NASA Finds Saturn Moons Might Be Creating New Rings
Washington – Scientists involved in the Cassini-Huygens mission are looking for the missing moons of Saturn.
A recent observation by the Cassini spacecraft leads them to believe that they will find the moons near newly discovered rings around the planet, according to an October 11 press release from the NASA Jet Propulsion Laboratory in California.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and Agenzia Spaziale Italiana, the Italian space agency.
With the sun poised behind Saturn, Cassini scientists took advantage of a rare observational opportunity to discover two new rings and confirm the presence of two others. The new rings are associated with one or more small moons and share their orbits with the moons. Scientists suspect another moon is hiding near a third ring.
"We are hot on the trail of these possible elusive moonlets," said Joe Burns, Cassini imaging scientist at Cornell University in New York. "Finding the moons and learning about their interactions with the rings will help us understand how the moons formed and perhaps how the Saturn system formed."
Under the cover of Saturn's shadow in mid-September, the entire ring system became visible and never-before-seen microscopic particles began to appear.
A single, faint new ring at the orbits of two moonlets, Janus and Epimetheus, was discovered. A second ring was found a week later. It is narrow and overlies the orbit of the tiny moon Pallene, which Cassini discovered in 2004. Third and fourth rings are visible in the Cassini Division, the big gap in Saturn's main ring system.
The rings have letter names in order of their discovery. Moving out from the planet, the main rings are C, B and A. The Cassini Division is the largest gap in the rings and separates rings B and A. The D ring is very faint and closest to the planet. The F ring is a narrow feature just outside the A ring. Beyond that are two far-fainter rings, G and E.
When viewed by Cassini's infrared instrument, one of the rings in the Cassini Division has unusual coloring and brightening, a trait it shares with fresh, faint rings like the F ring, or those in a feature called the Encke Gap in Saturn's outer A ring.
Saturn's smallest moons have weak gravity and cannot retain loose material on their surfaces. When these moons are struck by rapidly moving interplanetary meteoroids, this loose material is blasted off their surfaces and into Saturn’s orbit, creating diffuse rings along the moons' orbital paths.
Collisions among several moonlets, or clumps of boulder-sized rubble, also might lead to debris trails. For instance, Saturn's G ring seems not to have any single moon large enough to see; it might have formed from a recent breakup of a moon.
The full text of the press release is available at the NASA Web site.