What's Baking on Titan?

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE 818-354-5011
http://www.jpl.nasa.gov

Jia-Rui C. Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jccook@jpl.nasa.gov

News feature: 2012-326 Oct. 16, 2012

What's Baking on Titan?

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.php?release=2012-326&cid=release_2012-326

Radar images from NASA's Cassini spacecraft reveal some new curiosities on
the surface of Saturn's mysterious moon Titan, including a nearly circular feature
that resembles a giant hot cross bun and shorelines of ancient seas. The results
were presented today at the American Astronomical Society's Division of
Planetary Sciences conference in Reno, Nev.

Steam from baking often causes the top of bread to lift and crack. Scientists think
some similar process involving heat may be at play on Titan. The image showing
the bun-like mound was obtained on May 22, 2012, by Cassini's radar
instrument. Scientists have seen similar terrain on Venus, where a dome-shaped
region about 20 miles (30 kilometers) across has been seen at the summit of a
large volcano called Kunapipi Mons. They theorize that the Titan cross, which is
about 40 miles (70 kilometers) long, is also the result of fractures caused by uplift
from below, possibly the result of rising magma.

"The 'hot cross bun' is a type of feature we have not seen before on Titan,
showing that Titan keeps surprising us even after eight years of observations
from Cassini," said Rosaly Lopes, a Cassini radar team scientist based at
NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The 'bun' may be the result
of what is known on Earth as a laccolith, an intrusion formed by magma pushing
up from below. The Henry Mountains of Utah are well-known examples of this
geologic phenomenon."

Another group of Cassini scientists, led by Ellen Stofan, who is based at
Proxemy Research, Rectortown, Va., has been scrutinizing radar images of
Titan's southern hemisphere. Titan is the only place other than Earth that has
stable liquid on its surface, though the liquids on Titan are hydrocarbon rather
than water. So far, vast seas have only been seen in Titan's northern
hemisphere.

A new analysis of Cassini images collected from 2008 to 2011 suggests there
were once vast, shallow seas at Titan's south pole as well. Stofan and colleagues
have found two good candidates for dry or mostly dry seas. One of these dry
seas appears to be about 300 by 170 miles (475 by 280 kilometers) across, and
perhaps a few hundred feet (meters) deep. Ontario Lacus, the largest current
lake in the south, sits inside of the dry shorelines, like a shrunken version of a
once-mighty sea.

Scientists led by Oded Aharonson, another radar team member based at the
California Institute of Technology in Pasadena, think that cycles analogous to
Earth's Croll-Milankovich cycles, which explain climate changes in terms of the
way Earth orbits around the sun, are at play on Titan, too. Such cycles on Titan
would cause long-term transfer of liquid hydrocarbons from pole to pole. By this
model, the south pole could have been covered with extensive seas less than 50,000 years ago.

"The seas on Titan are temporary hosts for experiments in prebiotic chemistry,
and we know they are cycling from one hemisphere to the other over 100,000
years," said Stofan. "I'd love to get a closer look at the seas of the north or these
dry seabeds to examine the extent to which this prebiotic chemistry has
developed."

The Cassini team has confirmed some of the stability of Titan's northern seas by
looking at radar images from Cassini taken about one Titan season (in this case,
six Earth years) apart. The newer images, from May 22, 2012, on the same flyby
as the hot cross bun images, show the shorelines stayed about the same,
indicating the northern lakes are not transient weather events, in contrast to the
temporary darkening of parts of the equator after a rainstorm in 2010.

The Cassini-Huygens mission is a cooperative project of NASA, the European
Space Agency and ASI, the Italian Space Agency. NASA's Jet Propulsion
Laboratory, a division of the California Institute of Technology in Pasadena,
manages the 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 US and several European countries. JPL is a division of the
California Institute of Technology in Pasadena.

-end-

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