Senkyo

The Cassini spacecraft once again dons its special infrared glasses to peer through Titan's haze and monitor its surface. Here, Cassini has recaptured the equatorial region dubbed "Senkyo." The dark features are believed to be vast dunes of hydrocarbon particles that precipitated out of Titan's atmosphere.

Titan, Saturn's largest moon, is 3,200 miles (5,150 kilometers) across. For more on Senkyo, see PIA08231.

This view looks toward Saturn-facing hemisphere of Titan. North on Titan is up and rotated 4 degrees to the left. The image was taken with the Cassini spacecraft narrow-angle camera on June 16, 2013 using a spectral filter sensitive to wavelengths of near-infrared light centered at 938 nanometers.

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

Saturn

A swing high above Saturn by NASA's Cassini spacecraft revealed this stately view of the golden-hued planet and its main rings. The view is in natural color, as human eyes would have seen it. This mosaic was made from 36 images in three color filters obtained by Cassini's imaging science subsystem on October 10, 2013. The observation and resulting image mosaic were planned as one of three images for Cassini's 2013 Scientist for a Day essay contest.

Saturn sports differently colored bands of weather in this image. For instance, a bright, narrow wave of clouds around 42 degrees north latitude appears to be some of the turbulent aftermath of a giant storm that reached its violent peak in early 2011. The mysterious six-sided weather pattern known as the hexagon is visible around Saturn's north pole.

When Cassini arrived in 2004, more of the northern hemisphere sported a bluish hue and it was northern winter. The golden tones dominated the southern hemisphere, where it was southern summer. But as the seasons have turned and northern spring is in full swing, the colors have begun to change in each hemisphere as well. Golden tones have started to dominate in the northern hemisphere and the bluish color in the north is now confined to a tighter circle around the north pole. The southern hemisphere has started getting bluer, too.

The rings shown here include Saturn's main rings. The innermost D ring, and the C, B and A rings are easily seen. The F ring is also there, but not easily seen without enhancing the contrast of the image. (Rings were named in order of their discovery rather than their position around Saturn.) The rings also cast a shadow on Saturn at the limb of the planet in the lower right quadrant.

Cassini is currently in a set of tilted orbits known as "inclined orbits" that allow it to swing up over the north pole and below the south pole. Much of Cassini's time is spent close to the equatorial plane, where most of Saturn's rings and moons are located.

Image credit: NASA/JPL-Caltech/SSI/Cornell

Note: For more information, see Cassini Swings Above Saturn to Compose a Portrait.

Titan's North Polar Lakes and Evaporite Deposits

This false-color mosaic, made from infrared data collected by NASA's Cassini spacecraft, reveals the differences in the composition of surface materials around hydrocarbon lakes at Titan, Saturn's largest moon. Titan is the only other place in the solar system that we know has stable liquid on its surface, though its lakes are made of liquid ethane and methane rather than liquid water. While there is one large lake and a few smaller ones near Titan's south pole, almost all of Titan's lakes appear near the moon's north pole.

Scientists mapped near-infrared colors onto the visible color spectrum. Red in this image was assigned a wavelength of 5 microns (10 times longer than visible light), green 2.0 microns (four times longer than visible light), and blue 1.3 microns (2.6 times longer than visible light).

The orange areas are thought to be evaporite -- the Titan equivalent of salt flats on Earth. The evaporated material is thought to be organic chemicals originally from Titan's haze particles that once dissolved in liquid methane. They appear orange in this image against the greenish backdrop of Titan's typical bedrock of water ice.

In this mosaic, Kraken Mare, which is Titan's largest sea and covers about the same area as Earth's Caspian Sea and Lake Superior combined, can be seen spreading out with many tendrils on the upper right,. The big dark zone up and left of Kraken is Ligeia Mare, the second largest sea. Below Ligeia, shaped similar to a sports fan's foam finger that points just up from left, is Punga Mare, the third largest Titan Sea. Numerous other smaller lakes dot the area. Titan's north pole is located in the geographic location just above the end of the "finger" of Punga Mare.

Figure 1 highlights a high-resolution strip and shows the north pole marked with a red cross. Other smaller lakes are also labeled.

The data shown here were obtained by Cassini's visual and infrared mapping spectrometer during a close flyby of Titan on September 12, 2013.

Until now, the spectrometer has only been able to capture distant, oblique or partial views of this area. The September 12, 2013, flyby provided better viewing geometry. And sunlight has begun to pierce the winter darkness that shrouded Titan's north pole at the time of Cassini's arrival in the Saturn system nine years ago. A thick cap of haze that once hung over the north pole has also dissipated as northern summer approaches. And, thankfully, Titan's beautiful, almost cloudless, rain-free weather continued during this flyby.

The resolution varies across this composite view depending on when each cube of data was acquired, but the best surface sampling is 2 miles (3 kilometers) per pixel.

Views of this area by other Cassini instruments include PIA17471, PIA17472, PIA17473 and PIA14584 from the imaging science subsystem; and PIA10008 and PIA17031 from the radar mapper. An earlier VIMS view can be seen at PIA16845.

Image credit: NASA/JPL-Caltech/University of Arizona/University of Idaho

Note: For more information, see Cassini Gets New Views of Titan's Land of Lakes.

Prometheus and Pan

Although their gravitational effects on nearby ring material look quite different, Prometheus and Pan -- pictured here -- are both shepherd moons, holding back nearby ring edges.

Pan (17 miles,or 28 kilometers across), near the right edge of the image, holds open the Encke gap that it orbits in. Prometheus (53 miles, or 86 kilometers across), near the upper left, helps shape the F ring and maintain its narrow form.

This view looks toward the unilluminated side of the rings from about 47 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on May 27, 2013.

The view was acquired at a distance of approximately 870,000 miles (1.4 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 81 degrees. Image scale is 5 miles (8 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Saturn and Rings in Infrared

This colorized mosaic from NASA's Cassini mission shows an infrared view of the Saturn system, backlit by the sun, from July 19, 2013. The image, made from data obtained by Cassini's visual and infrared mapping spectrometer, covers a swath of Saturn and its rings about 340,000 miles (540,000 kilometers) across that includes the planet and its rings out to the diffuse E ring, Saturn's second most distant ring. The mosaic covers an area about 9,800 miles (16,000 kilometers) from top to bottom.

When Saturn is blocking the direct light of the sun, scientists can get a better look at the fainter rings. When small particles are lit from behind, they show up like fog in the headlights of an oncoming vehicle. Conversely, a ring that is easily seen from Earth because it is densely packed with chunks of bright water ice looks dark in these images because it is so thick that it blocks almost all of the sunlight shining behind it.

Looking at Saturn in the infrared spectrum can tell scientists more about the sizes of the particles in the fainter rings, and how these sizes vary with location in the rings. Infrared data also provide clues to ring particles' chemical composition.

Looking at the Saturn system in infrared light also shows thermal, or heat, radiation, so while a visible-light image from this vantage point would simply show the face of the planet as dimly lit by sunlight reflected off the rings, Saturn glows brightly in this view with the heat from Saturn's interior.

The visual and infrared spectrometer team colorized the image by assigning blue to radiation detected in the 1.5-to-1.19-micron range, green to radiation detected in the 1.9-to-2.1-micron range and red to the radiation detected in the 4.88-to-5.06-micron range.

Image credit: NASA/JPL-Caltech/University of Arizona/Cornell

Note: For more information, see PIA17469: High-Contrast Infrared Scan of Saturn and its Rings and Rings, Dark Side of Saturn Glow in New Cassini Image.

Janus

The irregularly shaped moon Janus keeps up its lonely orbit. Even though Janus shares its orbit with the moon Epimetheus, they never get very close to one another thanks to the gravitational resonance that swaps their orbits roughly every four years and ensures that they don't collide.

This view looks toward the anti-Saturn side of Janus. North on Janus is up and rotated 32 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 15, 2013.

The view was obtained at a distance of approximately 750,000 miles (1.2 million kilometers) from Janus and at a Sun-Janus-spacecraft, or phase, angle of 8 degrees. Image scale is 4 miles (7 kilometers) per pixel. The F ring has been brightened by a factor of 1.4 relative to the rest of the image to enhance visibility.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Rings and Shadow

The shadow of Saturn cuts across the rings in this recent Cassini spacecraft image. As the ring particles enter Saturn's shadow, their temperature drops to even colder temperatures, only to warm back up again when they re-emerge into the sunlight. Ring scientists think that these temperature swings may help change the physical properties of the ring particles.

Eight stars are visible in this image, including one through the rings.

This view looks toward the unilluminated side of the rings from about 56 degrees below the ringplane. The image was taken in visible violet light with the Cassini spacecraft narrow-angle camera on May 29, 2013.

The view was acquired at a distance of approximately 639,000 miles (1.0 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 128 degrees. Image scale is 4 miles (6 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Cassini Orbits Through September 2017

This picture traces Cassini's orbits from Saturn orbit insertion, on 1 July 2004, through the planned end of the mission, on 15 September 2017.

Saturn is in the center, with the orbit of its largest moon Titan in red and the orbits of its six other inner satellites in white.

Cassini's prime mission, completed in 2008, is shown in green. Its first mission extension, which was known as the Equinox Mission and ended in 2010, is shown in orange. The completed orbits of its second mission extension, known as the Solstice Mission, are shown in purple. Orbits after Cassini's 15th anniversary of launch, on 15 October 2012, appear in dark grey. These include orbits that pass inside Saturn's innermost ring, which start in April 2017.

Flybys are a major element of Cassini's tour. The spacecraft's looping, elliptical path around Saturn is carefully designed to enable occasional visits to the many moons in the system. All flybys provide an opportunity to learn more about Saturn's icy satellites, and encounters with giant Titan are actually used to navigate the spacecraft, changing its orbit or setting up future flybys.

Many of the most exciting encounters are "targeted" flybys, for which Cassini's flight path is steered so the spacecraft will pass by a specific moon at a predetermined distance, referred to as "closest approach". Cassini's targeted flybys have yielded incredible close-up views and many groundbreaking science results.

Image credit: NASA/JPL-Caltech

Note: For more information, see The Active Sun Boosts Titan's Outer Atmosphere

NASA's Cassini Spacecraft Finds Ingredient of Household Plastic in Space

NASA's Cassini spacecraft looks toward the night side of Saturn's largest moon and sees sunlight scattering through the periphery of Titan's atmosphere and forming a ring of color.

NASA's Cassini spacecraft has detected propylene, a chemical used to make food-storage containers, car bumpers and other consumer products, on Saturn's moon Titan.

This is the first definitive detection of the plastic ingredient on any moon or planet, other than Earth.

A small amount of propylene was identified in Titan's lower atmosphere by Cassini's composite infrared spectrometer (CIRS). This instrument measures the infrared light, or heat radiation, emitted from Saturn and its moons in much the same way our hands feel the warmth of a fire.

Propylene is the first molecule to be discovered on Titan using CIRS. By isolating the same signal at various altitudes within the lower atmosphere, researchers identified the chemical with a high degree of confidence. Details are presented in a paper in the September 30 edition of the Astrophysical Journal Letters.

"This chemical is all around us in everyday life, strung together in long chains to form a plastic called polypropylene," said Conor Nixon, a planetary scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the paper. "That plastic container at the grocery store with the recycling code 5 on the bottom -- that's polypropylene."

CIRS can identify a particular gas glowing in the lower layers of the atmosphere from its unique thermal fingerprint. The challenge is to isolate this one signature from the signals of all other gases around it.

The detection of the chemical fills in a mysterious gap in Titan observations that dates back to NASA's Voyager 1 spacecraft and the first-ever close flyby of this moon in 1980.

Voyager identified many of the gases in Titan's hazy brownish atmosphere as hydrocarbons, the chemicals that primarily make up petroleum and other fossil fuels on Earth.

On Titan, hydrocarbons form after sunlight breaks apart methane, the second-most plentiful gas in that atmosphere. The newly freed fragments can link up to form chains with two, three or more carbons. The family of chemicals with two carbons includes the flammable gas ethane. Propane, a common fuel for portable stoves, belongs to the three-carbon family.

Previously, Voyager found propane, the heaviest member of the three-carbon family, and propyne, one of the lightest members. But the middle chemicals, one of which is propylene, were missing.

As researchers continued to discover more and more chemicals in Titan's atmosphere using ground- and space-based instruments, propylene was one that remained elusive. It was finally found as a result of more detailed analysis of the CIRS data.

"This measurement was very difficult to make because propylene's weak signature is crowded by related chemicals with much stronger signals," said Michael Flasar, Goddard scientist and principal investigator for CIRS. "This success boosts our confidence that we will find still more chemicals long hidden in Titan's atmosphere."

Cassini's mass spectrometer, a device that looks at the composition of Titan's atmosphere, had hinted earlier that propylene might be present in the upper atmosphere. However, a positive identification had not been made.

"I am always excited when scientists discover a molecule that has never been observed before in an atmosphere," said Scott Edgington, Cassini's deputy project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California. "This new piece of the puzzle will provide an additional test of how well we understand the chemical zoo that makes up Titan's atmosphere."

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

Density, Bending and Edge Waves in Saturn's A-Ring, with Daphnis

Saturn's A ring is decorated with several kinds of waves. Here the Cassini spacecraft has captured a host of density waves, a bending wave (in the upper-right corner), and the edge waves on the edge of the Keeler Gap caused by the small moon Daphnis. Daphnis itself appears as a tiny dot in the middle of the Keeler Gap.

See PIA10501 for a closer look at bending and density waves and to learn more about them. For more on the edge waves caused by Daphnis, see PIA11655.

This view looks toward the unilluminated side of the rings from about 41 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 28, 2013.

The view was obtained at a distance of approximately 777,000 miles (1.3 million kilometers) from Daphnis and at a Sun-Daphnis-spacecraft, or phase, angle of 76 degrees. Image scale is 5 miles (8 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute