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 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
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
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.
Pioneer 10 was built by TRW Inc., Redondo Beach, Calif., and
was launched 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 also charted the
gas giant's intense radiation belts, located the planet's
magnetic field, and established 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 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. At 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 (DSN)
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.
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 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 two million
years to reach it. Its sister ship, Pioneer 11, ended its
mission September 30, 1995, when the last transmission from
the spacecraft was received. Information about Pioneer 10 is
on the Internet at:
http://spaceprojects.arc.nasa.gov/Space_Projects/pioneer/PNhome.html
