Saturn 5 Active

[Mellissa Sprock]

Heatfrom friction could power hydrothermal activity on Saturn's moon Enceladus for billions of years if the moon has a highly porous core, according to a new modeling study by European and U.S. researchers working on NASA's Cassini mission.

The study, published today in the journal Nature Astronomy, helps resolve a question scientists have grappled with for a decade: Where does the energy to power the extraordinary geologic activity on Enceladus come from?

Cassini found that Enceladus sprays towering, geyser-like jets of water vapor and icy particles, including simple organics, from warm fractures near its south pole. Additional investigation revealed the moon has a global ocean beneath its icy crust, from which the jets are venting into space. Multiple lines of evidence from Cassini indicate that hydrothermal activity -- hot water interacting chemically with rock -- is taking place on the seafloor.

One of those lines was the detection of tiny rock grains inferred to be the product of hydrothermal chemistry taking place at temperatures of at least 194 degrees Fahrenheit (90 degrees Celsius). The amount of energy required to produce these temperatures is more than scientists think could be provided by decay of radioactive elements in the interior.

"Where Enceladus gets the sustained power to remain active has always been a bit of a mystery, but we've now considered in greater detail how the structure and composition of the moon's rocky core could play a key role in generating the necessary energy," said the study's lead author, Gal Choblet from the University of Nantes in France.

Choblet and co-authors found that a loose, rocky core with 20 to 30 percent empty space would do the trick. Their simulations show that as Enceladus orbits Saturn, rocks in the porous core flex and rub together, generating heat. The loose interior also allows water from the ocean to percolate deep down, where it heats up, then rises, interacting chemically with the rocks. The models show this activity should be at a maximum at the moon's poles. Plumes of the warm, mineral-laden water gush from the seafloor and travel upward, thinning the moon's ice shell from beneath to only half a mile to 3 miles (1 to 5 kilometers) at the south pole. (The average global thickness of the ice is thought to be about 12 to 16 miles, or 20 to 25 kilometers.) And this same water is then expelled into space through fractures in the ice.

The study is the first to explain several key characteristics of Enceladus observed by Cassini: the global ocean, internal heating, thinner ice at the south pole, and hydrothermal activity. It doesn't explain why the north and south poles are so different though. Unlike the tortured, geologically fresh landscape of the south, Enceladus' northern extremes are heavily cratered and ancient. The authors note that if the ice shell was slightly thinner in the south to begin with, it would lead to runaway heating there over time.

The researchers estimate that, over time (between 25 and 250 million years), the entire volume of Enceladus' ocean passes through the moon's core. This is estimated to be an amount of water equal to two percent of the volume of Earth's oceans.

Flexing of Enceladus' icy crust due to the tidal pull of Saturn had previously been considered as a heat source, but models showed this would not produce enough sustained power. The ocean in Enceladus would have frozen within 30 million years. Although past studies modeled how tidal friction could generate heat in the moon's core, they made simpler assumptions or simulated the moon in only two dimensions. The new study ramped up the complexity of the model and simulated Enceladus in 3-D.

Although the Cassini science team had suspected for years that a porous core might play an important role in the mystery of Enceladus' warm interior, this study brings together several more recent lines of evidence in a very elegant way, according to NASA's Cassini Project Scientist Linda Spilker at the agency's Jet Propulsion Laboratory in Pasadena, California. "This powerful research makes use of newer details -- namely that the ocean is global and has hydrothermal activity -- that we just didn't have until the past couple of years. It's an insight that the mission needed time to build, one discovery upon another," she said.

Launched in 1997, the Cassini spacecraft orbited Saturn from 2004 to 2017. Cassini made numerous dramatic discoveries, including the surprising activity on Enceladus and liquid methane seas on Saturn's largest moon, Titan. Cassini ended its journey with a dramatic plunge into Saturn's atmosphere on Sept. 15, 2017, returning unique science data until it lost contact with Earth.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter.

Unlike Y-cables, which simply wire the jacks together, the Saturnworks splitter/combiner utilizes summing resistors to minimize crosstalk. In other words, the level of one channel will minimally affect the level of the other.

The micro summer/splitter TRS to TS works like the micro summer/splitter, except it uses a TRS jack on one side, rather than two TS jacks. This can be handy to passively sum a stereo signal on a TRS cable, such as combining two separate signals on two pickups, into a mono signal to send through pedals, amps, etc.

The Saturnworks passive mixers and summers take two or three inputs and combines them to one output with volume control for each channel to allow fine volume trimming. The versions with switches adds on/off switches to each channel. The ABC summer is comparable to the Morley ABC combiner.

Using active electronics to balance the signals and eliminate crosstalk, the Saturnworks 2 and 3 channel active mixers blend two inputs into one output. Saturnworks mixers combine inputs from various instruments with differing impedance. Saturnworks active mixers are also perfect for the mixer section of a parallel pedal chain setup.

The active mixers with a phase switch adds an active phase reversal circuit + toggle switch. The phase circuit flips the phase 180 degrees. This can help with out-of-phase issues when summing or mixing.

Saturnworks pedals can be upgraded with a variety of premium upgrades and customizations, including our phenomenally smooth, quiet, and extremely durable soft click latching switch. Contact us for details.

If you just wire two signals together (like a y-cable, for example), they essentially become the same circuit. Being simply hooked together, whatever you do to one side you do to the other. With nothing to prevent interaction between the two channels, if you turn one side down the other will get softer as well. This is called crosstalk. Passive mixers are a step up from a y-cable in that they use summing resistors to combine/sum the signals. This reduces, but does not eliminate, crosstalk. Depending on the types of signals being mixed, with a passive mixer, if you turn one side down completely the other side gets around 20% softer. While you can minimize crosstalk with a passive mixer, you cannot eliminate it altogether.

Active mixers/summers are often a bit larger, more expensive, and require power to function. However, they do offer some key performance advantages. Active mixers and summers eliminate crosstalk between channels. This means that you can turn one channel down without affecting the level of the other(s). Active mixers/summers also balance mismatched impedance so that you can combine a wider range of signal types without levels issues.

Please note: The pedals in the images are stock photos and not the actual pedals you will receive. The pedals you receive may vary in their graphics, knob colors, and/or LED colors, where applicable. We have our graphics options here.

Wake up, make coffee, decide where I should go cross-country skiing *weather pending*. Pack gear, load up car, head out, pop-on some tunes, drive to destination, strap on skis and hop on the trail and see what we can find.

While there, I met Curt Stahr and many other amazing photographers. He constanly challenged me and kept me active. Sadly I was there for his last 2 years of teaching before he retired. While there he told so many crazy awesome stories from travels he had taken in his life and I guess, I to, want some crazy awesome stories

A volcano is a hole in a planet or moon where hotter material from the inside erupts out onto the surface or into the air. On Earth, there are hundreds to thousands of active and potentially active volcanoes. On the Big Island of Hawaii is Mauna Loa, the largest active volcano on Earth. It is 5.5 miles (9 km) high, but more than half of it is underwater. Yellowstone National Park in the United States sits over an extremely volcanic area. Three eruptions in the distant past created a crater 30-by-45 miles across (48-by-72 km). Under the Pacific Ocean lies Tamu Massif, a volcano so large it would cover the entire state of New Mexico.

Many worlds in our solar system show signs of ancient volcanoes and lava flows solidified in fascinating rock formations. Sapas Mons, an extinct volcano on Venus, has two peaks. It is 2.5 miles (4 km) tall and surrounded by old lava flows and landslides.

Ahuna Mons is a cryovolcano on the dwarf planet Ceres. It grew from eruptions of mud and salty water that froze on the surface. During the New Horizons mission that flew past Pluto in 2015, astronomers saw signs of cryovolcanoes. Ridges and mountains of ice and ammonia were stacked up in such an usual way that they appeared like frozen daggers rising above the otherwise flat plain.

Dean Regas is the Astronomer for the Cincinnati Observatory and author of the books 1000 Facts About Space, and How to Teach Grown-Ups About Pluto. For a daily Space Fact, follow him on Instagram: @deanregas.

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