Cassini spacecraft’s final planet Saturn research


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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’


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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.

Cassini spacecraft photographs Saturn


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NASA’s Cassini spacecraft releases first close-up photos of Saturn

7 December 2016

At just 240,000 miles from Saturn‘s north pole, NASA’s Cassini spacecraft snapped some stunning photos. These are the first images of the spacecraft’s new mission, which is taking it closer to Saturn than it has been since it arrived at Saturn in 2004.

By Brandon Russell in the USA, December 10, 2016:

NASA’s Cassini takes breathtaking images of Saturn’s northern hemisphere

NASA’s Cassini has been soaring through the cosmos for nearly 20 years and to celebrate the latest phase of its journey, the intrepid spacecraft has sent scientists new images of Saturn’s northern hemisphere.

The purpose of Cassini’s newest mission phase, called Ring-Grazing Orbits, is to skim past the outer edges of the planet’s main rings, according to NASA. The pictures … which highlight the planet’s hexagon-shaped jet stream, were taken in early December.

“This is it, the beginning of the end of our historic exploration of Saturn,” said Carolyn Porco, Cassini imaging team lead at Space Science Institute. “Let these images—and those to come—remind you that we’d lived a bold and daring adventure around the solar system’s most magnificent planet.”

Cassini will continue its ring-grazing orbits until April 22 of next year, where it will then begin its descent toward the planet’s surface. By September of 2017, Cassini will no longer exist.

The beginning of the end

Cassini launched all the way back in 1997 and has continued to study the Saturn system since arriving in 2004.

Over the years, the orbiter has uncovered a potential ocean on a Saturn moon, and sent back an incredibly beautiful image of a hurricane on the planet, among many other accomplishments.

Saturn’s 10th moon was the first satellite discovered in the modern space age. Excerpt from the January 14, 1967, issue of Science News: here.

NASA found the “Death Star” — or at least a moon of Saturn that looks just like it: here.

Jupiter, Mars, Saturn space news


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Juno Listens to Jupiter’s Auroras

2 September 2016

Thirteen hours of radio emissions from Jupiter’s intense auroras are presented here, both visually and in sound. The data was collected when the spacecraft made its first orbital pass of the gas giant on Aug 27, 2016, with all spacecraft instruments turned on. The frequency range of these signals is from 7 to 140 kilohertz. Radio astronomers call these “kilometric emissions” because their wavelengths are about a kilometer long.

The full story and more images from Juno‘s first pass of Jupiter with all instruments on is here.

From Science News:

Juno spacecraft goes into ‘safe mode’, continues to orbit Jupiter

by Christopher Crockett

6:57pm, October 19, 2016

PASADENA, Calif. — NASA’s Juno spacecraft, in orbit around Jupiter since July 4, is lying low after entering an unexpected “safe mode” early on October 19. A misbehaving valve in the fuel system, not necessarily related to the safe mode, has also led to a delay in a planned engine burn that would have shortened the probe’s orbit.

Juno turned off its science instruments and some other nonessential components this morning at 1:47 a.m. EDT after computers detected some unexpected situation, mission head Scott Bolton reported at an October 19 news conference. The spacecraft was hurtling toward its second close approach to the planet, soaring about 5,000 kilometers from the cloud tops. It has now passed that point and is moving back away from the planet with all science instruments switched off.

The rocket firing was intended to take Juno from a 53.5-day orbit to a 14-day orbit. Juno can stay in its current orbit indefinitely without any impact on the science goals, Bolton said. The goal of the mission — to peer deep beneath Jupiter’s clouds — depends on the close approaches that it makes with every orbit, not how quickly it loops around. “We changed to a 14-day orbit primarily because we wanted the science faster,” he said. “But there’s no requirement to do that.”

For now, mission scientists are trying to figure what happened with the fuel valve and what triggered the safe mode before proceeding with further instructions to the probe.

First peek under clouds reveals Jupiter’s surprising depths. Colorful bands stretch hundreds of kilometers inward, Juno spacecraft data show. By Christopher Crockett, 9:00am, October 21, 2016: here.

Also from Science News:

Mission scientists await signal from Mars lander

ExoMars probe went silent before touchdown

by Christopher Crockett

5:16pm, October 19, 2016

From the European Space Agency:

20 October 2016

Essential data from the ExoMars Schiaparelli lander sent to its mothership Trace Gas Orbiter during the module’s descent to the Red Planet’s surface yesterday has been downlinked to Earth and is currently being analysed by experts.

Early indications from both the radio signals captured by the Giant Metrewave Radio Telescope (GMRT), an experimental telescope array located near Pune, India, and from orbit by ESA’s Mars Express, suggested the module had successfully completed most steps of its 6-minute descent through the martian atmosphere. This included the deceleration through the atmosphere, and the parachute and heat shield deployment, for example.

But the signals recorded by both Pune and Mars Express stopped shortly before the module was expected to touchdown on the surface. Discrepancies between the two data sets are being analysed by experts at ESA’s space operations centre in Darmstadt, Germany.

ExoMars mission has both success and failure: here.

First signs of boron on Mars hint at past groundwater, habitability: here.

Red Planet’s interior may not churn much. Composition of 2.4-billion-year-old Martian meteorite matches that of younger ones. By Thomas Sumner
2:00pm, February 1, 2017: here.

Experts don’t agree on age of Saturn’s rings. Data from orbiting Cassini craft may help resolve debate. By Christopher Crockett, 8:53am, October 20, 2016: here.

Possibly cloudy forecast for parts of Pluto. Bright patches in New Horizons images hint at rare atmospheric formation. By Christopher Crockett, 3:05pm, October 19, 2016: here.

WE’RE STILL MOURNING PLUTO’S PLANET DEMOTION But there might just be another ninth planet out there. [NYT]

Saturn’s moon Dione, underground ocean?


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NASA’s Cassini Finds Hidden Ocean on Saturn’s Moon Dione

3 October 2016

New gravity data from recent Cassini flybys of the giant planet suggest that Dione’s crust floats on an ocean 62 miles below the surface, and may harbor microbial life.

From Science News:

Saturn’s moon Dione might harbor an underground ocean

by Christopher Crockett

2:14pm, October 7, 2016

A Saturnian satellite joins the club of moons with oceans. A subsurface sea might hide beneath the icy crust of Dione, a moon of Saturn, researchers report online September 28 in Geophysical Research Letters. That puts Dione in good company alongside Enceladus (another moon of Saturn), several moons of Jupiter and possibly even Pluto.

Dione’s ocean is about 100 kilometers below the surface and is roughly 65 kilometers deep, Mikael Beuthe, a planetary scientist at the Royal Observatory of Belgium in Brussels, and colleagues report. They inferred the ocean’s presence from measurements of Dione’s gravity made by the Cassini spacecraft, which has been in orbit around Saturn since 2004.

Ocean discovery on Saturn’s moon Enceladus


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NASA: Saturn‘s Moon Enceladus Has Global Ocean

16 September 2015

New research suggests the ocean underneath Saturn‘s moon Enceladus is global in nature.

Saturn‘s moon Enceladus likely contains a global ocean. Scientists working off of images obtained from the Cassini mission have observed a noticeable wobble in Enceladus that they say only makes sense if its inner core is not directly connected to its outer shell. Using over seven years’ worth of images, researchers were able to accurately determine the magnitude of the wobble and arrive at their conclusion.

Enceladus is home to what scientists call “tiger stripes”—large cracks in the moon’s south pole where ice particles, salts, water vapor and organic molecules are expelled in a thin mist. The geologic spraying activity has been observed for some time and was previously thought to be fed by a simple lens-like reservoir—something much smaller than a global ocean. But data culled from the Cassini mission‘s numerous flybys of the icy moon has supported the idea that the reservoir might be much larger. According to NASA, the latest findings independently confirm the global ocean hypothesis.

By Sebastian Murdock in the USA:

Global Ocean Discovered On Saturn’s Moon Enceladus

Pack your swimsuit! But not really.

09/16/2015 11:50 AM EDT

A sprawling global ocean has been discovered on Saturn’s moon Enceladus.

Scientists made the discovery after sifting through seven years worth of images taken by NASA’s Cassini mission. Although scientists were previously aware of a body of water under the moon’s icy crust, NASA announced Tuesday that the body of water expands across the entire moon.

By mapping the position of craters across hundreds of images, the researchers were able to measure a small wobble in the moon as it orbits Saturn. The wobble indicated the presence of a vast body of water between Enceladus’s icy crust and its rocky core, Gizmodo reported.

“If the surface and core were rigidly connected, the core would provide so much dead weight the wobble would be far smaller than we observe it to be,” Dr. Matthew Tiscareno, a Cassini scientist and co-author of a paper describing the discovery, said in a written statement. “This proves that there must be a global layer of liquid separating the surface from the core.”

The Cassini spacecraft can “‘see’ in wavelengths the human eye can’t and can ‘feel’ things about the magnetic fields and tiny dust particles that no human hand could detect,” according to NASA. The spacecraft was named after famed astronomer Jean-Dominique Cassini, who discovered four of Saturn’s whopping 62 moons.

On Oct. 28, Cassini will make it’s “deepest-ever dive” through the moon’s harsh, icy atmosphere when it passes just 30 miles above the surface.

Cassini Completes Final Close Enceladus Flyby: here.

Food for microbes found on Enceladus. Hydrogen in plume suggests hydrothermal activity on Saturnian moon. By Ashley Yeager, 2:00pm, April 13, 2017: here.

Saturn’s moon Enceladus, new study


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Warm Water Spots Found On Saturn’s Icy Moon Enceladus

12 March 2015

Astronomers have detected the first active hydrothermal vents outside of Earth’s seafloor on Saturn’s icy moon Enceladus, indicating conditions that could be hospitable to the initial development of life.

New research suggests the existence of warm spots on the ocean floor of Saturn’s icy moon Enceladus.

They could be the first active hydrothermal vents to be detected outside of Earth’s seafloor, and their conditions may even be similarly hospitable to the initial development of life.

Two studies, one led by the University of Colorado, Boulder and the other by the Southwest Research Institute in Texas, support the possible existence of this hydrothermal activity.

In 2005, the Cassini orbiter captured images of geysers shooting out of the moon’s surface, which led to the discovery of an underground sea believed to be approximately 6 miles deep and under about 25 miles of icy crust.

Scientists discovered particles from the geysers in one of Saturn’s rings and using an instrument onboard Cassini were able to analyze the tiny, uniform dust particles. They found they were rich in silica which is common on Earth but different from the usual ice crystals found in Saturn’s E-ring.

Because silica has such well-known properties, the only way they could create similar particles in the lab was using slightly alkaline, low-in-salinity water at temperatures of at least 194 degrees Fahrenheit.

Despite the ultra-cold environment, the moon’s high core temperature is thought to come from an effect called tidal heating where Saturn’s gravitational pull on the moon generates heat.

From the International Business Times:

On Saturn’s Moon Enceladus, Water Vapor Erupts In Giant Curtains: Study

By Avaneesh Pandey

May 08 2015 8:35 AM EDT

In 2005, NASA’s Cassini-Huygens spacecraft found evidence of an icy spray issuing from the southern polar region of Saturn’s sixth-largest moon, Enceladus. Now, just two months after scientists confirmed the presence of hydrothermal activity on the moon, researchers have claimed that the eruption of water vapor on its surface might be in the form of broad, curtain-like sheets, rather than discrete jets.

“We think most of the observed activity represents curtain eruptions from the ‘tiger stripe’ fractures, rather than intermittent geysers along them,” Joseph Spitale, a Cassini mission participating scientist and senior scientist at the Planetary Science Institute in Tucson, Arizona, said, in a statement, referring to prominent wavy fractures along the moon’s surface. “Some prominent jets likely are what they appear to be, but most of the activity seen in the images can be explained without discrete jets.”

According to a study published Thursday in the journal Nature, these “phantom jets” seen in simulated images produced by scientists line up perfectly with some of the features seen in real Cassini images. This means that the discrete geysers that scientists have observed on Enceladus are, in fact, an optical illusion created in places where these curtains fold against one another. This illusion is also responsible for creating regions of phantom brightness when viewers are looking through the folds of watery curtains.

“The viewing direction plays an important role in where the phantom jets appear,” Spitale said, in the statement. “If you rotate your perspective around Enceladus’ South Pole, such jets would seem to appear and disappear.”

On Earth, these curtain eruptions occur in regions of volcanic activity such as Hawaii, Iceland and the Galapagos Islands. However, unlike Enceladus’ watery curtains, these are curtains of fire.

Enceladus is believed to be covered with a layer of ice about 19 miles to 25 miles thick. Evidence strongly suggests that the moon harbors a six-mile-deep ocean, with temperatures reaching up to 194 degrees Fahrenheit below its thick, icy surface, making it a prime location to look for extraterrestrial life.