Donald Savage<br />Headquarters, Washington Feb. 25, 2003<br />(Phone: 202/358-1547)<br /><br />Michael Mewhinney<br />Ames Research Center, Moffett Field, Calif.<br />(Phone: 650/604-3937)<br /><br />RELEASE: 03-082<br /><br />PIONEER 10 SPACECRAFT SENDS LAST SIGNAL<br /><br /> After more than 30 years, it appears the venerable <br />Pioneer 10 spacecraft has sent its last signal to Earth. <br />Pioneer's last, very weak signal was received on Jan. 22, <br />2003.<br /><br />NASA engineers report Pioneer 10's radioisotope power source <br />has decayed, and it may not have enough power to send <br />additional transmissions to Earth. NASA's Deep Space Network <br />(DSN) did not detect a signal during the last contact attempt <br />Feb. 7, 2003. The previous three contacts, including the Jan. <br />22 signal, were very faint with no telemetry received. The <br />last time a Pioneer 10 contact returned telemetry data was <br />April 27, 2002. NASA has no additional contact attempts <br />planned for Pioneer 10.<br /> <br />"Pioneer 10 was a pioneer in the true sense of the word. <br />After it passed Mars on its long journey into deep space, it <br />was venturing into places where nothing built by humanity had <br />ever gone before," said Dr. Colleen Hartman, director of <br />NASA's Solar System Exploration Division, NASA Headquarters, <br />Washington. "It ranks among the most historic as well as the <br />most scientifically rich exploration missions ever <br />undertaken," she said.<br /><br />"Originally designed for a 21-month mission, Pioneer 10 <br />lasted more than 30 years. It was a workhorse that far <br />exceeded its warranty, and I guess you could say we got our <br />money's worth," said Pioneer 10 Project Manager, Dr. Larry <br />Lasher.<br /><br />Pioneer 10 was built by TRW Inc., Redondo Beach, Calif., and <br />was launched March 2, 1972, on a three-stage Atlas-Centaur <br />rocket. Pioneer 10 reached a speed of 32,400 mph needed for <br />the flight to Jupiter, making it the fastest human-made <br />object to leave the Earth; fast enough to pass the moon in 11 <br />hours and to cross Mars' orbit, about 50 million miles away, <br />in just 12 weeks. <br /><br />On July 15, 1972, Pioneer 10 entered the asteroid belt, a <br />doughnut-shaped area that measures some 175 million miles <br />wide and 50 million miles thick. The material in the belt <br />travels at speeds up to 45,000 mph and ranges in size from <br />dust particles to rock chunks as big as Alaska. <br /><br />Pioneer 10 was the first spacecraft to pass through the <br />asteroid belt, considered a spectacular achievement, and then <br />headed toward Jupiter. Accelerating to a speed of 82,000 mph, <br />Pioneer 10 passed by Jupiter on December 3, 1973. <br /><br />The spacecraft was the first to make direct observations and <br />obtain close-up images of Jupiter. Pioneer also charted the <br />gas giant's intense radiation belts, located the planet's <br />magnetic field, and established Jupiter is predominantly a <br />liquid planet. In 1983, Pioneer 10 became the first human-<br />made object to pass the orbit of Pluto, the most distant <br />planet from the Sun.<br /><br />Following its encounter with Jupiter, Pioneer 10 explored the <br />outer regions of the solar system, studying energetic <br />particles from the Sun (solar wind), and cosmic rays entering <br />our portion of the Milky Way. The spacecraft continued to <br />make valuable scientific investigations in the outer regions <br />of the solar system until its science mission ended March 31, <br />1997. <br /><br />Since that time, Pioneer 10's weak signal has been tracked by <br />the DSN as part of a new advanced-concept study of <br />communication technology in support of NASA's future <br />Interstellar Probe mission. At last contact, Pioneer 10 was <br />7.6 billion miles from Earth, or 82 times the nominal <br />distance between the Sun and the Earth. At that distance, it <br />takes more than 11 hours and 20 minutes for the radio signal, <br />traveling at the speed of light, to reach the Earth.<br /><br />"From Ames Research Center and the Pioneer Project, we send <br />our thanks to the many people at the Deep Space Network (DSN) <br />and the Jet Propulsion Laboratory (JPL), who made it possible <br />to hear the spacecraft signal for this long," said Pioneer 10 <br />Flight Director David Lozier.<br /><br />Pioneer 10 explored Jupiter, traveled twice as far as the <br />most distant planet in our solar system, and as Earth's first <br />emissary into space, is carrying a gold plaque that describes <br />what we look like, where we are, and the date when the <br />mission began. Pioneer 10 will continue to coast silently as <br />a ghost ship into interstellar space, heading generally for <br />the red star Aldebaran, which forms the eye of the <br />constellation Taurus (The Bull). Aldebaran is about 68 light-<br />years away. It will take Pioneer 10 more than two million <br />years to reach it. Its sister ship, Pioneer 11, ended its <br />mission September 30, 1995, when the last transmission from <br />the spacecraft was received. Information about Pioneer 10 is <br />on the Internet at:<br /><br />http://spaceprojects.arc.nasa.gov/Space_Projects/pioneer/PNhome.html