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PHOTO CAPTION
P-48524
April 9, 1997

This moderate-resolution view of the surface of one of Jupiter's moons,
Europa, shows the complex icy crust that has been extensively modified by
fracturing and the formation of ridges. The ridge systems superficially
resemble highway networks with overpasses, interchanges and junctions. From
the relative position of the overlaps, it is possible to determine the age
sequence for the ridge sets. For example, while the 8-kilometer-wide
(5-mile) ridge set in the lower left corner is younger than most of the
terrain seen in this picture, a narrow band cuts across the set toward the
bottom of the picture, indicating that the band formed later. In turn, this
band is cut by the narrow 2- kilometer-wide (1.2-mile) double ridge running
from the lower right to upper left corner of the picture. Also visible are
numerous clusters of hills and low domes as large as 9 kilometers (5.5
miles) across, many with associated dark patches of non-ice material. The
ridges, hills and domes are considered to be ice-rich material derived from
the subsurface. These are some of the youngest features seen on the surface
of Europa and could represent geologically young eruptions.

This area covers about 140 kilometers by 130 kilometers (87 miles by 81
miles) and is centered at 12.3 degrees north latitude, 268 degrees west
longitude. Illumination is from the east (right side of picture). The
resolution is about 180 meters (200 yards) per pixel, meaning that the
smallest feature visible is about a city block in size. The picture was
taken by the Solid State Imaging system on board the Galileo spacecraft on
February 20, 1997, from a distance of 17,700 kilometers (11,000 miles)
during its sixth orbit around Jupiter.

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.