Saturn

Experiments Show Titan Lakes May Fizz with Nitrogen

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Preston Dyches
Jet Propulsion Laboratory, Pasadena, Calif.

 

Radar images from Cassini showed a strange island-like feature in one of Titan’s hydrocarbon seas that appeared to change over time (series of images at left). One possible explanation for this “magic island” is bubbles. Image Credit: NASA/JPL-Caltech/Space Science Institute

 

A recent NASA-funded study has shown how the hydrocarbon lakes and seas of Saturn’s moon Titan might occasionally erupt with dramatic patches of bubbles.

For the study, researchers at NASA’s Jet Propulsion Laboratory in Pasadena, California, simulated the frigid surface conditions on Titan, finding that significant amounts of nitrogen can be dissolved in the extremely cold liquid methane that rains from the skies and collects in rivers, lakes and seas. They demonstrated that slight changes in temperature, air pressure or composition can cause the nitrogen to rapidly separate out of solution, like the fizz that results when opening a bottle of carbonated soda.

NASA’s Cassini spacecraft has found that the composition of Titan’s lakes and seas varies from place to place, with some reservoirs being richer in ethane than methane. “Our experiments showed that when methane-rich liquids mix with ethane-rich ones — for example from a heavy rain, or when runoff from a methane river mixes into an ethane-rich lake — the nitrogen is less able to stay in solution,” said Michael Malaska of JPL, who led the study.


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NASA Scientists Find ‘Impossible’ Cloud on Titan — Again

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The hazy globe of Titan hangs in front of Saturn and its rings in this natural color view from NASA’s Cassini spacecraft. Image credit: NASA/JPL-Caltech/Space Science Institute

 

The puzzling appearance of an ice cloud seemingly out of thin air has prompted NASA scientists to suggest that a different process than previously thought — possibly similar to one seen over Earth’s poles — could be forming clouds on Saturn’s moon Titan.

Located in Titan’s stratosphere, the cloud is made of a compound of carbon and nitrogen known as dicyanoacetylene (C4N2), an ingredient in the chemical cocktail that colors the giant moon’s hazy, brownish-orange atmosphere. 

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Saturn Spacecraft Samples Interstellar Dust

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Of the millions of dust grains Cassini has sampled at Saturn, a few dozen appear to have come from beyond our solar system. Scientists believe these special grains have interstellar origins because they moved much faster and in different directions compared to dusty material native to Saturn. Image credit: NASA/JPL-Caltech

 

NASA’s Cassini spacecraft has detected the faint but distinct signature of dust coming from beyond our solar system. The research, led by a team of Cassini scientists primarily from Europe, is published this week in the journal Science.

Cassini has been in orbit around Saturn since 2004, studying the giant planet, its rings and its moons. The spacecraft has also sampled millions of ice-rich dust grains with its cosmic dust analyzer instrument. The vast majority of the sampled grains originate from active jets that spray from the surface of Saturn’s geologically active moon Enceladus.

But among the myriad microscopic grains collected by Cassini, a special few — just 36 grains — stand out from the crowd. Scientists conclude these specks of material came from interstellar space — the space between the stars. 

Alien dust in the solar system is not unanticipated. In the 1990s, the ESA/NASA Ulysses mission made the first in-situ observations of this material, which were later confirmed by NASA’s Galileo spacecraft. The dust was traced back to the local interstellar cloud: a nearly empty bubble of gas and dust that our solar system is traveling through with a distinct direction and speed.

“From that discovery, we always hoped we would be able to detect these interstellar interlopers at Saturn with Cassini. We knew that if we looked in the right direction, we should find them,” said Nicolas Altobelli, Cassini project scientist at ESA (European Space Agency) and lead author of the study. “Indeed, on average, we have captured a few of these dust grains per year, travelling at high speed and on a specific path quite different from that of the usual icy grains we collect around Saturn.”

The tiny dust grains were speeding through the Saturn system at over 45,000 mph (72,000 kilometers per hour), fast enough to avoid being trapped inside the solar system by the gravity of the sun and its planets.

“We’re thrilled Cassini could make this detection, given that our instrument was designed primarily to measure dust from within the Saturn system, as well as all the other demands on the spacecraft,” said Marcia Burton, a Cassini fields and particles scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, and a co-author of the paper.

Importantly, unlike Ulysses and Galileo, Cassini was able to analyze the composition of the dust for the first time, showing it to be made of a very specific mixture of minerals, not ice. The grains all had a surprisingly similar chemical make-up, containing major rock-forming elements like magnesium, silicon, iron and calcium in average cosmic proportions. Conversely, more reactive elements like sulfur and carbon were found to be less abundant compared to their average cosmic abundance. 

“Cosmic dust is produced when stars die, but with the vast range of types of stars in the universe, we naturally expected to encounter a huge range of dust types over the long period of our study,” said Frank Postberg of the University of Heidelberg, a co-author of the paper and co-investigator of Cassini’s dust analyzer.

Stardust grains are found in some types of meteorites, which have preserved them since the birth of our solar system. They are generally old, pristine and diverse in their composition. But surprisingly, the grains detected by Cassini aren’t like that. They have apparently been made rather uniform through some repetitive processing in the interstellar medium, the researchers said.

The authors speculate on how this processing of dust might take place: Dust in a star-forming region could be destroyed and recondense multiple times as shock waves from dying stars passed through, resulting in grains like the ones Cassini observed streaming into our solar system.

“The long duration of the Cassini mission has enabled us to use it like a micrometeorite observatory, providing us privileged access to the contribution of dust from outside our solar system that could not have been obtained in any other way,” said Altobelli.

The Cassini-Huygens mission is a cooperative project of NASA, ESA and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate in Washington. The Cosmic Dust Analyzer is supported by the German Aerospace Center (DLR); the instrument is managed by the University of Stuttgart, Germany.

For more information about Cassini, visit: http://www.nasa.gov/cassini or http://saturn.jpl.nasa.gov

 

Saturn’s Geyser Moon Shines in Close Flyby Views

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NASA’s Cassini spacecraft has begun transmitting its latest images of Saturn’s icy, geologically active moon Enceladus, acquired during the dramatic Oct. 28 flyby in which the probe passed about 30 miles (49 kilometers) above the moon’s south polar region. The spacecraft will continue transmitting its data from the encounter for the next several days.

“Cassini’s stunning images are providing us a quick look at Enceladus from this ultra-close flyby, but some of the most exciting science is yet to come,” said Linda Spilker, the mission’s project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California.

Researchers will soon begin studying data from Cassini’s gas analyzer and dust detector instruments, which directly sampled the moon’s plume of gas and dust-sized icy particles during the flyby. Those analyses are likely to take several weeks, but should provide important insights about the composition of the global ocean beneath Enceladus’ surface and any hydrothermal activity occurring on the ocean floor. The potential for such activity in this small ocean world has made Enceladus a prime target for future exploration in search of habitable environments in the solar system beyond Earth.

In addition to the processed images, unprocessed, or “raw,” images appear on the Cassini mission website at: http://saturn.jpl.nasa.gov/mission/flybys/enceladus20151028

Cassini’s next and final close Enceladus flyby will take place on Dec. 19, when the spacecraft will measure the amount of heat coming from the moon’s interior. The flyby will be at an altitude of 3,106 miles (4,999 kilometers).

Additional information and multimedia products for Cassini’s final Enceladus flybys are available at: http://solarsystem.nasa.gov/finalflybys

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency’s Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. The Cassini imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about Cassini, visit: http://www.nasa.gov/cassini or http://saturn.jpl.nasa.gov

NASA’s Cassini spacecraft has begun transmitting its latest images of Saturn’s icy, geologically active moon Enceladus, acquired during the dramatic Oct. 28 flyby in which the probe passed about 30 miles (49 kilometers) above the moon’s south polar region. The spacecraft will continue transmitting its data from the encounter for the next several days.

“Cassini’s stunning images are providing us a quick look at Enceladus from this ultra-close flyby, but some of the most exciting science is yet to come,” said Linda Spilker, the mission’s project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California.
Researchers will soon begin studying data from Cassini’s gas analyzer and dust detector instruments, which directly sampled the moon’s plume of gas and dust-sized icy particles during the flyby. Those analyses are likely to take several weeks, but should provide important insights about the composition of the global ocean beneath Enceladus’ surface and any hydrothermal activity occurring on the ocean floor. The potential for such activity in this small ocean world has made Enceladus a prime target for future exploration in search of habitable environments in the solar system beyond Earth.
In addition to the processed images, unprocessed, or “raw,” images appear on the Cassini mission website at: http://saturn.jpl.nasa.gov/mission/flybys/enceladus20151028

Cassini’s next and final close Enceladus flyby will take place on Dec. 19, when the spacecraft will measure the amount of heat coming from the moon’s interior. The flyby will be at an altitude of 3,106 miles (4,999 kilometers).
Additional information and multimedia products for Cassini’s final Enceladus flybys are available at: http://solarsystem.nasa.gov/finalflybys

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency’s Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. The Cassini imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about Cassini, visit: http://www.nasa.gov/cassini or http://saturn.jpl.nasa.gov

Seven Key Facts About Cassini’s Oct. 28 ‘Plume Dive’

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Cassini Flyby

 

NASA’s Cassini spacecraft will sample the ocean of Saturn’s moon Enceladus on Wednesday, Oct. 28, when it flies through the moon’s plume of icy spray.

Cassini launched in 1997 and entered orbit around Saturn in 2004. Since then, it has been studying the huge planet, its rings and its magnetic field. Here are some things to know about the mission’s upcoming close flyby of Enceladus:

  • Enceladus is an icy moon of Saturn. Early in its mission, Cassini discovered Enceladus has remarkable geologic activity, including a towering plume of ice, water vapor and organic molecules spraying from its south polar region. Cassini later determined the moon has a global ocean and likely hydrothermal activity, meaning it could have the ingredients needed to support simple life.
  • The flyby will be Cassini’s deepest-ever dive through the Enceladus plume, which is thought to come from the ocean below. The spacecraft has flown closer to the surface of Enceladus before, but never this low directly through the active plume.
  • The flyby is not intended to detect life, but it will provide powerful new insights about how habitable the ocean environment is within Enceladus.
  • Cassini scientists are hopeful the flyby will provide insights about how much hydrothermal activity — that is, chemistry involving rock and hot water — is occurring within Enceladus. This activity could have important implications for the potential habitability of the ocean for simple forms of life. The critical measurement for these questions is the detection of molecular hydrogen by the spacecraft.
  • Scientists also expect to better understand the chemistry of the plume as a result of the flyby. The low altitude of the encounter is, in part, intended to afford Cassini greater sensitivity to heavier, more massive molecules, including organics, than the spacecraft has observed during previous, higher-altitude passes through the plume
  • The flyby will help solve the mystery of whether the plume is composed of column-like, individual jets, or sinuous, icy curtain eruptions — or a combination of both. The answer would make clearer how material is getting to the surface from the ocean below.
  • Researchers are not sure how much icy material the plumes are actually spraying into space. The amount of activity has major implications for how long Enceladus might have been active.

An online toolkit for all three final Enceladus flybys is available at:  http://solarsystem.nasa.gov/finalflybys

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. JPL manages the mission for NASA’s Science Mission Directorate in Washington.

For more information about Cassini, visit:

http://www.nasa.gov/cassini

http://saturn.jpl.nasa.gov

Cassini Begins Series of Flybys with Close-up of Saturn Moon Enceladus

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Cassini Begins Series of Flybys with Close-up of Saturn Moon Enceladus

NASA’s Cassini spacecraft will wrap up its time in the region of Saturn’s large, icy moons with a series of three close encounters with Enceladus starting Wednesday, Oct. 14. Images are expected to begin arriving one to two days after the flyby, which will provide the first opportunity for a close-up look at the north polar region of Enceladus.

Wednesday’s flyby is considered a moderately close approach for Cassini, which will pass at an altitude of 1,142 miles (1,839 kilometers) above the moon’s surface. Closest approach to Enceladus will occur at 3:41 a.m. PDT (6:41 a.m. EDT). The spacecraft’s final two approaches will take place in late October and mid-December.

During Cassini’s early-mission encounters with the moon, the northern terrain of Enceladus was masked by wintry darkness. Now that the summer sun is shining on the high northern latitudes, scientists will be looking for signs of ancient geological activity similar to the geyser-spouting, tiger-stripe fractures in the moon’s south polar region. Features observed during the flyby could help them understand whether the north also was geologically active at some time in the past.

“We’ve been following a trail of clues on Enceladus for 10 years now,” said Bonnie Buratti, a Cassini science team member and icy moons expert at NASA’s Jet Propulsion Laboratory in Pasadena, California. “The amount of activity on and beneath this moon’s surface has been a huge surprise to us. We’re still trying to figure out what its history has been, and how it came to be this way.”

Since Cassini’s 2005 discovery of continually-erupting fountains of icy material on Enceladus, the Saturn moon has become one of the most promising places in the solar system to search for present-day habitable environments. Mission scientists announced evidence in March that hydrothermal activity may be occurring on the seafloor of the moon’s underground ocean. In September they broke news that its ocean — previously thought to be only a regional sea — was, in fact, global.

“The global nature of Enceladus’ ocean and the inference that hydrothermal systems might exist at the ocean’s base strengthen the case that this small moon of Saturn may have environments similar to those at the bottom of our own ocean,” said Jonathan Lunine, an interdisciplinary scientist on the Cassini mission at Cornell University in Ithaca, New York. “It is therefore very tempting to imagine that life could exist in such a habitable realm, a billion miles from our home.”

The Oct. 14 encounter will serve as a prelude to the main event, a flyby of Enceladus on Wednesday, Oct. 28, during which Cassini will come dizzyingly close to the icy moon, passing a mere 30 miles (49 kilometers) above the moon’s south polar region. During this encounter, Cassini will make its deepest-ever dive through the moon’s plume of icy spray, collecting images and valuable data about what’s going on beneath the frozen surface. Cassini scientists are hopeful data from that flyby will provide evidence of how much hydrothermal activity is occurring in the moon’s ocean, and how the amount of activity impacts the habitability of Enceladus’ ocean.

Cassini’s final close flyby on Dec. 19 will examine how much heat is coming from the moon’s interior from an altitude of 3,106 miles (4,999 kilometers).

An online toolkit for all three final Enceladus flybys is available at:

http://solarsystem.nasa.gov/finalflybys

Cassini arrived at Saturn in 2004 and still has about two years left on its mission. Beginning in November, mission controllers will begin to slowly raise Cassini’s orbit out of the space around the Saturn’s equator, where flybys of the large moons are more common. Coming up are a number of closest-ever brushes with the small moons that huddle near the planet’s rings.

“We’ll continue observing Enceladus and its remarkable activity for the remainder of our precious time at Saturn,” said Linda Spilker, Cassini project scientist at JPL. “But these three encounters will be our last chance to see this fascinating world up close for many years to come.”

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

For more information about Cassini, visit:

http://www.nasa.gov/cassini

http://saturn.jpl.nasa.gov

NASA Jet Propulsion Laboratory | jplnewsroom | NASA’s Jet Propulsion Laboratory | 4800 Oak Grove Dr | Pasadena, CA 91109

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NASA-funded Study Explains Saturn’s Epic Tantrums

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This series of images from NASA’s Cassini spacecraft shows the development of a huge storm of the type that erupts about every 30 years on Saturn. Credit: NASA/JPL-Caltech/SSI

The long-standing mystery of why Saturn seethes with enormous storms every 30 years may have been solved by scientists working with data from NASA’s Cassini mission. The tempests, which can grow into bright bands that encircle the entire planet, are on a natural timer that is reset by each subsequent storm, the researchers report.

In 140 years of telescope observations, great storms have erupted on Saturn six times. Cassini and observers on Earth tracked the most recent of these storms from December 2010 to August 2011. During that time, the storm exploded through the clouds, eventually winding its way around Saturn.

In a paper published online today in the journal Nature Geoscience, scientists describe the effect they believe is responsible for the periodic outbursts. The basic idea is that water vapor is heavier than the hydrogen and helium that make up the bulk of Saturn’s atmosphere, so once each giant storm dumps its huge mass of rain, the air within the clouds is left lighter than the atmosphere below. For a time, this situation shuts off the process of convection — in which warm, moist air rises, and cool, dense air sinks — that creates new clouds and storms.

“For decades after one of these storms, the warm air in Saturn’s deep atmosphere is too wet, and too dense, to rise,” said Cheng Li, a graduate student at the California Institute of Technology in Pasadena, who led the study. “The air above has to cool off, radiating its heat to space, before its density is greater than that of the hot, wet air below. This cooling process takes about 30 years, and then come the storms.”

Li thinks the episodic nature of the storms indicates Saturn’s deep atmosphere contains more water, relative to the other atmospheric constituents, than Jupiter. The researchers suggest Saturn’s extra-wet interior might explain why the planet has such epic tantrums, whereas Jupiter does not. If Saturn’s deep atmosphere were drier, scientists would expect continuous, smaller storms, as observed on Jupiter, Li said. Instead, Saturn’s outbursts are episodic and quite explosive.

Other observations by ground and space-based telescopes have hinted at a wet interior for Saturn. “Previous studies using spectroscopy have shown that Saturn’s interior is enriched in methane and other volatiles, by two or three times, compared to Jupiter. From there, it’s a short leap to expect that Saturn is also rich in oxygen, which is also a volatile and a big part of every H2O molecule,” said Andrew Ingersoll, a member of the Cassini science team, also at Caltech, who co-authored the paper with Li. Volatiles are elements and chemical compounds that change from solid to liquid or gas at relatively low temperatures.

Scientists are interested in understanding the amount of oxygen and other volatile ingredients in Saturn and Jupiter. These ingredients provide important clues about the formation of the two planets — which are thought to have formed before all the others — and conditions in the early solar system.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. JPL, a division of Caltech, manages the mission for NASA’s Science Mission Directorate in Washington. 

For previous news and images related to Saturn’s giant storm:

http://go.nasa.gov/1H89e3p

For more information about Cassini, visit:

http://www.nasa.gov/cassini

http://saturn.jpl.nasa.gov

 

Saturn Spacecraft Returns to the Realm of Icy Moons

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A dual view of Saturn’s icy moon Rhea marks the return of NASA’s Cassini spacecraft to the realm of the planet’s icy satellites. This follows nearly two years during which the spacecraft’s orbits carried it high above the planet’s poles. Those paths limited the mission’s ability to encounter the moons, apart from regular flybys of Titan.

Cassini’s orbit will remain nearly equatorial for the remainder of 2015, during which the spacecraft will have four close encounters with Titan, two with Dione and three with the geyser-moon, Enceladus.

The two views of Rhea were taken about an hour-and-a-half apart on Feb. 9, 2015, when Cassini was about 30,000 to 50,000 miles (50,000 to 80,000 kilometers) away from the moon. Cassini officially began its new set of equatorial orbits on March 16.

The views show an expanded range of colors from those visible to human eyes in order to highlight subtle color variations across Rhea’s surface. In natural color, the moon’s surface is fairly uniform. The image at right represents the highest-resolution color view of Rhea released to date.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency’s Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. The Cassini imaging operations center is based at the Space Science Institute in Boulder, Colorado.

More information about Cassini, visit:

http://www.nasa.gov/cassini

http://saturn.jpl.nasa.gov