Cassini Spacecraft Photographs Three Saturn Moons

NASA'sCassini spacecraft swung by three Saturn moons in cosmic triple playand beamednew photos of the satellites home to Earth.

The newlyreleased photos from the flyby reveal the surfaces of Dione, EnceladusandTethys in intriguing detail. The images, taken between Aug.13-14,arestill in their raw form and have yet to be processed by Cassini missionscientists, yet still reveal the terrain of three very different Saturnmoons.[Newphoto of Saturn's moon Enceladus.]

One snapshotof Dione, taken Aug. 13 from 74,000 miles (119,000 km)away, shows themany craters pocking the moon's water-ice surface. Dione is about 700miles (1,120km) in diameter, and it orbits at 234,000 miles (377,000 km) fromSaturn—aboutthe same distance as our own moon is from Earth.

Tethysshares many characteristics with Dione; it's nearly the same size – 662miles (1,066km) across and is composed mostly of water ice. And like Dione, Tethysboasts arugged, crater-laden beauty, which the Cassinispacecraft captured inanother photo.

Cassini wasabout 24,000 miles (38,000 km) from the surface of Tethys when itphotographed Penelopecrater, which at 90 miles (150 km) wide is the moon'ssecond-largest crater.

Enceladus,however, is a different beast than Dione and Tethys entirely.

While alsocovered in water ice, Enceladus is only about 313 miles (505km) across,and it appears to be more geologically active than the other twosatellites.Previous Cassini flybys have spotted great geyser-like plumes of watervaporand organic particles venting from long fissures in Enceladus' surface.

On this mostrecent flyby Cassini was checking these fissures, which scientists havedubbed "tigerstripes," in Enceladus' southern polar region. Some of Cassini'spictureswere taken with an infrared camera, which mission scientists plan toanalyze tocreate temperature maps of the fissures.

In one setof observations, the Enceladusfissure DamascusSulcus standsout clearin visible and infrared views, Cassini mission managers said in astatement.

"Scientistsare still analyzing the results," they added.Other visible light photosdon'thighlight the fissures, but they do yield a good look at Enceladus,which mayhave a liquid interior, researchers have said. In one view, a shadowyEnceladusappears to hover over the bright limb of Saturn.

TheEnceladus snapshots were taken from a range of 24,000 miles and 36,500miles (39,000-59,000km).

The Cassiniprobe launched in 1997 and arrived at Saturn in 2004. Cassini alsodropped theHuygens probe onto the surface of Titan, thelargest of Saturn's morethan 60 known moons and a body that some scientists think might becapable ofsupporting Earth-like life.

Cassini hasswooped by Titan several times before, most recently in June. Thecloud-coveredmoon is the target of the probe's next photo-op flyby, scheduled forSept. 24.

TheCassini-Huygens mission is a joint effort of NASA, the European SpaceAgencyand the Italian Space Agency. Though initially slated to bedecommissioned nextmonth, its activities have been extended through 2017. 

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Mike Wall
Senior Space Writer

Michael Wall is a Senior Space Writer with and joined the team in 2010. He primarily covers exoplanets, spaceflight and military space, but has been known to dabble in the space art beat. His book about the search for alien life, "Out There," was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Michael on Twitter.