Carolyn Porco | This Is Saturn | TED

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Color Variation Across Rhea and Dione

The cratered ice moons Rhea and Dione come alive with vibrant color that reveals new information about their surface properties.

To create these false-color views, ultraviolet, green and infrared images were combined into a single black and white picture that isolates and maps regional color differences. This “color map” was then superposed over a clear-filter image of each moon.

The combination of color map and brightness image shows how the colors vary across the moon’s surface in relation to geologic features. The origin of the color differences is not yet understood, but may be caused by subtle differences in the surface composition or the sizes of grains making up the icy soil.

The images have not been scaled to show the moons’ proper relative sizes.

Credit: NASA/JPL/Space Science Institute

(Source: spaceplasma, via spaceplasma)

Cassini Finds Hints of Activity at Saturn Moon Dione

From a distance, most of the Saturnian moon Dione resembles a bland cueball. Thanks to close-up images of a 500-mile-long (800-kilometer-long) mountain on the moon from NASA’s Cassini spacecraft, scientists have found more evidence for the idea that Dione was likely active in the past. It could still be active now.

“A picture is emerging that suggests Dione could be a fossil of the wondrous activity Cassini discovered spraying from Saturn’s geyser moon Enceladus or perhaps a weaker copycat Enceladus,” said Bonnie Buratti of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who leads the Cassini science team that studies icy satellites. “There may turn out to be many more active worlds with water out there than we previously thought.”

Read More.

(Source: christinetheastrophysicist)

pappubahry:

Saturn’s moon Polydeuces, a trojan moon orbiting near Dione’s L5 point which is only about 3km in length, photographed by Cassini, 22 September 2011.

ckck:

Dione lit by the sun and sunlight reflected off of Saturn. March 22nd, 2008.

Photographed by the Cassini Orbiter.

spaceplasma:

Titan, Dione, and Saturn

This animation is composed of sixteen wide-angle frames captured by Cassini on July 29, 2007. The images were taken through a filter in a methane “window,” so details in Saturn’s clouds and on Titan’s surface that are usually obscured by methane haze are visible. Each image has been colorized based upon other natural-color Cassini images.

Titan transits Saturn from left to right as much smaller, brighter Dione moves from right to left at the extreme right edge of this image. Saturn’s rings are seen edge-on so are almost invisible. The rings cast broad black shadows on Saturn’s northern hemisphere. The full-size version is best viewed as a Quicktime movie (264k)

Credit: NASA / JPL / SSI / color and animation by Gordan Ugarkovic

distant-traveller:

“Colorful” Dione

Although made mostly of ice and rock, Saturn’s moon Dione does have some color to it, as seen in this color-composite made from raw images acquired by Cassini on December 23.

1120 km wide, Dione is covered pole-to-pole in craters and crisscrossed by long, bright regions of “wispy line” terrain — the reflective faces of sheer ice cliffs and scarps that are too steep for darker material drifting in from Saturn’s E ring to remain upon.

The view above looks at a region on Dione’s mid-northern hemisphere. The bright-walled crater in the center surrounded by warmer-hued terrain is named Creusa, and the long rift system next to it is Tibur Chasmata, which runs north-to-south. Dione’s north pole is to the upper left.

Dione’s heavily cratered areas are most common on its trailing hemisphere. Logically, a moon’s leading hemisphere should be the more heavily cratered, so it has been hypothesized that a relatively recent impact spun Dione around 180 degrees. The moon’s small size mean that even a modest-scale impact could have done the job.

Image credit: NASA/JPL/SSI. Composite by J. Major.

spaceplasma:

Ringside with Dione

Speeding toward pale, icy Dione, Cassini’s view is enriched by the tranquil gold and blue hues of Saturn beyond. The spacecraft was very nearly in the plane of the rings at this time, thinning them by perspective and masking their awesome scale. The thin, curving shadows of the C ring and part of the B ring adorn the northern latitudes visible here, a reminder of the rings’ grandeur.

It is notable that Dione, like most of the other icy Saturnian satellites, looks no different in natural color than in monochrome images.

Images taken with blue, green and infrared (centered at 752 nanometers) spectral filters were used to create this color view, which approximates the scene as it would appear to the human eye. The images were obtained with the wide angle camera from a distance of approximately 39,000 kilometers (24,200 miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 22 degrees. The image scale is about 2 kilometers (1 mile) per pixel.

Credit: NASA/JPL/Space Science Institute

Saturn Moon Enceladus Eyed for Sample-Return Mission

image 1: Enceladus vents water into space from its south polar region. The moon is lit by the Sun on the left, and backlit by the vast reflecting surface of its parent planet to the right. Icy crystals from these plumes are likely the source of Saturn’s nebulous E ring, within which Enceladus orbits. Mosaic composite photograph. Cassini, December 25, 2009.
CREDIT: NASA/JPL-Caltech/Michael Benson/Kinetikon Pictures. © All rights reserved.

image 2: This photo of water geysers spouting from Saturn’s moon Enceladus was taken by NASA’s Cassini orbiter in October 2007
CREDIT: Cassini Imaging Team, SSI, JPL, ESA, NASA

Scientists are developing a mission concept that would snag icy particles from Saturn’s moon Enceladus and return them to Earth, where they could be analyzed for signs of life.

The spacecraft would fly through the icy plume blasted into space by geysers near Enceladus’ south pole, then send the collected particles back to our planet in a return capsule. Enceladus may be capable of supporting life, and the flyby sample-return mission would bring pieces from its depths to Earth at a reasonable price, researchers said.

“This is really the low-hanging fruit” of sample-return missions, said study leader Peter Tsou of Sample Exploration Systems in La Canada, Calif., who presented the idea here Wednesday (Dec. 5) at the annual fall meeting of the American Geophysical Union. “It would be a shame not to pick it.”

Flying through Enceladus’ plume
Enceladus is the sixth-largest moon of Saturn, with a diameter of 314 miles (505 kilometers). Scientists believe a large ocean of liquid water sloshes beneath the moon’s icy shell.

Life as we know it requires four things, Tsou said: liquid water, carbon, nitrogen and an energy source. All four are present at Enceladus, and as a result many researchers regard it as one of the solar system’s best bets to host life as we know it.

Enceladus generates huge amounts of heat internally, with much of it perhaps being produced by tidal interactions with Dione, another Saturn satellite. This heat powers the geysers from Enceladus’ south pole, which eject water ice, carbon-containing organic compounds and other materials from the moon’s subsurface into space.

The proposed spacecraft would enter into Saturn orbit to slow down and enable possible multiple passes by Enceladus. It would then fly through the moon’s icy plume, collecting geyser particles in a cushioning aerogel.

A small return capsule would deliver the samples to Earth, where scientists could search them for amino acids and other possible biomolecules.

Sample-return is the preferred strategy when it comes to hunting for signs of life on other worlds, Tsou said. An automated probe in the depths of space would have a bare-bones analytical toolset, and it could perform only a limited number of experiments for a relatively short time.

But here on Earth, researchers in fully equipped labs all over the world could conduct numerous experiments and potentially corroborate big discoveries claimed by other groups.

“You need very precise, repeated measurements,” Tsou told SPACE.com.

Launching in 2020?
No big technological advances are necessary to make the mission happen, Tsou said. In fact, something similar has already been done. NASA’s Stardust mission — which Tsou served as deputy principal investigator for — collected particles from Comet Wild 2 and successfully returned them to Earth in 2006.

“Technology-wise, Stardust proved that this can be done,” Tsou said.

Cost is a bigger issue. Initial incarnations of the Enceladus sample-return concept were estimated to cost around $1.2 billion, Tsou said — an uncomfortably large sum in these tough fiscal times. (The White House cut funding for NASA’s planetary science program by 20 percent in its proposed 2013 budget.)

But Tsou and his colleagues have pared the potential mission down, making the spacecraft — which would be roughly 16 feet high and 10 feet wide (5 meters by 3 meters) — leaner and more focused.

As currently envisioned, the probe’s science gear would consist of an aerogel collector, a tool for trapping volatile chemicals, a mass spectrometer, a navigation camera and a dust counter (so mission scientists could confirm that they’d flown through the plume).

For power, the spacecraft would rely on an advanced stirling radioisotope generator (ASRG), which converts the heat produced by radioactive decay of plutonium-238 into electricity. Tsou said that the ASRG is much more efficient at this conversion than radioisotope thermoelectric generators (RTGs), which have powered space probes for decades.

Tsou said the team wants Enceladus sample-return to fly as a NASA Discovery mission, meaning it would be capped at $425 million in 2010 dollars, not including the launch vehicle. The researchers hope to propose the mission at the next Discovery opportunity, which may come in 2015 or so, Tsou said.

If the mission is approved, it could probably be ready to launch by 2020, Tsou added. Samples from Enceladus’ plume would make it to Earth about 14 years later.

Enceladus is a great candidate for sample-return, Tsou said. Its geyser-blasted particles are fresh, having come right out of the moon’s subsurface ocean. The mission can be done without landing on and re-launching from another world, two costly and complicating extra steps. And Enceladus seems to have all the ingredients necessary to support life.

“That doesn’t mean life is there,” Tsou said. “But we want to find out.”

astronomer-in-progress:

Bright Cliffs Across Saturn’s Moon Dione 

Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

Explanation: What causes the bright streaks on Dione? Recent images of this unusual moon by the robot Cassini spacecraft now orbiting Saturn are helping to crack the mystery. Close inspection of Dione’s trailing hemisphere, pictured above, indicates that the white wisps are composed of deep ice cliffs dropping hundreds of meters. The cliffs may indicate that Dione has undergone some sort of tectonic surface displacements in its past. The bright ice-cliffs run across some of Dione’s many craters, indicating that the process that created them occurred later than the impacts that created those craters. Dione is made of mostly water ice but its relatively high density indicates that it contains much rock inside. Giovanni Cassini discovered Dione in 1684. The above image was taken at the end of July from a distance of about 263,000 kilometers. Other high resolution images of Dione were taken by the passing Voyager spacecraft in 1980.

(via astronomerinprogress)

fuckyeahcassini:

Map of Dione’s north pole - December 2011

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ikenbot:

Evander & the Rings

Credit: NASA / JPL / SSI / color composite by Emily Lakdawalla

Dione’s Evander basin caught against Saturn and rings.

(Source: kenobi-wan-obi, via scinerds)

Cassini Visits Dione

After completing its most recent flyby of Enceladus, Cassini made a pass by Dione — its final visit of the icy moon for the next three years. Coming within  5,000 miles (8000 km) of Dione on May 2, Cassini captured some fantastic images of the moon’s heavily-cratered and frozen surface. 

These are just a few of the raw images that arrived back here on Earth earlier today.

698 miles (1123 km) in diameter, Dione orbits Saturn at about the same distance that the Moon orbits Earth. Its composition is two-thirds water ice, which at the incredibly cold temperatures found around Saturn behaves like rock does here on Earth

Cassini won’t visit Dione so closely again until June 2015, after spending three years angled high out of the equatorial plane while it studies Saturn’s rings and polar regions.

As Carolyn Porco, Cassini Imaging Team Leader said today, “This is exploration at its finest. It won’t continue forever. So, enjoy it while it lasts!”

See more on the Cassini Imaging Central Laboratory for Operations (CICLOPS) site here.

Image credits: NASA/JPL/Space Science Institute 

the-star-stuff:

Views of Moons

1. Can you tell which of these moons in the foreground? It’s Titan, the large one (diameter 5,150 kilometres; bigger than our Moon) with the orange atmosphere, with smaller, shiny, icy Tethys in the background. Titan was 2.3 million kilometres from Titan, and 3.4 million from Tethys when it took this image. Saturn’s rings can be seen edge-on in the distance.

2. This view shows Titan again, this time with the much smaller moon Dione (1,123 km diameter) peering around from behind, with Saturn and its rings (edge-on) in the background. Cassini was 2.3 million kilometres from Titan and 3.2 million kilometres from Dione when it took the image. The haze that surrounds Titan can clearly be seen. Titan has a mostly nitrogen atmosphere that extends far from the surface. The surface pressure is about 1.5 times that on Earth.

Images courtesy NASA / JPL-Caltech / Space Science Institute.

(via itsfullofstars)

Original Caption Released with Image:
The Cassini spacecraft examines the anti-Saturnian side of Dione and shows the cratered surface east of the moon’s distinctive wispy terrain.

The wispy terrain, which consists of bright cliffs on the moon’s trailing hemisphere, can just barely be seen on the limb of the moon on the left of the image. North on Dione (698 miles, or 1,123 kilometers across) is up. See PIA12608 for a better view of the wisps. See PIA07769 for more southern view of Dione presented in dramatic false colors.

This view looks toward the northern, sunlit side of the rings from just above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Oct. 2, 2011. The view was obtained at a distance of approximately 174,000 miles (280,000 kilometers) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 11 degrees. Image scale is 2 miles (3 kilometers) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

Image Credit:
NASA/JPL-Caltech/Space Science Institute