Elevated View of Enceladus' South Pole

This dramatic view looks across the region of Enceladus' geyser basin and down on the ends of the Baghdad and Damascus fractures that face Saturn. The image, which looks approximately in the direction of Saturn, was taken from a more elevated viewpoint than other Cassini survey images of this area of the moon's south pole.

The geysering segments of the fractures seen here are among the most active and warmest in the whole region. As seen from the spacecraft from an elevation angle of 25 degrees south, the jets are projected against the bright surface as opposed to black sky. Consequently, despite the pronounced activity, the jets appear fuzzy, or indistinct, in this image and their tilts are consequently not measurable. Though their source locations are clearly seen, this image was not used in the process of triangulation, but instead it was used to confirm source locations determined from triangulation using other images.

The image was taken with Cassini's narrow-angle camera through the clear filter on August 13, 2010, with an image scale about 230 feet (70 meters) per pixel and a Sun-Enceladus-spacecraft, or phase, angle of about 151 degrees.

This image was one of those used to confirm the sources of Enceladus' geysers as described in a paper by Porco, DiNino, and Nimmo, and published in the online version of the Astronomical Journal in July 2014: http://dx.doi.org/10.1088/0004-6256/148/3/45.

A companion paper, by Nimmo et al. is available at: http://dx.doi.org/10.1088/0004-6256/148/3/46.

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

Note: For more information, see PIA17186: Geyser Basin in 3-D, PIA17187: Enceladus' Plume Brightness Variations, PIA17188: Surveyor's Map of Enceladus' Geyser Basin, PIA17189: What Lies Beneath: Close Up View (Artist's Concept), PIA17190: What Lies Beneath: Regional View (Artist's Concept), and Cassini Spacecraft Reveals 101 Geysers and More on Icy Saturn Moon.

Enceladus Geysers

This Cassini narrow-angle camera image -- one of those acquired in the survey conducted by the Cassini imaging science team of the geyser basin at the south pole of Enceladus -- was taken as Cassini was looking across the moon's south pole. At the time, the spacecraft was essentially in the moon's equatorial plane. The image scale is 1280 feet (390 meters) per pixel and the sun-Enceladus-spacecraft, or phase, angle is 162.5 degrees.

The image was taken through the clear filter of the narrow angle camera on November 30, 2010, 1.4 years after southern autumnal equinox. The shadow of the body of Enceladus on the lower portions of the jets is clearly seen.

In an annotated version of the image, the colored lines represent the projection of Enceladus' shadow on a plane normal to the branch of the Cairo fracture (yellow line), normal to the Baghdad fracture (blue line) and normal to the Damascus fracture (pink line).

Post-equinox images like this, clearly showing the different projected locations of the intersection between the shadow and the curtain of jets from each fracture, were useful for scientists in checking the triangulated positions of the geysers, as described in a paper by Porco, DiNino, and Nimmo, and published in the online version of the Astronomical Journal in July 2014: http://dx.doi.org/10.1088/0004-6256/148/3/45.

A companion paper, by Nimmo et al. is available at: http://dx.doi.org/10.1088/0004-6256/148/3/46.

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

Note: For more information, see 101 Geysers on Icy Saturn Moon.

Enceladus' Plumes

Dramatic plumes, both large and small, spray water ice out from many locations along the ‘tiger stripes’ near the south pole of Saturn’s moon Enceladus. The tiger stripes are fissures that spray icy particles, water vapor and organic compounds. More than 30 individual jets of different sizes can be seen in this image, which is a mosaic created from two high-resolution images captured when Cassini flew past Enceladus and through the jets on 21 November 2009. This view was obtained at a distance of about 14,000 km from Enceladus.

Image credit: NASA/JPL/Space Science Institute

Enceladus' Ocean

This diagram illustrates the possible interior of Saturn's moon Enceladus based on a gravity investigation by NASA's Cassini spacecraft and NASA's Deep Space Network, reported in April 2014. The gravity measurements suggest an ice outer shell and a low density, rocky core with a regional water ocean sandwiched in between at high southern latitudes.

Views from Cassini's imaging science subsystem were used to depict the surface geology of Enceladus and the plume of water jets gushing from fractures near the moon's south pole.

Enceladus is 313 miles (504 kilometers) in diameter.

Illustration credit: NASA/JPL-Caltech

Note: This is the big story of the day. For more information, see Inside Enceladus, Icy Moon Enceladus Has Underground Sea, NASA Space Assets Detect Ocean inside Saturn Moon, and Deep Ocean Detected Inside Saturn's Moon.

Squeezing and Releasing Enceladus

This set of images from NASA's Cassini mission shows how the gravitational pull of Saturn affects the amount of spray coming from jets at the active moon Enceladus. Enceladus has the most spray when it is farthest away from Saturn in its orbit (inset image on the left) and the least spray when it is closest to Saturn (inset image on the right).

Water ice and organic particles gush out of fissures known as "tiger stripes" at Enceladus' south pole. Scientists think the fissures are squeezed shut when the moon is feeling the greatest force of Saturn's gravity. They theorize the reduction of that gravity allows the fissures to open and release the spray. Enceladus' orbit is slightly closer to Saturn on one side than the other. A simplified version of that orbit is shown as a white oval.

Scientists correlate the brightness of the Enceladus plume to the amount of solid material being ejected because the fine grains of water ice in the plume are very bright when lit from behind. Between the dimmest and brightest images, they detected a change of about three to four times in brightness, approximately the same as moving from a dim hallway to a brightly lit office.

This analysis is the first clear finding that shows the jets at Enceladus vary in a predictable manner. The background image is a mosaic made from data obtained by Cassini's imaging science subsystem in 2006. The inset image on the left was obtained on October 1, 2011. The inset image on the right was obtained on January 30, 2011.

A related image, PIA17039, shows just the Enceladus images. The Saturn system mosaic was created from data obtained by Cassini's imaging cameras in 2006.

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

Note: For more information, see PIA17039: Enceladus "On" and "Off"; also, NASA's Cassini Sees Forces Controlling Enceladus Jets.

Stress at Enceladus

These images, based on ones obtained by NASA's Cassini spacecraft, show how the pull of Saturn's gravity can deform the surface of Saturn's moon Enceladus in the south polar region crisscrossed by fissures known as "tiger stripes." The blue arrows show the different kinds of stress that can occur at the tiger stripes, allowing jets of water vapor and organic particles to spray out. As Enceladus orbits Saturn, Saturn's gravitational forces can cause the fissure to pull apart (middle panel) or cause the two banks to move side-to-side like California's San Andreas Fault. The red stripe shows where gaps open because of motion and would be places where material could erupt. The images here focus on the tiger stripe known as Alexandria Sulcus.

Image credit: NASA/JPL-Caltech/SSI/LPI/GSFC

Note: For more information, see Cassini Sees Saturn Stressing out Enceladus.

Damascus Sulcus Hot Spot

Data from NASA's Cassini spacecraft have enabled scientists to make the highest-resolution heat intensity maps yet for the hottest part of a "tiger stripe" fissure on Saturn's moon Enceladus. The moon's south polar region features several of these long fissures that spray water and icy particles, and the one in this image is called Damascus Sulcus.

The thermal infrared data, shown in color, come from Cassini's composite infrared spectrometer (CIRS). The grayscale background image, which is illuminated by light reflected from Saturn rather than by direct sunlight, is from Cassini's high-resolution imaging camera (ISS). The CIRS scan gives scientists confidence that the peak temperature along Damascus Sulcus, the most active tiger stripe, was about 190 Kelvin (minus 120 degrees Fahrenheit). This temperature is slightly higher than the previous maximum temperatures measured by CIRS at Damascus, which were around 170 Kelvin (minus 150 degrees Fahrenheit).

The intensity of heat radiation, measured by CIRS at wavelengths from 7 to 9 microns, is color-coded, with blue, purple, red, orange and yellow denoting progressively more intense radiation, due to higher temperatures and/or larger expanses of warm material. The image is centered near 80 degrees South latitude and 315 degrees West longitude, and covers a region about 16 kilometers (10 miles) wide. The smallest details seen in the CIRS overlay are about 800 meters (0.5 miles) in size.

The region of peak temperature is sharply bounded by the sides of the trench. Thanks to its high resolution, the CIRS map also shows for the first time that the regions on either side of the central trench are also radiating heat (shown as blue strips flanking the central multicolored strip in this image). CIRS measured temperatures of about 120 Kelvin (minus 240 degrees Fahrenheit) in the flanking regions about 400 to 1,200 meters (a quarter to three-quarters of a mile) away from the central trench.

These data were obtained on August 13, 2010 as the south pole of Enceladus began to go into winter darkness.

Photo credit: NASA/JPL/GSFC/SWRI/SSI

Enceladus Tiger Stripe Hot Spots

This image shows a high-resolution heat intensity map of part of the south polar region of Saturn's moon Enceladus, made from data obtained by NASA's Cassini spacecraft.

The map reveals never-before-seen details of warm fractures that branch off like split ends from the ends of the main trenches of two "tiger stripes." The features nicknamed "tiger stripes" are long fissures that spray water vapor and icy particles. These two fissures, Cairo Sulcus (left) and Alexandria Sulcus (right), extend to the lower right, off the bottom of the image. The map also shows an intriguing isolated warm spot, shown in purple-red in the upper left of the image, that is separated from other active fissures.

The thermal data came from Cassini's composite infrared spectrometer during an August 13, 2010, flyby of Enceladus. Scientists overlaid the data on a background map of that region made from Cassini images taken in July 2005. The intensity of thermal radiation, measured at wavelengths from 12 to 16 microns, is color-coded, with dark blue, purple, red and orange denoting progressively more intense radiation, due to higher temperatures and/or larger expanses of warm material. The pale blue color indicates regions that were mapped but that were too cold to emit significant radiation. Alignment of the thermal map with the underlying base map is approximate. The map shows a region approximately 130 kilometers (80 miles) across.

These data were obtained as winter darkness began to engulf the south polar region of Enceladus. Away from the warm tiger stripes, which reach temperatures up to 190 Kelvin (minus 120 degrees Fahrenheit), Cassini measured surface temperatures near Enceladus' south pole as low as 52 Kelvin (minus 365 degrees Fahrenheit), and still colder temperatures are expected as winter advances. Scientists are still analyzing the data to calculate a temperature for the cross-cutting fractures and the isolated warm spot.

Image credit: NASA/JPL/GSFC/SWRI/SSI

Looming Enceladus

Small water ice particles fly from fissures in the south polar region of Saturn's moon Enceladus in this image taken during the August 13, 2010, flyby of the moon by NASA's Cassini spacecraft.

This view looks toward the night side of Saturn, which is in the lower left of the image. Enceladus, in the top right, is closer to the spacecraft than the planet is in this view. Sunlight scatters through the planet's atmosphere and forms the bright diagonal line running from the left to bottom right of the image. The atmosphere appears layered here. Scientists think the different layers on the limb are real and not an artifact of the camera's exposure.

The famous jets, imaged by Cassini's cameras for the first time in 2005, are faintly seen here erupting from the fractures that cross the south polar region of the moon.

Illuminated terrain seen on Enceladus is on the leading hemisphere of the moon, or the side facing forward in the moon's orbit around Saturn. North on Enceladus (504 kilometers, 313 miles across) is up. The jets appear faint here, but can be seen near the center of the image. See PIA11688 to learn more.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was obtained at a distance of approximately 59,000 kilometers (37,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 155 degrees. Image scale on Enceladus is 353 meters (1,157 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute