First Cassini Science Photos Show That Spacecraft Cameras Are in Top Form

Sept. 1, 1999

Contact:

Carolyn C. Porco, Cassini Imaging Science Team leader
Cassini Imaging Central Laboratory for Operations
Lunar and Planetary Laboratory, University of Arizona
Phone: 520-621-2390
E-mail: carolyn@raven.lpl.arizona.edu

Scientists are delighted with photos of Earth's moon snapped by cameras
aboard the Cassini spacecraft during its recent Earth flyby. This was the
first real space test of Cassini_s imaging system. The test was conducted
Aug.18 (GMT), when Cassini flew more than 700 miles over the Pacific Ocean,
while getting a slingshot-like power boost from Earth's gravity field for
the next leg of the long trip to Saturn.

Cassini images and brief video clips are being released today on the
Internet at , the official web site of the
Cassini Imaging Science Team, and at .

CICLOPS, the Cassini Imaging Central Laboratory for Operations, is the hub
of imaging team operations and is located in the Lunar and Planetary
Laboratory at the University of Arizona in Tucson. CICLOPS houses the
Cassini Imaging Diary, the collection of released images that will document
Cassini's travels over the next decade as it makes its way by Jupiter and
into Saturn orbit for its four-year tour of the Saturn system.

"These are the first images taken by Cassini for both photogenic and
scientific purposes, and they illustrate that the cameras are functioning
beautifully" said Carolyn C. Porco, leader of the 14-member Cassini Imaging
Science Team (ISS). "The cameras promise a bonanza of imaging delights at
Jupiter in late 2000 and at Saturn beginning in the year 2004," she added.
Porco is associate professor of planetary sciences at the University of
Arizona in Tucson.

The images released today are a wide-angle movie, a narrow-angle video clip,
the moon in ultraviolet and "triptych" of the moon. They were taken from a
distance of about 234,000 miles about 80 minutes prior to Cassini_s closest
approach to Earth.

The wide-angle movie is a brief movie taken with the ISS wide-angle camera
as the Cassini spacecraft glided by the moon. The narrow-angle video is a
3-frame clip made from the highest resolution images taken as the moon
passed through the narrow-angle field of view. The moon in ultraviolet is
one of the best, highest resolution frames taken at ultraviolet wavelengths
during Cassini_s closest approach to the moon. The "triptych" of the moon is
a composite image made from the three narrow-angle Cassini images included
in the video clip.

The Cassini Imaging Science System was specifically designed for exploring
the Saturn system, and includes spectral filters and imaging capabilities
for a multitude of scientific objectives. At Saturn, Cassini_s imaging
system will search for lightning, investigate the cloud structure and
meteorology of Saturn_s and Titan_s atmospheres, photograph the surfaces of
Saturn_s many icy satellites, study the ring system and peer
through Titan_s hazy atmosphere to view that moon_s mysterious surface. The
imaging system will be further tested and used in studying Jupiter and its
satellites and rings during the Cassini Jupiter flyby in late 2000, Porco
said.

The ISS consists of two framing cameras. The narrow-angle camera is a
reflecting telescope with a focal length of 2000 mm and a field of view of
0.35 degrees. The wide-angle camera is a refractor with a focal length of
200 mm and a field of view of 3.5 degrees. (The full moon as seen from Earth
would cover a half degree of the sky. The narrow-angle camera view of the
moon seen from Cassini at moon closest approach is about 70 percent of
that.)

Each camera is outfitted with a large number of spectral filters which,
taken together, span the electromagnetic spectrum from the ultraviolet (2000
Angstroms) to the infrared (1.1 microns). The Cassini cameras cover a
wavelength region four times greater than did Voyager cameras that visited
the outer solar system planets in the 1980s.

At the heart of each camera is a charged coupled device (CCD) detector
consisting of a 1024 square array of pixels. The data system allows many
options for data collection, including choices for a data-compression
technique called "on-chip summing."

Cassini ISS scientists are:
* Porco (team leader)
* Andre Brahic of the University of Paris (France)
* Joseph Burns of Cornell University
* Anthony Del Genio of NASA's Goddard Institute of Space Studies
* Henry C. Dones of the Southwest Research Insititute
* Andrew Ingersoll of the California Institute of Technology
* Torrence V. Johnson of the Jet Propulsion Laboratory
* Alfred McEwen of the University of Arizona Lunar and Planetary Laboratory
* Carl Murray of Queen Mary and Westfield College (London)
* Gerhard Neukum of the Institute for Planetary Exploration (Berlin,
Germany)
* Steven W. Squyres of Cornell University
* Peter Thomas of Cornell University
* Joseph Veverka of Cornell University
* Robert West of the Jet Propulsion Laboratory.

The Cassini mission, which is a joint mission of NASA, the European Space
Agency (ESA) and the Italian Space Agency (ASI) is scheduled to reach Saturn
in mid-2004. The Cassini orbiter will then begin its 4-year study of Saturn,
its rings, moons and magnetic environment. The spacecraft carries ESA's
Huygens probe. The probe will detach from the orbiter a few months after
arrival at Saturn and parachute six science instruments to the surface of
Titan.

The Cassini mission is managed by NASA's Jet Propulsion Laboratory in
Pasadena, Calif., for NASA_s Office of Space Science, Washington, D.C. JPL
is a division of the California Institute of Technology.

Related links:

http://ciclops.lpl.arizona.edu
http://photojournal.jpl.nasa.gov