Computer Model Explains Sustained Eruptions On Icy Moon Of Saturn

The Cassini spacecraft has observed geysers erupting on Saturn’s moon Enceladus since 2005, but the process that drives and sustains these eruptions has remained a mystery. Now, scientists at the University of Chicago and Princeton University have pinpointed a mechanism by which cyclical tidal stresses exerted by Saturn can drive Enceladus’s long-lived eruptions.

moon

“On Earth, eruptions don’t tend to continue for long,” said Edwin Kite, assistant professor of geophysical sciences at UChicago. “When you do see eruptions that continue for a long time, they’ll be localized into a few pipelike eruptions with wide spacing between them.”

But Enceladus, which probably has an ocean underlying its icy surface, has somehow managed to sprout multiple fissures along its south pole. These “tiger stripes” have been erupting vapor and tiny frost particles continuously along their entire length for decades and probably much longer.

“It’s a puzzle to explain why the fissure system doesn’t clog up with its own frost,” Kite said. “And it’s a puzzle to explain why the energy removed from the water table by evaporative cooling doesn’t just ice things over.”

What’s needed is an energy source to balance the evaporative cooling. “We think the energy source is a new mechanism of tidal dissipation that had not been previously considered,” Kite said. Kite and Princeton’s Allan Rubin present their findings the week of March 28 in the Early edition of the Proceedings of the National Academy of Sciences.

“I was very happy to see this new work by Kite and Rubin that brings to the fore a process that had escaped notice: the pumping of water in and out of the deep fractures of the south polar ice shell by tidal action,” said Carolyn Porco, head of Cassini’s imaging science team and a leading scientist in the study of Enceladus.

Astrobiology experiment

Enceladus, which Kite calls “an opportunity for the best astrobiology experiment in the solar system,” serves as a leading candidate for extraterrestrial life. Cassini data have strongly indicated that the cryovolcanic plumes of Enceladus probably originate in a biomolecule-friendly oceanic environment.

Cryovolcanism may also have shaped the surface of Europa, one of Jupiter’s moons. “Europa’s surface has many similarities to Enceladus’s surface, and so I hope that this model will be useful for Europa as well,” Kite said.

One of the problems that attracted Kite and Rubin was the anomalous tidal response of the Enceladus eruptions. The eruptions reach their peak approximately five hours later than expected, even when taking into account the 40 minutes needed for the erupted particles to reach the altitude at which Cassini can detect them. Other scientists had previously suggested reasons for the lag, which included a delay in the eruptions as well as a squishy, slowly responding ice shell.

“The new proposal is really a way to get a delay in the eruptions. You really don’t need to propose any terribly squishy ice shell to do it,” Porco said.

Kite and Rubin also wanted to know why Enceladus maintains a base level of cryovolcanic activity, even when at that point in its orbit where the fissures should clamp shut and curtail the eruptions. Other key questions: Why does the volcanic system generate five gigawatts of power instead of a lot more or a lot less? Why don’t the eruptions frost over or freeze over?

The Kite-Rubin model of the Enceladus plumbing system seems to answer them all. Their model consists of a series of nearly parallel, vertical slots that reach from the surface down to the water below. They applied Saturn’s tidal stresses to their model on a desktop computer and watched what happened.

The tricky part

“The only tricky part quantitatively is calculating the elastic interactions between the different slots and the varying water level within each slot as a response to the tidal stress,” Kite explained. The width of the slots affects how quickly they can respond to the tidal forces. With wide slots, the eruptions respond quickly to tidal forcing. With narrow slots, the eruptions occur eight hours after the tidal forces reach their peak.

“In between there’s a sweet spot,” Kite said, where tidal forces turn water motion into heat, generating enough power to produce eruptions that match the observed five-hour lag. Porco called it “the best thing in my mind about this new work.”

Tidal pumping heats the water and the ice shell via turbulence. Kite and Rubin have proposed that new Cassini data can test this idea by revealing whether or not the ice shell in the south polar region is warm.

“If the new mechanism is a major contributor to the heat coming from the fractures, then the south polar ice in between the fractures may in fact be cold,” Porco said. “The jury is still on out on this until the results from the final Enceladus flybys of last year are fully analyzed.”

Kite and UChicago geophysical sciences Prof. Douglas MacAyeal are interested in studying an Earth analogue to the Enceladus geysers. A crack has formed across a section of the Ross Ice Shelf in Antarctica, partially breaking it away from the continent.

“In that crack you have strong tidal flow, so it would be interesting to see what a real ice sheet does in an environment that’s analogous in terms of the amplitude of the stresses and the temperatures of the ice,” Kite said.

New Simulation Sun Shows both Large and Small Scale Processes

A team of researchers from the U.S., China and Japan has developed a computer simulation of the Sun that is able to show both large and small-scale processes. In their paper published in the journal Science, the team describes how their simulation works and why they believe it will help solve one of the big questions in solar research.

large and small-scale processes

Over the years, scientists have developed different tools for helping to understand how the Sun works, in more recent years, simulations have been developed that seek to demonstrate the Sun’s activities, one of which is the 11 year cycle of magnetic field reversal. But, such simulations have been divided into two main categories, those that simulate large processes, and those that simulate relatively small processes.

The goal has been to merge both large and small-scale processes to allow for a better overall look at how the Sun works in general. Also, to answer the question of how it is that the Sun manages to maintain a steady large-scale magnetic field in spite of what appears to be nothing but chaos at smaller scales. In this new effort, the researchers believe they have moved closer to being able to answer that question, by developing a new type of simulation of the Sun that finally allows for including both large and small processes.

Thus far, the simulation has not answered the question of how the Sun is able to maintain its large-scale magnetic field, but the researchers suggest it has to do with small-scale but strong magnetic fields with low viscosity, suppressing the apparent chaos, thereby allowing for the maintenance of the large overall field. They hope to use their new simulation method to better understand the 11-year cycle because of the important role it plays in sending particles to Earth, causing problems for satellites and other electronic equipment.

JUST IN: Ancient Super-Eruptions in the Yellowstone Caldara Found to be ‘Significantly Larger’ Than Expected

New research published today in the journal Geological Society of America, has discovered the 12 recorded mega-eruptions of the Yellowstone super-volcano or (caldera) located in the north-central US states of Idaho, Montana, and Wyoming near the U.S./Canadian border – have been found to be were ‘significantly larger’ than research has previously suggested.

Yellowstone-Volcano-Eruption

Dr Tom Knott, Professor Mike Branney and Dr Marc Reichow, from the University of Leicester’s Department of Geology’s Volcanology Group, conducted the research with a team of international collaborators from the University of California at Santa Cruz, the University of Copenhagen, Denmark and Idaho State University.

Using a multi-technique approach, including whole-rock and mineral chemistries, palaeomagnetic data and radio-isotopic dates – the team has been able to ‘fingerprint’ individual eruption deposits and correlate these over vast regions covering over 620 sq. miles (1000 km2).

magma in cubic miles

In establishing widespread correlations, the team drastically reduced the number of eruptions previously thought to have originated from the central Snake River Plain by more than half.

The researchers have reported that one of the super-eruptions from the Yellowstone caldera,  defined as the Castleford Crossing eruption, occurred about 8.1 million years ago and estimated the eruption volume to have exceeded 456 cubic miles (1,900 km3). This would equate to approximately 501,926,899,480,000 gallons of magma

Ancient super-eruptions in Yellowstone Hotspot track 'significantly larger' than expected

This is just one of 12 giant eruptions reported from the area by the Leicester team, who show that intense hotspot magmatism caused major crustal subsidence, forming the 100 km-wide Snake River Basin. The team also demonstrates that these eruptions were in fact significantly larger than previously thought and may rival those better known at Yellowstone.

Dr Knott said: “While it is well-know that Yellowstone has erupted catastrophically in recent times perhaps less widely appreciated is that these were just the latest in a protracted history of numerous catastrophic super-eruptions that have burned a track along the Snake River eastwards from Oregon to Yellowstone from 16 Ma to present.

diag_caldera_440x375

“The size and magnitude of this newly defined eruption is as large, if not larger, than better known eruptions at Yellowstone, and it is just the first in an emerging record of newly discovered super-eruptions during a period of intense magmatic activity between 8 and 12 million years ago.”

Several former University of Leicester undergraduates, including Mark Baldwin, Stuart Hatter, Liam McDonnell, Fabian Wadsworth and Luke Wooldridge, helped with the US fieldwork. They also enjoyed the opportunity of gaining experience through interacting with the international scientists, such as palaeomagnetists David Finn and Rob Coe of the University of California, Santa Cruz.

 

Ancient Super-Eruptions in Yellowstone Hotspot Track ‘Significantly Larger’ Than Expected

A number of giant super-eruptions between 8 and 12 million years ago that could be larger than the colossal eruptions known to have taken place at Yellowstone have been identified in the United States through research led by the University of Leicester.

hotspot

The international research team suggests that while the number of volcanic eruptions thought to have originated from the central Snake River Plain in Idaho, USA is less than previously believed, the 12 recorded giant eruptions were likely ‘significantly larger’ than research has previously suggested.

Dr Tom Knott, Professor Mike Branney and Dr Marc Reichow, from the University of Leicester’s Department of Geology’s Volcanology Group, conducted the research with a team of international collaborators from the University of California, Santa Cruz, USA, the University of Copenhagen, Denmark and Idaho State University, USA.

Using a multi-technique approach, including whole-rock and mineral chemistries, palaeomagnetic data, and radio-isotopic dates, the team has been able to ‘fingerprint’ individual eruption deposits and correlate these over vast regions (e.g., 1000’s km2).

In establishing widespread correlations, the team drastically reduced the number of eruptions previously thought to have originated from the central Snake River Plain by more than half.

The researchers have reported that one of the super-eruptions from the Yellowstone hotspot-track, defined as the Castleford Crossing eruption, occurred about 8.1 million years ago and estimate the eruption volume to have exceeded 1,900 km3. The single volcanic sheet covers an area over 14,000 km2 in southern Idaho, and is more than 1.3 km thick in the caldera of the super-volcano.

This is just one of 12 giant eruptions reported from the area by the Leicester team, who show that intense hotspot magmatism caused major crustal subsidence, forming the 100 km-wide Snake River Basin. The team also demonstrates that these eruptions were in fact significantly larger than previously thought and may rival those better known at Yellowstone.

Dr Knott said: “While it is well-know that Yellowstone has erupted catastrophically in recent times perhaps less widely appreciated is that these were just the latest in a protracted history of numerous catastrophic super-eruptions that have burned a track along the Snake River eastwards from Oregon to Yellowstone from 16 Ma to present.

“The size and magnitude of this newly defined eruption is as large, if not larger, than better known eruptions at Yellowstone, and it is just the first in an emerging record of newly discovered super-eruptions during a period of intense magmatic activity between 8 and 12 million years ago.”

The Principle of Ascension and Easter

During this time of year I turn my attention to themes of spirit. As many of you know my religious faith originates with Catholicism which remains at the core of my beliefs. However, I actively sought and embrace several spiritual beliefs, or perhaps better put ‘spiritual understandings’. One can ‘believe’ – but not ‘understand’. This is often referred to as “faith”. On the other hand — one can understand but not believe. This is called “choice”. So it is with choice and understanding that I formulate principles of faith in my life; and nothing grabs my attention more than the principle of Easter.

easter_sunrise

I say “principle” of Easter to broaden the message and meaning as it relates to spiritual evolution. I would suggest this ‘principle’ of ascension is not tied only to Christians or Catholics. In fact, history suggests Christianity is really the ‘new kid on the block’. Our ancestors have known of the principle of spiritual evolution for centuries. Some might say it is the foundation of our being. This is where you might hear the popular saying: “we are not human beings seeking a spiritual experience; we are spiritual beings seeking a human experience.” If this is true, then our journey is more about “remembering” rather than “finding”.

science_and_spirituality

One of my most favorite biblical writings is a time when after the most loyal of Jesus’ followers – better known as his “disciples” – would repeatedly ask Jesus for his guidance and wanting him to make every single decision for them as if they were in a never ending loop of indecision and helplessness. Then on this one day Jesus turned to his disciples and said: (paraphrase) “Stop following (mimic) me. It is not for me to be your idol of worship. I am not the one who has the only power. The power dwells within each of you. I am the way, the giver of life (renewal), in my name I make all things holy. God is my father, I am the Son, and you are my brothers and sisters.”

jesus25

I believe Jesus was wanting to instill the knowledge and principle of resurrection; the principle of “ascension”. The understanding of what we Catholics know as the “Holy Trinity”.

holy_trinity

The ‘Trinity’ is made up of the uniting of three.

1) the Father (God, Creator, Great Spirit)
2)
the Son (Jesus and all his brothers and sisters. In other words…all of us)
3) 
the Holy Spirit (some might call this the soul, or life force energy)

Some describe the ‘ascension’ process as raising our vibration to a higher frequency. This is certainly one area I step beyond the structure of the Catholic Church and venture into several more metaphysical realms. Some believe in the principle of “Christ Consciousness”. This idea would suggest the higher levels of spiritual knowingness is described as the “Christ”. Hence the term Jesus the Christ, which of course is different than Jesus Christ…or is it?

divine-self3_lg

The idea of rising into a higher state of being is an exciting premise I so well remember during Easter. Not the punishment, not the sacrifice, but the renewal and ascension back to a place of which we began.

Blessings to all, Mitch

Deadly Stars: Our Sun Could Also Be Superflare Star

Earth is often struck by solar eruptions. These eruptions consist of energetic particles that are hurled away from the Sun into space, where those directed towards Earth encounter the magnetic field around our planet. When these eruptions interact with Earth’s magnetic field they cause beautiful auroras.

sun

When the Sun pours out gigantic amounts of hot plasma during the large solar eruptions, it may have severe consequences on Earth. Solar eruptions are, however, nothing compared to the eruption we see on other stars, the so-called ‘superflares’. Superflares have been a mystery since the Kepler mission discovered them in larger numbers four years ago.

Questions arose: Are superflares formed by the same mechanism as solar flares? If so, does that mean that the Sun is also capable of producing a superflare?

An international research team led by Christoffer Karoff from Aarhus University, Denmark, has now provided answers to some of these questions. These alarming answers are published in Nature Communications.

The dangerous neighbor

The Sun is capable of producing monstrous eruptions that can break down radio communication and power supplies here on Earth. The largest observed eruption took place in September 1859, where gigantic amounts of hot plasma from our neighboring star struck Earth.

On 1 September 1859, astronomers observed how one of the dark spots on the surface of the Sun suddenly lit up and shone brilliantly over the solar surface. This phenomenon had never been observed before and nobody knew what was to come. On the morning of September 2, the first particles from, what we now know was an enormous eruption on the Sun, reached Earth.

The 1859 solar storm is also known as the “Carrington Event.” Auroras associated with this event could be seen as far south as Cuba and Hawaii, telegraph system worldwide went haywire, and ice core records from Greenland indicate that Earth’s protective ozone layer was damaged by the energetic particles from the solar storm.

The cosmos, however, contains other stars and some of these regularly experience eruptions that can be up to 10,000 times larger than the Carrington event.

Solar flares occur when large magnetic fields on the surface of the Sun collapse. When that happens, huge amounts of magnetic energy are released. Christoffer Karoff and his team have use observations of magnetic fields on the surface of almost 100,000 stars made with the new Guo Shou Jing telescope in China to show that these superflares are likely formed via the same mechanism as solar flares.

“The magnetic fields on the surface of stars with superflares are generally stronger than the magnetic fields on the surface of the Sun. This is exactly what we would expect, if superflares are formed in the same way as solar flares” explains Christoffer Karoff.

Can the Sun create a superflare?

It does therefore not seem likely that the Sun should be able to create a superflare, its magnetic field is simply to weak. However…

Out of all the stars with superflares that Christoffer Karoff and his team analyzed, around 10% had a magnetic field with a strength similar to or weaker than the Sun’s magnetic field. Therefore, even though it is not very likely, it is not impossible that the Sun could produce a superflare.

“We certainly did not expect to find superflare stars with magnetic fields as week as the magnetic fields on the Sun. This opens the possibility that the Sun could generate a superflare — a very frightening thought” elaborates Christoffer Karoff.

If an eruption of this size was to strike Earth today, it would have devastating consequences. Not just for all electronic equipment on Earth, but also for our atmosphere and thus our planet’s ability to support life.

Trees hid a secret

Evidence from geological archives has shown that the Sun might have produced a small superflare in AD 775. Here, tree rings show that anomalously large amounts of the radioactive isotope 14C were formed in Earth’s atmosphere. 14C is formed when cosmic-ray particles from our galaxy, the Milky Way, or especially energetic protons from the Sun, formed in connection with large solar eruptions, enter Earth’s atmosphere.

The studies from the Guo Shou Jing telescope support the notion that the event in AD 775 was indeed a small superflare, i.e. a solar eruption 10-100 times larger that the largest solar eruption observed during the space age.

“One of the strengths of our study is that we can show how astronomical observations of superflares agree with Earth-based studies of radioactive isotopes in tree rings.” Explains Christoffer Karoff.

In this way, the observations from the Guo Shou Jing telescope can be used to evaluate how often a star with a magnetic field similar to the Sun would experience a superflare. The new study shows that the Sun, statistically speaking, should experience a small superflare every millennium. This is in agreement with idea that the event in AD 775 and a similar event in AD 993 were indeed caused by small superflares on the Sun.

It is no coincidence that the new Guo Shou Jing telescope in China was used for this study. In order to measure the magnetic fields, Christoffer Karoff and his team used a spectrum for every star of the 100,000 stars available for this analysis. A spectrum shows the colors, or wavelengths, of the light from the stars. Here, certain short ultraviolet wavelengths can be used to measure the magnetic fields around the stars.

The problem is, however, that conventional telescopes are only capable of obtaining one spectrum of a single star at a time. Therefore, if the observations were to be made with another telescope, such as the Nordic Optical Telescope on La Palma — a telescope the research group has used before — it would require 15-20 years of continuous observations.

The Guo Shou Jing telescope, or LAMOST as it is also called, is optimized for obtaining spectra of up to 4,000 stars simultaneously, as 4,000 optical fibers are connected to the telescope. This makes it possible to observe 100,000 stars in only a few weeks and it is this special capability that has made it possible to generate the new results.

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Earth’s Moon Wandered Off Axis Billions Of Years Ago

A new study published in Nature reports discovery of a rare event — that Earth’s moon slowly moved from its original axis roughly 3 billion years ago. Ancient lunar ice indicates the moon’s axis slowly shifted by 125 miles, or 6 degrees, over 1 billion years. Earth’s moon now a member of solar system’s exclusive ‘true polar wander’ club, which includes just a handful of other planetary bodies.

earth

Planetary scientist Matt Siegler at Southern Methodist University, Dallas, and colleagues made the discovery while examining NASA data known to indicate lunar polar hydrogen. The hydrogen, detected by orbital instruments, is presumed to be in the form of ice hidden from the sun in craters surrounding the moon’s north and south poles. Exposure to direct sunlight causes ice to boil off into space, so this ice — perhaps billions of years old — is a very sensitive marker of the moon’s past orientation.

An odd offset of the ice from the moon’s current north and south poles was a tell-tale indicator to Siegler and prompted him to assemble a team of experts to take a closer look at the data from NASA’s Lunar Prospector and Lunar Reconnaissance Orbiter missions. Statistical analysis and modeling revealed the ice is offset at each pole by the same distance, but in exactly opposite directions.

This precise opposition indicates the moon’s axis — the imaginary pole that runs north to south through it’s middle, and around which the moon rotates — shifted at least six degrees, likely over the course of 1 billion years, said Siegler.

“This was such a surprising discovery. We tend to think that objects in the sky have always been the way we view them, but in this case the face that is so familiar to us — the Man on the Moon — changed,” said Siegler, who also is a scientist at the Planetary Science Institute, Tucson, Ariz.

“Billions of years ago, heating within the Moon’s interior caused the face we see to shift upward as the pole physically changed positions,” he said. “It would be as if Earth’s axis relocated from Antarctica to Australia. As the pole moved, the Man on the Moon turned his nose up at the Earth.”

The discovery is reported today in an article in the scientific journal Nature, “Lunar true polar wander inferred from polar hydrogen.” Siegler’s primary co-authors are astrophysicist Richard S. Miller, a professor at the University of Alabama Huntsville, and planetary dynamicist James T. Keane, a graduate student at the University of Arizona.

Very few planetary bodies known to permanently shift their axis

Planetary bodies settle into their axis based on their mass: A planet’s heavier spots lean it toward its equator, lighter spots toward the pole. On the rare occasion mass shifts and causes a planet to relocate on its axis, scientists refer to the phenomenon as “true polar wander.”

Discovery of lunar polar wander gains the moon entry into an extremely exclusive club. The only other planetary bodies theorized to have permanently shifted location of their axis are Earth, Mars, Saturn’s moon Enceladus and Jupiter’s moon Europa.

What sets the moon apart is its polar ice, which appears to effectively “paint out” the path along which its poles moved.

Moon’s axis likely started relocating about 3 billion years ago

On Earth, polar wander is believed to have happened due to movement of the continental plates. Polar wander on Mars resulted from a heavy volcanic region. The moon’s change in mass was internal — the shift of a large, single mantle “plume.” Ancient volcanic activity some 3.5 billion years ago melted a portion of the moon’s mantle, causing it to bubble up toward its surface, like goo drifting upward in a lava lamp.

“The moon has a single region of the crust, a large basaltic plain called Procellarum, where radioactive elements ended up as the moon was forming,” Siegler said. “This radioactive crust acted like an oven broiler heating the mantle below.”

Some of the material melted, forming the dark patches we see at night, which are ancient lava, he said.

“This giant blob of hot mantle was lighter than cold mantle elsewhere,” Siegler said. “This change in mass caused Procellarum — and the whole moon — to move.”

The moon likely relocated its axis starting about 3 billion years ago or more, slowly moving over the course of a billion years, Siegler said, etching a path in its ice.

Over time, the axis shifted 125 miles or 200 kilometers — about half the distance from Dallas to Houston, or equal the distance from Washington D.C. to Philadelphia.

Neutrons can indicate the presence of water or ice

Polar wander explains why the moon appears to have lost much of its ice.

Siegler compares true polar wander to holding a glass filled with water. Most planets are like a steady hand holding a glass, their axis doesn’t shift and the water stays put. A planet whose mass is changing is like a wobbly hand, causing its axis to shift and the water to spill out. Similarly, as Earth’s moon changed its axis, much of its ice ceased to be hidden from the sun and was lost.

Co-author Richard Miller mapped the moon’s remaining ice by using data from NASA’s Lunar Prospector mission, which orbited the moon from 1998 to 1999. The presence of ice is inferred by measuring the energy of neutrons emitted from the lunar surface. Instruments on NASA’s satellite, including a neutron spectrometer, measured neutrons liberated from the moon by a rain of stellar particles scientists call cosmic rays. Low energy neutrons indicate the presence of hydrogen, the dominant molecule in water and ice.

“The maps show four key features,” said Siegler and his colleagues. “First, the largest quantity of hydrogen is offset from the current rotation axis of the moon by roughly 5.5 degrees. Second, the hydrogen enhancements are of similar magnitude at both poles. Third, the asymmetric enhancements do not correlate with expectations from the current thermal or permanently shadowed environment. And lastly, and most significantly, the spatial distributions of polar hydrogen appear to be nearly antipodal.”

Lunar ice is ancient time capsule; may hold answers to deep mysteries

Siegler’s discovery opens the door to further discoveries around an even deeper question — the mystery of why there is water on the moon and on Earth. Scientific theory surrounding the formation of the solar system postulates water could not have formed much closer to the sun than Jupiter, Siegel said.

“We don’t know where the Earth’s water came from. It appears to have come from the outer solar system well after the Earth and moon formed,” he said. “Ice on other bodies, like the moon or Mercury, might give us a clue to its origin.”

The fact lunar ice correlates so well with true polar wander implies that it predates this motion, Siegler said, making the ice very ancient.

“The ice may be a time capsule from the same source that supplied the original water to Earth,” he said. “This is a record we don’t have on Earth. Earth has reworked itself so many times, there’s nothing that old left here. Ancient ice from the moon could provide answers to this deep mystery.”

Other co-authors on the scientific paper include Matthieu Laneuville, David A. Paige, Isamu Matsuyama, David J. Lawrence, Arlin Crotts and Michael J. Poston.