The Cassini-Huygens mission has explored Saturn and its system of moons since 2004. Shortly after arriving there, the main spacecraft dropped the Huygens probe to the surface of Titan, Saturn's largest moon. It landed in mud rich with ethane, methane, and other organic molecules. All these molecules exist in a transient state between liquid and gas because of a surface temperature of minus 290 degrees Fahrenheit.
Planetary scientist still works on the Cassini program; the orbiter still sends back new information about Saturn and its moons daily. But, she says, Titan is so remarkable that it deserves a new look with even better equipment.
"One scientist back in the Voyager era, I think in the 1980s, called ‘the Earth in deep freeze,' " Buratti says. "Since we landed Huygens on the surface, we've found lakes of liquid ethane or methane, we've seen clouds and rain, we've seen channels where the liquid has pooled and flown. . . It's very Earth-like."
Titan may also harbor a liquid-water ocean beneath its mushy crust, and volcanoes that spew the material upward. Mixed with the organic molecules, life may not be an absurd notion. "All of life's building blocks seem to be on Titan. Who knows? Maybe simple bacteria are living under the surface," she says.
Buratti says that if money were no object, she'd send a trio of spacecraft: a wheeled rover to poke around the lakeshores, a balloon to sample the atmosphere as the dirigible rises and falls, and an orbiter to study weather and erosion on the megamoon from high above. Her rover would have a digger to look under the cold muck, a microscope to analyze samples, a mass spectrometer to sniff chemicals, and more.
"We could learn a lot about the same processes on Earth by going to Titan," she says. "It's a wonderful place for comparison."
Outlook: Very possible.
Over the past two years, NASA looked at 28 candidates to be the next Discovery mission, a $425 million planetary science mission, and narrowed the competition to three: a Mars Phoenix–like lander, a comet-hopping robot, and a boat for Titan's lakes. So far, most planetary scientists seem to be rooting for the boat, called the , or TiME. If NASA selects TiME later this year, the boat would be scheduled to land in 2023. And if it makes some tantalizing discoveries, the U.S. could invest more in the exploration of Titan—perhaps in Buratti's rover, balloons and orbiter.