Cruising past Saturn's moon Dione this past weekend, NASA's Cassini spacecraft got its best look yet at the north polar region of this small, icy moon and returned stark raw images of the fractured, cratered surface.

The new images also show new views of the long, bright canyon ice walls, which scientists working with NASA's Voyager spacecraft called "wispy terrain" in the early 1980s. These ice walls thread along the surface of the moon's trailing hemisphere and cut across craters.

The following new images taken by the Imaging Science Subsystem (ISS) on the Cassini spacecraft are now available:

• Tethys Before Titan (Released 30 August 2010)
  Terrain on Saturn's moon Tethys, defined with craters, is shown in front of the hazy atmosphere of the larger moon Titan in this Cassini spacecraft image.
• 'Fan' Spread (Released 31 August 2010)
  Cassini spies a "fan" in Saturn's tenuous F ring.
• Crescent Dione (Released 1 September 2010)
  A thin crescent of cratered terrain is illuminated on Saturn's third largest moon, Dione.
• Beyond Curved Rings (Released 2 September 2010)
  Saturn's rings appear curved in this view, which also shows the moon Janus in the distance.
• High-Phase Plumes (Released 3 September 2010)
  Enceladus imaged at high phase, shows off its spectacular water ice plumes emanating from its south polar region./li>

The following new images taken by the Imaging Science Subsystem (ISS) on the Cassini spacecraft are now available:

• Smooth Telesto (Released 23 August 2010)
  The smooth surface of Saturn's moon Telesto is documented in this image captured during the Cassini spacecraft's Aug. 27, 2009, flyby.
• Activity Past Dark Side (Released 24 August 2010)
  Saturn's moon Enceladus, seen beyond the outline of the planet's night side, spews water ice from its south polar region.
• Infringing Darkness (Released 25 August 2010)
  Some of Iapetus' dark surface interrupts the moon's lighter terrain.
• A-ring Propeller (Released 26 August 2010)
  A propeller-shaped structure, created by an unseen moon, can be seen in Saturn's A ring.
• Narrow Band (Released 27 August 2010)
  The shadows of Saturn's rings cast onto the planet appear as a thin band at the equator in this image taken as the planet approached its August 2009 equinox.

The following new images taken by the Imaging Science Subsystem (ISS) on the Cassini spacecraft are now available:

• Spoke Embellishment (Released 16 August 2010)
  Bright spokes grace Saturn's B ring in this Cassini spacecraft snapshot that also features a couple of the planet's moons large and small.
• Epimetheus Close-Up (Released 17 August 2010)
  Cassini snapped this high-resolution image of Saturn's small moon Epimetheus during the spacecraft's non-targeted flyby on April 7, 2010.
• Vast Saturn (Released 18 August 2010)
  The immense size of Saturn is emphasized in this portrait that features the moon Mimas shown in front of the planet.
• Cratered Rhea (Released 19 August 2010)
  Cassini looks to the cratered surface of Saturn's second largest moon, Rhea.
• Shadow Before Equinox (Released 20 August 2010)
  Saturn's moon Prometheus casts a long shadow across the A ring in the middle-right side of this image taken shortly before the planet's August 2009 equinox.

Saturn's moon Titan ripples with mountains, and scientists have been trying to figure out how they form. The best explanation, it turns out, is that Titan is shrinking as it cools, wrinkling up the moon's surface like a raisin.

A new model developed by scientists working with radar data obtained by NASA's Cassini spacecraft shows that differing densities in the outermost layers of Titan can account for the unusual surface behavior. Titan is slowly cooling because it is releasing heat from its original formation and radioactive isotopes are decaying in the interior. As this happens, parts of Titan's subsurface ocean freeze over, the outermost ice crust thickens and folds, and the moon shrivels up. The model is described in an article now online in the Journal of Geophysical Research.

The following new images taken by the Imaging Science Subsystem (ISS) on the Cassini spacecraft are now available:

• Spokes Before Night (Released 9 August 2010)
  Bright spokes can be seen on Saturn's B ring just in front of the shadow cast on the rings on the night side of the planet in this Cassini spacecraft image.
• Atmospheric Aspects (Released 10 August 2010)
  Cassini examines the characteristics of Titan's atmosphere as it peers at Saturn's largest moon using a filter sensitive to visible violet light.
• Rhea, Rings and Shadow (Released 11 August 2010)
  Saturn's moon Rhea is gently lit in front of a background of the planet with a wide shadow cast by the rings which are seen nearly edge-on.
• Yin and Yang (Released 12 August 2010)
  With its light and dark surface, Iapetus appears almost like a yin and yang symbol or a comma punctuation mark in this image.
• Closest Daphnis (Released 13 August 2010)
  Cassini captures here one of its closest views of Saturn's ring-embedded moon Daphnis.

The following new images taken by the Imaging Science Subsystem (ISS) on the Cassini spacecraft are now available:

• Beyond Saturn's South (Released 2 August 2010)
  Looking up toward Saturn's southern hemisphere, Cassini pictures a pair of the planet's moons orbiting in the distance.
• Flying by Pandora (Released 3 August 2010)
  Cassini captured this close view of Saturn's moon Pandora during the spacecraft's flyby on June 3, 2010.
• Pan in Action (Released 4 August 2010)
  Saturn's small, ring-embedded moon Pan, on the extreme right of this Cassini image, can be seen interacting with the ringlets that share the Encke Gap of the A ring with this moon.
• Black Blemish (Released 5 August 2010)
  A crescent Saturn is blemished by the black spot of its moon Dione seen orbiting between the planet and the Cassini spacecraft.
• Orbiting in Its Ice (Released 6 August 2010)
  As Enceladus spews water ice from its south polar region, Cassini chronicles the moon creating Saturn's faint E ring, in which the moon orbits.

Something unknown is causing a strange, symmetrical structure in the charged-particle environment around Rhea, Saturn's second-largest moon. But contrary to 2008 reports, it's not a system of rings.

Using NASA's Cassini spacecraft, a team of astronomers led by Cornell research associate Matthew Tiscareno searched for narrow rings, broad rings and any material from dust to giant boulders that might be orbiting the 1,500 km- (950 mile)-wide moon.

The answer to the mystery of dune patterns on Saturn's moon Titan did turn out to be blowing in the wind. It just wasn't from the direction many scientists expected.

Basic principles describing the rotation of planetary atmospheres and data from the ESA's Huygens probe led to circulation models that showed surface winds streaming generally east-to-west around Titan's equatorial belt. But when NASA's Cassini spacecraft obtained the first images of dunes on Titan in 2005, the dunes' orientation suggested the sands -- and therefore the winds -- were moving from the opposite direction, or west to east.

The following new images taken by the Imaging Science Subsystem (ISS) on the Cassini spacecraft are now available:

• Fleeing the Scene (Released 26 July 2010)
  Saturn's moon Prometheus, having perturbed the planet's thin F ring, continues in its orbit.
• Wider Shadow (Released 27 July 2010)
  The shadow of Saturn's rings grows wider on the planet as the planet moves away from its August 2009 equinox, when the rings cast a pencil-thin shadow.
• Chasma Crescent (Released 28 July 2010)
  Sunlight illuminates the deep cut of Ithaca Chasma on Saturn's moon Tethys.
• The Mimas Atlas (Released 28 July 2010)
  Presented here is a complete set of cartographic map sheets from a high-resolution atlas of Saturn's moon Mimas.
• Rhea Past Rings (Released 29 July 2010)
  The Cassini spacecraft looks past Saturn's rings and small moon Janus to spy the planet's second largest moon, Rhea.
• Pushing and Pulling (Released 30 July 2010)
  Rather than being an unchanging disk of peaceful particles, the material that makes up Saturn's rings is constantly pushed and pulled into spectacular shapes.

The following new images taken by the Imaging Science Subsystem (ISS) on the Cassini spacecraft are now available:

• Upstart Moon (Released 19 July 2010)
  The smaller moon Mimas upstages the larger moon Dione as the dramatic Herschel Crater is spotlighted on Mimas.
• Only Half the Rings (Released 20 July 2010)
  Saturn's moon Janus orbits in front of the rings, which are partially darkened by the shadow of the planet.
• Sliver of Iapetus (Released 21 July 2010)
  The Cassini spacecraft looks toward a crescent of Saturn's moon Iapetus and glimpses a bit of that moon's yin-yang appearance.
• Before Immense Saturn (Released 22 July 2010)
  The moons Mimas and Janus seem insignificant in front of the immensity of Saturn.
• Chunks of Ice (Released 23 July 2010)
  A pair of Saturn's small, icy satellites accompany the planet's rings.

NASA's Mars Odyssey orbiter put itself into a safe standby mode on Wednesday, July 14, and the team operating the spacecraft has begun implementing careful steps designed to resume Odyssey's science and relay operations this week.

Engineers have diagnosed the cause of the safe-mode entry as the spacecraft's proper response to unexpected performance by an electronic encoder. That encoder controls motion of a gimbal that adjusts the position of the solar array. Odyssey switched to a redundant encoder, and there is no sign of any mechanical problem with the gimbal.

While orbiting Saturn for the last six years, NASA's Cassini spacecraft has kept a close eye on the collisions and disturbances in the gas giant's rings. They provide the only nearby natural laboratory for scientists to see the processes that must have occurred in our early solar system, as planets and moons coalesced out of disks of debris.

New images from Cassini show icy particles in Saturn's F ring clumping into giant snowballs as the moon Prometheus makes multiple swings by the ring. The gravitational pull of the moon sloshes ring material around, creating wake channels that trigger the formation of objects as large as 20 km (12 miles) in diameter.

The following new images taken by the Imaging Science Subsystem (ISS) on the Cassini spacecraft are now available:

• Flying by Dione (Released 12 July 2010)
  Wispy terrain stretches across the trailing hemisphere of Saturn's moon Dione on the right of this Cassini image taken during the spacecraft's flyby on April 7, 2010.
• Prometheus Amid Rings (Released 13 July 2010)
  Saturn's small, potato-shaped moon Prometheus orbits between the main rings and the thin F ring in this Cassini view.
• Melanthius on Tethys (Released 14 July 2010)
  Cassini looks toward an area between the trailing hemisphere and anti-Saturn side of Tethys and spies the large crater Melanthius near the moon's south pole.
• Quarter Saturn (Released 15 July 2010)
  Roughly a quarter of majestic Saturn is illuminated in this view captured while Cassini was orbiting near the planet's equatorial plane.
• Study in Contrasts (Released 16 July 2010)
  Crisp details on Dione contrast with the haziness of Titan in this Cassini image of a pair of Saturn's moons.

On Earth, lake levels rise and fall with the seasons and with longer-term climate changes, as precipitation, evaporation, and runoff add and remove liquid.

Now, for the first time, scientists have found compelling evidence for similar lake-level changes on Saturn's largest moon, Titan -- the only other place in the solar system seen to have a hydrological cycle with standing liquid on the surface.