MOUNTAIN VIEW, Calif. -- Applause broke out at the Ames Research Center when a model of the Pioneer on the wall was moved at 5 a.m. PDT past a red line marking the orbit of Neptune, currently the most distant known planet from the sun.
It will take 4 hours for the signal from Pioneer to reach the center, confirming its new location.
Jack Dyer, chief of the Spacecraft operations, said it was 'thrilling that Pioneer 10 has gotten farther from the sun than any known planet.'
He added that it was 'performing the greatest of any major spacecraft I've ever been involved in.'
The 570-pound spacecraft was originally designed for a two-year mission, but has been sending signals back to space experts for 11 years. Dyer said that it could remain in contact with Earth for another decade, but he added: 'It will go out there forever -- until or unless it hits something. There is a distinct possibility it will still exist a lot longer than the Earth does, because 5 billion years from now the sun is expected to explode and blow up the Earth.'
Many scientists and technicians working in the control room said the impact of the event was more emotional than scientific.
Fred Wirth, who has been with Pioneer since the beginning, said: 'It's a significant event, but it does not have as much significance for us scientists as it does for the public. It's like driving down Interstate 5 if you cross the state line into Oregon. Nothing significantly happens to your car or to yourself. It's just a point in space.'
But James Van Allen of the University of Iowa, who discovered the Van Allen radiation belt, said, 'I consider Pioneer to be one of the greatest of human acheievements.'
Asked if Pioneer could ever be intercepted by life in another galaxy, he said he considered the chances 'very infinitesimal that anyone will actually pick it up. We don't know if there are any intelligent beings elsewhere in the universe, but the chances are very small.'
NASA scientists say the spacecraft could outlive the Earth and still be cruising trillions of miles out through interstellar space when the Earth burns up and disintegrates.
'We've got the first of a fleet of spaceships going to the stars,' science fiction writer Eric Burgess said during a weekend celebration at the research center.
'We have lived through an age of miracles, and this is a miracle. Our going beyond the solar system should tell us all that we can create our dreams,' he said.
Already about 3 billion miles from Earth and traveling at almost 1 million miles a day, the ship will continue to beam data back to earth until sometime in the early 1990s when its 8-watt transmitter is expected to run out of power.
The voyage not only accomplished all its original goals, it far outlasted anyone's expectations. Built for a 21-month trip to Jupiter, it is now expected to last virtually forever because it will be voyaging through a region of space where there is nothing to damage it.
Van Allen said that in the planning stages some scientists thought the Pioneer mission, which has cost only about $130 million, was hopeless.
'We had actually launched the spacecraft before we started thinking about it escaping the solar system,' said Charles Hall, Pioneer project manager for the first several years of the ship's voyage.
By proving that travel to the outer planets was possible, Pioneer led the way for Pioneer 11 and Voyager 1 and 2, which eventually will also leave the solar system.
During its long journey, Pioneer has continued making its reports in workman-like fashion. Among the information it transmits is a daily solar weather report.
It reported the sun's temperature Sunday at 15,000 degrees centigrade, up 10,000 degrees from Thursday's 5,000 degree temperature. Solar winds were 1,030,000 miles an hour, NASA said.
The ship is also looking for evidence of a mysterious 10th planet in the solar system. Astronomers have long suspected its existence because of a strange wobbling of the orbits of Neptune and Uranus. They say a 10th planet or a nearby dark star would explain the oscillations, but no evidence of either has ever been found.
Scientists also hope Pioneer will locate a band of radiation called 'gravity waves,' which were predicted by Einstein's Theory of Relativity and are thought to be 1 billion miles long.
There is also a trace of hope that intelligent beings might one day find the ship. Just in case, astronomer Carl Sagan designed a gold plaque with an engraved message using universal symbols to explain the location of the earth and its solar system. The plaque also has a line drawing of a man and a woman.
Sagan admitted the chance Pioneer will be found is remote, but said 'over billions of years, the chance changes.'
The spaceship has achieved a long list of spectacular firsts, including the first flight beyond Mars and the crossing of the asteroid belt, which researchers had feared would be filled with specks of dust and asteroids waiting to rip apart Pioneer's metal skin.
It has sent back to earth close-up pictures of Jupiter, its moons and great red spot, and provided information indicating the planet is liquid.