Michael Mewhinney                                    Feb. 25, 2003
       NASA Ames Research Center, Moffett Field, Calif.
       Phone: 650/604-3937 or 650/604-9000
       E-mail: Michael.S.Mewhinney@nasa.gov
       
       
       RELEASE: 03-13AR
       
       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:
       http://spaceprojects.arc.nasa.gov/Space_Projects/pioneer/PNhome.html
       
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