Image: Dione and Saturn
NASA / JPL / SSI / Emily Lakdawalla
This wide-angle view from NASA's Cassini probe shows the Saturnian moon Dione set against the giant planet's disk and rings on May 2. Dark shadows from the edge-on rings fall on Saturn's cloud tops in this color composite view, assembled by the Planetary Society's Emily Lakdawalla.
updated 5/4/2012 8:36:16 PM ET 2012-05-05T00:36:16

NASA's Cassini spacecraft zoomed by two Saturn moons this week to take what scientists say are the last close-up views of the geyser-covered Enceladus and cratered Dione for several years.

Cassini made the two-moon rendezvous on Wednesday, creeping within 46 miles (74 kilometers) of icy Enceladus before zooming by Dione at a distance of 5,000 miles (8,000 km), NASA officials said in a statement. Raw photos from the Saturn moon flybys reveal Enceladus as a slender crescent, while Dione appears as a battered and bruised body.

"The flybys were the last close encounters of these icy moons that Cassini will make for three years," Cassini mission scientists wrote in the update.

NASA / JPL / Space Science Institute
The camera was pointed at Dione, about 8,416 kilometers away, and the image was taken using the CL1 and CL2 filters. This image has not been validated or calibrated.

The main goal of Wednesday's swing by Enceladus, a Saturn moon known for its geysers of water ice and vast fissures, was to study the moon's gravitational field using Cassini's radio science instruments. But mission scientists did not let the flyby go without a photo session. [ More photos of Enceladus ]

During its approach to Enceladus, Cassini's cameras snapped new photos of the spectacular plume of water ice erupting from the moon's south pole. The geysers on Enceladus were first discovered by Cassini in 2005 and have been a target for researchers ever since.

The eruptions produce a plume of water ice, water vapor and organic compounds through vast cracks in Enceladus' ice-covered surface. The geysers are so prolific that Cassini's cameras were able to see the plume from distances of between 259,000 miles (416,000 km) to 66,000 miles (106,000 km) from the moon.

Cassini's radio science team also hoped to probe the interior of Enceladus during the flyby to determine if the moon is hiding pockets of liquid water at its south pole, or if some warmer-than-average ice could be responsible for the geysers.

After the Enceladus flyby, Cassini turned its cameras on Dione even though a close study of that moon wasn't initially planned. Despite the vast distance, Cassini managed to create several photo mosaics to reveal amazing views of Dione, including a detailed look at a huge crack in the moon's surface known as Latium Chasma, according to a photo description.

Image: Enceladus
NASA / JPL / Space Science Institute
This raw, unprocessed image was taken by NASA's Cassini spacecraft on Wednesday. The camera was pointing at Enceladus, about 239,799 miles (385,919 kilometers) away. The moon's geysers of ice crystals are backlit by the sun.

"Other mosaics cover much of Dione's northern hemisphere that faces away from Saturn in its orbit, focusing particularly on the moon's ridges, an ancient impact basin and the wispy streaks that Cassini scientists now know are tectonic fractures," NASA officials said.

The Enceladus and Dione flybys are not the only Saturn moon encounters for Cassini in May. Later this month, on May 22, Cassini will fly by Titan, Saturn's largest moon.

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The Cassini mission is a collaborative project involving NASA, the European Space Agency and the Italian Space Agency.

The spacecraft launched in 1997 and arrived at Saturn in 2004. In early 2005, Cassini released the Huygens lander, an ESA probe, which touched down on Titan to relay the first photos ever from the surface of that cloud-covered moon.

Thanks to the Planetary Society's Emily Lakdawalla for sharing her color composite image of Dione and Saturn, assembled from Cassini imagery in infrared, green and violet wavelengths. Check out Lakdawalla's blog post for more about how the color image was created.

Follow Space.com for the latest in space science and exploration news on Twitter @Spacedotcom  and on Facebook.

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Photos: Best of Cassini

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  1. Starring Saturn

    This backlit view of Saturn was voted the favorite image to come from the Cassini orbiter - and it has been described as "perhaps the most stunning photograph ever taken." The image, captured on Sept. 15, 2006, shows two faint rings that were discovered by the Cassini team. And at the highest resolution, Earth itself appears as a pale blue dot just to the left of the brightest rings, at about the 10 o'clock position. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  2. Dark rings

    An infrared image from the Cassini orbiter, acquired May 24, 2007, reveals clouds beneath the hazes in Saturn's atmosphere, as well as the unilluminated side of the giant planet's rings. The shadows of the rings fall upon the planet's cloud layer. This image shares the honors as the favorite black-and-white picture from Cassini. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  3. Abstract art

    A Cassini image from May 10, 2006, shows the shaded edge of Saturn's disk, rounded by dark rings seen nearly edge-on. The crescent disk of Titan, Saturn's largest moon, can be seen in the background beyond the rings. This image shares the honors as the favorite black-and-white image from Cassini. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  4. Pearly moons

    Two of Saturn's moons - Tethys and Enceladus - look like pearls backdropped by the planet's disk in this image, captured on July 24, 2007. The thin "string" connecting the pearls is actually the plane of the planet's rings, seen edge-on. The rings cast a dark shadow on Saturn's disk. Two other moons appear in this image, although they can barely be made out at the highest resolution: Hyperion is near the lower left corner of the image, and Epimetheus is the slightest of specks between Tethys and Enceladus. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  5. Saturn from on high

    The Cassini spacecraft provides a high-contrast view of Saturn and its rings, as seen from above. This portrait is actually a mosaic of 36 images taken on Jan. 19, 2007, from about 40 degrees above the plane of the rings. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  6. Shadows on clouds

    Saturn's darkened rings cast shadows on the planet's blue and gold cloud tops, while the moon Dione hangs like a dot in the black sky beyond. This image was taken by the Cassini spacecraft on Feb. 4, 2007, from a distance of about 800,000 miles. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  7. View from below

    Cassini coasts beneath giant Saturn, staring upward at its gleaming crescent and icy rings. A great bull's-eye pattern is centered on the south pole, where a vast, hurricane-like storm spins. This view, obtained on Jan. 30, 2007, looks toward the lit side of the rings from about 26 degrees below the ring plane. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  8. Pastel planet

    Dark and sharply defined ring shadows appear to constrict the flow of color from Saturn's warmly hued south to the bluish northern latitudes. Scientists studying Saturn are not yet sure about the precise cause of the color change from north to south. The different colors may be due to seasonal effects on the atmosphere. The images that went into this mosaic were obtained by the Cassini spacecraft on Feb. 4, 2007. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  9. Ringing success

    This ultraviolet image from the Cassini spacecraft shows the detailed composition of Saturn's outer C and inner B rings from left to right, with the inner B ring beginning a little more than halfway across the image. The general pattern is from "dirty" red particles to the denser ice shown in turquoise as the ringlets spread outward. (University Of Colorado, LASP / AP) Back to slideshow navigation
  10. A is for amazing

    This ultraviolet image shows the A ring, beginning with a 'dirty' interior of red followed by a general pattern of more turquoise as it spreads away from the planet, indicating a denser material made up of ice. The red band roughly three-fourths of the way outward in the A ring is known as the Encke gap. (University Of Colorado, LASP - NASA / Reuters) Back to slideshow navigation
  11. Casting a shadow

    This image taken by Cassini shows the planet Saturn casting a shadow over its rings. (NASA - JPL - Caltech / Reuters) Back to slideshow navigation
  12. Titan revealed

    This is an infrared image of Titan, one of Saturn's moons, mapping the surface hidden beneath the moon's opaque atmosphere. Green areas represent water ice, while yellow areas have higher concentrations of hydrocarbons. The white spot is a methane cloud. (NASA) Back to slideshow navigation
  13. Ripples in the ring

    Scallops in the ring on the left side of this image were likely caused by a Saturnian moon rolling along the edge. One bright ringlet is visible within the gap, and at least one other faint ringlet can be made out. "This is textbook ring physics, right there, in one image," says Cassini imaging team leader Carolyn Porco. (NASA - SSI) Back to slideshow navigation
  14. Wisps in space

    A close-up of one of Saturn's rings shows a wispy pattern of ripples that may have been stirred up by a moonlet's orbit. Such unprecedented views of ring details are possible because of the Cassini camera's resolution. (NASA TV) Back to slideshow navigation
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