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

                                                                              For Release July 26
Contact: Jim Doyle
Public Information Office
(818) 354-5011

       By the end of July the Magellan spacecraft will have circled Venus 2,351 times and will have traveled 75 million miles around the planet in its mapping mission, said Magellan Project Scientist Dr. Steve Saunders at NASA's Jet Propulsion Laboratory.

       One complete circuit of Venus takes eight months, the length of one Venus day. Magellan is in the second of at least seven planned cycles in which it will continue to observe the complex surface of Venus.

       Magellan has collected radar images of nearly 90 percent of the planet thus far. The data set is double the amount of all other image data collected in the U.S. planetary program to date, Saunders said.

       With each day's images the Magellan scientists have an opportunity to search the data for evidence of volcanic activity by comparing new images with those taken eight months previously during the first cycle.

       "Just as on Earth, it is very likely that somewhere on the planet a volcano is erupting at any given time; the problem is to find it," Saunders said.

       Venus has been revealed as a planet with at least as complex a geologic record as Earth, with many of the same geologic processes revealed on its surface, he said. Volcanism is the dominant process, seen in many forms on the plains.

       "Volcanism, the eruption of molten rock onto the surface, and tectonism, or faulting and folding of crustal rocks, on Venus act much like erosion by running water on Earth to modify the landscape," he said.

       "We see evidence of continuing volcanism and tectonism everywhere on the planet, in the vast lava floods and the fractures, faults and ridge belts of the volcanic plains."

       He added that fractured and faulted older terrains also are seen. Tessera, a term for highly-fractured terrains, probably represent the oldest rocks, but the deformation that has so completely distorted them appears to be continuing at present.

       "Now the search by Magellan continues for evidence that Earth's sister planet remains today as violent as the images suggest it has been in the recent past," Saunders said.

EDITORS' NOTE: Three new black & white images of Venus are available to news media at the Jet Propulsion Laboratory, Public Information Office (818) 354-5011.


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