PUBLIC INFORMATION OFFICE
JET PROPULSION LAB0RATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

PHOTO CAPTION

                                           Magellan
                                           P38722 MGN74
                                           October 21, 1991

Sif Mons is displayed in this computer-simulated view of the
surface of Venus. The viewpoint is located 360 kilometers (223
miles) north of Sif Mons at a height of 7.5 kilometers (4.7
miles) above the lava flows. Lava flows extend for hundreds of
kilometers across the fractured plains shown in the foreground to
the base of Sif Mons. The view is to the south. Sif Mons, a
volcano with a diameter of 300 kilometers (186 miles) and a
height of 2 kilometers (1.2 miles), appears in the upper half of
the image. Magellan synthetic aperture radar data is combined
with radar altimetry to produce a three-dimensional map of the
surface. Rays, cast in a computer, intersect the surface to
create a three-dimensional perspective view. Simulated color and
a digital elevation map developed by the U.S. Geological Survey
are used to enhance small-scale structure. The simulated hues are
based on color images recorded by the Soviet Venera 13 and 14
spacecraft. The image was produced at the JPL Multimission Image
Processing Laboratory and is a single frame from a video released
at the March 5, 1991, JPL news conference.