

Cassini's radar has also revealed dozens of lake-like features (see Titan may be a land of lakes after all).

And new radar images obtained during Cassini's latest Titan flyby on 22 February have revealed yet more lakes, including one with a large island in its centre (see image below right). The island is 150 by 90 kilometres, about the size of the Big Island of Hawaii.

http://space.newscientist.com/article/d ... n-sea.html
 
Probe reveals seas on Saturn moon

Nasa's Cassini probe has found evidence for seas, probably filled with liquid hydrocarbons, at the high northern latitudes of Saturn's moon Titan.
The dark features, detected by Cassini's radar, are much bigger than any lakes already detected on Titan.

The largest is some 100,000 sq km (39,000 sq miles) - greater in extent than North America's Lake Superior.

It covers a greater fraction of Titan than the proportion of Earth covered by the Black Sea.

The Black Sea is the Earth's largest inland sea and covers about 0.085% of our planet's surface.

The newly observed body on Titan covers at least 0.12% of that world's surface. Cassini team members argue that this gives them reason to call it a sea.

Since Cassini's radar has caught only a portion of each of the new features, only their minimum size is known.

Methane and ethane

Titan is the second largest moon in the Solar System and is about 50% larger than Earth's Moon.

While there is no definitive proof that these seas contain liquid, their shape, their dark appearance in radar that indicates smoothness, along with other properties, point to the presence of liquids.

The liquids are probably a combination of methane and ethane, given the conditions on Titan and the abundance of methane and ethane gases and clouds in Titan's atmosphere.

"Carl Sagan [the astronomer] said that Titan must be covered with oceans, and that these replenished the atmosphere with methane," explained Charles Wood, chair of space studies at the University of North Dakota.

But that vision of hydrocarbon oceans had to be scrapped when Cassini peered through Titan's organic haze and found a chaotic, geologically active surface, but no large bodies of liquid.

Recently, the orbiter started to spot lake-like features at Titan's northerly regions.

"They are limited to about 65 degrees latitude," said Charles Wood, although he added that river-like channels seemed to be everywhere on Titan.

The discovery of these even larger bodies might hold the solution to the problem of replenishment of the atmosphere with methane.

After making these findings, Cassini team members plan to re-point the orbiter's radar instrument during a May flyby so that it can pass directly over the large dark features imaged by the cameras.

The Cassini-Huygens mission is a cooperative project of the US space agency (Nasa), the European Space Agency (Esa) and the Italian Space Agency (Asi).

http://news.bbc.co.uk/1/hi/sci/tech/6449081.stm
 
Mysterious signal hints at subsurface ocean on Titan
22:29 11 June 2007
NewScientist.com news service
David Shiga

Enlarge image
The Huygens probe seems to have detected low frequency radio waves as it parachuted down to the surface of Titan in January 2005 (Illustration: ESA/D Ducros) The tentative detection of low frequency radio waves on Saturn's icy moon, Titan, could signal an underground ocean of liquid water, a new study says. If so, it would be good news for the possibility of life beneath the surface of this bizarre world.

Titan's crust is thought to be made largely of water ice, kept rock hard by the prevailing surface temperature of -178° Celsius. But theoretical models of the moon's interior suggest that ammonia-rich water deep beneath the surface could stay liquid, perhaps forming a global ocean.

Now, scientists led by Fernando Simoes of the Centre d'Etudes Terrestres et Planetaires in Saint Maur, France, may have the first observational evidence of such an ocean. Their research is based on an enigmatic radio signal detected by the European Space Agency's Huygens probe as it descended to the moon's surface after being jettisoned from the Cassini spacecraft in 2005.

The radio signal was detected only in a very narrow range of extremely low frequencies around 36 Hertz. The Huygens radio team noticed it just a few hours after the probe's descent and have been working to understand its source since then.

Echo effect
On Earth, lightning produces a similar low frequency radio signal. The radio waves then bounce back and forth between the ground and the upper reaches of our atmosphere. This echo effect enhances some frequencies and lets others die out, resulting in signals with precisely defined frequencies, similar to what was detected on Titan.

The water ice that makes up Titan's exterior is a poor reflector of radio waves, so if the signal comes from an echo effect like that on Earth, there would have to be a more reflective material below the surface. An ocean of liquid water beneath the surface could do the job, the team says.

"We do not need a subsurface ocean but require a subsurface reflector," Simoes told New Scientist. "If a subsurface ocean exists, the solid-liquid interface would be a good reflector."

Instrumental effects
The researchers cannot tell how deep the reflector lies, and they are puzzled by some aspects of the signal. For one thing, no lightning has been detected on Titan so far, yet the signal is about 10 times stronger than the one seen on Earth.

These puzzles made the team suspicious that the signal could be due to interference from other parts of the probe, but laboratory experiments with copies of the instruments have ruled this out.

The team has also tested whether parts of the radio instrument might vibrate at 36 Hertz to produce the signal. So far that does not appear to be the case, although they have yet to try the tests at the very low temperatures prevalent on Titan.

"At the present stage we are convinced [that whatever] it is, at least it is not an obvious artefact," Simoes says.

Buried deep
Cassini science team member Ralph Lorenz of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, US, who did not participate in Simoes's study, says there likely is an ocean of liquid water below the planet's surface.

"A subsurface water ocean is certainly expected on Titan, probably with 10% or more of ammonia acting as antifreeze," he told New Scientist. "It would likely be 50 kilometres beneath an ice crust."

He says it is possible for a subsurface ocean to create radio echoes, but says he is not familiar enough with this phenomenon to know whether what Huygens saw is strong evidence for such an ocean.

Jonathan Lunine of the University of Arizona in Tucson, US, who also did not participate in the study, says he is sceptical that radio waves could penetrate the 50 or more kilometres needed to reflect from a subsurface ocean and create the signal Huygens sees.

Squeezed and stretched
But he says evidence of such an ocean could come in future flybys of Titan by the Cassini spacecraft. The Cassini team will try to use data from the flybys to measure the way Titan is squeezed and stretched by the uneven gravitational pull of Saturn, which could provide evidence of an ocean, he says.

"Expect nothing until 2009 in terms of a conclusion," he told New Scientist. "But the conclusion they do get could be definitive."

The research suggests life may be able to take hold on the giant moon – in 2000, Andrew Fortes of University College in London, UK, published a study saying that life could survive in a subsurface ocean on Titan.
Cassini: Mission to Saturn - Learn more in our continually updated special report.

Journal reference: Planetary and Space Science (DOI: 10.1016/j.pss.2007.04.016)

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http://www.newscientist.com/article.ns?id=dn11378
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Life in the deep freeze
http://www.newscientist.com/article.ns? ... 125641.300
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Weblinks

Cassini-Huygens, ESA
http://saturn.esa.int/

Ralph Lorenz, University of Arizona
http://www.lpl.arizona.edu/~rlorenz/

Jonathan Lunine, University of Arizona
http://www.lpl.arizona.edu/faculty/lunine.html


Sirens of Titan
 
Last edited by a moderator:
This might well be the next step. Full text at link.


Titan Triple Threat
http://www.saturndaily.com/reports/Tita ... t_999.html
by Leslie Mullen
for Astrobiology Magazine
Moffett Field CA (SPX) Nov 07, 2008

A hot air balloon drifts gently in the breeze, gliding over mountain ranges and vast lakes. Thick clouds extend over the entire horizon, threatening rain. The meager light that filters through illuminates one side of the balloon, making it look like a giant question mark in the sky.
This is a vision that floats in the minds of scientists who study Titan, Saturn's largest moon. The Cassini spacecraft currently traveling around the Saturn system has provided us with our best glimpse yet of Titan, but there is still much to be explored.

Athena Coustenis, an astrophysicist and planetologist with the Paris Observatory, is helping draft a plan to send a hot air balloon to Titan, as well as an orbiting spacecraft and a surface probe. Called TSSM - the Titan and Saturn System Mission - this three-tiered approach to exploration could shed more light on the still-mysterious moon.

Seeing Through the Fog
"Titan is the best place to go with a balloon because of the atmosphere," says Coustenis. Although the atmosphere of Titan is filled with a smoggy orange hydrocarbon haze, it is primarily composed of nitrogen - just like Earth's. In fact, Astrobiologists think Titan's atmosphere may be quite similar to how the Earth's was billions of years ago, before life on our planet generated oxygen.
 
Ah it's been a while...time for an update from Cassini radar team member Randy Kirk...

Cassini Provides Virtual Flyover of Saturn's Moon Titan

PASADENA, Calif. – "Fly me to the moon" -- to Saturn's moon Titan, that is. New Titan movies and images are providing a bird's-eye view of the moon's Earth-like landscapes.
The new flyover maps show, for the first time, the 3-D topography and height of the 1,200-meter (4,000-foot) mountain tops, the north polar lake country, the vast dunes more than 100 meters (300 feet) high that crisscross the moon, and the thick flows that may have oozed from possible ice volcanoes.

The topographic maps were made from stereo pairs of radar images. They are available at saturn.jpl.nasa.gov and http://www.nasa.gov/cassini .

Cassini radar team member Randy Kirk with the Astrogeology Science Center at the U.S. Geological Survey in Flagstaff, Ariz., created the maps. He used some of the 20 or so areas where two or more overlapping radar measurements were obtained during 19 Titan flybys. These stereo overlaps cover close to two percent of Titan's surface. The process of making topographic maps from them is just beginning, but the results already reveal some of the diversity of Titan's geologic features.

"These flyovers let you take in the bird's-eye sweeping views of Titan, the next best thing to being there," said Kirk. "We've mapped many kinds of features, and some of them remind me of Earth. Big seas, small lakes, rivers, dry river channels, mountains and sand dunes with hills poking out of them, lava flows."

Kirk will present these results today at the Lunar and Planetary Science Conference in The Woodlands, Texas.

High and low features are shown in unprecedented detail at about 2.4-kilometer (1.5-mile) resolution. The maps show some features that may be volcanic flows. These flows meander across a shallow basin in the mountains. One area suspected to be an ice volcano, Ganesa Macula, does not appear to be a volcanic dome. It may still have originated as a volcano, but it's too soon to know for sure. "It could be a volcanic feature, a crater, or something else that has just been heavily eroded," added Kirk.

The stereo coverage includes a large portion of Titan's north polar lakes of liquid ethane and methane. Based on these topographical models, scientists are better able to determine the depth of lakes. The highest areas surrounding the lakes are some 1,200 meters (about 4,000 feet) above the shoreline. By comparing terrain around Earth to the Titan lakes, scientists estimate their depth is likely about 100 meters (300 feet) or less.

More 3-D mapping of these lakes will help refine these depth estimates and determine the volume of liquid hydrocarbons that exist on Titan. This information is important because these liquids evaporate and create Titan's atmosphere. Understanding this methane cycle can provide clues to Titan's weather and climate.

Launched in 1997, Cassini completed its primary four-year mission in 2008 and is now in extended mission operations, which run through September 2010. Over the course of the mission, Cassini plans to map more than three percent of Titan's surface in 3-D. About 38 percent of Titan's surface has been mapped with radar so far. On March 27, Cassini will complete its 52nd targeted flyby of Titan.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the Cassini-Huygens mission for NASA's Science Mission Directorate. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

http://saturn.jpl.nasa.gov/news/newsrel ... e20090324/
 
Titan moon resembles Earth
By John von Radowitz, Press Association
Thursday, 6 August 2009

Saturn's smog-ridden moon Titan bears a striking resemblance to Earth despite its alien environment, a study has revealed.

Scientists have now mapped a third of Titan's surface using radar to pierce the planet-sized moon's thick atmosphere.

The probe has revealed mountain ranges, dunes, numerous lakes and suspected volcanoes.

Just as on Earth, the weather on Titan appears to have erased most evidence of meteorite craters.

US planetary geologist Dr Rosaly Lopes, from the Jet Propulsion Laboratory in Pasadena, California, said: "It really is surprising how closely titan's surface resembles Earth's.

"In fact, Titan looks more like the Earth than any other body in the Solar System, despite the huge differences in temperature and other environmental conditions."

Titan is a supercooled world with average surface temperatures of around minus 180C, where water cannot exist except as deep-frozen, rock-hard ice.

Methane and ethane take the place of water in Titan's hydrological cycle, falling as rain or snow, and forming lakes and drainage channels.

Titan is the only moon known to possess a thick atmosphere, and the only celestial body other than the Earth to have stable pools of liquid on its surface.

The American space agency Nasa's Cassini probe has been investigating Saturn and its moons for the past five years.

It acted as "mothership" to the European Space Agency probe Huygens which landed on the surface of Titan in 2005.

Dr Lopes presented the latest results from the mission today at the International Astronomical Union (IAU) General Assembly in Rio de Janeiro, Brazil.

Other findings presented at the meeting showed evidence of water-ice and ammonia "cryovolcanoes" on Titan.

New infrared images obtained by Cassini suggest that the volcanoes have deposited ammonia on the moon's surface.

The chemical environment on Titan closely resembles that of the early Earth around the time life first emerged.

Dr Robert Nelson, a senior Jet Propulsion Laboratory research scientist who also addressed the meeting, said: "One exciting question is whether Titan's chemical processes today support a pre-biotic chemistry similar to that under which life evolved on Earth
."

http://www.independent.co.uk/news/scien ... 68268.html
 
Scientists find a 'hint of life' on Saturn's moon Titan
By Daily Mail Reporter
Last updated at 7:33 AM on 5th June 2010

Scientists have found evidence that there is life on Saturn's biggest moon, Titan.
They have discovered clues that primitive aliens are breathing in Titan's atmosphere and feeding on fuel at the surface.

The startling discoveries, made using an orbiting spacecraft, are revealed in two separate reports.

Data from Nasa's Cassini probe has analysed the complex chemistry on the surface of Titan - the only moon known to have a dense atmosphere.

Its surface is covered with mountains, lakes and rivers which has led astronomers to call it the most Earthlike world in the solar system.

Organic chemicals had already been detected on the 3,200-mile wide planet. But the liquid on Titan is not water but methane and the scientists expect life there to be methane-based.

The first paper, in the journal Icarus, shows that hydrogen gas flowing down through Titan's atmosphere disappears at the surface, suggesting it could be being breathed by alien bugs.

The second paper, in the Journal of Geophysical Research, reports there is a lack of a certain chemical on the surface, leading scientists to believe it may be being consumed by life.

Scientists had expected sunlight interacting with chemicals in the atmosphere to produce acetylene that falls down to coat Titan's surface. But Cassini detected no acetylene there.
Experts warn that there could be other explanations for the results.

But taken together, they fulfil two important conditions necessary for methane-based life to exist.
Nasa astrobiologist Chris McKay said: 'If these signs do turn out to be a sign of life, it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth.'

Scientists believe that when the Sun swells up, swallowing Earth, conditions could be ideal on a warmer Titan.
Professor John Zarnecki, of the Open University, said: 'We believe the chemistry is there for life to form. It just needs heat and warmth to kick-start the process.
'In four billion years' time, when the Sun swells into a red giant, it could be paradise on Titan.'

Read more: http://www.dailymail.co.uk/sciencetech/ ... z0pxycx5J3
 
Giant ice volcano may have been found on Titan
http://www.newscientist.com/article/dn1 ... titan.html

* 19:03 14 December 2010 by Eric Betz, Inside Science News Service

A potential new ice volcano has been found on Saturn's moon Titan.

Named Sotra, the volcano is nearly 1 kilometre tall and has a 1.6-kilometre-deep pit alongside it. Surrounded by giant sand dunes, it is thought to be the largest in a string of several volcanoes that once spewed molten ice from deep beneath the moon's surface.

"We think we have found the strongest case yet for an ice volcano on Titan," said Randy Kirk, a geophysicist at the US Geological Survey in Flagstaff, Arizona. "What we see is not just a flow like we see in other places, it's like a volcanic field would be on Earth."

Titan is about the size of the planet Mercury but has an atmosphere thicker than Earth's. This makes it incredibly difficult for astronomers to know what's happening on the surface. Planetary scientists, including Kirk, are using NASA's Cassini spacecraft to map the moon, but so far only about half of Titan has been imaged.

Kirk and his team created a 3D mapping technique that patches together multiple images of the same area, so they were lucky that Sotra was in one of the rare places imaged twice.

"The classical volcano everybody thinks of when you say the word is a mountain with a crater on it and lava flows coming out of it," said Kirk. "That's what we've found on Titan."
'This is it'

The team cannot be certain if the chain is active, but described the find as the best evidence found so far for a cryovolcano, or ice volcano. Previously, bright spots seen in low-resolution satellite images have been interpreted as volcanic flows and craters. However, once those areas were mapped in 3D, it became obvious they weren't volcanoes.

"We had noted Sotra Facula as a candidate cryovolcano before," said Rosaly Lopes at NASA's Jet Propulsion Laboratory in Pasadena, California. "But it was only when Randy got the topography done that we realised, wow, this is it."

Earth's interior is divided into distinct layers of rock and liquid magma. When this molten rock erupts through the planet's crust, it's known as volcanism. Titan's volcanism is more complicated because beneath the moon's surface lies a layer of ice. Even a small amount of internal heat could create molten ices. Because the liquid would be less dense, it would force its way to the surface. The result would be a massive eruption of slushy liquid and gases similar to what scientists have seen on other icy moons.

"Ice at outer solar system temperatures is very rigid," Kirk said. "Ice at close to its melting point is soft. What would be a glacier on Earth would be a volcano on a body that's made of that same material. It's the difference between the cake and the frosting."
Methane source

Some have theorised that volcanoes on Titan are the best way to explain the strange abundance of methane gas in its atmosphere. This gas is constantly being stripped from Titan's upper atmosphere by the sun. Without a source to replenish it, all of the methane would disappear in a few million years.

However, if an ice volcano like Sotra were to erupt, it would release volatiles like methane and ethane from inside Titan. Kirk's team calculates that it would take a Sotra-sized volcanic eruption every 1000 years to maintain the current level of methane in Titan's atmosphere.

Others are sceptical about ice volcano claims and have proposed alternative theories to explain the methane abundance.

"There's been this whole list of volcanoes (on Titan) that have been published and then subsequently shot down," said planetary scientist Jeffrey Moore at NASA's Ames Research Center in Moffett Field, California. "This new feature doesn't make me change my tune that no one has unambiguously found a volcano on Titan."
Ice cube

Moore believes that unlike Earth's well defined and separate layers, beneath Titan's surface is a huge layer of mixed rock and ice, or what is called a partially differentiated interior. If this is the case, it would be much more difficult to heat ice enough to cause an eruption onto the surface.

Moore and others believe that Titan was once an enormous ice cube. According to their theory, as the sun aged and warmed, it heated Titan's surface. This process could have put methane into the atmosphere and subsequently fuelled a rain cycle that erased all impact craters. Moore said this would also have given Titan the young appearance that many have attributed to volcanism.

"If you press forward in time, all the methane will be erased and (Titan) will have a blue sky and a nitrogen atmosphere with sand dunes of hydrocarbons," Moore said.
 
Analysis of two year old data.

Oxygen envelops Saturn's icy moon
http://www.bbc.co.uk/news/science-environment-17225127
By Pallab Ghosh
Science correspondent, BBC News

The Cassini spacecraft flew by Dione nearly two years ago

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A Nasa spacecraft has detected oxygen around one of Saturn's icy moons, Dione.

The discovery supports a theory that suggests all of the moons near Saturn and Jupiter might have oxygen around them.

Researchers say that their finding increases the likelihood of finding the ingredients for life on one of the moons orbiting gas giants.

The study has been published in Geophysical Research Letters.

According to co-author Andrew Coates of University College London, Dione has no liquid water and so does not have the conditions to support life. But it is possible that other moons of Jupiter and Saturn do.

"Some of the other moons have liquid oceans and so it is worth looking more closely at them for signs of life," Prof Coates said.

The discovery was made using the Cassini spacecraft, which flew by Dione nearly two years ago. Instruments on board the unmanned probe detected a thin layer of oxygen around the moon, so thin that scientists prefer to call it an "exosphere" rather than an atmosphere.

But the discovery is important because it suggests there is a process at work around the solar system's gas giants, Saturn and Jupiter, in which oxygen is released from their icy satellites.

It seems that highly charged particles from the planets' powerful radiation belts split the water in the ice into hydrogen and oxygen.

Dione's sister moon, Enceladus is thought to harbour a liquid ocean below its icy surface. The same is thought to be true of Europa, Callisto and Ganymede which orbit Jupiter.

Prof Coates is among a group of scientists lobbying the European Space Agency to send an orbiter to explore Jupiter's icy moons - known as the Juice mission.

"These are fascinating places to look for signs of life," he said.

As is Titan, Saturn's largest satellite. Its nitrogen and methane atmosphere is reminiscent of the early Earth, according to Prof Coates.

"It may be an Earth waiting to happen as the outer Solar System warms up," he said.

Nasa is developing a proposal to send a landing craft, or lander, to float on one of the planet's oily lakes.
 
More analysis of the Cassini data.

Thousand-year wait for Titan's methane rain
http://www.bbc.co.uk/news/science-environment-17454005
By Paul Rincon
Science editor, BBC News website, The Woodlands, Texas

Saturn and its moons have given up many of their secrets to the Cassini mission

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Titan: Treasures of Earth's oily twin

Places on Saturn's moon Titan see rainfall about once every 1,000 years on average, a new analysis concludes.

Earth and Titan are the only worlds in the Solar System where liquid rains on a solid surface - though on Titan, the rain is methane rather than water.

The calculation is based on findings from the Cassini probe of rainstorms that occurred in 2004 and 2010.

Dr Ralph Lorenz presented details of his work at the Lunar and Planetary Science Conference (LPSC) in Texas.

Titan is a fascinating, "same but different" analogue of the Earth. Wind and rain sculpt the surface, producing river channels, lakes, dunes and shorelines.


Titan: strong methane rain, but rarely
But here, liquid hydrocarbons take the place of water. On Titan, where the surface temperature averages -179C, it rains methane.

"You get centuries between rainshowers; but when they occur, they dump tens of centimetres or even metres of rainfall," Dr Lorenz, from the Johns Hopkins Applied Physics Laboratory (JHUAPL) in Maryland, told BBC News.

"That's consistent with the deeply incised river channels that we see."

These channels have been observed by both Cassini and the Huygens probe, which plunged through Titan's thick atmosphere in 2005.

Dr Lorenz says the latest results are remarkably close to the theoretical predictions of Titan rainfall he made 12 years ago.

When it rains...
Continue reading the main story

Start Quote

We're anxious to see when we'll see clouds appearing again”

Dr Elizabeth Turtle
JHUAPL
In 2004 and 2010, at different locations on Titan, the Cassini spacecraft observed a darkening of the moon's surface associated with cloud activity - events that scientists interpret as rain showers.

Dr Elizabeth Turtle, also from JHUAPL, presented an analysis of the Autumn 2010 storms observed at Concordia Regio, near Titan's equator.

"In the wake of this storm, we saw significant changes on the surface... a month later, there was this large darkened swathe that's longer than 2,000km, covering an area of about 500,000 sq km," she explained.

"The simplest interpretation is that this is caused by precipitation wetting the surface - possibly ponding in some areas.

"It's the easiest way to cover [an area this large] in such a short timescale. It's also consistent with the fact that the changes revert over several months afterwards."

Ralph Lorenz's analysis of the rainfall represents a global average; but the seasonal cycle on Titan concentrates rainfall during the polar summer.


The TiME mission will see further exploration of the Saturn system, if it is selected
Hypothetically, he says, if an observer were to sit somewhere at one of Titan's poles for 96 Earth days (six days on Titan), they would have a 50% chance of being rained on directly, and be able to observe five rainstorms.

This is of particular relevance to the proposed space mission that Dr Lorenz is currently involved with.

The Titan Mare Explorer (TiME) would splash down in one of Titan's largest lakes - Ligeia Mare - to spend 96 days analysing its depth and chemistry. It would also gather data on the surrounding environment, including weather patterns.

TiME is one of three finalists competing to be selected as a Nasa Discovery mission - the others are InSight and CHopper. A decision should be made next month.

Meanwhile, Dr Turtle's team has continued to monitor Titan, but has seen very few clouds since the events in 2010. A similar lapse was seen after the storms in 2004, and could be the result of methane in the atmosphere being depleted.

"That may be what happened here; this depleted the atmosphere significantly and it takes a while for it to reset," she said.

"We're anxious to see when we'll see clouds appearing again."

While many aspects of Earth's weather can be seen on Titan, one difference is that the moon is probably too small for the kind of activity that generates cyclones and hurricanes on Earth.

[email protected]. and follow me on Twitter
 
Cassini finds Saturn moon Phoebe has planet-like qualities
http://phys.org/news/2012-04-cassini-sa ... -like.html
April 27th, 2012 in Space & Earth / Space Exploration

Phoebe's true nature is revealed in startling clarity in this mosaic of two images taken during Cassini's flyby on June 11, 2004. Credit: NASA/JPL/Space Science Institute

(Phys.org) -- Data from NASA's Cassini mission reveal Saturn's moon Phoebe has more planet-like qualities than previously thought.
Scientists had their first close-up look at Phoebe when Cassini began exploring the Saturn system in 2004. Using data from multiple spacecraft instruments and a computer model of the moon's chemistry, geophysics and geology, scientists found Phoebe was a so-called planetesimal, or remnant planetary building block. The findings appear in the April issue of the Journal Icarus.

"Unlike primitive bodies such as comets, Phoebe appears to have actively evolved for a time before it stalled out," said Julie Castillo-Rogez, a planetary scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Objects like Phoebe are thought to have condensed very quickly. Hence, they represent building blocks of planets. They give scientists clues about what conditions were like around the time of the birth of planets and their moons."

Cassini images suggest Phoebe originated in the far-off Kuiper Belt, the region of ancient, icy, rocky bodies beyond Neptune's orbit. Data show Phoebe was spherical and hot early in its history, and has denser rock-rich material concentrated near its center. Its average density is about the same as Pluto, another object in the Kuiper Belt. Phoebe likely was captured by Saturn's gravity when it somehow got close to the giant planet.

Saturn is surrounded by a cloud of irregular moons that circle the planet in orbits tilted from Saturn's orbit around the sun, the so-called equatorial plane. Phoebe is the largest of these irregular moons and also has the distinction of orbiting backward in relation to the other moons. Saturn's large moons appear to have formed from gas and dust orbiting in the planet's equatorial plane. These moons currently orbit Saturn in that same plane.

This panel of images shows the nearly spherical shape of Saturn's moon Phoebe, as derived from imaging obtained from NASA's Cassini spacecraft. Each image represents a 90-degree turn. Credit: NASA/JPL-Caltech/SSI/Cornell

"By combining Cassini data with modeling techniques previously applied to other solar system bodies, we've been able to go back in time and clarify why it is so different from the rest of the Saturn system," said Jonathan Lunine, a co-author on the study and a Cassini team member at Cornell University, Ithaca, N.Y.

analyses suggest that Phoebe was born within the first 3 million years of the birth of the solar system, which occurred 4.5 billion years ago. The moon may originally have been porous but appears to have collapsed in on itself as it warmed up. Phoebe developed a density 40 percent higher than the average inner Saturnian moon.

Objects of Phoebe's size have long been thought to form as "potato-shaped" bodies and remained that way over their lifetimes. If such an object formed early enough in the solar system's history, it could have harbored the kinds of radioactive material that would produce substantial heat over a short timescale. This would warm the interior and reshape the moon.

"From the shape seen in Cassini images and modeling the likely cratering history, we were able to see that Phoebe started with a nearly spherical shape, rather than being an irregular shape later smoothed into a sphere by impacts," said co-author Peter Thomas, a Cassini team member at Cornell.

Phoebe likely stayed warm for tens of millions of years before freezing up. The study suggests the heat also would have enabled the moon to host liquid water at one time. This could explain the signature of water-rich material on Phoebe's surface previously detected by Cassini.

The new study also is consistent with the idea that several hundred million years after Phoebe cooled, the moon drifted toward the inner solar system in a solar-system-wide rearrangement. Phoebe was large enough to survive this turbulence.

More than 60 moons are known to orbit Saturn, varying drastically in shape, size, surface age and origin. Scientists using both ground-based observatories and Cassini's cameras continue to search for others.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the mission for the agency's Science Mission Directorate in Washington. The California Institute of Technology in Pasadena manages JPL for NASA.

More information: http://saturn.jpl.nasa.gov

Provided by JPL/NASA
 
Tropical lakes on Saturn moon could expand options for life
http://www.nature.com/news/tropical-lak ... fe-1.10824
Subsurface source of liquid methane may be replenishing equatorial lakes on Titan.

Maggie McKee
13 June 2012 Corrected: 14 June 2012

Saturn's moon Titan (orange, in background) seems to have lakes of methane near the equator, as well as at the poles.
NASA/JPL/SPACE SCIENCE INSTITUTE

Nestling among the dunes in the dry equatorial region of Saturn's moon Titan is what appears to be a hydrocarbon lake. The observation, by the Cassini spacecraft, suggests that oases of liquid methane — which might be a crucible for life — lie beneath the moon's surface. The work is published today in Nature1.

Besides Earth, Titan is the only solid object in the Solar System to circulate liquids in a cycle of rain and evaporation, although on Titan the process is driven by methane rather than water.

This cycle is expected to form liquid bodies near the moon's poles, but not at its dune-covered equator, where Cassini measurements show that humidity levels are low and little rain falls to the surface. "The equatorial belt is like a desert on Earth, where evaporation trumps precipitation," says astrobiologist Jonathan Lunine of Cornell University in Ithaca, New York.

Any surface liquid there should evaporate and be transported to the cooler poles, where it should condense as rain. "Lakes at the poles are easy to explain, but lakes in the tropics are not," says Caitlin Griffith, a planetary scientist at the University of Arizona in Tucson. Indeed, Cassini has spotted hundreds of lakes and three seas in Titan's polar regions.

Now Griffith and her colleagues think they have found a tropical lake — some 60 kilometres long and 40 kilometres wide, and at least 1 metre deep — in Cassini observations made between 2004 and 2008. It appears as a black splotch at seven near-infrared wavelengths that can travel relatively unimpeded through the moon's thick atmosphere, which blocks visible light.

Caverns measureless to man

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The team also found four smaller, brighter splotches, which Griffith says may be "shallower ponds similar to marshes on Earth, with knee-to-ankle-level depths". Because tropical lakes on Titan should evaporate over a period of just a few thousand years, the researchers argue that these ponds and lakes are being replenished by subsurface oases of liquid methane.

That would expand the number of places on the moon where life could potentially originate. Methane, which is made up of one carbon and four hydrogen atoms, is the source of more complicated organic molecules found on Titan. "There may be organic chemical processes that occur in liquid hydrocarbons that could lead to compounds analogous to proteins and information-carrying molecules," says Lunine, who was not involved in the work. "There might be a kind of life that works in liquid hydrocarbons."

Lunine and Griffith are members of a proposed NASA mission to look for such complex chemistry, called the Titan Mare Explorer (TiME). The TiME probe would spend three months bobbing around Ligeia Mare, a sea near Titan's north polar region, measuring its chemistry with a mass spectrometer.

But should that mission, the fate of which will soon be decided by NASA, land on a tropical lake instead? No, says Lunine. He points out that a number of lines of evidence — including telltale radar signatures — show that the polar regions are filled with liquid hydrocarbon lakes and seas. So far there is less evidence for the tropical features. "Something else that just happens to be dark at those wavelengths", such as a solid organic compound, might mimic a lake, he says.

Only 17% of the equatorial region's surface area has been analysed at the high resolutions required to spot these small features, but Lunine says that lower-resolution observations suggest tropical lakes are relatively few and far between. Still, the idea of oases on Titan appeals to him. "There's a place on Titan named Xanadu, and if you go back to the Coleridge poem on Xanadu, he talks about 'caverns measureless to man',” Lunine says. He adds that he would love to find such caverns filled with methane on Titan.

Nature doi:10.1038/nature.2012.10824

Corrections

Corrected:

The is story originally stated that Titan and Earth were the only bodies in the solar system to experience rain. While it also rains on the gas giant Jupiter, they are the only solid bodies to experience it. The text has been updated to reflect this.

References

Griffith, C. A. et al. Nature 486, 237–239 (2012).
ArticlePubMed
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From nature.com

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03 January 2007
Planetary science: Titan's exotic weather
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From elsewhere

Caitlin Griffith
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Vid at link.

Beneath the mask, Titan looks surprisingly smooth and youthful
July 27th, 2012 in Space & Earth / Space Exploration


Caption: Images from the Cassini mission show methane river networks draining into lakes in Titan’s north polar region. Credit: NASA/JPL/USG

Saturn’s largest moon, Titan has long been hidden beneath the thick shroud of its methane- and nitrogen-rich atmosphere. That all changed in 2004 when NASA’s Cassini mission was able to penetrate the haze and sent back detailed radar images of the surface. These showed an icy terrain, carved over millions of years, by rivers similar to those found here on Earth. However, Titan’s surface doesn’t look as old and weather-beaten as it should. The rivers have caused surprisingly little erosion and there are fewer impact craters than would be expected. So what is the secret to Titan’s youthful complexion?

Titan is around four billion years old, roughly the same age as the rest of the solar system. But the low number of impact craters put estimates of its surface at only between 100 million and one billion years old.

Researchers at MIT and the University of Tennessee at Knoxville have analyzed images of Titan’s river networks and suggest two possible explanations: either erosion on Titan is extremely slow, or some recent phenomena has wiped out older surface features.

Taylor Perron, the Cecil and Ida Green Assistant Professor of Geology at MIT explains, “It’s a surface that should have eroded much more than what we’re seeing, if the river networks have been active for a long time. It raises some very interesting questions about what has been happening on Titan in the last billion years.”

Perron suggests that geological processes on Titan may be like those we see here on Earth. Here too, impact craters are scarce, as plate tectonics, erupting volcanoes, advancing glaciers and river networks reshaped our planet’s surface over billions of years, so, on Titan, tectonic upheaval, cryovolcanic eruptions, erosion and sedimentation by rivers could be altering the surface.

Discovering which processes are at work is not easy. The images from Cassini are like aerial photos but with much coarser resolution. They are flat, with no information about a surface elevation or depth.

Perron and MIT graduate student Benjamin Black analyzed the images and mapped 52 prominent river networks from four regions on Titan. They then compared the images with a model of river network evolution developed by Perron. Their data depicts the evolution of a river over time, taking into account variables such as the strength of the underlying material and the rate of flow through the river channels. As a river erodes, it transforms from a long, spindly thread into a dense, treelike network of tributaries. Titan’s river networks have maintained their long and spindly composition. They compare with recently renewed landscapes here including volcanic terrain on the island of Kauai and recently glaciated landscapes in North America.

Besides Earth, Titan is the only world with an active hydrologic cycle forming active river networks. Titan’s surface temperature may be about 94 K and its rivers run with liquid methane but as Perron says “It’s a weirdly Earth-like place, even with this exotic combination of materials and temperatures, and so you can still say something definitive about the erosion. It’s the same physics.”

Below is a video of Black and Perron explaining their research:

Source: Universe Today

"Beneath the mask, Titan looks surprisingly smooth and youthful." July 27th, 2012. http://phys.org/news/2012-07-beneath-ma ... mooth.html
 
Isnt this wonderful, a world that is like ours...but alien.

If Titan didnt exist, we would have to invent it
 
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