Almost
all of the hydrocarbon seas and lakes on the surface of Saturn's moon
Titan cluster around the north pole, as can be seen in this mosaic from
NASA's Cassini mission. Image Credit: NASA/JPL-Caltech/SSI/JHUAPL/Univ. of Arizona. Full image and caption
Ultracold
hydrocarbon lakes and seas (dark shapes) near the north pole of
Saturn's moon Titan can be seen embedded in some kind of bright surface
material in this infrared mosaic from NASA's Cassini mission. Image Credit: NASA/JPL-Caltech/SSI/JHUAPL/Univ. of Arizona. Full image and caption
The
vast hydrocarbon seas and lakes (dark shapes) near the north pole of
Saturn's moon Titan sprawl out beneath the watchful eye of NASA's
Cassini spacecraft. Image Credit: NASA/JPL-Caltech/SSI/JHUAPL/Univ. of Arizona. Full image and caption
PASADENA,
Calif.-- With the sun now shining down over the north pole of Saturn's
moon Titan, a little luck with the weather, and trajectories that put
the spacecraft into optimal viewing positions, NASA's Cassini spacecraft
has obtained new pictures of the liquid methane and ethane seas and
lakes that reside near Titan's north pole. The images reveal new clues
about how the lakes formed and about Titan's Earth-like "hydrologic"
cycle, which involves hydrocarbons rather than water.
The new images are available online at: http://www.nasa.gov/mission_pages/cassini/multimedia/index.html.
While there is one large lake and a few smaller ones near Titan's
south pole, almost all of Titan's lakes appear near the moon's north
pole. Cassini scientists have been able to study much of the terrain
with radar, which can penetrate beneath Titan's clouds and thick haze.
And until now, Cassini's visual and infrared mapping spectrometer and
imaging science subsystem had only been able to capture distant, oblique
or partial views of this area.
Several factors combined recently to give these instruments great
observing opportunities. Two recent flybys provided better viewing
geometry. Sunlight has begun to pierce the winter darkness that shrouded
Titan's north pole at Cassini's arrival in the Saturn system nine years
ago. A thick cap of haze that once hung over the north pole has also
dissipated as northern summer approaches. And Titan's beautiful, nearly
cloudless, rain-free weather continued during Cassini's flybys this past
summer.
The images are mosaics in infrared light based on data obtained
during flybys of Titan on July 10, July 26, and Sept. 12, 2013. The
colorized mosaic from the visual and infrared mapping spectrometer,
which maps infrared colors onto the visible-color spectrum, reveals
differences in the composition of material around the lakes. The data
suggest parts of Titan's lakes and seas may have evaporated and left
behind the Titan equivalent of Earth's salt flats. Only at Titan, the
evaporated material is thought to be organic chemicals originally from
Titan's haze particles that once dissolved in liquid methane. They
appear orange in this image against the greenish backdrop of Titan's
typical bedrock of water ice.
"The view from Cassini's visual and infrared mapping spectrometer
gives us a holistic view of an area that we'd only seen in bits and
pieces before and at a lower resolution," said Jason Barnes, a
participating scientist for the instrument at the University of Idaho,
Moscow. "It turns out that Titan's north pole is even more interesting
than we thought, with a complex interplay of liquids in lakes and seas
and deposits left from the evaporation of past lakes and seas."
The near-infrared images from Cassini's imaging cameras show a bright
unit of terrain in the northern land of lakes that had not previously
been visible in the data. The bright area suggests that the surface here
is unique from the rest of Titan, which might explain why almost all of
the lakes are found in this region. Titan's lakes have very distinctive
shapes -- rounded cookie-cutter silhouettes and steep sides -- and a
variety of formation mechanisms have been proposed. The explanations
range from the collapse of land after a volcanic eruption to karst
terrain, where liquids dissolve soluble bedrock. Karst terrains on Earth
can create spectacular topography such as the Carlsbad Caverns in New
Mexico.
"Ever since the lakes and seas were discovered, we've been wondering
why they're concentrated at high northern latitudes," said Elizabeth
(Zibi) Turtle, a Cassini imaging team associate based at the Johns
Hopkins Applied Physics Laboratory, Laurel, Md. "So, seeing that there's
something special about the surface in this region is a big clue to
help narrow down the possible explanations."
Launched in 1997, Cassini has been exploring the Saturn system since
2004. A full Saturn year is 30 years, and Cassini has been able to
observe nearly a third of a Saturn year. In that time, Saturn and its
moons have seen the seasons change from northern winter to northern
summer.
"Titan's northern lakes region is one of the most Earth-like and
intriguing in the solar system," said Linda Spilker, Cassini project
scientist, based at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
"We know lakes here change with the seasons, and Cassini's long mission
at Saturn gives us the opportunity to watch the seasons change at Titan,
too. Now that the sun is shining in the north and we have these
wonderful views, we can begin to compare the different data sets and
tease out what Titan's lakes are doing near the north pole."
The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. JPL manages the
mission for NASA's Science Mission Directorate, Washington. The
California Institute of Technology in Pasadena manages JPL for NASA. The
VIMS team is based at the University of Arizona in Tucson. The imaging
operations center is based at the Space Science Institute in Boulder,
Colo.
For more information about the Cassini mission, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .
Jia-Rui Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jccook@jpl.nasa.gov
