Archive for the ‘Saturn’ Category

saturn

t sounds like a wacky fantasy, but scientists believe that it rains diamonds in the clouds of Saturn and Jupiter.

Diamonds are made from highly compressed and heated carbon. Theoretically, if you took a charcoal bricket out of your grill and heated it and pressed it hard enough for long enough, you could make a diamond.

On Earth, diamonds form about 100 miles underground. Volcanic magma highways then bring them closer to the surface, providing us with shiny gemstones that we stick in rings and ear studs.

But in the dense atmospheres of planets like Jupiter and Saturn, whose massive size generates enormous amounts of gravity, crazy amounts of pressure and heat can squeeze carbon in mid-air — and make it rain diamonds.

Scientists have speculated for years that diamonds are abundant in the cores of the smaller, cooler gas giants, Neptune and Uranus. They believed that the larger gaseous planets, Jupiter and Saturn, didn’t have suitable atmospheres to forge diamonds.

But when researchers recently analyzed the pressures and temperatures for Jupiter’s and Saturn’s atmospheres, then modeled how carbon would behave, they determined that diamond rain is very likely.

Diamonds seem especially likely to form in huge, storm-ravaged regions of Saturn, and in enormous quantities — Kevin Baines, a researcher at University of Madison-Wisconsin and NASA JPL, told BBC News it may rain as much as 2.2 million pounds of diamonds there every year.

The diamonds start out as methane gas. Powerful lightning storms on the two huge gas giants then zap it into carbon soot.

“As the soot falls, the pressure on it increases,” Baines told the BBC. “And after about 1,000 miles it turns to graphite – the sheet-like form of carbon you find in pencils.”

And the graphite keeps falling. When it reaches the deep atmosphere of Saturn, for example — around 3,700 miles down — the immense pressure squeezes the carbon into diamonds, which float in seas of liquid methane and hydrogen.

Eventually the gems sink toward the interior of the planet (a depth of 18,600 miles), where nightmarish pressure and heat melts the diamonds into molten carbon.

“Once you get down to those extreme depths,” Baines told the BBC, “the pressure and temperature is so hellish, there’s no way the diamonds could remain solid.”

http://www.techinsider.io/diamond-rain-saturn-jupiter-2016-4

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Taking a simultaneously imaginative and rigidly scientific view, Cornell chemical engineers and astronomers offer a template for life that could thrive in a harsh, cold world – specifically Titan, the giant moon of Saturn. A planetary body awash with seas not of water, but of liquid methane, Titan could harbour methane-based, oxygen-free cells that metabolise, reproduce and do everything life on Earth does.

Their theorised cell membrane, composed of small organic nitrogen compounds and capable of functioning in liquid methane temperatures of 292 degrees below zero, was published in Science Advances, 27th February. The work is led by chemical molecular dynamics expert Paulette Clancy, the Samuel W. and Diane M. Bodman Professor of Chemical and Biomolecular Engineering, with first author James Stevenson, a graduate student in chemical engineering. The paper’s co-author is Jonathan Lunine, the David C. Duncan Professor in the Physical Sciences in the College of Arts and Sciences’ Department of Astronomy.
Lunine is an expert on Saturn’s moons and an interdisciplinary scientist on the Cassini-Huygens mission that discovered methane-ethane seas on Titan. Intrigued by the possibilities of methane-based life on Titan, and armed with a grant from the Templeton Foundation to study non-aqueous life, Lunine sought assistance about a year ago from Cornell faculty with expertise in chemical modeling. Clancy, who had never met Lunine, offered to help.

“We’re not biologists, and we’re not astronomers, but we had the right tools,” Clancy said. “Perhaps it helped, because we didn’t come in with any preconceptions about what should be in a membrane and what shouldn’t. We just worked with the compounds that we knew were there and asked, ‘If this was your palette, what can you make out of that?’”

On Earth, life is based on the phospholipid bilayer membrane, the strong, permeable, water-based vesicle that houses the organic matter of every cell. A vesicle made from such a membrane is called a liposome. Thus, many astronomers seek extraterrestrial life in what’s called the circumstellar habitable zone, the narrow band around the Sun in which liquid water can exist. But what if cells weren’t based on water, but on methane, which has a much lower freezing point?

The engineers named their theorised cell membrane an “azotosome,” “azote” being the French word for nitrogen. “Liposome” comes from the Greek “lipos” and “soma” to mean “lipid body;” by analogy, “azotosome” means “nitrogen body.”

The azotosome is made from nitrogen, carbon and hydrogen molecules known to exist in the cryogenic seas of Titan, but shows the same stability and flexibility that Earth’s analogous liposome does. This came as a surprise to chemists like Clancy and Stevenson, who had never thought about the mechanics of cell stability before; they usually study semiconductors, not cells.

The engineers employed a molecular dynamics method that screened for candidate compounds from methane for self-assembly into membrane-like structures. The most promising compound they found is an acrylonitrile azotosome, which showed good stability, a strong barrier to decomposition, and a flexibility similar to that of phospholipid membranes on Earth. Acrylonitrile – a colourless, poisonous, liquid organic compound used in the manufacture of acrylic fibres, resins and thermoplastics – is present in Titan’s atmosphere.

Excited by the initial proof of concept, Clancy said the next step is to try and demonstrate how these cells would behave in the methane environment – what might be the analogue to reproduction and metabolism in oxygen-free, methane-based cells.

Lunine looks forward to the long-term prospect of testing these ideas on Titan itself, as he put it, by “someday sending a probe to float on the seas of this amazing moon and directly sampling the organics.”

Stevenson said he was in part inspired by science fiction writer Isaac Asimov, who wrote about the concept of non-water-based life in a 1962 essay, “Not as We Know It.”

Said Stevenson: “Ours is the first concrete blueprint of life not as we know it.”

http://astronomynow.com/2015/03/01/life-not-as-we-know-it-possible-on-saturns-moon-titan/

Thanks to Da Brayn for bringing this to the attention of the It’s Interesting community.

NASA’s Cassini spacecraft and Deep Space Network have uncovered evidence Saturn’s moon Enceladus harbors a large underground ocean of liquid water, furthering scientific interest in the moon as a potential home to extraterrestrial microbes.

Researchers theorized the presence of an interior reservoir of water in 2005 when Cassini discovered water vapor and ice spewing from vents near the moon’s south pole. The new data provide the first geophysical measurements of the internal structure of Enceladus, consistent with the existence of a hidden ocean inside the moon. Findings from the gravity measurements are in the Friday, April 4 edition of the journal Science.

“The way we deduce gravity variations is a concept in physics called the Doppler Effect, the same principle used with a speed-measuring radar gun,” said Sami Asmar of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., a coauthor of the paper. “As the spacecraft flies by Enceladus, its velocity is perturbed by an amount that depends on variations in the gravity field that we’re trying to measure. We see the change in velocity as a change in radio frequency, received at our ground stations here all the way across the solar system.”

The gravity measurements suggest a large, possibly regional, ocean about 6 miles (10 kilometers) deep, beneath an ice shell about 19 to 25 miles (30 to 40 kilometers) thick. The subsurface ocean evidence supports the inclusion of Enceladus among the most likely places in our solar system to host microbial life. Before Cassini reached Saturn in July 2004, no version of that short list included this icy moon, barely 300 miles (500 kilometers) in diameter.

“This then provides one possible story to explain why water is gushing out of these fractures we see at the south pole,” said David Stevenson of the California Institute of Technology, Pasadena, one of the paper’s co-authors.

Cassini has flown near Enceladus 19 times. Three flybys, from 2010 to 2012, yielded precise trajectory measurements. The gravitational tug of a planetary body, such as Enceladus, alters a spacecraft’s flight path. Variations in the gravity field, such as those caused by mountains on the surface or differences in underground composition, can be detected as changes in the spacecraft’s velocity, measured from Earth.

The technique of analyzing a radio signal between Cassini and the Deep Space Network can detect changes in velocity as small as less than one foot per hour (90 microns per second). With this precision, the flyby data yielded evidence of a zone inside the southern end of the moon with higher density than other portions of the interior.

The south pole area has a surface depression that causes a dip in the local tug of gravity. However, the magnitude of the dip is less than expected given the size of the depression, leading researchers to conclude the depression’s effect is partially offset by a high-density feature in the region, beneath the surface.

“The Cassini gravity measurements show a negative gravity anomaly at the south pole that however is not as large as expected from the deep depression detected by the onboard camera,” said the paper’s lead author, Luciano Iess of Sapienza University of Rome. “Hence the conclusion that there must be a denser material at depth that compensates the missing mass: very likely liquid water, which is seven percent denser than ice. The magnitude of the anomaly gave us the size of the water reservoir.”

There is no certainty the subsurface ocean supplies the water plume spraying out of surface fractures near the south pole of Enceladus, however, scientists reason it is a real possibility. The fractures may lead down to a part of the moon that is tidally heated by the moon’s repeated flexing, as it follows an eccentric orbit around Saturn.

Much of the excitement about the Cassini mission’s discovery of the Enceladus water plume stems from the possibility that it originates from a wet environment that could be a favorable environment for microbial life.

“Material from Enceladus’ south polar jets contains salty water and organic molecules, the basic chemical ingredients for life,” said Linda Spilker, Cassini’s project scientist at JPL. “Their discovery expanded our view of the ‘habitable zone’ within our solar system and in planetary systems of other stars. This new validation that an ocean of water underlies the jets furthers understanding about this intriguing environment.”

The Cassini-Huygens mission is a cooperative project of NASA, the 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

and

http://saturn.jpl.nasa.gov

http://www.jpl.nasa.gov/news/news.php?release=2014-103&utm_source=iContact&utm_medium=email&utm_campaign=NASAJPL&utm_content=cassini20140403

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.

Saturn

In July, you will have the photo opp of a lifetime.

According to the Cassini Solstice Mission website, the sun will backlight Saturn on July 19, allowing you to clearly see the planet’s rings, photograph them and observe the changes over the past seven years, since Saturn was last photographed.

The positioning of the planets against the sun will also allow for a clear photo of Earth from 898 million miles away. This shot of the Earth will be only the third of its kind in the history of U.S. space travel. The first was taken from the Voyager in 1990, from 4 billion miles away; the second from Cassini in 2006, from 926 million miles away.

NASA posted directions on its website for waving at Saturn on July 19. Since the picture of Earth will be tiny, NASA is encouraging people to capture their own photos of Saturn and send them in, which they will then compile into a collage and post on its website.

NASA is promoting Wave at Saturn with a Flickr group, Facebook event page and a #waveatsaturn Twitter hashtag.

The Cassini portrait session of Earth is expected to last around 15 minutes, beginning at 5:27 p.m. ET on July 19.

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.

http://mashable.com/2013/06/25/saturn-photo/

 

The robotic Cassini spacecraft completed the first flyby ever of Saturn’s small moon Methone in May and discovered that the moon has no obvious craters. Craters, usually caused by impacts, have been seen on every moon, asteroid, and comet nucleus ever imaged in detail — until now. Even the Earth and Titan have craters. The smoothness and egg-like shape of the 3-kilometer diameter moon might be caused by Methone‘s surface being able to shift — something that might occur were the moon coated by a deep pile of sub-visual rubble. If so, the most similar objects in our Solar System would include Saturn’s moons Telesto, Pandora, Calypso, as well as asteroid Itokawa, all of which show sections that are unusually smooth. Methone is not entirely featureless, though, as some surface sections appears darker than others. Although flybys of Methone are difficult, interest in the nature and history of this unusual moon is sure to continue.

http://apod.nasa.gov/apod/ap121106.html

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.

 

Enceladus is little bigger than a lump of rock and has appeared, until recently, as a mere pinprick of light in astronomers’ telescopes. Yet Saturn‘s tiny moon has suddenly become a major attraction for scientists. Many now believe it offers the best hope we have of discovering life on another world inside our solar system.

The idea that a moon a mere 310 miles in diameter, orbiting in deep, cold space,   1bn miles from the sun, could provide a home for alien lifeforms may seem extraordinary. Nevertheless, a growing number of researchers consider this is a real prospect and argue that Enceladus should be rated a top priority for future space missions.

This point is endorsed by astrobiologist Professor Charles Cockell of Edinburgh University. “If someone gave me several billion dollars to build whatever space probe I wanted, I would have no hesitation,” he says. “I would construct one that could fly to Saturn and collect samples from Enceladus. I would go there rather than Mars or the icy moons of Jupiter, such as Europa, despite encouraging signs that they could support life. Primitive, bacteria-like lifeforms may indeed exist on these worlds but they are probably buried deep below their surfaces and will be difficult to access. On Enceladus, if there are lifeforms, they will be easy to pick up. They will be pouring into space.”

The cause of this unexpected interest in Enceladus – first observed by William Herschel in 1789 and named after one of the children of the Earth goddess Gaia – stems from a discovery made by the robot spacecraft Cassini, which has been in orbit of Saturn for the past eight years. The $3bn probe has shown that the little moon not only has an atmosphere, but that geysers of water are erupting from its surface into space. Even more astonishing has been its most recent discovery, which has shown that these geysers contain complex organic compounds, including propane, ethane, and acetylene.

“It just about ticks every box you have when it comes to looking for life on another world,” says Nasa astrobiologist Chris McKay. “It has got liquid water, organic material and a source of heat. It is hard to think of anything more enticing short of receiving a radio signal from aliens on Enceladus telling us to come and get them.”

Cassini’s observations suggest Enceladus possesses a subterranean ocean that is kept liquid by the moon’s internal heat. “We are not sure where that energy is coming from,” McKay admits. “The source is producing around 16 gigawatts of power and looks very like the geothermal energy sources we have on Earth – like the deep vents we  see in our ocean beds and which bubble up hot gases.”

At the moon’s south pole, Enceladus’s underground ocean appears to rise close to the surface. At a few sites, cracks have developed and water is bubbling to the surface before being vented into space, along with complex organic chemicals that also appear to have built up in its sea.

Equally remarkable is the impact of this water on Saturn. The planet is famed for its complex system of rings, made of bands of small particles in orbit round the planet. There are seven main rings: A, B, C, D, E, F and G, and the giant E-ring is linked directly with Enceladus. The water the moon vents into space turns into ice crystals and these feed the planet’s E-ring. “If you turned off the geysers of Enceladus, the great E-ring of Saturn would disappear within a few years,” says McKay. “For a little moon, Enceladus has quite an impact.”

Yet the discovery of Enceladus’s strange geology was a fairly tentative affair, says Professor Michele Dougherty of Imperial College London. She was the principal investigator for Cassini’s magnetometer instrument. “Cassini had been in orbit round Saturn for more than six months when it passed relatively close to Enceladus. Our results indicated that Saturn’s magnetic field was being dragged round Enceladus in a way that suggested it had an atmosphere.”

So Dougherty and her colleagues asked the Cassini management to direct the probe to take a much closer look. This was agreed and in July 2005 Cassini moved in for a close-up study. “I didn’t sleep for two nights before that,” says Dougherty. “If Cassini found nothing we would have looked stupid and the management team might not have listened to us again.”

Her fears were groundless. Cassini swept over Enceladus at a height of 173km and showed that it did indeed possess an atmosphere, albeit a thin one consisting of water vapour, carbon dioxide, methane and nitrogen. “It was wonderful,” says Dougherty. “I just thought: wow!”

Subsequent sweeps over the moon then revealed those plumes of water. The only other body in the solar system, apart from Earth, possessing liquid water on its surface had  been revealed. Finally came the discovery of organics, and the little moon went from being merely an interesting world to one that was utterly fascinating.

“Those plumes do not represent a torrent,” cautions McKay. “This is not the Mississippi pouring into space. The output is roughly equivalent to that of the Old Faithful geyser in Yellowstone national park. On the other hand, it would be enough to create a river that you could kayak down.

“The fact that this water is being vented into space and is mixed with organic material is truly remarkable, however. It is an open invitation to go there. The place may as well have a big sign hanging over it saying: ‘Free sample: take one now’.”

Collecting that sample will not be easy, however. At a distance of 1bn miles, Saturn and its moons are a difficult target. Cassini took almost seven years to get there after its launch from Cape Canaveral in  1997.

“A mission to Enceladus would take a similar time,” says McKay. Once there, several years would be needed to make several sweeps over Enceladus to collect samples of water and organics. “Then we would need a further seven years to get those samples back to Earth.”

Such a mission would therefore involve almost 20 years of space flight – on top of the decade needed to plan it and to construct and launch the probe. “That’s 30 years in all, a large chunk of any scientist’s professional life,” says McKay.

McKay and a group of other Nasa scientists based at the Jet Propulsion Laboratory in Pasadena are undaunted, however. They are now finalising plans for an Enceladus Sample Return mission, which would involve putting a probe in orbit round Saturn. It would then use the gravity of the planet’s biggest moon, Titan, to make sweeps over Enceladus. Plume samples would then be stored in a canister that would eventually be fired back to Earth on a seven-year return journey.

Crucially, McKay and his colleagues believe such a mission could be carried out at a relatively modest cost – as part of Nasa’s Discovery programme, which funds low-budget missions to explore the solar system. Previous probes have included Lunar Prospector, which studied the moon’s geology; Stardust, which returned a sample of material scooped from a comet’s tail; and Mars Pathfinder, which deployed a tiny motorised robot vehicle on the Red Planet in 1997.

“The criteria for inclusion in the Discovery programme demand that any mission must cost less than $500m, though that does not include the price of launch,” says McKay. “We think we can adapt the technology that was developed on the Stardust mission to build an Enceladus Sample Return. If so, we can keep the cost below $500m. We are finalising plans and will announce our proposals in autumn.”

Such a mission is backed by Dougherty. “I think Enceladus is one of the best bets we now have for finding life on another world in our solar system. It is certainly worth visiting but it is not the only hope we have. The icy moons of Jupiter – such as Ganymede, Callisto and Europa – still look a very good prospect as well.”

And there is one problematic issue concerning Enceladus: time. “Conditions for life there are good at present but we do not know how long they have been in existence,” says McKay. “They might be recent or ancient. For life to have evolved, we need the latter to have been the case. At present, we have no idea about their duration, though geologists I have spoken to suggest that water and organics may have been there for a good while. The only way we will find out is to go there.”

The late entry of Enceladus in the race to find extraterrestrial life adds an intriguing new destination for astrobiologists in their hunt for aliens. Before its geysers were discovered, two main targets dominated their research: Mars and the icy moons of Jupiter. The former is the easiest to get to and has already received visits from dozens of probes. On 6 August, the $2.5bn robot rover Curiosity is set to land there and continue the hunt for life on the Red Planet. “For life to evolve you need liquid water, and although it is clear it once flowed on Mars, its continued existence there is debatable,” says Cockell. “By contrast, you can see water pouring off Enceladus along with those organics.”

Many scientists argue that water could exist deep below the Martian surface, supporting bacteria-like lifeforms. However, these reservoirs could be many metres, if not kilometres, below Mars’s surface and it could take decades to find them. Similarly, the oceans under the thick ice that covers Europa – and two other moons of Jupiter, Ganymede and Callisto – could also support life. But again, it will be extremely difficult for a robot probe to drill through the kilometres of ice that cover the oceans of these worlds.

Enceladus, by these standards, is an easy destination – but a distant one that will take a long time to reach. “No matter where we look, it appears it will take two or three decades to get answers to our questions about the existence of life on other worlds in the solar system,” says Cockell. “By that time, telescopes may have spotted signs of life on planets elsewhere in the galaxy. Our studies of extra-solar planets are getting more sophisticated, after all, and one day we may spot the presence of oxygen and water in our spectrographic studies of these distant worlds – an unambiguous indication that living entities exist there.

However, telescopic studies of extra-solar planets won’t reveal the nature of those lifeforms. Only by taking samples from planets in our solar system and returning them to laboratories on Earth, where we can study them, will we be able to reveal their exact nature and mode of replication – if they exist, of course. The little world of Enceladus could then have a lot to teach us.

http://www.guardian.co.uk/science/2012/jul/29/alien-life-enceladus-saturn-moon