Spectacular view of Saturn's moon Dione captured as Cassini probe hurtles past (DailyMail)

By ROB WAUGH
Daily Mail
May 22, 2012

The robotic Cassini spacecraft captured a spectacular view of Saturn's moon Dione on its closest-ever fly-past - and caught two of the ringed planet's 62 other moons in the background.

The picture, shown off this week on Nasa's Astronomy Picture of the Day site, shows off Epimetheus and Prometheus, as well as the snow-white surface of the 680-mile-wide moon Dione, where oxygen was detected by the probe on an earlier fly-past.

The robotic Cassini spacecraft captured a spectacular view of Saturn's moon Dione on its closest-ever fly-past - and caught two of the ringed planet's 62 other moons in the background. Photo credit: DailyMail/NASA/JPL/ESA

The image was taken when Cassini was only about 62,000 kilometers from the large icy moon last year.

The probe was launched in 1997, and continues its mission - it will fly past Titan tomorrow, and later this year will take a picture of Earth passing behind Saturn in June.

Dione has become an object of particular interest to the Cassini mission since oxygen was detected in its upper atmosphere.

The discovery was made by instruments on board the Cassini spacecraft, launched in 1997, and relayed back to scientists at the Los Alamos National Laboratory in New Mexico.

A sensor aboard the Cassini spacecraft called the Cassini Plasma Spectrometer detected the oxygen ions during a flyby of the moon in 2010.


Dione: Oxygen was found in the iccy moon's atmosphere by instruments on board the Cassini spacecraft, launched in 1997, and relayed back to scientists at the Los Alamos National Laboratory in New Mexico. Photo credit: DailyMail/NASA/JPL/ESA

Dione - discovered in 1684 by astronomer Giovanni Cassini, after whom the spacecraft was named, orbits Saturn at roughly the same distance as our own moon orbits Earth.

The tiny moon is a mere 700 miles wide and appears to be a thick, pockmarked layer of water ice surrounding a smaller rock core.

As it orbits Saturn every 2.7 days, Dione is bombarded by charged particles (ions) emanating from Saturn’s very strong magnetosphere.

These ions slam into the surface of Dione, displacing molecular oxygen ions into Dione’s thin atmosphere through a process called sputtering.

Molecular oxygen ions are then stripped from Dione’s exosphere by Saturn’s strong magnetosphere.

Read more:
Spectacular APOD Image of Saturn's Moon Dione

Could the seas of Saturn`s moon Titan harbor life?

By Alan Boyle

MSNBC Cosmic Blog

November 28, 2011

This infrared image from the Cassini orbiter shows the hydrocarbon lake known as Kraken Mare toward the northern edge of the disk. The dark Senkyo sand sea dominates the central area of the image. -NASA / JPL-Caltech / SSI

A fresh photo from the Cassini orbiter shows the hydrocarbon-rich seas and dunes of Titan, a Saturnian moon that might be capable of sustaining life as we don't know it.

The picture, published today on the websites of NASA's Saturn mission and Cassini's imaging team, shows the huge sea known as Kraken Mare as a dark spot on the northern edge of Titan's disk. The dark Senkyo dune field is front and center. Cassini's narrow-angle camera captured the view in near-infrared wavelengths from a distance of 1.2 million miles (1.9 million kilometers) on Sept. 14.

Titan is totally shrouded in smog, but Cassini's camera filters are set up to pierce through the haze and spot details on the surface below. The cold condtions on the moon are such that hydrocarbons such as ethane and methane can exist in liquid form. This rare picture from Cassini shows the glint of sunlight off the sheen of Kraken Mare, which is larger than the Caspian Sea on Earth. (And yes, Kraken is named after the mythical sea creature. "Mare" is Latin for "sea.")

This image, obtained using Cassini's Visual and Infrared Mapping Spectrometer, shows the first observed flash of sunlight reflected off a lake on Saturn's Titan moon. -NASA/JPL

Titan's seas, lakes and rivers of hydrocarbons are among the reasons why the murky Saturnian moon ranks higher than Mars on a recently published list assessing planetary habitability. That may sound strange, considering that the typical temperature on Titan is 289 degrees below zero Fahrenheit (-178 degrees Celsius). But Dirk Schulze-Makuch, an astrobiologist at Washington State University who helped put together the list, told me that it makes sense to rank Titan as the top prospect for extraterrestrial habitability.

"If you think about it, Titan has a thick protective atmosphere like Earth's, similar to the early Earth atmosphere," he said. "It has a lot of nitrogen and methane in it, and...

(Click here to read the full article)

Additional Resources:

Cassini image confirms liquid on Saturn moon:
Reflection off Titan lake is the first seen on a world other than Earth -MSNBC