One of Saturn's rings 'does housecleaning'
Astronomers claim to have found evidence that one of Saturn's rings does housecleaning, soaking up material gushing from the fountains on the outer planet's tiny ice moon Enceladus.Updated: Feb 17, 2008 12:29 IST
Astronomers claim to have found evidence that one of Saturn's rings does housecleaning, soaking up material gushing from the fountains on the outer planet's tiny ice moon Enceladus.
The NASA astronomers studied images from the Cassini spacecraft before reaching the conclusion.
According to lead astronomer William Farrell of NASA's Goddard Space Flight Centre in Greenbelt, "Saturn's A-ring and Enceladus are separated by 100,000 kilometres, yet there is a physical connection between the two.
"Prior to Cassini, it was believed that the two bodies were separate and distinct entities, but Cassini's unique observations indicate that Enceladus is actually delivering a portion of its mass directly to the outer edge of the A-ring."
In fact, this is the latest surprising phenomenon associated with the ice geysers of Enceladus to be discovered by the NASA astronomers.
Earlier, the geysers were found to be responsible for the content of the E-ring and the whole magnetic environment of Saturn was found to be weighed down by material spewing from Enceladus, which becomes plasma.
Now, the astronomers have found that the plasma, which creates a donut-shaped cloud around Saturn, is being snatched by the planet's A-ring, which acts like a giant sponge where the plasma is absorbed, the NASA said.
Shot from Enceladus' interior, the gas particles become electrically charged by sunlight and collisions with other atoms and electrons. Once charged, the particles feel magnetic force and are swept into the space around Saturn dominated by the planet's powerful magnetic field.
There, Saturn's magnetic field lines, bouncing back and forth from pole-to-pole, trap them. The fun ends, however, if their bouncing path carries them inward toward Saturn to the A-ring. There they stick, in essence becoming part of the ring.
"Once they get to the outer A-ring, they are stuck. This is an example of how Saturn's rings mitigate the overall radiation environment around the planet, sponging up low and high-energy particles," Farrell said.
The Cassini observations confirm a prediction by John Richardson and Slobodan Jurac of the Massachusetts Institute of Technology.
In the early 1990s, the Hubble Space Telescope observations revealed the presence of a large body of water related molecules in orbit about 240,000 km from the planet.
Richardson and Jurac modelled this water cloud and showed it could migrate inward to the A-ring.
"We relied on their predictions to help us interpret our data. They predicted it, and we were seeing it," are according to Farrell.