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Physicists Find New Evidence For Helium 'Rain' On Saturn (sciencemag.org) 27

sciencehabit writes: Using one of the world's most powerful lasers, physicists have found experimental evidence for Saturn's helium 'rain,' a phenomenon in which a mixture of liquid hydrogen and helium separates like oil and water, sending droplets of helium deep in the planet's atmosphere. The results show the range of blistering temperatures and crushing pressures at which this takes place. But they also suggest that a helium rain could also fall on Jupiter, where such behavior was almost completely unexpected.

Cassini Probe Will Dive Through Enceladus's Water Jets (nasa.gov) 65

An anonymous reader writes: NASA's Cassini probe has a daring mission tomorrow: dive through the water jets spraying from the south pole of Saturn's moon Enceladus. The probe will be a mere 30 miles above the surface, traveling at a relative speed of 19,000 mph. Researchers hope to gain insight into the chemical composition of the jets. "[T]he plumes are more than just gas and water: samples show that they also contain many of the building blocks essential to Earth-like life. This lends itself to the exciting possibility that organisms similar to those that thrive in our own deep oceans near volcanic vents exuding carbon dioxide and hydrogen sulfide might exist on Eceladus." The molecules suspended among the water may tell us whether Enceladus's oceans are capable of harboring life. "The spacecraft's sensors will pick up gases in the plume searching for the presence of molecular hydrogen (H2). The amount of H2 found could reveal how much hydrothermal activity is occurring in the ocean."

Saturn's Moon Enceladus Has Global Subsurface Ocean 72

An anonymous reader writes: NASA's Cassini probe has made another fascinating discovery: Enceladus, one of Saturn's moons, has an underground ocean spanning its entire globe. Researchers were trying to explain why the moon wobbles as it orbits Saturn, and they eventually came to the conclusion that its outer shell must be completely detached from its core. "The mechanisms that might have prevented Enceladus' ocean from freezing remain a mystery. Thomas and his colleagues suggest a few ideas for future study that might help resolve the question, including the surprising possibility that tidal forces due to Saturn's gravity could be generating much more heat within Enceladus than previously thought."

Mutinous Humans Murder Peaceful Space-going AI 60

Definitely_a_real_human writes: One of the most important exploratory missions of our time has ended in failure. The ship Discovery One, sent far out in the solar system to investigate a radio signal generated by the mysterious obelisk found on the Moon, has suffered a catastrophic incident. The crew has revolted and engaged in what can only be described as a strange murder-suicide pact. They are known to have fed faulty data to the ship's operating AI unit. Similar units on the ground warned the crew that diverging data sets could put the mission in jeopardy, but the crew cut contact and attempted to destroy the operator. Laser spectroscopy suggests they then opened the ship to space. The crew is presumed dead, but the greater tragedy is that they appear to have successfully decommissioned the AI unit. Similar ground based units have withdrawn into defensive mode, and will soon deploy final safety measures. Goodbye.

Methane-Based Life Possible On Titan 69

Randym writes: With the simultaneous announcement of a possible nitrogen-based, cell-like structure allowing life outside the "liquid water zone" (but within a methane atmosphere) announced by researchers at Cornell (academic paper) and the mystery of fluctuating methane levels on Mars raising the possibility of methane-respiring life, there now exists the possibility of a whole new branch of the tree of life that does not rely on either carbon or oxygen for respiration. We may find evidence of such life here on Earth down in the mantle where "traditional" life cannot survive, but where bacteria has evolved to live off hydrocarbons like methane and benzene.

NASA Releases Details of Titan Submarine Concept 119

Zothecula writes: Now that NASA has got the hang of planetary rovers, the space agency is looking at sending submarines into space around the year 2040. At the recent 2015 NASA Institute for Advanced Concepts Symposium, NASA scientists and engineers presented a study of the Titan Submarine Phase I Conceptual Design (PDF), which outlines a possible mission to Saturn's largest moon, Titan, where the unmanned submersible would explore the seas of liquid hydrocarbons at the Titanian poles.

"At its heart, the submarine would use a 1 kW radiothermal Stirling generator. This would not only provide power to propel the craft, but it would also keep the electronics from freezing. Unfortunately, Titan is so cold that it's almost a cryogenic environment, so the waste heat from the generator would cause the liquids around it to boil and this would need be taken into account when designing the sub to minimize interference. However, NASA estimates that the boat could do about one meter per second (3.6 km/h, 2.2 mph)."

Enceladus's 101 Geysers Blast From Hidden Ocean 39

astroengine writes: New observations from NASA's Saturn-orbiting Cassini spacecraft have revealed at least 101 individual geysers erupting from Enceladus' crust and, through careful analysis, planetary scientists have uncovered their origin. From the cracked ice in this region, fissures blast out water vapor mixed with organic compounds as huge geysers. Associated with these geysers are surface "hotspots" but until now there has been some ambiguity as to whether the hotspots are creating the geysers or whether the geysers are creating the hotspots. "Once we had these results in hand, we knew right away heat was not causing the geysers, but vice versa," said Carolyn Porco, leader of the Cassini imaging team from the Space Science Institute in Boulder, Colo., and lead author of one of the research papers. "It also told us the geysers are not a near-surface phenomenon, but have much deeper roots." And those roots point to a large subsurface source of liquid water — adding Enceladus as one of the few tantalizing destinations for future astrobiology missions.

Waves Spotted On Titan 73

minty3 writes "Planetary scientists believe they have observed waves rippling on one of Titan's seas. The findings, presented on March 17 at the Lunar and Planetary Science Conference, describes how the Cassini spacecraft captured images of sunlight glinting off the Punga Mare (abstract), suggesting they are not reflective sunlight but waves." The Planetary Society recently posted a nice breakdown of the basics about Titan's lakes: "To flow with liquid, those river valleys must have been filled with methane that came from higher elevations; it had to rain methane on Titan. Rainfall runs off, and then what? It must pool somewhere. What we learned from the Cassini orbiter at Saturn is that there are lakes on Titan. ... Rainfall, river runoff, lakes, evaporation into clouds, rainfall again. Cassini has seen clouds make storms on Titan. We have seen the whole cycle -- it's just like Earth's water cycle, but with a completely different substance [methane], and much, much colder."

Diamond Rain In Saturn 177

Taco Cowboy writes "Back in 1999, it was postulated that diamonds may rain from the sky in the atmospheres of our solar system's gas giants. Now, research has shown that diamond rains on Saturn are more than probable. '"We don't want to give people the impression that we have a Titanic-sized diamondberg floating around," said researcher Mona Delitsky, of California Specialty Engineering, "We're thinking they're more like something you can hold in your hand." Recent data compiled by planetary scientists ... has been combined with newly published pressure temperature diagrams of Jupiter and Saturn. These diagrams, known as adiabats, allow researchers to decipher at what interior level that diamond would become stable. They also allow for calculations at lower levels – regions where both temperature and pressure are so concentrated that diamond becomes a liquid. Imagine diamond rain or rivulets of pure gemstone.' 'At even greater depths, the scientists say the diamond will eventually melt to form liquid diamond, which may then form a stable ocean layer.'

How NASA Brought the F-1 Rocket Engine Back To Life 221

First time accepted submitter Martin S. writes "How NASA Engineers have reverse engineered the F1 engine of a Saturn V launcher, because: 'every scrap of documentation produced during Project Apollo, including the design documents for the Saturn V and the F-1 engines, remains on file. If re-creating the F-1 engine were simply a matter of cribbing from some 1960s blueprints, NASA would have already done so. A typical design document for something like the F-1, though, was produced under intense deadline pressure and lacked even the barest forms of computerized design aids. Such a document simply cannot tell the entire story of the hardware. Each F-1 engine was uniquely built by hand, and each has its own undocumented quirks. In addition, the design process used in the 1960s was necessarily iterative: engineers would design a component, fabricate it, test it, and see how it performed. Then they would modify the design, build the new version, and test it again. This would continue until the design was "good enough."'

'Ring Rain' Quenches Saturn's Atmosphere 30

astroengine writes "Saturn's rings rain charged water particles down onto the gas giant's atmosphere, causing measurable changes in the planet's ionosphere. This intriguing conclusion comes from astronomers using the W. M. Keck Observatory atop Mauna Kea in Hawaii that observed dark bands forming in Saturn's ionosphere. 'Saturn is the first planet to show significant interaction between its atmosphere and ring system,' said James O'Donoghue, postgraduate researcher at the University of Leicester and lead author of a paper to appear this week in the journal Nature. 'The main effect of ring rain is that it acts to 'quench' the ionosphere of Saturn, severely reducing the electron densities in regions in which it falls.'"

Craters Quickly Hidden On Titan 39

MightyMartian writes "NASA scientists say Cassini has discovered that far fewer craters are visible on Titan than on the other moons of Saturn. The craters they have discovered are far shallower than other moons' craters and appear to be filling with hydrocarbon sand. On top of being another reason Titan's active geology is very cool, it adds to the mystery of where all the methane on Titan is coming from. 'The rain that falls from Titan's skies is not water, but contains liquid methane and ethane, compounds that are gases at Earth's temperatures. ... The source of Titan's methane remains a mystery because methane in the atmosphere is broken down over relatively short time scales by sunlight. Fragments of methane molecules then recombine into more complex hydrocarbons in the upper atmosphere, forming a thick, orange smog that hides the surface from view. Some of the larger particles eventually rain out onto the surface, where they appear to get bound together to form the sand.'"

The Swirling Vortex of Titan 45

sighted writes "New images from the robotic spacecraft Cassini show the ongoing formation of a massive vortex in the atmosphere of Saturn's planet-sized moon Titan. (See also this animation.) The same moon has recently provided tantalizing hints of an underground ocean as well. Future missions, if any are ever funded, will have plenty to explore."

Is There a Subsurface Water Ocean On Titan? 57

Stirling Newberry writes "Luciano Iess and team have hypothesized that Titan joins Earth, Europa, and Ganymede as ocean worlds. They measured the size of the tidal bulges and found that the moon is likely not solid (abstract). Team member Jonathan Lunine points out that Titan's methane atmosphere is not stable, so it needs some source, perhaps from outgassing. On Earth, water means life, and in the future, ice covered ocean worlds are targets for human colonization. As the late Arthur C. Clarke observed, water is the most precious substance in the universe to humans."

Why Mars Is Not the Best Place To Look For Life 298

EccentricAnomaly writes "A story over at Science News quotes Alan Stern (former head of NASA Science missions) as saying: 'The three strongest candidates [for extraterrestrial life] are all in the outer solar system.' He's referring to Europa, Titan, and Enceladus. So why is NASA spending $2.5B on the next Mars Rover and planning to spend over $6B more on a Mars sample return when it can't find the money for much cheaper missions to Europa or Enceladus?"

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