Michael Mewhinney Feb. 25, 2003
NASA Ames Research Center, Moffett Field, Calif.
Phone: 650/604-3937 or 650/604-9000
PIONEER 10 SPACECRAFT SENDS LAST SIGNAL
After more than 30 years, it appears the venerable Pioneer 10
spacecraft has sent its last signal to Earth. Pioneer's last, very
weak signal was received
on Jan. 22, 2003.
NASA engineers report that Pioneer 10's radioisotope power source has
decayed, and it may not have enough power to send additional
transmissions to Earth. NASA's Deep Space Network (DSN) did not
detect a signal during the last contact attempt on Feb. 7, 2003. The
previous three contacts, including the Jan. 22 signal, were very
faint, with no telemetry received. The last time a Pioneer 10 contact
returned telemetry data was April 27, 2002. NASA has no additional
contact attempts planned for Pioneer 10.
"Pioneer 10 was a pioneer in the true sense of the word. After it
passed Mars on its long journey into deep space, it was venturing
into places where nothing built by humanity had ever gone before,"
said Dr. Colleen Hartman, director of NASA's Solar System Exploration
Division, NASA Headquarters, Washington. "It ranks among the most
historic as well as the most scientifically rich exploration missions
ever undertaken," she said.
"Originally designed for a 21-month mission, Pioneer 10 exceeded all
expectations and lasted more than 30 years. It was a workhorse that
far exceeded its warranty, and I guess you could say we got our
money's worth," said Pioneer 10 Project Manager, Dr. Larry Lasher of
NASA Ames Research Center, located in California's Silicon Valley.
Pioneer 10 was built by TRW Inc., Redondo Beach, Calif., and was
launched on March 2, 1972 on a three-stage Atlas-Centaur rocket.
Pioneer 10 reached a speed of 32,400 mph needed for the flight to
Jupiter, making it the fastest human-made object to leave the Earth;
fast enough to pass the moon in 11 hours and to cross Mars' orbit,
about 50 million miles away, in just 12 weeks.
On July 15, 1972, Pioneer 10 entered the asteroid belt, a
doughnut-shaped area that measures some 175 million miles wide and 50
million miles thick. The material in the belt travels at speeds up to
45,000 mph and ranges in size from dust particles to rock chunks as
big as Alaska.
Pioneer 10 was the first spacecraft to pass through the asteroid
belt, considered a spectacular achievement, and then headed toward
Jupiter. Accelerating to a speed of 82,000 mph, Pioneer 10 passed by
Jupiter on December 3, 1973.
The spacecraft was the first to make direct observations and obtain
close-up images of Jupiter. Pioneer 10 also charted the gas giant's
intense radiation belts, located the planet's magnetic field, and
established that Jupiter is predominantly a liquid planet. In 1983,
Pioneer 10 became the first human-made object to pass the orbit of
Pluto, the most distant planet from the sun.
Following its encounter with Jupiter, Pioneer 10 explored the outer
regions of the solar system, studying energetic particles from the
sun (solar wind), and cosmic rays entering our portion of the Milky
Way. The spacecraft continued to make valuable scientific
investigations in the outer regions of the solar system until its
science mission ended on March 31, 1997.
Since that time, Pioneer 10's weak signal has been tracked by the DSN
as part of a new advanced concept study of communication technology
in support of NASA's future Interstellar Probe mission. At last
contact, Pioneer 10 was 7.6 billion miles from Earth, or 82 times the
nominal distance between the sun and the Earth. A that distance, it
takes more than 11 hours and 20 minutes for the radio signal,
traveling at the speed of light, to reach the Earth.
"From Ames Research Center and the Pioneer Project, we send our
thanks to the many people at the Deep Space Network and the Jet
Propulsion Laboratory (JPL), who made it possible to hear the
spacecraft signal for this long," said Pioneer 10 Flight Director
David Lozier, also of NASA Ames.
Pioneer 10 explored Jupiter, traveled twice as far as the most
distant planet in our solar system, and as Earth's first emissary
into space, is carrying a gold plaque that describes what we look
like, where we are and the date when the mission began. Pioneer 10
will continue to coast silently as a ghost ship through deep space
into interstellar space, heading generally for the red star
Aldebaran, which forms the eye of the constellation Taurus (The
Bull). Aldebaran is about 68 light years away. It will take Pioneer
10 more than 2 million years to reach it. Its sister ship, Pioneer
11, ended it mission Sept. 30, 1995, when the last transmission from
the spacecraft was received.
Further information about Pioneer 10 is available on the Internet at:
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