Cassini's First Look at Jupiter

October 5, 2000

First look at Jupiter from CassiniNASA scientists are extremely pleased with the first image of Jupiter,
received yesterday, from the Cassini spacecraft, which is closing in on a fly-by of the huge planet. The image, first in a series of images and other measurements of Jupiter which Cassini will be making over the next
several months as it flies by Jupiter, clearly shows the exceptional resolving power of the imaging system even at the distance of more than 52 million miles (84 million kilometers). Clouds, storms and latitudinal bands are clearly seen in the image. Color images will be processed in coming days. A steady stream of ever-closer color and black-and-white images will be released in the weeks ahead.


The new image of Jupiter is available from NASA's Jet Propulsion
Laboratory at
http://www.jpl.nasa.gov/pictures/cassinijupiter
. It is
also available from the University of Arizona's Lunar and Planetary
Laboratory at
http://ciclops.lpl.arizona.edu.


"This has been our first opportunity to exercise the Cassini flight and
ground systems in a mode very similar to how we expect to operate at
Saturn, and I'm extremely pleased with how it is working," said Bob
Mitchell, Cassini program manager at NASA's Jet Propulsion Laboratory,
Pasadena, Calif.


"The spacecraft is steadier than any spacecraft I've ever seen," said Dr.
Carolyn Porco of the University of Arizona, team leader for the camera on
Cassini. "It's so steady, the images are unexpectedly sharp and clear,
even in the longest exposures taken and most challenging spectral
regions."


At the same time, mission engineers at NASA are working with their
counterparts at the European Space Agency (ESA) on a concern with the
communication system on ESA's Huygens probe, which is attached to the
Cassini spacecraft. Huygens is to drop from the Cassini spacecraft in
late 2004 onto the large moon of Saturn called Titan as the Cassini
orbiter begins its own exploration of the ringed planet and its system of
moons.


The concern, which was identified in early September with tests at ESA's
Operations Center at Darmstadt, Germany, involves the radio receiver
supplied by ESA to receive signals from the Huygens probe as it descends
through Titan's atmosphere. According to the tests, the signal sent to
Cassini from Huygens will change in frequency as both spacecraft rapidly
change position in relation to each other, much as a train whistle appears
to change in pitch as it passes by a person standing alongside the tracks
(called the Doppler effect). The engineering test found that the
ESA-supplied receiver carried on the U.S. Cassini main spacecraft could
not receive all the data from the Huygens probe.


"Cassini has given us the first tantalizing taste of its enormous
scientific potential," said Dr. Jay Bergstralh, Cassini Program Scientist
at NASA Headquarters, Washington, D.C. "The spacecraft has operated
perfectly since its launch three years ago, so we can look forward to even
greater things in the coming months. We are, of course, concerned about
communications with the Huygens probe, but the best minds in the business
are working on solutions."


ESA and NASA mission scientists and engineers are developing options to
address the situation, including changing the trajectory of Cassini during
the Huygens probe's entry into Titan's atmosphere. A plan of action is
expected to be ready by next summer for review and approval by officials
of ESA and NASA.



Additional information about Cassini is available online at:


http://saturn.jpl.nasa.gov.


Cassini is a joint mission of NASA, ESA, and the Italian Space Agency
(ASI). JPL manages the Cassini program for NASA's Office of Space
Science, Washington, D.C. JPL is a division of the California Institute
of Technology in Pasadena.


Information on the Huygens probe is available from ESA at
http://sci.esa.int/


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