| By ANDREW BRIDGES AP Science
Writer
NASA scientists
said Sunday they have contacted the Pioneer 10 spacecraft, ending
fears that the robotic probe had gone silent 29 years into a mission
that has carried it more than 7 billion miles from Earth.
A radio antenna
outside Madrid received a signal from Pioneer 10 on Saturday,
marking the first time the spacecraft had been heard from since
Aug. 19. The spacecraft was launched March 2, 1972.
``Pioneer
10 lives on,'' project manager Larry Lasher said in a status report
posted Sunday on the mission's Web site.
Pioneer 10
was the first spacecraft to pass through the asteroid belt and
the first to obtain close-up images of Jupiter. In 1983, it became
the first manmade object to leave the solar system when it passed
the orbit of distant Pluto.
The spacecraft
is currently 7.29 billion miles from Earth, traveling at 27,380
mph relative to the sun. At that distance, radio signals take
21 hours and 45 minutes to make the roundtrip between the Earth
and the spacecraft.
The Pioneer
10 mission came to a formal close in 1997, but the probe had remained
in fairly regular contact with Earth, returning limited scientific
data before going silent in August.
Picking out
the faint signal of the spacecraft's eight-watt transmitter put
the National Aeronautics and Space Administration's international
network of antennas to the test. Further communications with Pioneer
likely will remain difficult, because engineers can contact the
spacecraft only by first beaming signals to it.
``In order
(for Pioneer 10) to talk to us, we need to talk to it,'' said
Ric Campo, the mission's chief flight controller.
Even in silence,
the spacecraft will continue its steady voyage toward the constellation
Taurus. It should pass one of the stars in the constellation more
than 2 million years from now.
The spacecraft
carries a gold plaque engraved with a message of goodwill and
a map showing the Earth's location within the solar system.
NASA's oldest
operating spacecraft is Pioneer 6, which scientists contacted
in December to mark the 35th anniversary of its launch.
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