The Cassini spacecraft is heading for its first close encounter with
Saturn’s moon Titan tomorrow. University of Arizona scientists on the
mission say Cassini will get its first real glimpse of Titan surface
geology and digest its first gulp of rich Titan air.

The Oct. 26 flyby is the first of Cassini’s 45 close Titan passes over the
next four years. Scientists will combine unique types of information
from a dozen instruments on the orbiter for new insights on Titan,
Saturn’s largest and most exotic moon. The NASA spacecraft will deploy the
European SpaceAgency’s Huygens probe to Titan in December. The probe,
carrying six instruments, will descend through Titan’s atmosphere in
January 2005.

UA’s Cassini scientists will be at NASA’s Jet Propulsion Laboratory in
Pasadena, Calif., this week for this first close Titan flyby.

Cassini imaging cameras will photograph Titan every 15 minutes or so
during approach, said Alfred S. McEwen, a member of the Cassini imaging
team. “We’ll get a movie of Titan’s very interesting clouds. They form and
dissipate and blow in the wind. Some of them are strange shapes and
streaks and things we really don’t understand.

“Then, as we get closer, we’ll start mapping. We’ll make a full disk,
four-color mosaic. We’ll see the surface, we’ll see the limb hazes,
we’ll see whatever clouds there are,” McEwen said. “These are things we’ll
make posters of, and that everyone will have on their walls.”

“As we get closer and closer, we map specific regions at higher and
higher resolution. This includes a mosaic over the Huygens landing site.
It should be our best look at that location,” McEwen said.

Cassini cameras will continue snapping high-resolution pictures of
different Titan terrains as the spacecraft zooms on to Titan’s night side.
Cassini imaging operations involve an international team of scientists
headed by Carolyn Porco, UA adjunct professor of planetary sciences.

Porco directs the Space Science Institute in Boulder, Colo. Most of the
uplink and downlink imaging tasks are handled at the Boulder facility.

“The Titan imaging atmosphere observations for the upcoming flyby
have been planned by scientists at the Jet Propulsion Laboratory and
sequenced in Boulder,” Porco said. “But the very close observations, those
with the goal of mapping the Titan surface at between 50 and 200 meters
per pixel, have all been planned, designed and sequenced by our team
members at the Lunar and Planetary Laboratory. It’s a very challenging
task to plan imaging sequences during a close flyby when the geometry is
changing rapidly. And they’ve done an excellent job. We’re in for quite a
show.”

Robert H. Brown leads Cassini’s visual and infrared mapping spectrometer
(VIMS) team, based at UA’s Lunar and Planetary Lab in Tucson. “We know VIMS
will see through the haze to Titan’s surface,” Brown said. “At closest
approach – 1,200 kilometers (745 miles) – we’ll have 600-meter-pixel
resolution. We’ll be able to see very small geologic features. We’ll
get very high resolution looks at atmospheric phenomena, too. But from
my perspective, the really important thing about this encounter is
really digging down below the atmosphere and getting our first real
glimpse of Titan geology.

“We don’t know what we’re going to encounter there. I suppose you can
assume we’ll see common geologic forms like mountains and craters and
tectonic faults, maybe even volcanism,” Brown said.

Titan is possibly the land of a thousand hydrocarbon lakes. UA planetary
sciences and physics Professor Jonathan I. Lunine theorized as a
graduate student more than 20 years ago that Titan could have liquid
hydrocarbon seas or lakes. Lunine is the only U.S. scientist selected by
the European Space Agency for its three-member Huygens probe
interdisciplinary science team. He and Ralph Lorenz of UA’s Lunar and
Planetary Laboratory also are members of the radar team. Cassini will get
its first radar images of Titan on tomorrow’s flyby.

“If either the radar or VIMS system on the orbiter take images of
liquid-filled crater basins, that to me would be very, very
exciting,” Lunine said. Scientists would then have evidence that surface
lakes are a source and sink for methane in Titan’s hydrologic cycle.
VIMS will see Titan’s hydrocarbon pools, if they exist and aren’t
hidden by some low-lying fog or other strange phenomenon, Brown said.

VIMS team member Caitlin Griffith said, “Closest approach will give
us the most exciting VIMS data because we have that clear view down to the
surface. We want to isolate different terrain types and start seeing
texture.”

When the Cassini spacecraft flew within 339,000 kilometers (210,600
miles) of Titan in July, VIMS was so far away that everything it saw was
smeared over 150 kilometers (93 miles), Griffith said. “That’s like taking
a picture of Arizona but smearing all of Tucson with all of Phoenix and
beyond, towards Flagstaff. This time, we’ll be close enough to isolate and
identify lakes and mountains, and maybe see shadows cast at different
illumination angles.”

Cassini won’t just look at Titan next Tuesday. Cassini’s Ion and
Neutral Mass Spectrometer (INMS) will taste mysterious, subtle flavors in
Titan’s atmosphere, team member and UA planetary sciences Professor Roger
Yelle said.

“Our instrument will scoop up a breath of Titan’s puffy atmosphere
during the flyby,” Yelle said. The experiment will measure how many
molecules of different masses it got in the gulp of Titan’s mostly
nitrogen, methane-laced atmosphere.

“Scientists with telescopes have so far seen 19 different chemical
molecules in Titan’s atmosphere — more than in any other solar system
body’s atmosphere except Earth’s,” Yelle said. Laboratory experiments show
there are probably many more kinds of chemicals in Titan’s atmosphere, he
added.

Yelle and other INMS scientists want to identify the big, complicated and
interesting hydrogen-and-carbon-containing molecules because they
are part of a planetary system that possibly rains methane and produces
ethane ponds. “Titan is a big laboratory where you get to play with
atmospheres on planetary scales,” Yelle said.

In addition, Yelle said, he is fascinated by Titan chemistry as a
scientist interested in the origins of life.

Learning more about how carbon-containing, or “organic,” molecules
form doesn’t explain how DNA came to be, Yelle said. “A single strand of
DNA contains about 3 billion nucleotides that if stretched out, would be
something like 1.7 meters long. We’re trying to understand molecules
with just 10 or 12 atoms.”

But Titan’s hydrocarbon chemistry holds clues that explain the very
first steps of how nature assembled organic molecules, which are the
precursors to amino acids, the building blocks of life, he said.

The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. The Jet Propulsion
Laboratory, a division of the California Institute of Technology in
Pasadena, manages the Cassini-Huygens mission for NASA’s Office of Space
Science, Washington, D.C. The Cassni orbiter and its two onboard cameras
were designed, developed and assembled at JPL. The imaging team is based
at the Space Science Institute, Boulder, Colo. The visual and infrared
mapping spectrometer team is based at the University of Arizona Lunar and
Planetary Laboratory, Tucson, Ariz.

Science Contact Information

UA Cassini science contacts listed at end of release

UA Media Contact

Lori Stiles 520-621-1877 lstiles@u.arizona.edu

CICLOPS Media Contact

Heidi Finn, 720-974-5859 media@ciclops.org

Related Web sites

Cassini-Huygens mission – http://saturn.jpl.nasa.gov
and http://www.nasa.gov/cassini

Cassini imaging team home page – http://ciclops.org
(Updated images are available on this website)

Cassini VIMS team home page – http://wwwvims.lpl.arizona.edu

UA Lunar & Planetary Laboratory – http://www.lpl.arizona.edu

UA SCIENCE CONTACTS ON CASSINI/HUYGENS – Scientists from UA’s Lunar
and Planetary Laboratory (LPL) who work on the Cassini/Huygens mission
include:

* Jonathan Lunine, 520-621-2789, e-mail to
jlunine@lpl.arizona.edu

UA professor of theoretical planetary science and physics, Lunine is
an interdisciplinary scientist on the Cassini mission specializing in
Titan’s surface and atmosphere. He is also a member of both the Radar and
the Gas Chromatograph-Mass Spectrometer (GCMS) teams. Lunine began
planning the Cassini mission as a graduate student. He titled his feature
article on the mission, published in the June 2004 Scientific American,
“Saturn at Last!” Lunine is one of the most widely interviewed Cassini
scientists when the ubject is Titan, Saturn’s largest moon. Titan, Lunine
says, is “our best chance to study organic chemistry in a planetary
environment that hasremained lifeless over billions of years. With a
thick, nitrogen-rich atmosphere and possibly hydrocarbon seas, Titan may
harbor organic compounds important in the chain of chemistry that led to
life on Earth.”

* Robert H. Brown, 520-626-9045, e-mail to rhb@lpl.arizona.edu
Professor Brown is the leader of the Cassini Visual and Infrared
Mapping Spectrometer (VIMS) Science team. The $60 million imaging
spectrometer takes pictures in 352 separate colors simultaneously, with
wavelengths between 300 and 5100 microns, covering the visible and
extending into the infrared. VIMS will identify the chemical make-up and
propeties of Saturn’s moons.

This team determined from the June 11 flyby that Saturn’s moon Phoebe
came from the outer solar system beyond Neptune.

Rick McCloskey (520-626-3255) built VIMS’ ground data system, which is the
system that controls the experiment and stores all its data. Others on the
VIMS grounds operations team headquartered at the Lunar & Planetary Lab
are Dan Moynihan, Dyer Lytle and John Ivens. VIMS home page:
http://wwwvims.lpl.arizona.edu/

* Caitlin Griffith, 520-626-3806, e-mail to griffith@lpl.arizona.edu
Griffith is a team member on the Visual and Infrared Mapping
Spectrometer (VIMS) experiment on the Cassini orbiter, which will image
Titan’s little known lower atmosphere and surface, and measure the surface
composition, cloud morphology and methane humidity. Griffith and her
colleagues discovered the presence of methane clouds in Titan’s
atmosphere, which indicates that Titan has a methane cycle like the
hydrologic cycle on Earth, with clouds, rain and seas. Griffith’s work
also indicates that water ice is exposed on Titan’s surface, despite the
likely existence of organic sediments and possible methane oceans.

* Ralph Lorenz, 520-621-5585, e-mail to rlorenz@lpl.arizona.edu
Lorenz is a member of both the Cassini spacecraft’s radar mapping
team and a co-investigator of the Surface Science Package on the Huygens
probe.

One of Lorenz’ major goals is to map Titan’s landscape. He began working
on the Huygens project as an engineer for the European Space Agency in
1990, and then earned his doctorate from the University of Kent at
Canterbury, England, while building one of the probe’s experiments. He
joined the University of Arizona in 1994 where he started work on
Cassini’s Radar investigation. He is a co-author of the book, “Lifting
Titan’s Veil” published in 2002 by Cambridge University Press.

* Alfred McEwen, 520-621-4573, e-mail to mcewen@pirl.lpl.arizona.edu
McEwen is member of Cassini’s Imaging Science Subsystem (ISS) team
and is a planetary geologist and director of the Planetary Image Research
Laboratory (PIRL). He also was a member of the imaging science teams of
the Galileo mission to Jupiter and is a participating scientist on Mars
Global Surveyor (MGS) and Mars Odyssey. He is principal investigator for
the High Resolution Imaging Science Experiment (HiRISE) for Mars
Reconnaissance Orbiter (MRO) to launch in 2005. For Galileo, McEwen led
the sequence planning and science analysis for Jupiter’s volcanically
active moon Io. For Cassini, he is leading the planning for imaging
observations of Saturn’s giant satellite Titan. In his cover story,
“Journey to Saturn,” for the Jan. 2004 issue of Astronomy magazine, McEwen
identified 10 top mission highlights.

Elizabeth Turtle, Doug Dawson, undergraduate student Jason Perry and
graduate student Stephanie Campbell work with McEwen in planning the Titan
observations.

* Elizabeth Turtle, 520-621-8284, e-mail to turtle@lpl.arizona.edu
Turtle is part of McEwen’s group that planned and will analyze Cassini’s
imaging observations of Titan’s surface. She will use the Cassini
images to map Titan’s surface and study its landforms. It parallels her
work on the Galileo mission to Jupiter, where she mapped and studied
landforms, particularly for the moons Io and Europa.

* Roger Yelle, 520-621-6243, e-mail to yelle@lpl.arizona.edu
Yelle is a team member on the Ion and Neutral Mass Spectrometer
(INMS) experiment on the Cassini mission. It will analyze the composition
of Titan’s atmosphere down to the parts per million level. Yelle and
his colleagues, including collaborators from the Imperial College London
and Boston University, are developing a comprehensive model for the
chemistry, energetics and dynamics of Titan’s upper atmosphere.

* Martin Tomasko, 520-621-6969, email to mtomasko@lpl.arizona.edu
Tomasko, research professor in planetary atmospheres and radiative
transfer, is the principal investigator on the Descent Imager Spectral
Radiometer (DISR) on the European Space Agency’s Huygens probe. The DISR
is the optical package in the probe, which will separate from the orbiter
Dec. 24 and cruise down through Titan’s atmosphere mid-January 2005. As
the probe descends toward Titan’s surface, DISR will take pictures of
Titan’s atmosphere and surface using three camera lenses pointed at three
different angles. One camera looks straight down, one camera points at an
angle of almost 45 degrees, and one camera looks almost straight out
horizontally. Tomasko and other scientists will create 20 panoramic
mosaics from their Titan images. As the probe gets closer to the ground,
it will take too long for the cameras to take panoramic pictures, so
they-ll begin transmitting individual images.

* Bashar Rizk, 520- 621-1160, e-mail to bashar@lpl.arizona.edu.
Rizk is a co-investigator on the DISR instrument. His responsibilities
include fitting the 750 or so images the instrument will acquire
into a global context in order to derive the Huygens probe’s ground track,
its attitude history, its descent trajectory and the horizontal and
vertical winds blowing on its journey to Titan’s surface. Trying to
display the downward-looking and very wide-angle field of view of the DISR
imagers when fully mosaicked is challenging: The lower hemisphere below
the probe from one horizon to nadir to the opposite horizon has led to the
routine development and use of several different projections in order to
lay what is basically a spherical surface onto a flat piece of paper. Rizk
and other team members will develop perspective animation from their
imaging to convey look and feel of this alien world. Rizk is also refining
a spherical model of Titan’s radiative transfer, including polarization,
which will be used to refine the knowledge of Titan’s aerosols and
radiative energy balance when used with other DISR data returned from the
Huygens probe.

* Peter Smith, 520-621-2725, e-mail to psmith@lpl.arizona.edu
Smith, an LPL senior research scientist, is a co-investigator on the
DISR instrument. He has been involved with the team since 1989 when he
helped write the proposal for the building and design of the instrument.
He became project manager during the first 4 years of the project
monitoring progress at Lockheed Martin Astronautics. Smith has done
notable research on Titan, and will be working with surface data sent back
from the Huygens probe, comparing it to observations of the surface
obtained by the Hubble Space Telescope. He will also analyze the
distribution and type of aerosol particles found in Titan’s atmosphere.
Smith is principal investigator for the $355 million, 2007-2008 Phoenix
lander mission to Mars. This NASA Scout mission is the first Mars mission
run by a university.

* Lyn Doose, 520-621-2127, e-mail to ldoose@lpl.arizona.edu
Doose is a co-investigator on the Descent Imager Spectral Radiometer
(DISR) on the Huygens probe. He will study radiative transfer in Titan’s
atmosphere, looking at where clouds and haze are found in the
atmosphere. He also will interpret data to find the heat budget of Titan
(looking at how much solar energy is absorbed, and where on Titan it is
absorbed), and study the abundance and absorption properties of gases in
Titan’s atmosphere.

* Donald M. Hunten, 520-621-4002, e-mail to dhunten@lpl.arizona.edu
Hunten, Regents’ Professor in Earth and planetary atmospheres, is a
co-investigator on the gas chomatograph-mass spectrometer (GCMS) on
the Huygens probe. The GCMS will measure the atmosphere composition of
Titan as the probe descends, and, with luck, after the probe lands. Hunten
and other scientists are interested in learning what elements are present
in Titan’s thick atmosphere.

* Gabriel Tobie, 520-626-0093, e-mail to gtobie@lpl.arizona.edu
Tobie is a visiting scholar who has done previous modeling of
Titan’s surface and interior. He will use data sent back from the Cassini
mission to learn more about the evolution of Titan, the surface
cryovolcanic activity and the methane cycle.