The Pioneer 11 spacecraft launched from Cape Canaveral forty years ago, on April 5, 1973. Pioneer 11’s path through Saturn’s outer rings took it within 21,000 km of the planet, where it discovered two new moons (almost smacking into one of them in September 1979) and a new “F” ring. The spacecraft also discovered and charted the magnetosphere, magnetic field and mapped the general structure of Saturn’s interior. The spacecraft’s instruments measured the heat radiation from Saturn’s interior and found that its planet-sized moon, Titan, was too cold to support life. This image from Pioneer 11 shows Saturn and its moon Titan. The irregularities in ring silhouette and shadow are due to technical anomalies in the preliminary data later corrected. At the time this image was taken, Pioneer was 2,846,000 km (1,768,422 miles) from Saturn.
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The Pioneer 11 spacecraft launched from Cape Canaveral forty years ago, on April 5, 1973. Pioneer 11’s path through Saturn’s outer rings took it within 21,000 km of the planet, where it discovered two new moons (almost smacking into one of them in September 1979) and a new “F” ring. The spacecraft also discovered and charted the magnetosphere, magnetic field and mapped the general structure of Saturn’s interior. The spacecraft’s instruments measured the heat radiation from Saturn’s interior and found that its planet-sized moon, Titan, was too cold to support life.

This image from Pioneer 11 shows Saturn and its moon Titan. The irregularities in ring silhouette and shadow are due to technical anomalies in the preliminary data later corrected. At the time this image was taken, Pioneer was 2,846,000 km (1,768,422 miles) from Saturn.

Source: nasa.gov

New data from NASA’s Cassini mission suggests that ice rich in methane and ethane could be floating on a hydrocarbon sea on Saturn’s moon Titan. This artist’s conception, released January 8 by NASA’s Jet Propulsion Laboratory, envisions otherworldly icebergs basking in a reddish glow. (Related: “Launch Boat to Saturn Moon, Scientists Propose.”)
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New data from NASA’s Cassini mission suggests that ice rich in methane and ethane could be floating on a hydrocarbon sea on Saturn’s moon Titan. This artist’s conception, released January 8 by NASA’s Jet Propulsion Laboratory, envisions otherworldly icebergs basking in a reddish glow. (Related: “Launch Boat to Saturn Moon, Scientists Propose.”)

Source: National Geographic

Launch Boat to Saturn Moon, Scientists Propose

Titan’s allure is manyfold: It has a thick atmosphere—the only moon in the solar system to have one—stable liquid on its surface, and a landscape of lakes, seas, and dunes. So it’s no surprise that astronomers are keeping an eye on Saturn’s largest satellite.

Scientists now say the Huygens probe that landed on Titan in 2005 did so with a bounce, slide, and wobble, yielding new clues about its Earthlike terrain.

Meanwhile, a Spanish team has proposed sending a boatlike probe that could paddle or propel itself across Ligeia Mare, a vast, liquid hydrocarbon lake near Titan’s north pole. The inspiration for the probe’s design includes Mississippi River paddleboats and an amphibious Soviet vehicle with screwlike propellers.

“We thought, why not be capable of moving after landing so you can study the landing site, cruise to the shore, and explore the shore?” said Igone Urdampilleta, an aerospace engineer with SENER, a private Spanish engineering firm.

NEXT PLANETARY FRONTIER: NAVIGATING AN ALIEN SEA

Since NASA’s skateboard-sized Sojourner rover bounced to a landing on Mars in 1997, we have been co-explorers via to a succession of rovers, culminating in the fiery touchdown of the Volkswagen-sized Curiositylast summer.

We’ve spent a lot of time and effort exploring the arid “red rock” country of Mars. But Mars is frozen in geological time. Its water is locked away as ice. The last rainfall was billions of years ago.

Curiosity’s biggest excitement recently was when it came across an ancient dried streambed. It’s reminiscent of the Neil Youg song, “A Horse With No Name.”

But imagine visiting a dynamic world of lakes and rivers; imagine navigating an extraterrestrial sea sprinkled with methane rain under hazy orange skies, looming anvil-shaped clouds.

Is this a science fiction fantasy from a Jules Verne novel? No, it’s the planet-sized Saturnian moon Titan, sometimes dubbed “Earth II.”

The first potential “boat” to Titan might have been the European Space Agency’s Huygens probe, which landed on a dried river shoreline in 2005. The Huygens lander was designed to float for a short period should it have wound up plopping down on a lake of liquid ethane. (Titan is far too cold for bodies of liquid water, a methane hydrologic cycle replaces the action of water.)

However, Huygens landed in the comparatively dry equatorial region of the moon, which is Titan’s equivalent of Arizona. Lakes on Titan weren’t definitively identified until the summer of 2006 when NASA’s prolific Cassini probe swept over Titan’s north polar region. Cassini’s radar uncovered dark and unusually smooth regions that could best be explained as bodies of standing liquid.

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(via yesastronomyyes)

Saturn and its Largest Moon Reflect Their True Colors

Posing for portraits for NASA’s Cassini spacecraft, Saturn and its largest moon, Titan, show spectacular colors in a quartet of images being released today. One image captures the changing hues of Saturn’s northern and southern hemispheres as they pass from one season to the next.

The images can be found at http://www.nasa.gov/cassini,http://saturn.jpl.nasa.gov and http://ciclops.org .

 wide-angle view in today’s package captures Titan passing in front of Saturn, as well as the planet’s changing colors. Upon Cassini’s arrival at Saturn eight years ago, Saturn’s northern winter hemisphere was an azure blue. Now that winter is encroaching on the planet’s southern hemisphere and summer on the north, the color scheme is reversing: blue is tinting the southern atmosphere and is fading from the north.

The other three images depict the newly discovered south polar vortex in the atmosphere of Titan, reported recently by Cassini scientists. Cassini’s visible-light cameras have seen a concentration of yellowish haze in the detached haze layer at the south pole of Titan since at least March 27. Cassini’s visual and infrared mapping spectrometer spotted the massing of clouds around the south pole as early as May 22 in infrared wavelengths. After a June 27 flyby of the moon, Cassini released a dramatic image and movie showing the vortex rotating faster than the moon’s rotation period. The four images being released today were acquired in May, June and July of 2012.

Some of these views, such as those of the polar vortex, are only possible because Cassini’s newly inclined — or tilted — orbits allow more direct viewing of the polar regions of Saturn and its moons.

What’s happening over the south pole of Titan? A vortex of haze appears to be forming, although no one is sure why. The above natural-color image shows the light-colored feature. The vortex was found on images taken last month when the robotic Cassini spacecraft flew by the unusual atmosphere-shrouded moon of Saturn. Cassini was only able to see the southern vortex because its orbit around Saturn was recently boosted out of the plane where the rings and moons move. Clues as to what created the enigmatic feature are accumulating, including that Titan’s air appears to be sinking in the center and rising around the edges. Winter, however, is slowly descending on the south of Titan, so that the vortex, if it survives, will be plunged into darkness over the next few years.
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What’s happening over the south pole of Titan? A vortex of haze appears to be forming, although no one is sure why. The above natural-color image shows the light-colored feature. The vortex was found on images taken last month when the robotic Cassini spacecraft flew by the unusual atmosphere-shrouded moon of Saturn. Cassini was only able to see the southern vortex because its orbit around Saturn was recently boosted out of the plane where the rings and moons move. Clues as to what created the enigmatic feature are accumulating, including that Titan’s air appears to be sinking in the center and rising around the edges. Winter, however, is slowly descending on the south of Titan, so that the vortex, if it survives, will be plunged into darkness over the next few years.

Source: apod.nasa.gov

Humanity’s robot orbiting Saturn has recorded yet another amazing view. That robot, of course, is the spacecraft Cassini, while the new amazing view includes a bright moon, thin rings, oddly broken clouds, and warped shadows. Titan, Saturn’s largest moon, appears above as a featureless tan as it is continually shrouded in thick clouds. The rings of Saturn are seen as a thin line because they are so flat and imaged nearly edge on. Details of Saturn’s rings are therefore best visible in the dark ring shadows seen across the giant planet’s cloud tops. Since the ring particles orbit in the same plane as Titan, they appear to skewer the foreground moon. In the upper hemisphere of Saturn, the clouds show many details, including dips in long bright bands indicating disturbances in a high altitude jet stream. Recent precise measurements of how much Titan flexes as it orbits Saturn hint that vast oceans of water might exist deep underground.
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Humanity’s robot orbiting Saturn has recorded yet another amazing view. That robot, of course, is the spacecraft Cassini, while the new amazing view includes a bright moon, thin rings, oddly broken clouds, and warped shadows. Titan, Saturn’s largest moon, appears above as a featureless tan as it is continually shrouded in thick clouds. The rings of Saturn are seen as a thin line because they are so flat and imaged nearly edge on. Details of Saturn’s rings are therefore best visible in the dark ring shadows seen across the giant planet’s cloud tops. Since the ring particles orbit in the same plane as Titan, they appear to skewer the foreground moon. In the upper hemisphere of Saturn, the clouds show many details, including dips in long bright bands indicating disturbances in a high altitude jet stream. Recent precise measurements of how much Titan flexes as it orbits Saturn hint that vast oceans of water might exist deep underground.

Source: apod.nasa.gov

Cassini Finds Likely Subsurface Ocean on Saturn Moon

Data from NASA’s Cassini spacecraft have revealed Saturn’s moon Titan likely harbors a layer of liquid water under its ice shell.

Researchers saw a large amount of squeezing and stretching as the moon orbited Saturn. They deduced that if Titan were composed entirely of stiff rock, the gravitational attraction of Saturn would cause bulges, or solid “tides,” on the moon only 3 feet (1 meter) in height. Spacecraft data show Saturn creates solid tides approximately 30 feet (10 meters) in height, which suggests Titan is not made entirely of solid rocky material. The finding appears in today’s edition of the journal Science.

“Cassini’s detection of large tides on Titan leads to the almost inescapable conclusion that there is a hidden ocean at depth,” said Luciano Iess, the paper’s lead author and a Cassini team member at the Sapienza University of Rome, Italy. “The search for water is an important goal in solar system exploration, and now we’ve spotted another place where it is abundant.”

Titan takes only 16 days to orbit Saturn, and scientists were able to study the moon’s shape at different parts of its orbit. Because Titan is not spherical, but slightly elongated like a football, its long axis grew when it was closer to Saturn. Eight days later, when Titan was farther from Saturn, it became less elongated and more nearly round. Cassini measured the gravitational effect of that squeeze and pull.

Scientists were not sure Cassini would be able to detect the bulges caused by Saturn’s pull on Titan. By studying six close flybys of Titan from Feb. 27, 2006, to Feb. 18, 2011, researchers were able to determine the moon’s internal structure by measuring variations in the gravitational pull of Titan using data returned to NASA’s Deep Space Network (DSN).

“We were making ultrasensitive measurements, and thankfully Cassini and the DSN were able to maintain a very stable link,” said Sami Asmar, a Cassini team member at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “The tides on Titan pulled up by Saturn aren’t huge compared to the pull the biggest planet, Jupiter, has on some of its moons. But, short of being able to drill on Titan’s surface, the gravity measurements provide the best data we have of Titan’s internal structure.”

An ocean layer does not have to be huge or deep to create these tides. A liquid layer between the external, deformable shell and a solid mantle would enable Titan to bulge and compress as it orbits Saturn. Because Titan’s surface is mostly made of water ice, which is abundant in moons of the outer solar system, scientists infer Titan’s ocean is likely mostly liquid water.

On Earth, tides result from the gravitational attraction of the moon and sun pulling on our surface oceans. In the open oceans, those can be as high as two feet (60 centimeters). While water is easier to move, the gravitational pulling by the sun and moon also causes Earth’s crust to bulge in solid tides of about 20 inches (50 centimeters).

The presence of a subsurface layer of liquid water at Titan is not itself an indicator for life. Scientists think life is more likely to arise when liquid water is in contact with rock, and these measurements cannot tell whether the ocean bottom is made up of rock or ice. The results have a bigger implication for the mystery of methane replenishment on Titan.

“The presence of a liquid water layer in Titan is important because we want to understand how methane is stored in Titan’s interior and how it may outgas to the surface,” said Jonathan Lunine, a Cassini team member at Cornell University, Ithaca, N.Y. “This is important because everything that is unique about Titan derives from the presence of abundant methane, yet the methane in the atmosphere is unstable and will be destroyed on geologically short timescales.”

A liquid water ocean, “salted” with ammonia, could produce buoyant ammonia-water liquids that bubble up through the crust and liberate methane from the ice. Such an ocean could serve also as a deep reservoir for storing methane.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The mission is managed by JPL for NASA’s Science Mission Directorate in Washington. DSN, also managed by JPL, is an international network of antennas that supports interplanetary spacecraft missions and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected Earth-orbiting missions. Cassini’s radio science team is based at Wellesley College in Massachusetts. JPL is a division of the California Institute of Technology in Pasadena.

Source: nasa.gov

Saturn Moon Has Tropical "Great Salt Lake," Methane Marshes

Saturn’s hazy moon Titan has a huge tropical lake and marshes of liquid methane near its equator, suggest surprising new images from a NASA spacecraft.

Titan is the only moon in the solar system to host a significant atmosphere—a roiling haze of organic molecules, which some scientists think might include the ingredients for life as we know it.

It’s also the only object in the solar system, other than Earth, to have bodies of liquid on its surface—previous data from NASA’s Cassini orbiter revealed hundreds of lakes near the frigid moon’s poles.

What’s that past Dione? When making its closest pass yet of Saturn’s moon Dione late last year, the robotic Cassini spacecraft snapped this far-ranging picture featuring Dione, Saturn’s rings, and the two small moons Epimetheus and Prometheus. The above image captures part of the heavily cratered snow-white surface of the 1,100 kilometer wide Dione, the thinness of Saturn’s rings, and the comparative darkness of the smaller moon Epimetheus. The image was taken when Cassini was only about 100,000 kilometers from the large icy moon. Future events in Cassini’s continuing exploration of Saturn and its moons include tomorrow’s flyby of Titan and imaging the distant Earth passing behind Saturn in June.
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What’s that past Dione? When making its closest pass yet of Saturn’s moon Dione late last year, the robotic Cassini spacecraft snapped this far-ranging picture featuring Dione, Saturn’s rings, and the two small moons Epimetheus and Prometheus. The above image captures part of the heavily cratered snow-white surface of the 1,100 kilometer wide Dione, the thinness of Saturn’s rings, and the comparative darkness of the smaller moon Epimetheus. The image was taken when Cassini was only about 100,000 kilometers from the large icy moon. Future events in Cassini’s continuing exploration of Saturn and its moons include tomorrow’s flyby of Titan and imaging the distant Earth passing behind Saturn in June.

Source: apod.nasa.gov

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