SoylentNews

Walzmyn writes:

Apparently there were reports that the theorized "Planet 9" (Planet 10, Planet X...) was affecting the course of the Cassini Space Probe. JPL said Friday that this is not true:

Personally, I'd be very surprised if we found a new planet at this stage of the game. However, these guys surprise me all the time.

Original Submission

Phoenix666 writes:

The aptly named Titan, Saturn's largest moon, is remarkably Earth-like. Its diameter is only about 40% that of our planet, but Titan's nitrogen-rich, dense atmosphere and the geological activity at the moon's surface make comparisons between the two bodies inevitable.

This image, taken with the radar on the Cassini spacecraft, shows just how similar the features in Titan's surface are to Earth's landforms.

Aside from Earth, Titan is the only other body where we have found evidence of active erosion on a large scale. There are seas, lakes and rivers filled with liquid hydrocarbons – mainly methane and some ethane – that etch the moon's surface, in much the same way water erodes Earth's.

A striking example is Vid Flumina, the Nile-like, branching river system visible on the upper-left quadrant of the image. The river, in the moon's north polar region, flows into Ligeia Mare, a methane-rich sea that appears as a dark patch on the right side of the image.

Researchers in Italy and the US analysed Cassini radar observations from May 2013 and recently revealed that the narrow channels that branch off Vid Flumina are deep, steep-sided canyons filled with flowing hydrocarbons.

Do Titanians worry about too much oxygen in their atmosphere?

Original Submission

kurenai.tsubasa writes:

Cassini moves in closer to the jewel of our solar system! According to NASA Jet Propulsion Laboratory's article Cassini Makes First Ring-Grazing Plunge:

The BBC brings us news of new Saturn images from the Cassini mission, including the hexagon-shaped storm in Saturn's northern atmosphere:

See also NASA JPL's release regarding the new images.

For more information, NASA JPL also provides a summary page for Cassini's ring-grazing orbits, including a diagram of the probe's projected orbital path, a glossary, and a countdown timer to the second ring-grazing orbit.

Original Submission

takyon writes:

Saturn's moons may be significantly younger than their home planet, favoring a theory that they formed from Saturn's rings:

Freshly harvested data from NASA's Cassini mission reveals that Saturn's bulging core and twisting gravitational forces offer clues to the ages of the planet's moons. Astronomers now believe that the ringed planet's moons are younger than previously thought. [...] The Encelade team – lead by Valéry Lainey of the Paris Observatory – provided two key measurements in the research, "New Constraints on Saturn's Interior From Cassini Astrometric Data" [DOI: 10.1016/j.icarus.2016.07.014] [DX]. The scientists measured Saturn's Love number (the rigidity of a planet) for the first time and confirmed Saturnian moons move away from the planet at a faster rate than expected. (Most moons, including Earth's moon, move away from their parent planet.)

Using photographic images taken from century-old glass negatives and Cassini spacecraft observations, the group measured the Love number – named for Augustus E.H. Love, a famed British mathematician who studied elasticity – that describes the rigidity of the tidal bulge and the dissipation factor, which controls the speed at which moons move away.

While Saturn is mostly a gigantic shroud of liquid hydrogen and liquid helium, it contains a rocky core – about 18 times the size of Earth, which responds to tidal forces from all of Saturn's major moons by bulging. The forces of the bulging core, in turn, push the moons slightly away.

[...] "By monitoring these disturbances, we managed to obtain the first measurement of Saturn's Love number and distinguish it from the planet's dissipation factor," Tajeddine said. "The moons are migrating away much faster than expected." Tajeddine explains that if Saturn moons actually formed 4.5 billion years ago, their current distances from the home planet should be greater. Thus, this new research suggests, the moons are younger than 4.5 billion years, favoring a theory that the moons formed from Saturn's rings.

Original Submission

An Anonymous Coward writes:

Newly released images showcase the incredible closeness with which NASA's Cassini spacecraft, now in its "Ring-Grazing" orbits phase, is observing Saturn's dazzling rings of icy debris.

The views are some of the closest-ever images of the outer parts of the main rings, giving scientists an eagerly awaited opportunity to observe features with names like "straw" and "propellers." Although Cassini saw these features earlier in the mission, the spacecraft's current, special orbits are now providing opportunities to see them in greater detail. The new images resolve details as small as 0.3 miles (550 meters), which is on the scale of Earth's tallest buildings.

Cassini is now about halfway through its penultimate mission phase—20 orbits that dive past the outer edge of the main ring system. The ring-grazing orbits began last November, and will continue until late April, when Cassini begins its grand finale. During the 22 finale orbits, Cassini will repeatedly plunge through the gap between the rings and Saturn. The first finale plunge is scheduled for April 26.

Source: https://m.phys.org/news/2017-01-views-saturn-unprecedented.html

Original Submission

takyon writes:

The Cassini spacecraft has imaged the dumpling/walnut/ravioli-shaped Pan, a shepherd moon in Saturn's Encke Gap with a mean radius of around 14.1 km:

Even as it nears a sad end in September, the Cassini spacecraft is continuing to delight as it makes some of its final orbits through the Saturn system. As part of these "ring-grazing" maneuvers, the spacecraft has just returned the best-ever images of the small, walnut-shaped moon Pan. [...] In earlier research, [Carolyn] Porco and other planetary scientists have suggested that Pan, as well as Daphnis and some of the other small moons in the Saturn system, were once denser cores that had about one-third to one-half their present size.

Also at NASA JPL, Science Magazine and The Verge.

Raw images.

Original Submission

takyon writes:

Data collected by the Cassini spacecraft during a 2011 flyby of Saturn's moon Enceladus suggests that an internal liquid ocean may be closer to the surface than previously thought. Ice near the south pole of Enceladus, where plumes of water vapor have been detected, was found to be up to 20 K warmer than expected:

"These observations provide a unique insight into what is going on beneath the surface. They show that the first few metres below the surface of the area that we investigated, although at a glacial 50-60 K, are much warmer than we had expected: likely up to 20 K warmer in some places," [Alice Le Gall] adds. "This cannot be explained only as a result of the Sun's illumination and, to a lesser extent, Saturn's heating so there must be an additional source of heat."

The detected heat appears to be lying under a much colder layer of frost, as no similar anomaly was found in infrared observations of the same region – these probe the temperature of the surface but are not sensitive to what is underneath. [...] Even if the observations cover only a small patch of the southern polar terrains, it is likely that the entire region is warm underneath and Enceladus' ocean could be a mere 2 km under the icy surface. The finding agrees well with the results of a recent study, led by Ondrej Cadek [DOI: 10.1002/2016GL068634] and published in 2016, which estimated the thickness of the crust on Enceladus. With an average depth of 18–22 km, the ice shell appears to reduce to less than 5 km at the south pole.

Thermally anomalous features in the subsurface of Enceladus's south polar terrain (open, DOI: 10.1038/s41550-017-0063) (DX)

Original Submission

takyon writes:

At a NASA press conference on Thursday, scientists from the Jet Propulsion Laboratory, NASA's D.C. Headquarters, and the Space Telescope Science Institute announced new observations about the "ocean worlds" Enceladus and Europa. At Enceladus, one of Saturn's moons, the Cassini spacecraft has measured emissions of hydrogen gas that could indicate a source of chemical energy for life forms. 2016 Hubble observations of Jupiter's moon Europa have found evidence of a water plume emanating from the same location as a plume measured in 2014.

The Cassini spacecraft took a "deep dive" into one of the Enceladus plumes on Oct. 28, 2015. The plume contains about 98% water, 0.4-1.4% hydrogen, and a mixture of carbon dioxide, methane, ammonia, and other molecules. The findings support the conclusion of hot water interacting with rock at hydrothermal vents on the seafloor, a type of habitat known to support life without the need for sunlight. NASA scientists have concluded that Enceladus has all of the conditions and ingredients necessary to support life, although the detection of hydrogen gas does not prove that the internal ocean currently contains life forms, and phosphorus and sulfur have yet to be measured.

The new Hubble images of Europa show that the height of the plume is about twice that of the one measured in 2014. The location of this periodic plume corresponds with a thermal hotspot on Europa's surface found by the Galileo spacecraft in the 1990s, which was once dismissed as an anomaly. The lack of craters on Europa's surface indicates that water is spraying out of the internal ocean through cracks and reshaping the surface. However, Europa's ice shell is thought to be thicker than that of Enceladus, with water vapor escaping the crust less often. NASA is currently developing a Europa Clipper mission that would conduct a series of 45 or more flybys of Europa, with the possibility of flying directly through water vapor plumes for sampling. The European Space Agency's Jupiter Icy Moons Explorer will study Europa and Callisto, but end its mission by orbiting Ganymede.

The same chemistry detected at Enceladus could also be taking place in interior oceans on other icy worlds, such as Ceres, Titan, Ganymede, Callisto, Dione, Rhea, Titania, Triton, Pluto, Eris, Sedna, etc.

Here's the press briefing (48m16s). Also at Science Magazine, BBC, Space.com, and Popular Mechanics (mhajicek's link).

Cassini finds molecular hydrogen in the Enceladus plume: Evidence for hydrothermal processes (open, DOI: 10.1126/science.aai8703) (DX)

Active Cryovolcanism on Europa? (DOI: 10.3847/2041-8213/aa67f8) (DX)

Original Submission #1  Original Submission #2 

takyon writes:

The Cassini spacecraft has taken the closest-ever images of Saturn's 40.8 × 35.4 × 18.8 km moon Atlas. The images were taken on April 12th from a closest approach of about 11,000 km.

Next up is a final flyby of Titan on April 22nd, and the Cassini Grand Finale from April 26th to September 15th.

Previously: Cassini Spacecraft to Begin Diving Between Saturn and its Rings This Month

Original Submission

The Mighty Buzzard writes:

From the expensive toy breaking folks over at NASA:

"Cassini's up-close exploration of Titan is now behind us, but the rich volume of data the spacecraft has collected will fuel scientific study for decades to come," said Linda Spilker, the mission's project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California.

The flyby also put Cassini on course for its dramatic last act, known as the Grand Finale. As the spacecraft passed over Titan, the moon's gravity bent its path, reshaping the robotic probe's orbit slightly so that instead of passing just outside Saturn's main rings, Cassini will begin a series of 22 dives between the rings and the planet on April 26. The mission will conclude with a science-rich plunge into Saturn's atmosphere on Sept. 15.

Look, guys, if it's a driving ability problem I'll be happy to come over and show you now to not run into a gigantic planet...

Original Submission

takyon writes:

A study using Cassini's radar observations of Titan's surface has estimated the roughness of its hydrocarbon lakes and seas:

The liquid-hydrocarbon lakes and seas on Titan are incredibly calm, suggesting that future missions to the huge Saturn moon could enjoy a smooth ride to the surface, a new study reports.

The waves rippling the three largest lakes in Titan's northern hemisphere are tiny, according to the study — just 0.25 inches (1 centimeter) high by about 8 inches (20 cm) long.

"There's a lot of interest in one day sending probes to the lakes, and when that's done, you want to have a safe landing, and you don't want a lot of wind," study lead author Cyril Grima, a research associate at the University of Texas Institute for Geophysics (UTIG), said in a statement. "Our study shows that because the waves aren't very high, the winds are likely low."

From older observations:

Calculations of the waves' height suggested they were a puny few centimetres high.

Another way to explore Titan would be to use winged drones or quadcopters, which would be capable of generating more lift than on Earth.

Also at University of Texas at Austin.

Surface roughness of Titan's hydrocarbon seas (DOI: 10.1016/j.epsl.2017.06.007) (DX)

Original Submission

martyb writes:

The end is nigh for NASA's Cassini spacecraft, according to a report at NASA (Javascript required -- non-JS version available at Science Daily.)

NASA's Cassini spacecraft will enter new territory in its final mission phase, the Grand Finale, as it prepares to embark on a set of ultra-close passes through Saturn's upper atmosphere with its final five orbits around the planet.

Cassini will make the first of these five passes over Saturn at 12:22 a.m. EDT Monday, Aug. 14. The spacecraft's point of closest approach to Saturn during these passes will be between about 1,010 and 1,060 miles (1,630 and 1,710 kilometers) above Saturn's cloud tops.

The spacecraft is expected to encounter atmosphere dense enough to require the use of its small rocket thrusters to maintain stability -- conditions similar to those encountered during many of Cassini's close flybys of Saturn's moon Titan, which has its own dense atmosphere.

"Cassini's Titan flybys prepared us for these rapid passes through Saturn's upper atmosphere," said Earl Maize, Cassini project manager at NASA's Jet Propulsion Laboratory (JPL) in California. "Thanks to our past experience, the team is confident that we understand how the spacecraft will behave at the atmospheric densities our models predict."

If the thrusters operate between 10 and 60 percent of their capability, then things will proceed unchanged. If more than 60 percent thrust is required, that means the atmosphere is more dense than predicted and the engineers will perform a "pop-up maneuver" to boost the altitude of later orbits — likely by 200 kilometers (120 miles). If, on the other hand, the thruster use required less than 10 percent of their capability, then the atmosphere was thinner than predicted and they will perform a "pop down maneuver" to reduce the altitude by about 200 kilometers.

Original Submission

takyon writes:

https://www.jpl.nasa.gov/news/news.php?release=2017-231&rn=news.xml&rst=6935

In its final week, Cassini will pass several milestones en route to its science-rich Saturn plunge. (Times below are predicted and may change slightly; see https://go.nasa.gov/2wbaCBT for updated times.)

• Sept. 9 Cassini will make the last of 22 passes between Saturn itself and its rings -- closest approach is 1,044 miles (1,680 kilometers) above the clouds tops.
• Sept. 11 -- Cassini will make a distant flyby of Saturn's largest moon, Titan. Even though the spacecraft will be at 73,974 miles (119,049 kilometers) away, the gravitational influence of the moon will slow down the spacecraft slightly as it speeds past. A few days later, instead of passing through the outermost fringes of Saturn's atmosphere, Cassini will dive in too deep to survive the friction and heating.
• Sept. 14 -- Cassini's imaging cameras take their last look around the Saturn system, sending back pictures of moons Titan and Enceladus, the hexagon-shaped jet stream around the planet's north pole, and features in the rings.
• Sept. 14 (5:45 p.m. EDT / 2:45 p.m. PDT / 9:45 p.m. UTC) -- Cassini turns its antenna to point at Earth, begins a communications link that will continue until end of mission, and sends back its final images and other data collected along the way.
• Sept. 15 (4:37 a.m. EDT / 1:37 a.m. PDT / 8:37 a.m. UTC) -- The "final plunge" begins. The spacecraft starts a 5-minute roll to position INMS for optimal sampling of the atmosphere, transmitting data in near real time from now to end of mission.
• Sept. 15 (7:53 a.m. EDT / 4:53 a.m. PDT / 11:53 a.m. UTC) -- Cassini enters Saturn's atmosphere. Its thrusters fire at 10 percent of their capacity to maintain directional stability, enabling the spacecraft's high-gain antenna to remain pointed at Earth and allowing continued transmission of data.
• Sept. 15 (7:54 a.m. EDT / 4:54 a.m. PDT / 11:54 a.m. UTC) -- Cassini's thrusters are at 100 percent of capacity. Atmospheric forces overwhelm the thrusters' capacity to maintain control of the spacecraft's orientation, and the high-gain antenna loses its lock on Earth. At this moment, expected to occur about 940 miles (1,510 kilometers) above Saturn's cloud tops, communication from the spacecraft will cease, and Cassini's mission of exploration will have concluded. The spacecraft will break up like a meteor moments later.

Original Submission

Phoenix666 writes:

The hunt for habitable (and already inhabited) worlds has largely focused on a "Goldilocks zone" around a star, where it's neither too hot nor too cold for liquid water to exist. But astrobiologists have begun to broaden their search – thanks to discoveries by NASA's Cassini orbiter.

Saturn sits too far from the sun for its rays to melt ice, and yet Cassini discovered that one of the planet's moons, Enceladus, has a vast ocean sloshing beneath its icy crust. Instead of sunlight, tidal forces keep Enceladus's ocean warm. The gravity of Saturn pulls at Enceladus's core, driving thermal processes that create a new Goldilocks zone inside the moon itself.

"It's definitely been a paradigm shift in where you might find life," says Cassini project scientist Linda Spilker.

Still, it takes a lot more than water to make a place habitable. But here, too, Enceladus delivers. Icy geysers fueled by Enceladus's ocean shoot out from cracks in the moon's surface, allowing the Cassini spacecraft to sample them directly during flybys. What it found is that Enceladus has almost everything required for life as we know it: a source of energy, a source of carbon, and salts and minerals.

Thank goodness for Cassini, after that whole thing about being banned from Europa.

Original Submission

takyon writes:

Yuri Milner, the Russian billionaire backer of Breakthrough Initiatives and Breakthrough Prizes, has set his sights on Saturn's moon Enceladus:

Milner founded the $100 million Breakthrough Starshot project, an attempt to send small probes to Alpha Centauri. Now, he has announced plans to explore funding a mission to Enceladus.

[...] "Can we design a low-cost, privately funded mission to Enceladus which can be launched relatively soon, and that can look more thoroughly at those plumes, try to see what's going on there?" Milner asked the New Space Age conference in Seattle this week.

A probe to Enceladus could be done for well under $1 billion, but it likely wouldn't be able to drill through the icy surface.

The Cassini spacecraft already flew as close as 49 km above the surface of Enceladus, and flew through a plume of water vapor released by the satellite. A proposed mission such as the Enceladus Life Finder could repeatedly fly through plumes and use better sensors to attempt to detect evidence of organic materials or microbes.

Two upcoming missions will be studying Jupiter's moon Europa: the ESA's Jupiter Icy Moons Explorer and NASA's Europa Clipper. Europa is easier for spacecraft to reach than Enceladus, but has thicker ice blocking its internal ocean.

Also at Newsweek.

Related: NASA Releases Europa Lander Study 2016 Report
Hydrogen Emitted by Enceladus, More Evidence of Plumes at Europa
Could a Dedicated Mission to Enceladus Detect Microbial Life There?
How the Cassini Mission Led a 'Paradigm Shift' in Search for Alien Life
Cassini Spacecraft Post-Mortem
Porous Core Could be Keeping Enceladus Warm

Original Submission

takyon writes:

Cosmic ravioli and spaetzle

The small inner moons of Saturn look like giant ravioli and spaetzle. Their spectacular shape has been revealed by the Cassini spacecraft. For the first time, researchers of the University of Bern show how these moons were formed. The peculiar shapes are a natural outcome of merging collisions among similar-sized little moons as computer simulations demonstrate.

[...] Based on the current orbit of the moons and their orbital environment, the researchers were able to estimate that the impact velocities were of the order of a few 10 m/s. Simulating collisions in this range for various impact angles, they obtained various stable shapes similar to ravioli and spaetzle, but only for low impact angles. "If the impact angle is bigger than ten degrees, the resulting shapes are not stable anymore," says Adrien Leleu. Any duck-shaped object like comet [67P/Churyumov–Gerasimenko] would fall apart because of Saturn's tides. "That is why Saturn's small moons look very different to comets that often have bilobed shapes," explains Martin Jutzi.

Also at Scientific American.

The peculiar shapes of Saturn's small inner moons as evidence of mergers of similar-sized moonlets (DOI: 10.1038/s41550-018-0471-7) (DX)

Related: Cassini Captures Best Ever Images of Saturn's Tiny Moon Pan
Cassini's Final Flyby of Atlas
Cassini Spacecraft Post-Mortem

Original Submission

takyon writes:

Saturn moon a step closer to hosting life

Scientists have found complex carbon-based molecules in the waters of Saturn's moon Enceladus.

Compounds like this have only previously been found on Earth, and in some meteorites. They are thought to have formed in reactions between water and warm rock at the base of the moon's subsurface ocean.

Though not a sign of life, their presence suggests Enceladus could play host to living organisms. The discovery came from data gathered by the Cassini spacecraft.

Also at SwRI, ScienceAlert, Space.com, National Geographic, Popular Mechanics, and The Guardian.

Macromolecular organic compounds from the depths of Enceladus (DOI: 10.1038/s41586-018-0246-4) (DX)

Related: Minerals In Plumes of Enceladus Indicate Hydrothermal Activity
Hydrogen Emitted by Enceladus, More Evidence of Plumes at Europa
Could a Dedicated Mission to Enceladus Detect Microbial Life There?
How the Cassini Mission Led a 'Paradigm Shift' in Search for Alien Life
Cassini Spacecraft Post-Mortem
Porous Core Could be Keeping Enceladus Warm
Yuri Milner Considering Privately Funded Mission to Enceladus
Organic Molecules Found on Ceres
NASA Finds Evidence of Water Plume on Europa
Organic Matter Found on Mars
Study Finds Evidence of More Organic Material on Ceres

Original Submission