30th Anniversary Contact with Pioneer 10

By John Cooper

On March 2, 2002 (PST) NASA's Deep Space Network made contact with Pioneer 10 and confirmed that the spacecraft is still operational thirty years after its launch on March 3, 1972 (UT). The uplink signal was transmitted on March 1st (PST) from the DSN's Goldstone, California facility and a downlink response was received twenty-two hours later by the 70-meter antenna at Madrid, Spain. At this time the spacecraft was 11.9 billion kilometers from Earth at about 79.9 AU (1 AU is the mean distance between the sun and the Earth) from the Sun and heading outward into interstellar space in the general direction of Aldebaran at a distance of about 68 light years and a travel time of two million years from Earth. Although science operations were officially terminated on March 31, 1997, Pioneer's onboard Radioisotope Thermal Generator (RTG) still provides just enough electrical power for operations of the radio transmitter and receiver systems and for the Geiger Tube Telescope experiment of Prof. James A. Van Allen of the University of Iowa. NASA Ames Research Center continues to support occasional tracking of Pioneer 10 for development and testing of communications technology that might be used for a future interstellar probe mission. Pioneer 10's signal is also used as a standard test source for SETI radio telescope studies.

This spacecraft long held the record for the greatest heliocentric radial distance of a man-made object until it was overtaken by Voyager 1 on February 17, 1998, while also being the first mission to traverse the Asteroid belt (July 1972) and explore the Jovian system (closest approach on Dec. 3, 1973). Pioneer 10 provided relatively continuous science data to the NSSDC archives over twenty-two years from 1972 to 1994, although the still operational IMP-8 satellite has provided a longer stream of data to date since its launch on Oct. 26, 1973. The honor for the longest operational spacecraft actually goes to Pioneer 10's much earlier predecessor, Pioneer 6, launched on Dec. 16, 1965 and last tracked successfully with good telemetry on Dec. 8. 2000, but the last acquisition of archival data received later at NSSDC was in 1975. Pioneer 10's sister spacecraft, Pioneer 11, was launched on April 6, 1973 and was the first spacecraft to explore the Saturnian system (Aug.-Sept. 1979), but it experienced a more rapid loss of RTG power and could no longer operate any science instruments or be tracked after Oct. 1995.

Further information on the Pioneer 10 and 11 missions, science instruments, and archival data sets can be found on our mission page for these spacecraft at http://nssdc.gsfc.nasa.gov/planetary/pioneer10-11.html . The history and current status of the Pioneer spacecraft missions (Pioneer 1 - 11, Pioneer Venus Orbiter) are also given at the Pioneer Project home page at http://spaceprojects.arc.nasa.gov/Space_Projects/pioneer/PNhome.html .