Voyager searched between Jupiter and its beguiling moon Io today for the origins of two of the most puzzling bodies in the solar system.
Flying as close as 12,000 miles to Io while 422 million miles from Earth, the 1,800-pound Voyager spacecraft took more than 100 pictures of Io's surprising surface, then turned around and took more than 100 pictures of Jupiter, 173,000 miles away. The unmanned spacecraft moved on late today to photograph the moons Ganymede and Callisto, and by tonight was more than 500,000 miles beyond Jupiter on its way to a November 1980 encounter with Saturn and its mysteious rings.
"We had a total success with these encounters today," project scientist Edward C. Stone said at the Jet Propulsion Laboratory here where the Voyager flight is directed. "We came through the day's events in fine shape."
The eight-hour flight through the most intense radiation fields surrounding Jupiter was not without tense moments.
A filter wheel that swings around the lens of the spacecraft's polarimeter jammed, forcing flight directors to turn off the instrument for six hours. An on-bored clock began running slow. The shutter on the camera tripped open several times by accident, suggesting that stray electric currents were arcing across portions of the spacecraft.
"Key spacecraft parts were protected," Stone said. "The radiation intensities were about what we expected."
During its long, curving flight by Jupiter, Voyager passed Io in front of Jupiter and again behind the planet. The Io photographs portrayed a moon that Dr. Laurence A. Soderblom of the U.S. Geological Survey described as "one of the strangest bodies in the solar system."
Io's surface possesses almost every imaginable geological feature -- plateaus, scarps, rilles, channels, rifts and mesas.
One Voyager photo showed a continuous ridge several miles long. Circular sags in the crust Covered regions the size of Michigan. What appeared to be an enormous extinct volcano showed up in another photograph.
But as rough as some of its features were, Io was surprisingly smooth and almost bereft of craters, which could make it the only rocky body in the solar system to be free of craters.
Photographs taken later in the day of Jupiter's moon Ganymede showed numerous craters on its surface. The few craters on Io that could be identified looked as if some mysterious process was trying to fill and cover them.
"Some of the features look as if they've been blown over with sand, but there's no wind on Io to account for that," Soderblom said. "We're led to the inescapable conclusion that there is some surface process on Io that's eroding the surface even today."
The only serious candidate for the Io eroder are the "winds" of radiation that blow so fiercely in close to Jupiter that they may be digging up the surface like giant invisible shovels.
"It looks as if the surface is being gobbled away," Soderblom said. "We have to ask ourselves the question: Is the erosion on an order of 300 feet, which it does not appear to be, or is it more like a mile, which it could be?"
Besides showing patterns of erosion, features on Io look as if they're being washed over with some liquid that's being belched out through cracks in the surface and then sucked back below the surface through the same cracks. Soberblom said the features look like they're being washed with water, but scientists believe that Io is as bereft of water as it is of craters.
"Some liquid is carrying things out and leaving evaporated salts on the surface," Soderblom said. "It could be liquid ammonia for all we know."
Color photographs of Io taken today showed a moon that was less red and had more mustards, oranges and whites than Sunday's picutres showed. Circular white-and-tan basins were surrounded by yellow almost perfect circles.
"It's better looking than a lot of pizzas I've seen," said Dr. Bradford Smith of the University of Arizona.
While Io gripped most of the attention of Voyager scientists today, a mosaic photograph sent back of the Great Red Spot of Jupiter itself turned more than a few heads. The photo revealed at least five huge swirls of gas circling counterclockwise like a hurricane and covering a region three times the size of Earth.
"We now see the red spot close enough so that we think we see these rapid vortices of gas calming in the center," said the University of Arizona's Brad Smith, "just like the storm clouds over very high-pressure regions on Earth." Or the eye of a hurricane.
The period of close encounter with Jupiter and Io today began at 3:30 a.m. PST at the Jet Propulsion Laboratory, where the hundreds of invited guests included California Gov. Edmund G. (Jerry) Brown Jr. He stayed at the laboratory for more than six hours, wandering through the auditorium, where the television sets are, and the press room where repoters covering the event were working.
By one count, Brown held at least five impromptu news conferences, spoke freely to radio correspondents taping descriptions of the flight, and was interviewed several times by network and local television reporters. On several occasions, his presence was noted by the Public Broadcasting Service, whose live telecast was beamed back to Washington where it was seen in Congress and the White House.
President Carter was said to have watched for 90 minutes this morning, at times in the company of Defense Secretary Harold Brown. It was not known whether the president saw his potential election rival on the tube.
The National Aeronautics and Space Administration paid $42,000 to broadcast or to carry the live telecast back to Washington through the RCA Satcom satellite in orbit above the United States. How much of the $42,000 was spent carrying the telecast to the White House and Congress was unclear. NASA said the cost ran between $500 and $800 apiece, but it was not clear if that was an hourly or daily rate.