Tag: Saturn

Saturn Hasn’t Always Had Rings

Precise measurements of Cassini’s final trajectory have now allowed scientists to make the first accurate estimate of the amount of material in the planet’s rings, weighing them based on the strength of their gravitational pull.

That estimate about 40 percent of the mass of Saturn’s moon Mimas, which itself is 2,000 times smaller than Earth’s moon tells them that the rings are relatively recent, having originated less than 100 million years ago and perhaps as recently as 10 million years ago.

Their young age puts to rest a long-running argument among planetary scientists.

Some thought that the rings formed along with the planet 4.5 billion years ago from icy debris remaining in orbit after the formation of the solar system.

Others thought the rings were very young and that Saturn had, at some point, captured an object from the Kuiper belt or a comet and gradually reduced it to orbiting rubble.

The new mass estimate is based on a measurement of how much the flight path of Cassini was deflected by the gravity of the rings when the spacecraft flew between the planet and the rings on its final set of orbits in September 2017.




Initially, however, the deflection did not match predictions based on models of the planet and rings.

Only when the team accounted for very deep flowing winds in atmosphere on Saturn, something impossible to observe from space, did the measurements make sense, allowing them to calculate the mass of the rings.

They also calculated that the surface clouds at Saturn’s equator rotate 4 percent faster than the layer 9,000 kilometers (about 6,000 miles) deep.

That deeper layer takes 9 minutes longer to rotate than do the cloud tops at the equator, which go around the planet once every 10 hours, 33 minutes.

Militzer also was able to calculate that the rocky core of the planet must be between 15 and 18 times the mass of Earth, which is similar to earlier estimates.

The team, led by Luciano Iess at the Sapienza University of Rome, Italy, reported their results today in the journal Science.

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Saturn’s Northern Pole Is Home To A Six-Sided Feature That Mystifies Scientists

This stunning new image reveals the massive hexagonal storm at Saturn’s North Pole, and its gigantic rings. Each latitudinal band represents air flowing at different speeds, and clouds at different heights, compared to neighboring bands.

At first glance, it looks like a serene planet.

However, stunning new images reveals the massive hexagonal storm at Saturn’s North Pole, and its gigantic rings.

In reality, the planet’s atmosphere is an ever-changing scene of high-speed winds and evolving weather patterns, punctuated by occasional large storms, Nasa says.

The latest image shows Saturn’s north polar region’s bands and swirls, which Nasa says somewhat resemble the brushwork in a watercolor painting.

Each latitudinal band represents air flowing at different speeds, and clouds at different heights, compared to neighboring bands.

Where they meet and flow past each other, the bands’ interactions produce many eddies and swirls.

The northern polar region of Saturn is dominated by the famous hexagon shape which itself circumscribes the northern polar vortex – seen as a dark spot at the planet’s pole in the above image – which is understood to the be eye of a hurricane-like storm.




Such collisions play a key role in the rings’ numerous waves and wakes, which are the manifestation of the subtle influence of Saturn’s moons and, indeed, the planet itself.

The long duration of the Cassini mission has allowed scientists to study how the atmosphere and rings of Saturn change over time, providing much-needed insights into this active planetary system.

It has long baffled astronomers, and now the strange hexagon at Saturn’s north pole has a new mystery.

The mysterious six-sided hexagon on Saturn’s North Pole has long captivated astronomer, and is thought to be nearly 20,000 miles (32,190 km) wide.

The hexagon is made of a band of upper-atmospheric winds which creates its shape.

A polar cyclone can be seen at its centre.

Recent natural colour images from NASA’s Cassini spacecraft show the changing appearance of Saturn’s north polar region between 2012 and 2016.

It shows a clear change from blue to gold – and nobody knows why.

The stunning image reveals the massive hexagonal storm at Saturn’s North Pole, and its gigantic rings. The rings, consist of countless icy particles, which are continually colliding.

Scientists are investigating potential causes for the change in color of the region inside the north-polar hexagon on Saturn.

The colour change is thought to be an effect of Saturn’s seasons.

In particular, the change from a bluish color to a more golden hue may be due to the increased production of photochemical hazes in the atmosphere as the north pole approaches summer solstice in May 2017,” Nasa said.

Researchers think the hexagon, which is a six-sided jetstream, might act as a barrier that prevents haze particles produced outside it from entering.

During the seven-year-long Saturnian winter, the polar atmosphere became clear of aerosols produced by photochemical reactions – reactions involving sunlight and the atmosphere.

This helps to explain why the hexagon is not influenced by seasonal changes, said the researchers.

It is hoped that by studying the movement of the hexagon it may be possible to understand more about the winds that are hidden beneath the stormy clouds in the gas giant’s upper atmosphere.

Speaking to Space.com, Professor Morales-Juberías said: “With a very simple model, we have been able to match many of the observed properties of the hexagon.

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Voyager Spacecraft Sail On, 41 Years After Launch

Science is primary object of Voyager mission. A science boom deploys in one direction, a magnetometer boom in another; 12-foot parabolic antenna rests on 10-sided basic bus. Nuclear generator will provide power.

Nearly 41 years after lifting off, NASA’s historic Voyager mission is still exploring the cosmos.

The twin spacecraft launched several weeks apart in 1977 — Voyager 2 last Aug. 20 and Voyager 1 last Sept. 5 — with an initial goal to explore the outer solar system.

Voyager 1 flew by Jupiter and Saturn, while its twin took advantage of an unusual planetary alignment to visit Jupiter, Saturn, Uranus and Neptune.

And then the spacecraft kept on flying, for billions and billions of miles. Both remain active today, beaming data home from previously unexplored realms.

Indeed, in August 2012, Voyager 1 became the first human-made object ever to reach interstellar space.

The mission’s legacy reached into film, art and music with the inclusion of a “Golden Record” of Earth messages, sounds and pictures designed to give any prospective alien who encountered it an idea of what humanity and our home planet are like.

This time capsule is expected to last billions of years.

The spacecraft are now flying through space far away from any planet or star; their next close encounter with a cosmic object isn’t expected to occur for 40,000 years.




Their observations, however, are giving scientists more insight into where the sun’s influence diminishes in our solar system, and where interstellar space begins.

Voyager 1 is nearly 13 billion miles (21 billion kilometers) from Earth and has spent five years in interstellar space.

This zone is not completely empty; it contains material left over from stars that exploded as supernovas millions of years ago.

The “interstellar medium” (as the space in this region is called) is not a threat to Voyager 1. Rather, it’s an interesting environment that the spacecraft is studying.

Voyager 2 is nearly 11 billion miles (18 billion km) from Earth and will likely enter interstellar space in a few years, NASA officials have said.

Uranus’ icy moon Miranda is seen in this image captured by Voyager 2 on Jan. 24, 1986.

Its observations from the edge of the solar system help scientists make comparisons between interstellar space and the heliosphere.

When Voyager 2 crosses the boundary, the two spacecraft can sample the interstellar medium from two different locations at the same time.

Mission designers made the spacecraft robust to make sure they could survive the harsh radiation environment at Jupiter.

This included so-called redundant systems — meaning the spacecraft can switch to backup systems if needed — and power supplies that have lasted well beyond the spacecraft’s primary mission.

Each of the spacecraft is powered by three radioisotope thermoelectric generators, which convert the heat produced by the radioactive decay of plutonium-238 into electricity.

An artist’s rendering of a Voyager spacecraft flying past Jupiter, Saturn, and their respective moons

The power available to each Voyager, however, decreases by about 4 watts per year.

This requires engineers to dig into 1970s documentation (or to speak with former Voyager personnel) to operate the spacecraft as its power diminishes.

Even with an eye to efficiency, the last science instrument will have to be shut off around 2030, mission team members have said.

But even after that, the Voyagers will continue their journey (albeit without gathering data), flying at more than 30,000 mph (48,280 km/h) and orbiting the Milky Way every 225 million years.

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Mars Is Spectacular This Month – Here’s The Best Way To Spy The Red Planet

If you look at the sky tonight and spot a very bright star, it may well be a planet. Mars is the closest it has been to Earth for 15 years – and therefore the brightest.

Mars shines through reflected light,” says Robert Massey, the deputy executive director of the Royal Astronomical Society.

That means that when it’s closer to the Earth it appears brighter, because its apparent size is bigger.” It won’t be this visible again until 2035.

So, how best to see it? First, make sure tall trees or buildings are not obscuring the view. Ideally, you want a clear horizon. Then, look south.




It will be obvious, because it’s bright, it doesn’t twinkle and it has a distinct reddish tinge,” says Massey, who suggests Somerset, Devon and Dorset as good locations for spotting it.

The best Mars-gazing time is 1am, but it rises earlier in the evening.

You can see Mars with the naked eye, but a pair of binoculars would help,” says Massey. “If you have a small telescope, you may be lucky to see a polar ice cap.

If you are an amateur with good equipment, the details to look out for are two polar ice caps, mountains or volcanoes, and sunken, crater-like features. Massey suggests contacting your local astronomical society about public viewing events.

Hubble’s views of Mars at two recent oppositions

When is the best time to see Mars?

According to NASA, Mars Opposition begins Friday, July 27 around midnight.

Mars will be visible between Friday, July 27 and Monday, July 30, making its closest approach — 35.8 million miles to be exact — on Tuesday, July 31 at around 4 a.m. E.T.

Mars will be at its brightest Friday night due to an opposition surge that is affected by the planet’s angle of the sun — giving you the clearest view of the Red Planet.

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Saturn Found To Have Noontime Auroras

An international team of researchers has found that Saturn’s fast rotation speed makes it possible for the planet to experience noontime auroras.

In their paper published in the journal Nature Astronomy, the group describes the factors that lead to creation of auroras and how Saturn’s appear to arise.

Auroras on Earth occur when magnetic reconnections (magnetic fields colliding) cause solar flares on the sun. When it happens, plasma carrying a magnetic field is shot out into space, some of which makes its way to Earth.

When it collides with our planet’s magnetic field, auroras occur. The same process has been observed on Venus, Mars, Jupiter, Saturn and Uranus.

In this new effort, the researchers were studying data sent back from the Cassini spacecraft, which orbited Saturn for 13 years.




They were looking specifically at data that would provide more information regarding magnetic reconnections on the planet—prior research had shown that they occur on the dayside of the magnetopause (the point where the planet’s magnetic field meets the solar wind).

There was also evidence that they occur on the nightside of its magnetodisk, which is a plasma ring formed near the equator by water and other materials emitted from its moons.

But prior research had also suggested that there would be no reconnections on the dayside of the planet’s magnetodisk because the solar winds made the to too thick for them to occur.

But the researchers found evidence of reconnections in the magnetodisk at noontime anyway. The researchers suggest this apparent anomaly is likely due to Saturn’s high spin rate (a day is just 10 hours).

The high rate, they note, likely compresses the magnetodisk, making it thin enough for reconnections to occur. The team also suggests that the reconnections they measured appear to be strong enough to create auroras.

The researchers suggest that their findings indicate that unknown auroras might be happening on other planets as well, but have been overlooked because planet spin speed was not factored into calculations.

They further suggest that similar reconnections might also be behind some unexplained pulses seen from Jupiter.

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Saturn’s Moon Wears The Weirdest Mountain Range In The Solar System

photo by Cassini Imaging Team/SSI/NASA/JPL/ESA

SallOf all the moons in the solar system, Iapetus has to be among the weirdest. Named after a spear-wielding Titan, the strange Saturnian satellite is less than half the size of Earth’s moon.

But it’s a cluster of enigmas: Squished at its poles, the moon is walnut-shaped, has a face as black as coal and a bright white backside, and wears a big, spiky mountain range as a belt.

Even its orbit is weird: Iapetus is roughly three times farther from Saturn than its closest neighbor, Titan.

And the path it takes around the planet is tilted, meaning it swings up and down as it orbits, rather than staying in the plane of Saturn’s rings like the rest of the “normal” satellites.

In other words, it’s kind of like the rebel of the Saturnian system, a moon who’d prefer to hang out behind the dumpster and cut class rather than play ball with the other kids.




Among the strangest of Iapetus’ unsolved mysteries is its super-chic, spiky mountain range.

Running straight as an arrow along three-quarters of the moon’s equator, the thing is huge: Roughly 20 kilometers tall and up to 200 kilometers wide.

There’s nothing else like it in the solar system.

Scientists first spotted the ridge in 2004, and since then, they’ve been trying to figure out how such a thing formed.

Early theories suggested geologic activity within the moon itself – maybe something akin to Earth’s plate tectonics or volcanism had forced the ridge to rise up along the equator.

But that didn’t make a lot of sense. The moon’s crust wasn’t spongy when the ridge formed, the evidence for active geology tepid.

Then, scientists thought maybe the ridge had formed as a result of the moon’s rotation period abruptly slowing down. Some early simulations suggest a day on the moon used to last for a mere 16 hours.

Now, though, a day on Iapetus lasts 79 Earth-days – the same amount of time it takes the little guy to shuffle once around Saturn.

photo by Cassini Imaging Team/SSI/NASA/JPL/ESA

Maybe, teams said, a giant impact had knocked Iapetus into its current rotation state, and the resulting braking action caused the crust to buckle.

But most of these theories also predict other strange geologic features (which aren’t observed), or hinge upon the crust being a certain thickness.

As the moonlet broke up, Dombard said, its pieces formed an ephemeral ring around Iapetus’ equator. The ring eventually rained down upon the satellite and deposited the giant ridge.

In 2011, another team suggested something similar, this time with a giant impact forming both a ring and a moonlet.

The ring would go on to form the mountain range, while the moonlet would smash into Iapetus and create one of its many large impact basins.

Recent evidence, gleaned from the shape of the mountain ridge itself (steep and triangular), suggests that pieces falling from on high could make total sense.

It’s kind of the same shape you get when you take a handful of sand and slowly sprinkle it into a pile. Why the ridge only runs along three-quarters of the equator isn’t explained by this scenario, though.

In short, we still don’t know how Iapetus grew its monstrous mountains. But the idea of a moon with a moon, or a moon with a ring, is strangely compelling. Too bad Iapetus had to go and tear its little friend to bits.

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NASA To Send Probe To Titan Or A Comet By 2025

NASA has picked two concepts for a solar system mission planned to launch in the mid-2020s — a comet sample return mission and a drone-like rotor-craft that would explore potential landing sites on Saturn’s largest moon, Titan.

Which of these two mission will finally make it will be known only in 2019.

Both missions will receive funding through the end of 2018 to further develop and mature their concepts.

NASA plans to select one of these investigations in the spring of 2019 to continue on to subsequent mission phases,” the US space agency said on Wednesday.

These are tantalising investigations that seek to answer some of the biggest questions in our solar system today,” said Thomas Zurbuchen, Associate Administrator for NASA’s Science Mission Directorate in Washington.




The Comet Astrobiology Exploration Sample Return (CAESAR) mission seeks to return a sample from 67P/Churyumov-Gerasimenko, a comet that was successfully explored by the European Space Agency’s Rosetta spacecraft, to determine its origin and history.

The other selected mission, Dragonfly, is a drone-like rotorcraft that would explore the prebiotic chemistry and habitability of dozens of sites on Saturn’s moon Titan, an ocean world in our solar system.

NASA announced the concepts following an extensive and competitive peer review process.

The concepts were chosen from 12 proposals submitted in April under a New Frontiers programme announcement of opportunity.

The selected mission will be the fourth in NASA’s New Frontiers portfolio, a series of principal investigator-led planetary science investigations that fall under a development cost cap of approximately $850 million, NASA said.

Its predecessors are the New Horizons mission to Pluto and a Kuiper Belt object known as 2014 MU69, the Juno mission to Jupiter, and OSIRIS-REx, which will rendezvous with and return a sample of the asteroid Bennu.

NASA also announced the selection of two mission concepts that will receive technology development funds to prepare them for future mission competitions.

The concepts selected for technology development are – Enceladus Life Signatures and Habitability (ELSAH) and Venus In situ Composition Investigations (VICI)

The ELSAH mission concept will receive funds to develop cost-effective techniques that limit spacecraft contamination and thereby enable life detection measurements on cost-capped missions.

The VICI mission concept will further develop the Venus Element and Mineralogy Camera to operate under the harsh conditions on Venus.

The instrument uses lasers on a lander to measure the mineralogy and elemental composition of rocks on the surface of Venus.

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These Weird Red Arcs On Saturn’s Moon Tethys Can’t Be Explained

An icy moon of Saturn has mysterious red arcs of material crisscrossing its surface — and no one knows exactly how they got there.

The Cassini spacecraft caught these graffiti-like features on camera as it imaged the northern side of the Tethys, which is one of Saturn’s larger moons.

While the arcs faintly show up in 2004 pictures, the latest images, from April, are the first to really show their colors by incorporating the right viewing conditions and wavelengths invisible to the human eye.

This is partly because Saturn and its moons’ northern hemispheres are currently in summer, providing better illumination of this region.

The features were a surprise to scientists because red tints are rare in the solar system.




Until now, astronomers have spotted a few small, reddish craters on Saturn’s icy moon Dione, and identified many rouge zones on the icy surface of Jupiter’s Europa.

Scientists don’t exactly know how these features occurred. Perhaps they are ice with chemical impurities, leftovers from gas released from the moon or artifacts from features that were smaller than the resolution of the image.

The red arcs must be geologically young, because they cut across older features like impact craters, but we don’t know their age in years.” Paul Helfenstein, a Cassini imaging scientist at Cornell University who helped plan the observations, said in a statement.

If the stain is only a thin, colored veneer on the icy soil, exposure to the space environment at Tethys’ surface might erase them on relatively short time scales.

Icy moons lke Tethys are considered a key area of interest in our solar system because they could host microbial life if enough chemical energy and warmth is available in the oceans below the ice.

In recent years, plumes of gas have been repeatedly observed at Enceladus, another of Saturn’s moons, and in 2013 the Hubble Space Telescope spotted a single, large-plume event at Europa.

Cassini will do follow-up observations of Tethys at a higher resolution later this year. The mission is in the final two years of work before the spacecraft runs low on fuel in September 2017.

When that happens, it will plunge into Saturn’s atmosphere to protect the icy moons from possible contamination.

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Back to Saturn? Five Missions Proposed To Follow Cassini

For 13 years, NASA’s Cassini spacecraft sent back captivating observations of Saturn, and its rings and moons, solving some mysteries but raising plenty of new questions.

With the spacecraft’s demise on Friday, the stream of data from Saturn has dried up.

Until we go back, that’s a very distant world now,” Linda Spilker, the project scientist for Cassini, said during a news conference on Friday.

The details of the rings, and those small moons snuggled in so close — those are all gone until we go back.

NASA currently has no plans to return to Saturn, but that could change. In the latest round in a scientific competition called New Frontiers, NASA specified categories of missions it would consider.

Those include a probe to study Saturn’s atmosphere or a mission to go to Titan or Enceladus, two moons known to have oceans.

The New Frontiers program solicits ideas for missions from teams of scientists and engineers. These projects can be ambitious, costing up to about $1 billion.

Earlier proposals included Juno, now orbiting Jupiter, and Osiris-Rex, currently en route to the asteroid Bennu.

NASA may announce finalists by the end of the year. A winning mission is to be selected by summer 2019 for launch around 2025.

At least five submitted proposals take aim at Saturn, Titan or Enceladus.




Titan

As a spacecraft, Dragonfly would be an oddity: It would have propellers, like a helicopter — “a nuclear quadcopter to look for life on Saturn’s moon, Titan,” Peter Bedini, a program manager at Johns Hopkins Applied Physics Laboratory, said in a recent talk.

Proponents of this concept say a quadcopter would be an ideal way to explore Titan, Saturn’s largest moon. The air is thick there, thicker than on Earth.

The landscape is varied, interspersed with obstacles — rivers, lakes and seas of liquid methane — that could prove inaccessible for a rover.

The booming popularity of flying drones in recent years makes the technology potentially feasible for interplanetary exploration, too.

In the past, scientists have suggested exploring the moon with balloons and airplanes. But Titan’s geology — sand dunes, eroded gullies — is more interesting than what is in the air.

Dragonfly would fly from place to place, but would spend most of its time performing experiments on the ground.

A second Titan proposal, Oceanus, is led by Christophe Sotin, the chief scientist for solar system exploration at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., which was Cassini’s home base.

The Oceanus spacecraft would study the moon from orbit, potentially identifying habitable regions for life.

Enceladus

Jonathan I. Lunine, a planetary scientist at Cornell University, was a member of the science team managing the Huygens probe, which traveled to Saturn with Cassini and landed on Titan.

He would be the principal investigator on a proposed mission to revisit Enceladus, a small moon just 313 miles wide.

The discovery of geysers shooting from its south pole was a stunning surprise, and now the moon is considered a prime place for look for life.

The proposed spacecraft, called Enceladus Life Finder, would fly through the plumes like Cassini did but with more sophisticated instruments capable of identifying a wide variety of molecules including amino acids, which would hint at signs of life.

Saturn

The Saturn Probe Interior and Atmosphere Explorer would essentially do what Cassini did on Friday: descend into the planet’s atmosphere. But it would go much deeper.

The main part of the mission would end quickly — in about 90 minutes, as the probe parachuted into the atmosphere. It would take measurements of certain elements like helium that are hard to measure.

The ratio of helium to hydrogen is a crucial measure indicating how far from the sun a planet formed in the early days of the solar system.

Cassini attempted to measure that in its final plunge, but that data, from high in the atmosphere, will not be conclusive.

NASA’s Galileo spacecraft dropped an atmospheric probe into Jupiter in 1995, and this proposal is the “same exact idea as the Galileo probe,” said Amy Simon, an expert on planetary atmospheres at NASA Goddard Space Flight Center in Greenbelt, Md.

She would be the principal investigator for the mission.

To understand how the solar system formed, it’s crucial to understand its biggest fixtures. Saturn, of course, is the second largest planet, after Jupiter.

The two of them together tell you a lot of what happened in the early solar system,” Dr. Simon said. “It will answer those few fundamental questions that we could not do with Cassini.

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A Group Of 7 Moons Keep Saturn’s Rings From Breaking Apart

While the Cassini spacecraft is dead – engineers deliberately plunged it into Saturn’s atmosphere on September 15, ending its 13-year mission around the planet – analyzing the reams of data from the mission will take decades, NASA said in a statement, as new insights were released this week from the spacecraft’s final days.

The orbital resonances of nearby moon’s create the vinyl record-like grooves in Saturn’s A ring.

NASA explained: “In order to avoid the unlikely possibility of Cassini someday colliding with one of these moons, NASA has chosen to safely dispose of the spacecraft in the atmosphere of Saturn“.

The entirety of the main rings can be seen here, but due to the low viewing angle, the rings appear extremely foreshortened“, says NASA.

Ring scientists had thought the small moon Janus was responsible for confining the outer edge of the A ring.

Together they are strong. Scientists said if the magnetic field tilt is greater than 0.016 degrees, they should be able to “nail down the true length of the planet’s day.”




There are hundreds of density waves spread over the A ring that are generated by different moon resonances.

These resonance markers enabled scientists to deduce that the moons gravitational influence help to slow and reduce the spreading ring’s momentum.

Mima’s gravitational nudges keep the ring trimmed by pushing any wayward particles back inside.

When you enlarge the image, you can get lost in the geometric intricacies of the rings, which are made up of rock and ice. “That’s the novelty of this idea“.

Commenting on their findings, Tajeddine said nobody imagined that the rings were held by a shared responsibility.

The panorama makes it feel like the rings go on forever, though NASA says they actually stretch out over a distance of around 175,000 miles.

The team, which included Cassini participating scientist Mark Perry from the Johns Hopkins University Applied Physics Laboratory, not only discovered water raining down from the rings, but also methane, which was a surprise, since the team expected the gas was too volatile to survive within Saturn’s rings or its atmosphere.

Janus has been getting all of the credit for stopping the A ring, which has been unfair to the other moons“.

The team unveiled their new discoveries at the latest American Astronomical Society Division for Planetary Science.

In addition to Burns and Tajeddine, the paper’s co-authors are Philip D. Nicholson, professor of astronomy; Maryame El Moutamid, research associate; and Pierre-Yves Longaretti of the Institut de Planétologie et d’Astrophysique de Grenoble, France.

Linda Splicer, one of the mission’s project scientists, said: “There are whole careers to be forged in the analysis of data from Cassini“.

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