PUBLIC INFORMATION 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

PHOTO CAPTION                                     P-47095
                                                  October 18, 1996

Ganymede's Uruk Sulcus Region - Galileo Mosaic Overlayed on Voyager Data

A mosaic of four Galileo images of the Uruk Sulcus region on Ganymede
(Latitude 11 N, Longitude: 170 W) is shown overlayed on the data obtained by
the Voyager 2 spacecraft in 1979. North is to the top of the picture, and
the sun illuminates the surface from the lower left, nearly overhead. The
area shown is about 120 by 110 kilometers (75 by 68 miles) in extent and the
smallest features that can be discerned are 74 meters (243 feet) in size in
the Galileo images and 1.3 kilometers (0.8 miles) in the Voyager data. The
higher resolution Galileo images unveil the details of parallel ridges and
troughs that are principal features in the brighter regions of Ganymede.
High photometric activity (large light contrast at high spatial frequencies)
of this ice-rich surface was such that the Galileo camera's hardware data
compressor was pushed into truncating lines. The north-south running gap
between the left and right halves of the mosaic is a result of line
truncation from the normal 800 samples per line to about 540. The images
were taken on 27 June, 1996 Universal Time at a range of 7,448 kilometers
(4,628 miles) through the clear filter of the Galileo spacecraft's imaging
system.

Launched in October 1989, Galileo entered orbit around Jupiter on December
7, 1995. The spacecraft's mission is to conduct detailed studies of the
giant planet, its largest moons and the Jovian magnetic environment. The Jet
Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of
Space Science, Washington, DC.