NASA's Cassini orbiter has captured another close-up view of the Saturnian moon Helene, clearing the way for a global map of the 20-mile-wide "ice queen."

The spacecraft got its latest look at the icy moon on Saturday from a distance of 4,330 miles (6,968 kilometers), more than a year after its closest-ever Helene flyby in March 2010. This time, the pictures provided sunlit views of the moon's Saturn-facing side, improving on last year's imagery. Taken together, these pictures will enable astronomers to finish a global map that could shed additional light on the grooved, pockmarked moon's impact history, NASA's Jet Propulsion Laboratory said in today's image advisory.

Helene sticks out among Saturn's more than 60 moons for a couple of reasons: First of all, it is gravitationally bound in the same orbit as another, much larger icy moon called Dione. This makes it one of four "Trojan moons" in the Saturnian system, along with Polydeuces (which is also bound to Dione) and Telesto and Calypso (both bound to Tethys).

Helene's surface also reveals a network of gully-like features that may have been created by landslides (or, in this case, dustslides or iceslides). Working up a detailed map of the moon should help astronomers get a better grip on the gullies' genesis.

For more about the latest flyby, check out this posting from the Planetary Society's Emily Lakdawalla. And for more about Saturn's moons, check out these recent reports:

• Scientists bid to float their boat on Titan's seas
• Enceladus sparks auroral show on Saturn
• Can you spot the Saturnian moons?
• A double scoop of Saturn's moons
• Slideshow: Cassini's greatest hits

You can connect with the Cosmic Log community by "liking" the log's Facebook page or following @b0yle on Twitter. Also, give a look to "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

NASA / JPL / Space Science Institute

The Saturnian moon Rhea stars in an image captured by the Cassini orbiter during a flyby on Tuesday, but several other moons play supporting roles, along with Saturn's nearly edge-on rings. The moon Dione is just below Rhea and just above the rings. Tethys is to the right of Rhea, below the ring plane. Epimetheus appears as a speck in space between Rhea and Tethys. And the shepherd moon Prometheus is barely visible as a bump in the rings, just to the right of Dione.

Raw images of Saturn's icy moon Rhea captured by NASA's Cassini spacecraft during this week's flyby are delighting space enthusiasts and scientists.

In the image above, Rhea takes center stage, though Saturn's rings and three other moons make a cameo appearance. Below Rhea, just above the rings, is Dione. The moon Tethys is the larger circle in the lower right, while Epimetheus is the smaller dot to the right of Rhea and Dione. If you look closely, Prometheus is barely distinguishable as a speck embedded in the rings to the right of Dione.

Other images from the flyby show Rhea's cratered and fractured surface up close, which will allow scientists studying the images to understand just how often meteoroids bombard Rhea:

The Cassini orbiter's wide-angle camera took this image of Rhea as it flew past at a distance of about 120 miles (200 kilometers) from the Saturnian moon's surface.

In addition, NASA noted in an image advisory, scientists using fields and particles instruments are looking through their data to see if they gleaned any more information about Rhea's thin oxygen-and-carbon-dioxide atmosphere and the interaction between Rhea and the particles within Saturn's magnetosphere.

The scientific value of the data aside, the Planetary Society's Emily Lakdawalla, says the raw images left her "drooling." For more views of the icy moon, check out her post here.

John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).

NASA / JPL / SSI

This false-color view of the Saturnian moon Rhea shows the side that always faces the ringed planet. The colors accentuate subtle differences in Rhea's icy surface, likely related to systematic regional changes in surface composition or the sizes and structures of the grains making up Rhea's icy soil.

Pictures from Rhea reveal the composition and structure of the icy Saturnian moon in festive colors of green, blue and 3-D red. They're a holiday gift from the scientists who work with the imagery beamed back to Earth by the Cassini orbiter.

"In celebration of the holidays, and to mark the end of another fabulous year in orbit around Saturn, the Cassini imaging team is releasing today some very high-resolution views of Saturn's moon Rhea, including a 3-D look at a tectonically fractured region showing cracks as deep as 2.5 miles," the imaging team's leader, Carolyn Porco of the Colorado-based Space Science Institute, said in an e-mail sent out today.

The team also put out a fresh batch of raw imagery acquired during Monday's flyby of Enceladus, another one of Saturn's icy moons. Enceladus has geysers of water ice spewing from fissures in its surface, and the latest pictures take advantage of backlighting from the sun to highlight the fountains rising into space.

NASA / JPL / SSI

An image of Enceladus taken by the Cassini orbiter during a Monday flyby shows backlit geysers of ice rising up from fissures on the moon's surface.

This week's flyby brought Cassini within 50 kilometers (31 miles) of Enceladus' surface. One particularly intriguing picture shows a dark view of the moon's rippled terrain, with those enigmatic fountains just over the horizon. The raw picture is covered with bright speckles, presumably due to radiation effects.

Cassini has produced plenty of pictures showing those rising columns of ice particles. Last month, Porco and her colleagues reported that a "phenomenal amount of heat" was emanating from the fissures as well. Such findings support the view that water or slush is being pushed up from below, most likely due to the moon's tidal flexing. If there's water and warmth beneath the surface, could there be life as well? That's a huge question that will have to be left for future space missions.

Saturn's moons in context
Meanwhile, astronomers are trying to put Saturn's various moons in their proper context. That's where the pictures of Rhea, taken during flybys in November of last year and March of this year, are coming in handy.

"Since NASA's Voyager mission visited Saturn, scientists have thought of Rhea and Dione as close cousins, with some differences in size and density," Cornell's Paul Helfenstein, an imaging team associate, said in today's image advisory. "The new images show us they're more like fraternal twins, where the resemblance is more than skin-deep. This probably comes from their nearness to each other in orbit."

A false-color image traces subtle variations in Rhea's reflectiveness, using shades of green and blue. One side of the moon always faces Saturn, and that's the side shown in the image released today (and displayed at the top of this item). The left half of the visible disk is the part that faces in the direction of Rhea's orbital motion around the planet, and the right half trails behind. Scientists believe the differences in surface appearance, seen so graphically in the false-color view, could be caused by meteoric debris slamming into one side of the moon as it moves in its orbit. Or it could be due to "magnetic sweeping," a process that occurs when ions trapped in Saturn's magnetic field strike Rhea's surface.

Scientists were hoping to find evidence of a wispy ring surrounding Rhea during the flybys, which came as close as 62 miles (100 kilometers). They had no such luck, but they did see a web of bright, wispy fractures that are similar to those spotted on a different area of the moon by the Voyager probes in 1980 and 1981.

Those wisps turn out to be exposures of bright ice along steep cliff walls, most likely formed by tectonic activity. Some of the imagery collected last year was processed to produce a high-resolution 3-D image, showing fractures and troughs cutting through two of the largest craters in the scene. Those craters have few smaller craters superimposed on top of them, suggesting that they're relatively young. That would imply that Rhea's tectonic stresses have been active relatively recently, at least in some areas.

NASA / JPL / SSI

A stereo image of Rhea's icy surface shows a trough and a fracture cutting through the crater on the left. Use red-blue glasses to see the stereo effect. Click to select a wider, higher-resolution view.

Cassini's science team members have used the imagery to improve their maps of Rhea — and still better maps are on the way.

"The 11th of January 2011 will be especially exciting, when Cassini flies just 76 kilometers (47 miles) above the surface of Rhea," Thomas Roatsch, an imaging team scientist based at the German Aerospace Center Institute of Planetary Research, said in the advisory. "These will be by far the best images we've ever had of Rhea's surface — details down to just a few meters will become recognizable."

More about Saturn's moons and the Cassini mission:

• Oxygen. CO2 found in Rhea's wispy atmosphere
• Space walnut created by moons crashing
• Possible ice volcano spied on Titan
• Slideshow: Cassini's greatest hits

Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).

NASA / JPL / GSFC / SWRI / SSI

A false-color temperature map indicates hot spots along fissures in the "tiger stripes" on Enceladus' surface. These are the "split ends" of the stripes known as Alexandria Sulcus and Cairo Sulcus.

Temperature readings from the Cassini orbiter support the view that warmth is welling up through cracks in the icy surface of Enceladus, one of Saturn's most intriguing moons.

The readings were taken by the 6.4-ton spacecraft's infrared spectrometer and high-resolution camera during an August flyby, and discussed today in a series of news releases and advisories. In an e-mailed alert, Cassini imaging team leader Carolyn Porco said a "phenomenal amount of heat is emerging" through the south polar fractures known as tiger stripes.

The hot spots might not sound all that hot: The warmest areas registered surface temperatures of 120 degrees below zero Fahrenheit, or 190 Kelvin. But Porco said that's staggeringly higher than the coldest temperatures in the south polar terrain, which dip as low as 365 degrees below zero F (52 Kelvin). She called particular attention to a warm fissure known as Damascus Sulcus.

NASA / JPL / GSFC / SWRI / SSI

This map of the Damascus fissure on Enceladus is color-coded to reflect temperature readings, with blue, purple, red, orange and yellow denoting progressively more intense thermal radiation.

The readings indicate that the relatively warm material cools off quickly as you look farther away from Damascus' central trench. The heat also varies dramatically within just a few miles running along the trench. An associate on the imaging team, Cornell University's Paul Helfenstein, was quoted as saying that the warm section of Damascus Sulcus "is among the most structurally complex and tectonically dynamic of the tiger stripes."

So what's behind the heating? Porco said it's "undoubtedly the result of the tidal flexing of Enceladus brought about by its orbital resonance with Dione," another one of Saturn's more than 60 moons. "However, details of this heating process are still unclear and are being studied at this very moment," she added.

The temperature-coded picture of the Alexandria and Cairo fissures reveals another intriguing feature: an isolated warm spot toward upper left, just beyond the fissures' "split ends."

"The ends of the tiger stripes may be the places where the activity is just getting started, or is winding down, so the complex patterns of heat we see there may give us clues to the life cycle of tiger stripes," said John Spencer, a Cassini team member based at the Southwest Research Institute in Boulder, Colo.

Previous observations from Cassini have confirmed that geysers of water ice are welling up from the tiger stripes. The latest views add to the evidence suggesting that water or slush is pushing up through the fissures. And if there's a hidden ocean of water beneath the surface ice, could there be life as well?

A definitive answer to that question will have to be left to follow-up space missions. The August flyby served as Cassini's last chance to observe the active south polar region in sunlight. NASA says it was also Cassini's last chance to do remote thermal sensing at Enceladus until 2015. "The geometry of the many flybys between now and 2015 will not allow Cassini to do thermal scans like theses, because the spacecraft will be too close to scan the surface and will not view the south pole," NASA said in today's advisory.

NASA / JPL / SSI

Small water ice particles fly from fissures in the south poar region of the Saturnian moon Enceladus in this image, taken by the Cassini spacecraft during an August flyby. This view looks toward the night side of Saturn, which is in the lower left of the image. Sunlight scatters through the planet's atmosphere, forming the bright diagonal line.

A particularly close flyby took place today, when Cassini came within 30 miles (48 kilometers) of Enceladus' surface. Images from that flyby should be coming down over the next few days.

Enceladus isn't the only Saturnian moon in Cassini's spotlight: Today the spacecraft's science team also released images of Tethys, another moon that was observed during an August flyby. Just last week, Rhea and its thin, oxygen-rich atmosphere were in the news. And over the past couple of days, Cassini has gotten some good looks at Hyperion, a moon that's 165 miles wide (266 kilometers wide) and shaped like a potato.

For much, much more about the recent revelations, check out NASA's Cassini mission webpage as well as the online home for Cassini's imaging team. And be sure to check out our "Best of Cassini" slideshow.

Connect with the Cosmic Log community by "liking" the log's Facebook page or following @b0yle on Twitter. 

NASA

The Cassini orbiter, shown here in an artist's conception, has gone into safe mode of operation in advance of a flyby of Titan.

Updated 6:25 p.m. ET Nov. 5

The Cassini orbiter has gone into a precautionary standby mode, a week in advance of a planned flyby of the Saturnian moon Titan, NASA reported Thursday.

Engineers at NASA's Jet Propulsion Laboratory said they don't expect Cassini to be back to normal in time for the Nov. 11 flyby, which was to focus on infrared mapping of the mysterious world's smoggy atmosphere. Scientists expected the bus-sized probe's camera to capture images of two prominent regions on Titan's surface, known as Shangri-La and Adiri.

NASA said Cassini entered safe mode at around 7 p.m. ET on Tuesday, curtailing the flow of science data and sending back only data about engineering and spacecraft health. Cassini is programmed to put itself in safe mode anytime it encounters a condition on the spacecraft that requires action from the folks at JPL's Mission Control in Pasadena, Calif.

"The spacecraft responded exactly as it should have, and I fully expect that we will get Cassini back up and running with no problems," Cassini program manager Bob Mitchell said in Thursday's mission status report. "Over the more than six years we have been at Saturn, this is only the second safing event. So considering the complexity of demands we have made on Cassini, the spacecraft has performed exceptionally well for us."

Since its launch in 1997, Cassini has put itself into safe mode a total of six times, NASA said.

The glitch was a downer for folks celebrating Deep Impact/EPOXI probe's successful flyby past Comet Hartley 2 earlier Thursday. "How I dread the words 'status report' from JPL," the Planetary Society's Emily Lakdawalla tweeted. But the status report added a bit of positive spin as well: "Cassini has 53 more Titan flybys planned in its extended mission, which lasts until 2017."

Update for 6:25 p.m. ET Nov. 5: During a follow-up phone call, Mitchell told me that engineers are "still looking at the data" to figure out exactly what was scrambled up in Cassini's electronic brain. But he has a pretty good idea what happened.

"We believe the cause is due to some data that got corrupted on its way from Earth to Saturn via the radio link," he said. "It was not a human error."

When Cassini came across the corrupted data, it went into safe mode, just as it's supposed to do. "The spacecraft is very tolerant of error," Mitchell said. "It'd be hard to break it."

But it takes a while to return the spacecraft to full operation after safing. Valves have been closed, science data traffic has been stopped, software flags have been set ... and Cassini's mission controllers have to make sure that the data corruption is completely fixed before they start up everything again. Otherwise the probe would merely return to safe mode.

In this case, mission team members concluded that the job could not be done in time for the Titan flyby, so instead they've decided to take advantage of the most opportune moment. The way it looks as of now, that moment will come on Nov. 24, when Cassini is due to start executing its next sequence of commands, Mitchell said.

More about Cassini:

• This is how Saturn's rings roll
• Slideshow: Cassini's greatest hits
• Titan may foreshadow Earth's desert future
• Visit Cassini at JPL | Cassini imaging team

Connect with the Cosmic Log community by "liking" the log's Facebook page or following @b0yle on Twitter. You can also check out "The Case for Pluto," Alan's book about the controversial dwarf planet and the search for new worlds.