Titan , the largest moon of Saturn, has always intrigued scientists because of its similarities to Earth. As our planet seems to have a layered structure, similar to the concentric layers of an onion. Inside there is probably a core that is a mixture of ice and rock, covered by a vast ocean of liquid water and, above, a crust of ice , according to a new study from Stanford University, is twice of thicker than previously thought .Specifically, the icy shell may have as many as 200 miles thick , with variations in some points. Research also suggests that the internally generated heat, which keeps the ocean without freezing, depends on interactions with Saturn and other moons.
Howard Zebker, a professor of geophysics and electrical engineering at Stanford University, presented the findings at the annual meeting of the American Geophysical Union (AGU) in San Francisco (California).Zebker part of the team that plays the Titan radar data taken by the Cassini spacecraft of NASA, orbiting Saturn since 2004.
The new analysis of the survey data and the gravity of the moon have resulted in a new description. “The image we get Titan has a rocky, icy nucleus, with a radius of just over 2,000 miles, an ocean in the range of 225 to 300 kilometers thick and a layer of ice that is 200 kilometers thick,” explains Zebker. Early models of the structure of Titan’s crust estimated that ice was about 100 miles wide.
Scientists conclude that if there is more ice, then the nucleus should emit less heat than previously estimated (caused by decay of radioactive elements left over from the formation of the solar system, as in the Earth’s core). One way to justify less heat is generated internally is that there is less rock and ice at the core of what previous models had predicted.
All this seems simple enough, but there is a complication. Titan is not a true sphere. Its shape is distorted by the gravitational pull of Saturn, making it more elongated along the Ecuador and slightly flattened at the poles. The new data show that the shape of Titan is much more distorted than predicted by a gravity model simple. This difference means that the internal structure of the moon is more complex.
Thinner at the poles
The team reasoned that the ice should be slightly thinner at the poles than at the core. Thus, estimated the thickness of the ice layer is about 3,000 feet below average in the poles and 3,000 feet above the average in Ecuador. And the combination of gravity and topography further suggest that the average thickness of the ice layer is about 200 km.
Zebker believed that the variation in ice thickness could be the result of variation in the shape of the orbit around Saturn Titan , which is not perfectly circular. Other moons of the planet also exert some influence on the tides of Titan, as they all follow different orbits, but the main tidal influence is Saturn.
The Cassini mission has recently received funding to continue operating until 2017, so that new data can contribute more to the understanding of Saturn and its moons.