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Lawrence Livermore National Laboratory News Release

Contact: Anne M. Stark
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FOR IMMEDIATE RELEASE
May 12, 2005
NR-05-05-04

Cassini-Huygens observations show how Titan compares with the Earth

LIVERMORE, Calif. - Observations of Titan's atmosphere offer a unique
look at how Saturn's giant moon compares to Earth.

Titan is the only moon in the solar system with a substantial
atmosphere. Like Earth, Titan's atmosphere is primarily composed of
nitrogen, but unlike Earth, one of the most abundant constituents is
methane (CH4). Data from the European Space Agency's Huygens probe,
which parachuted through Titan's murky atmosphere in January, will
determine if the abundance of argon exceeds that of methane. Methane,
the main component in natural gas, plays a key role in the makeup of
atmospheric conditions on Titan.

The organic chemistry that occurs in Titan's atmosphere is an analog of
the processes that may have been present in the early terrestrial
atmosphere.

The research appears in the May 13 edition of the journal Science.
http://www.sciencemag.org/cgi/content/abstract/308/5724/975

Using an infrared spectrometer on the international Cassini-Huygens
Spacecraft, researchers have measured the temperature, winds and
chemical composition of Titan.

Edward Wishnow of Lawrence Livermore National Laboratory participated
in
the research by measuring the spectrum of methane in the laboratory at
temperatures and densities similar to Titan's - about 113 Kelvin
(-256?F) and about one atmosphere pressure. The measurements were
performed with a unique spectrometer and cryogenic gas absorption cell
in collaboration with H. Gush and I. Ozier at the University of British
Columbia and G. Orton at NASA's Jet Propulsion Laboratory.

"Titan"s spectrum shows sharp emission lines that arise due to methane
in the stratosphere that is warmer than the underlying denser
atmospheric layers," Wishnow said. The correspondence between the lab
and Titan spectra is obvious and the strength of the laboratory lines
is
used to determine the abundance of methane in Titan's upper atmosphere,
he said.

The Cassini Composite Infrared Spectrometer (CIRS) is an infrared
instrument that measures the intensity of far-infrared radiation -
light
with wavelengths between those of radar and near-infrared light. These
wavelengths are associated with radiation emission by the constituent
gases of Titan's atmosphere.

Other researchers on the project discovered that Titan exhibits
seasonal
changes in its stratospheric temperatures and winds that are similar to
Earth's.

"Part of the exhilaration of our scientific exploration comes from
understanding how Titan is similar to Earth as well as how it differs,"
said CIRS principal investigator F. Michael Flasar of NASA/Goddard
Space
Flight Center. "The CIRS observations of Titan's stratosphere indicate
that its winter (northern) pole has many properties in common with
Earth's: cold temperatures, strong circumpolar winds and anomalous
concentrations of several compounds (on Titan, organic molecules) that
are reminiscent of conditions within the winter polar regions on Earth,
the so-called ozone holes. In both cases the essential ingredient is
the strong winds, which isolate the polar air and inhibit mixing with
that at lower latitudes."

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managed by the University of California for the U.S. Department of
Energy's National Nuclear Security Administration.