Saturn’s rings, younger than dinosaurs?


This March 2016 video says about itself:

Saturn’s Moons and Rings May Be Younger Than the Dinosaurs

Some of Saturn‘s icy moons may have been formed after many dinosaurs roamed the Earth. New computer modeling of the Saturnian system suggests the rings and moons may be no more than 100 million years old.

Saturn hosts 62 known moons. All of them are influenced not only by the gravity of the planet, but also by each other’s gravities. A new computer model suggests that the Saturnian moons Tethys, Dione and Rhea haven’t seen the kinds of changes in their orbital tilts that are typical for moons that have lived in the system and interacted with other moons over long periods of time. In other words, these appear to be very young moons.

“Moons are always changing their orbits. That’s inevitable,” Matija Cuk, principal investigator at the SETI Institute and one of the authors of the new research, said in a statement. “But that fact allows us to use computer simulations to tease out the history of Saturn’s inner moons. Doing so, we find that they were most likely born during the most recent 2 percent of the planet’s history.”

The age of Saturn’s rings has come under considerable debate since their discovery in the 1600s. In 2012, however, French astronomers suggested that some of the inner moons and the planet’s well-known rings may have recent origins. The researchers showed that tidal effects — which refer to “the gravitational interaction of the inner moons with fluids deep in Saturn’s interior,” according to the statement — should cause the moons to move to larger orbits in a very short time.

“Saturn has dozens of moons that are slowly increasing their orbital size due to tidal effects. In addition, pairs of moons may occasionally move into orbital resonances. This occurs when one moon’s orbital period becomes a simple fraction of another. For example, one moon could orbit twice as fast as another moon, or three times as fast. Once an orbital resonance takes place, the moons can affect each other’s gravity, even if they are very small. This will eventually elongate their orbits and tilt them from their original orbital plane. By looking at computer models that predict how extended a moon’s orbit should become over time, and comparing that with the actual position of the moon today, the researchers found that the orbits of Tethys, Dione and Rhea are “less dramatically altered than previously thought,” the statement said.

The moons don’t appear to have moved very far from where they were born. To get a more specific value for the ages of these moons, Cuk used ice geysers on Saturn’s moon Enceladus. The researchers assumed that the energy powering those geysers comes from tidal interactions with Saturn and that the level of geothermal activity on Enceladus has been constant, and from there, inferred the strength of the tidal forces from Saturn.

Using the computer simulations, the researchers concluded that Enceladus would have moved from its original orbital position to its current one in just 100 million years — meaning it likely formed during the Cretaceous period. The larger implication is that the inner moons of Saturn and its gorgeous rings are all relatively young. (The more distant moons Titan and Iapetus would not have been formed at the same time.)

“So the question arises — what caused the recent birth of the inner moons?” Cuk said in the statement. “Our best guess is that Saturn had a similar collection of moons before, but their orbits were disturbed by a special kind of orbital resonance involving Saturn’s motion around the sun. Eventually, the orbits of neighboring moons crossed, and these objects collided. From this rubble, the present set of moons and rings formed.” The research is being published in the Astrophysical Journal.

From Space.com:

Saturn’s Rings May Be Younger Than the Dinosaurs

By Charles Q. Choi, Space.com Contributor | January 17, 2019 02:01pm ET

Saturn has not always had rings — the planet’s haloes may date only to the age of dinosaurs, or after it, a new study finds.

The age of Saturn’s rings has long proven controversial. Some researchers had thought the iconic features formed along with the planet about 4.5 billion years ago from the icy rubble left in orbit around it after the formation of the solar system. Others suggested the rings are very young, perhaps originating after Saturn’s gravitational pull tore apart a comet or an icy moon.

One way to solve this mystery is to weigh Saturn’s rings. The rings were initially made of bright ice, but over time have become contaminated and darkened by debris from the outer reaches of the solar system. A few years back, NASA’s Saturn-orbiting Cassini mission determined that the rings are only about 1 percent impure. If scientists could weigh Saturn‘s rings, they could estimate the amount of time it would take for them to accumulate enough contaminants to get 1 percent impure and thus calculate their age, lead study author Luciano Iess, a planetary scientist at the Sapienza University of Rome, told Space.com. [Saturn’s Glorious Rings in Pictures]

Iess and his colleagues relied on more Cassini data. Before the spacecraft plunged to its death into Saturn’s atmosphere in September 2017, it coasted between the planet and its rings and let their gravitational pulls tug it around. The strength of a body’s gravity depends on its mass, and by analyzing how much Cassini was pulled one way or the other during the “grand finale” phase of its mission, the mission team could measure the gravity and mass of both Saturn and its rings.

During six of Cassini’s crossings between Saturn and its rings at altitudes about 1,615 miles to 2,425 miles (2,600 to 3,900 kilometers) above the planet’s clouds, scientists monitored the radio link between the spacecraft and Earth. Much as how an ambulance siren sounds higher pitched as the vehicle drives toward you and lower pitched as it moves away, the radio signals would lengthen in wavelength as their source moved away Earth and shorten as their source moved toward it — an effect called the Doppler shift.

“I’m astonished by the fact that we were able to measure the velocity of a distant spacecraft 1.3 billion kilometers [807 million miles] away from Earth with an accuracy that is a hundredth or a thousandth the speed of a snail — a few hundreds of millimeters per second,” Iess said.

Previous estimates based on data from the Voyager flybys of Saturn suggested the rings’ mass was about 28 million billion metric tons. The new data from Cassini now suggests the rings’ mass is only about 15.4 million billion metric tons. (The largest asteroid, Ceres, has a mass of about 939 million billion metric tons.)

All in all, the researchers suggest the rings formed between 10 million to 100 million years ago. In comparison, the age of dinosaurs ended about 66 million years ago.

Cassini’s grand finale also revealed key details about the internal structure of Saturn. For example, it found that jet streams seen around Saturn’s equator — the strongest measured in the solar system, with winds of up to 930 mph (1,500 km/h) — extend to a depth of at least 5,600 miles (9,000 km), rotating a colossal amount of mass around the planet about 4 percent faster than the layer below it.

“The discovery of deeply rotating layers is a surprising revelation about the internal structure of the planet,” Cassini project scientist Linda Spilker at NASA’s Jet Propulsion Laboratory in Pasadena, California, who did not participate in the study, said in a statement. “The question is, What causes the more rapidly rotating part of the atmosphere to go so deep, and what does that tell us about Saturn’s interior?”

The new findings also suggest that Saturn’s rocky core is about 15 to 18 times the mass of Earth, similar to prior estimates.

The scientists detailed their findings online Jan. 17 in the journal Science.

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Cassini spacecraft’s suicide on Saturn


This video says about itself:

Cassini‘s Fatal Crash | Mission Saturn

13 September 2017

A three billion dollar spacecraft is hurtling towards destruction– but it’s no accident.

NASA’s biggest spacecraft plunges into Saturn in the final act of a 20-year mission showcasing the planet like never before.

IT’S BEEN A GOOD RUN “NASA’s Cassini spacecraft will end its groundbreaking 13-year mission to Saturn on Friday with a meteor-like plunge into the ringed planet’s atmosphere, transmitting data until the final fiery moment.” [Reuters]

These are Cassini’s parting shots of the Saturn system: here.

R.I.P. Cassini. After 20 years, nearly 300 orbits and pioneering discoveries, the spacecraft plunges to its death in Saturn’s atmosphere. By Lisa Grossman, 9:08am, September 15, 2017.

NASA REVEALS ODD SATURN PLASMA WAVES NASA said its Cassini spacecraft, which plunged into Saturn last year, picked up a series of plasma waves heading from the planet to its rings and into Enceladus, one of its moons. The agency described it as resembling an electrical circuit, with energy flowing back and forth. [HuffPost]

Saturn’s moons research


This video says about itself:

Exploring Saturn’s Moons | Mission Saturn

13 September 2017

On a flyby of Saturn‘s moon Enceladus, the Cassini spacecraft makes an unprecedented discovery that will push the mission to fly closer.

About Mission Saturn: NASA’s biggest spacecraft plunges into Saturn in the final act of a 20-year mission showcasing the planet like never before.

Final flyby puts Cassini on a collision course with Saturn, by Lisa Grossman. 4:00pm, September 11, 2017.

So long, Titan. Cassini snaps parting pics of Saturn’s largest moon, by Lisa Grossman, 4:05pm, September 13, 2017.

Spacecraft Cassini’s Saturn dive video


This video from the USA says about itself:

NASA: Cassini‘s First Fantastic Dive Past Saturn

3 May 2017

As NASA’s Cassini spacecraft made its first-ever dive through the gap between Saturn and its rings on April 26, 2017, one of its imaging cameras took a series of rapid-fire images that were used to make this movie sequence. The video begins with a view of the vortex at Saturn’s north pole, then heads past the outer boundary of the planet’s hexagon-shaped jet stream and continues further southward.

A detailed caption describing these video clips, and the unedited clips themselves, are available here. For more information about Cassini‘s Grand Finale, visit here.

The first Cassini to explore Saturn was a person. Space probe preparing to crash into ringed planet was named for an astronomical pioneer, by Tom Siegfried, 7:00am, May 15, 2017: here.

50 years ago, an Earth-based telescope spotted Saturn’s fourth ring: here.

As Cassini’s tour of Saturn draws to a close, a look back at postcards from the probe. NASA’s veteran spacecraft has revealed a lot about Saturn in its more than 20 years in space. By Lisa Grossman, 3:45pm, August 23, 2017: here.

Planet Saturn, spectacular Cassini spacecraft photos


This video says about itself:

Closest Saturn Pics Yet Snapped During Daring Cassini Dive

27 April 2017

NASA’s Cassini spacecraft’s ’Grand Finale’ has begun with the first of 22 planned dives between Saturn‘s innermost rings and the planet itself. The probe came within about 1900 miles (3000 km) of the planet’s cloudtops and captured some amazing images.

Read more here.

From Science News:

Cassini’s ring dive offers first close-up of Saturn’s cloud tops

Spacecraft images reveal stunning views of planet’s hurricane and more

By Ashley Yeager

5:49pm, April 27, 2017

Cassini has beamed back stunning images from the spacecraft’s daring dive between Saturn and its rings.

The first closeup pictures of the planet’s atmosphere reveal peculiar threadlike clouds and puffy cumulus ones, plus the giant hurricane first spotted on Saturn in 2008 (SN: 11/8/08, p. 9). Released April 27, the images of Saturn’s cloud tops are a “big step forward” for understanding the planet’s atmosphere, says Cassini imaging team member Andy Ingersoll, an atmospheric scientist at Caltech.

“I was pretty struck by the prevalence of the filamentary type of clouds,” he says. “It’s as if the long threads of clouds refuse to mix with each other.” Studying the interactions of these clouds and the cumulus ones will reveal what’s going on in Saturn’s skies.

During its dive, Cassini swooped to within 3,000 kilometers of the planet’s atmosphere and 300 kilometers of the innermost edge of the rings at 124,000 kilometers per hour. Slamming into even tiny particles from the rings could have damaged the spacecraft. To protect Cassini, mission scientists used the spacecraft’s 4-meter-wide antenna as a shield, putting the spacecraft temporarily out of contact with NASA.

Cassini reestablished contact with mission control early on April 27 and started to send back data minutes later. Shots of the rings and other features will be available in the coming days, and more stunning views are expected when the spacecraft shoots through the gap between Saturn and its rings again on May 2. It will ultimately orbit 20 more times before plunging into the planet’s atmosphere on September 15 (SN Online: 4/21/17).

Cassini gallery of raw Saturn images: here.

Cassini spacecraft’s final planet Saturn research


This video from the USA says about itself:

Cassini‘s final orbits around Saturn | Science News

21 April 2017

In Cassini‘s last act, the spacecraft will whiz 22 times between Saturn and its rings. This animation illustrates the spacecraft’s final orbits. Read more here.

‘Saturn moon Mimas has no ocean’


This video says about itself:

23 October 2014

SciShow Space News takes you to the solar system’s own Death StarSaturn’s moon Mimas, where something mysterious is going on. Plus, we share a stunning new photo from the Hubble Space Telescope that holds a few surprises!

Hosted by: Caitlin Hofmeister.

From Science News:

Saturn’s ‘Death Star’ moon may not conceal an ocean after all

by Thomas Sumner

2:07pm, February 28, 2017

An ocean of liquid water probably doesn’t lurk beneath the icy surface of Mimas, Saturn’s smallest major moon, new calculations suggest. Scientists had proposed the ocean in 2014 to help explain an odd wobble in the moon’s orbit.

Other ocean-harboring moons, such as Jupiter’s Europa and Saturn’s Enceladus, are crisscrossed by fractures opened by strong tides that cause their oceans to bulge outward. Mimas, though freckled with craters, lacks any such cracks.

Planetary scientist Alyssa Rhoden of Arizona State University in Tempe and colleagues calculated whether Mimas’ icy shell could withstand the stress of a subsurface ocean pushing outward. Taking into account the moon’s elongated orbit, the researchers estimate that a subsurface ocean would produce tidal stresses larger than those on crack-riddled Europa. Mimas therefore probably doesn’t have an ocean, the researchers conclude February 24 in the Journal of Geophysical Research: Planets.

In new Cassini portraits, Saturn’s moon Pan looks like pasta, by Helen Thompson, 5:30pm, March 10, 2017: here.

Satellite smashups could have given birth to Saturn’s odd moons. Weird moons orbiting the ringed planet might have been forged from head-on collisions. By Christopher Crockett, 11:00am, May 21, 2018.