Saturn Moon Ready for its Close-Up

Author:  Phillips Veronica

Date:  September 2007

NASA, in collaboration with the European Space Agency and the Italian Space Agency, took the next step in the Cassini-Huygens mission by commencing a flyby of Saturn's icy moon, Iapetus,100 times closer than its previous flyby three years ago. Radar images gathered from this flyby, the first by Cassini of an icy moon other than Titan, will help scientists learn to interpret surface features of an icy body with the aid of supplemental ultraviolet or visual light images.

"What is really neat is that we are doing radar of an icy object for which we actually have pictures," said Steve Ostro, a radar scientist for the Jet Propulsion Laboratory (JLP) in Pasadena, California, where the Cassini orbiter was designed.

NASA hopes that the interpretations of these radar images will help them to understand the surface of cloud-covered Titan, on which visibility is limited.

But before any observations can be applied to Titan, they must first attempt to make sense of Iapetus' unusual terrain. The walnut-shaped moon features a topographically distinct range of mountains all the way around its equator as well as a strange dichotomy between the brightness of its leading and trailing hemispheres.

There are many theorists trying to explain why the leading hemisphere is completely white while the trailing one is equally dark, but most are concerned with the origin of the dark material. The reddish tint to this material, also found on other moons of the Saturn system, may help trace its origin, according to Amanda Hendrix, also part of the JLP.

Other findings by Dale Cruikshank and his colleagues, part of NASA's Ames Research Center, suggest that this dark material may contain complex chemicals called polycyclic aromatic hydrocarbons. These chemicals have been found all over the universe,from comets to stardust coalescing into planets,and appear to play a key role in the origin of life.

The multiple instruments of the Cassini probe will also attempt to characterize the surface chemical composition of Iapetus, in addition to searching for an atmosphere or eruptions of gas on the surface and mapping the nighttime surface temperature.

Clearly, this flyby will yield a wealth of information on Iapetus for scientists to interpret. This knowledge may also help scientists understand one of Saturn's other moons, Titan, which presently holds much interest in the scientific community.

Author: Veronica Phillips

Reviewed by: Minnie Rai

Published by: Konrad Sawicki