Titan's Surface Organics Surpass Oil Reserves on Earth

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
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http://www.jpl.nasa.gov

Carolina Martinez 818-354-9382
Jet Propulsion Laboratory, Pasadena, Calif.

NEWS RELEASE: 2008-025 Feb. 13, 2008

Titan's Surface Organics Surpass Oil Reserves on Earth

Saturn's orange moon Titan has hundreds of times more liquid hydrocarbons than all the
known oil and natural gas reserves on Earth, according to new data from NASA's Cassini
spacecraft. The hydrocarbons rain from the sky, collecting in vast deposits that form
lakes and dunes.

The new findings from the study led by Ralph Lorenz, Cassini radar team member from
the Johns Hopkins University Applied Physics Laboratory, Laurel, Md., are reported in
the Jan. 29 issue of the Geophysical Research Letters.

"Titan is just covered in carbon-bearing material—it's a giant factory of organic
chemicals," said Lorenz. "This vast carbon inventory is an important window into the
geology and climate history of Titan."

At a balmy minus 179 degrees Celsius (minus 290 degrees Fahrenheit), Titan is a far cry
from Earth. Instead of water, liquid hydrocarbons in the form of methane and ethane are
present on the moon's surface, and tholins probably make up its dunes. The term
"tholins"was coined by Carl Sagan in 1979 to describe the complex organic molecules at
the heart of prebiotic chemistry.

Cassini has mapped about 20 percent of Titan's surface with radar. Several hundred lakes
and seas have been observed, with each of several dozen estimated to contain more
hydrocarbon liquid than Earth's oil and gas reserves. The dark dunes that run along the
equator contain a volume of organics several hundred times larger than Earth's coal
reserves.

Proven reserves of natural gas on Earth total 130 billion tons, enough to provide 300
times the amount of energy the entire United States uses annually for residential heating,
cooling and lighting. Dozens of Titan's lakes individually have the equivalent of at least
this much energy in the form of methane and ethane.

"This global estimate is based mostly on views of the lakes in the northern polar regions.
We have assumed the south might be similar, but we really don't yet know how much
liquid is there," said Lorenz. Cassini's radar has observed the south polar region only
once, and only two small lakes were visible. Future observations of that area are planned
during Cassini's proposed extended mission.

Scientists estimated Titan's lake depth by making some general assumptions based on
lakes on Earth. They took the average area and depth of lakes on Earth, taking into
account the nearby surroundings, like mountains. On Earth, the lake depth is often 10
times less than the height of nearby terrain.

"We also know that some lakes are more than 10 meters or so deep because they appear
literally pitch-black to the radar. If they were shallow we'd see the bottom, and we don't,"
said Lorenz.

The question of how much liquid is on the surface is an important one because methane is
a strong greenhouse gas on Titan as well as on Earth, but there is much more of it on
Titan. If all the observed liquid on Titan is methane, it would only last a few million
years, because as methane escapes into Titan's atmosphere, it breaks down and escapes
into space. If the methane were to run out, Titan could become much colder. Scientists
believe that methane might be supplied to the atmosphere by venting from the interior in
cryovolcanic eruptions. If so, the amount of methane, and the temperature on Titan, may
have fluctuated dramatically in Titan's past.

"We are carbon-based life, and understanding how far along the chain of complexity
towards life that chemistry can go in an environment like Titan will be important in
understanding the origins of life throughout the universe," added Lorenz.

Cassini's next radar flyby of Titan is on Feb. 22, when the radar instrument will observe
the Huygens probe landing site.

For images and more information visit: http://www.nasa.gov/cassini and

http://saturn.jpl.nasa.gov .

The Cassini-Huygens mission is a cooperative project of NASA, the European Space
Agency and the Italian Space Agency. JPL, a division of the California Institute of
Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science
Mission Directorate, Washington. The Cassini orbiter was designed, developed and
assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency,
working with team members from the United States and several European countries.

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