Follow this link to skip to the main content

International Edition Winners 2011: Australia, Target 2

International Edition Winners 2011: Australia, Target 2



Alicia Chen
Rhea and Titan
Rhea and Titan
Alicia Chen

Year 10
Genazzano FCJ College
Kew, Victoria






"Rhea and Titan, Saturn’s two largest moons, are the best choice for observations when the next flyby occurs. They are both peculiar moons that are surrounded by infinite mysteries that should be further investigated and studied. A few of the many reasons as to why we should focus on target 2 include the possibility of life on Titan, cause of “wispy” formations on Rhea’s surface and comparison of the two moons’ atmosphere. By studying Rhea, we can also relate to Dione and Tethys due to their similarity in size and structure.

Titan is the only moon in the solar system that possesses a dense atmosphere (10 times denser than Earth’s). This dense atmosphere is rich in organic compounds, which if were on Earth, would be signs of life. Organic compound is the result of sunlight breaking down methane. If sunlight is continuously breaking down methane, how is methane getting into the atmosphere? On Earth today, life is what rejuvenates methane supply. Methane is a by-product of the metabolism of many organisms. The wispy blue haze that surrounds Titan is made up of broken-down methane. If methane is raining down on to the surface and is still being broken down by UV light form the sun to cover the entire moon, then there must be a source of methane. According to titan’s moment of inertia, there is no way that this planet is uniformly solid. This brings about whether or not Titan has a subsurface ocean, perhaps consisting of methane. Because of its temperature, Titan is too cold for liquid water to exist and all known forms of life require liquid water. It was to have thought that long ago, the impact of a meteorite could’ve have provided enough heat to liquefy water, perhaps even to sustain life. Could life have existed on Titan? By focusing on Titan, perhaps answers to these questions could be found.

Rhea is Saturn’s second largest moon and is an intriguing target because of its light mass compared to its size. Its density is slightly lower about 1.233 g/cm³., but still greater than that of most Saturnian moons, indicating that it is made mostly of ice, but has a substantial minority of heavier materials; ¾ water and ¼ rock . Where did this large amount of water come from?

Rhea has two areas based on the crater density, they are known as the light area and the dark area. The light area is covered by larger craters and is constantly facing Saturn like how our moon is always facing earth. This suggests that a major resurfacing event occurred sometime during its formation. What was this supposed event that occurred? Could Rhea have been tectonically active once upon a time?

The surface of Rhea is shrouded in wispy formations. This questions the cause of these formations, which are also found on Dione. Where was the initial starting point of these formations? In which direction were these fissures headed? Could this link back to the law of physics to find a connection with Saturn and its influence over this moon?

Another major question is whether or not Rhea has rings. Till now no one knows but many suspect it. So does Rhea have the gravitational capacity to hold rocks around it to create rings? Does the core of Rhea hold enough gravity to attract any geological formations? If Rhea does have rings, are these connected to those found orbiting Saturn? By investigating these strange fixtures, we can also relate the same questions that arise on Dione.

All of these questions are wonderful reasons as to why Rhea and Titan should be chosen as the next Cassini flyby target. By obtaining pictures and further investigations, these intriguing mysteries can hopefully be solved."