March 27, 2013
Cassini Shows Saturn As The Solar System’s Antique Shop
Lee Rannals for redOrbit.com — Your Universe Online
NASA's Cassini spacecraft has unveiled new data about how Saturn's moons and rings are like an antique shop.
Gianrico Filacchione, a Cassini participating scientist at Italy's National Institute for Astrophysics, Rome, published a paper online in The Astrophysical Journal about how Saturn's moons and rings are gently worn, vintage goods from around the time of our solar system's birth. He suggests these bodies date back more than four billion years, and that they are from around the time that the planetary bodies in our neighborhood began to form.
"Studying the Saturnian system helps us understand the chemical and physical evolution of our entire solar system," said Filacchione. "We know now that understanding this evolution requires not just studying a single moon or ring, but piecing together the relationships intertwining these bodies."
Cassini's visual and infrared mapping spectrometer (VIMS) helped reveal how water ice and also colors are distributed throughout the Saturnian system. The data from this instrument show that coloring on the rings and moons generally is only skin-deep.
VIMS also detected an abundant amount of water ice, too much to have derived from comets. The researchers determined the water ice means it must have formed around the time of the birth of the solar system.
Scientists also found farther out that the surface of Saturn's moons generally were redder the further they orbited from the planet. Phoebe, one of Saturn's outer moons, is shedding reddish dust that eventually goes to the surface of nearby moons.
Meteoroids outside the system appear to have turned some parts of the main ring system a subtle reddish hue. Scientists believe this reddish color could be oxidized iron or polycyclic aromatic hydrocarbons.
NASA said one of the biggest surprises from the research was the similar reddish coloring of the potato-shaped moon Prometheus and nearby ring particles.
"The similar reddish tint suggests that Prometheus is constructed from material in Saturn's rings," said co-author Bonnie Buratti, a VIMS team member based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Scientists had been wondering whether ring particles could have stuck together to form moons -- since the dominant theory was that the rings basically came from satellites being broken up. The coloring gives us some solid proof that it can work the other way around, too."
Linda Spilker, a Cassini project scientist based at JPL, said observing the rings and moons with Cassini gives scientists a look at the intricate processes at work in the Saturn system, and perhaps in the evolution of planetary systems.
Cassini is a veteran spacecraft that has led to a plethora of knowledge about Saturn and its moons. The spacecraft has also taken some spectacular images as well. Earlier this month, NASA released a photo of Saturn's moon Rhea taken by Cassini. The picture was from the last close flyby of Rhea in Cassini's mission. Cassini is measuring the gravitational pull of Rhea to help scientists understand whether the moon is homogenous all the way through or whether it has differentiated into the layers of core, mantle or crust.