Rings of mystery

THERE are several questions about the Saturnian system that the Cassini-Huygens mission will seek to answer.

Mysteriously, Saturn emits 87 per cent more energy than it absorbs from sunlight. What is the source of heat inside Saturn that produces this excess energy?

Saturn's magnetosphere is much more symmetric than Jupiter's and generates much less radio noise. Yet it is strong enough to modify surfaces of icy moons, erode Titan's atmosphere, strip away particles from the rings and cause beautiful auroral displays above Saturn's poles.

What is the origin of Saturn's rings? Where do the subtle colours in the rings come from? Why are Saturn's rings much more massive and more dramatic than those of other giant planets in the solar system?

What are the kind of chemical reactions that are occurring in the Titan atmosphere? What is the source of the abundant methane, an organic compound that is associated with biological activity on the earth?

Are there ethane oceans on Titan? (Ethane is generated when ultraviolet (UV) light acts on methane in the atmosphere through the reaction UV + CH4 => CH3 + H, followed by CH3 + CH3 => C2H6. This ethane probably rains down on Titan's surface, a chemical reaction that has probably been going on for 4.5 billion years.)

Do more complex organic molecules and pre-biotic molecules exist on Titan?

With the exception of Titan, Saturn's moons are all much smaller than the four satellites of Jupiter and their densities do not follow the same pattern. Why is it so?

Why has the moon Enceladus such an abnormally smooth surface? Has it recently melted to erase the craters?

Are there more moons to be discovered?

What is the origin of the dark organic material covering one side of the moon Lapetus?