Titan is half the size of Earth and the only moon in the solar system with an atmosphere, which is loaded with methane and, like Earth's air, some nitrogen.
Ralph Lorenz, of the Lunar and Planetary Lab University of Arizona, presented the finished exploration plan over the weekend in Seattle at a meeting of the American Association for the Advancement of Science. It calls for 44 flybys of Titan over four years by Cassini after it arrives at Saturn this July. The craft will also deploy a probe to the surface of the moon next year.
Last week, Lorenz discussed with SPACE.com what he and colleagues hope to learn from Titan.
He explained that wind, waves and ocean currents are well understood only as they relate to current conditions on Earth. Scientists want to better grasp the underlying physics -- including what happens in wildly different conditions -- so they can predict how the natural world would react to change.
"We know that given the various factors that the result is X," Lorenz said. "We don't know for example, which of the factors is most important, or how the result will change if we change factor Y."
Earth's climate is heavily dependent on the transport of heat from equatorial regions to higher latitudes of the ocean and the atmosphere.
"Without, for example, the Gulf Stream, Northern Europe would be inhospitably cold, like much of Canada or Siberia at the same latitude," Lorenz said. "We don't know whether global warming might cause that ocean circulation to shut down. The only tool we have for studying that sort of effect is computer modeling, and that has many uncertainties. Observing Titan's ocean circulation and climate will give us more data to refine these models."
Cassini launched in 1997 and studied Jupiter on its way toward Saturn. It has taken a long, looping path that included flybys of inner planets to get gravitational boosts that saved fuel and reduced mission costs.
Lorenz works on Cassini's radar mapping team and is a co-investigator of the Surface Science Package on the Huygens probe, which will sample the atmosphere before landing Titan or splashing into an ocean. Huygens' measurements will complement various observations made by Cassini during the flybys, from radar mapping to optical and near-infrared imaging and a probe of the moon's gravity field.
"It's an absolute bonanza of science in many different fields," Lorenz said.
If Titan has seas, their composition will be markedly different from those on our planet.
Last year, observations by the Arecibo radio telescope suggested Titan has oceans of methane and ethane -- what we call natural gas on Earth. Because Titan's surface is about -290 degrees Fahrenheit (-179 Celsius) both compounds would be liquid in the Titan seas.
How will waves and tides behave? How do these waves sculpt beaches? How deep are the seas and what is their relationship to the atmosphere?
Lorenz thinks answers to these and other questions could sharpen idea about early Mars, which is thought to have harbored oceans or lakes that might have been water-based.
"We don't know very well how to predict what the wind generation would be like with a different atmosphere and gravity," he said. "By seeing the process in action on Titan, we'll be able to make better predictions."
Titan also looks to scientists like a ripe, prebiotic world. It is perhaps similar to Earth in its early era, before life developed. Theorists will try to use Titan's chemistry, once explored, to figure out how our own planet made the leap from lifeless to life bearing.
"Titan is the largest single unexplored piece of real estate in the solar system," Lorenz said, "and with an atmosphere and probably a hydrological cycle as well, it's likely to be the most interesting."
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