ARC Pioneer Plasma Group Home Page

Last modified: 12 Jan 1999

NASA Ames Pioneer Plasma Group

The Pioneer 10 and 11 Spacecraft

NASA's Pioneer 10 spacecraft, launched in 1972, was the first spacecraft to encounter the planet Jupiter (1973) and until 23 February 1998, when it was finally passed by Voyager 1, it was the farthest man-made object from the Sun. A gravitational boost from Jupiter launched the spacecraft onto a path leaving the solar system at approximately 3 Astronomical Units per year (1 AU = 150,000,000 km). By the end of 1998, the spacecraft was more than 70 AU from the Sun. Although the Pioneer Missions formally ended in 1997, the spacecraft continues to send back useful scientific data, adding to an enormous body of observations that now span more than 2 solar cycles and 70 AU.

The Pioneer 11 spacecraft, launched a year after Pioneer 10, reached Jupiter in 1974 and was the first spacecraft to encounter Saturn (1979). Pioneer 11 is also leaving the solar system, and by the end of 1995 was more than 44 AU from the Sun. By July 1995, exhaustion of the spacecraft power supplies had reached the point that most of the scientific instruments could no longer be operated, but over the preceding 21 years, Pioneer 11, like Pioneer 10, has provided a very large body of interplanetary data.

For additional information on the Pioneer 10 and 11 missions, see the Pioneer Project Home Page.

The Pioneer Venus Orbiter

The Pioneer Venus Orbiter and Probe were launched in 1978. The Orbiter spacecraft was inserted into a highly eccentric and nearly polar orbit about Venus on December 5, 1978. The spacecraft remained in operation until 1992, when the natural decay of its orbit led to its entry into the planet's atmosphere and subsequent destruction. The legacy of this mission is a vast body of data concerning the plasma environment of Venus, as well as a 14-year record of the state of the interplanetary medium at the heliocentric distance of Venus (0.72 AU).

For additional information on the Pioneer Venus Orbiter mission, see Colin, L., The Pioneer Venus Program, J. Geophys. Res., 85, 7575-7598, 1980.

The ARC Plasma Analyzers

The Ames Research Center Plasma Analyzers aboard the Pioneer 10 and Pioneer 11 spacecraft measure the charged particles that comprise the solar wind. This data is reduced to determine such parameters as the flow speed, density, and temperature of the solar wind plasma. The ARC plasma group also maintains the data set from the Plasma Analyzer aboard the Pioneer Venus Orbiter.

Instrument description: Pioneer 10 and 11 Plasma Analyzers
Instrument description: Pioneer Venus Orbiter Plasma Analyzer

Science staff

Aaron Barnes (Principal Investigator)
Paul R. Gazis (Information Contact)
John D. Mihalov
Romana Ratkiewicz


The Pioneer Plasma Analyzer Data Sets

The data from these WWW pages are freely available. If you use these data sets for detailed studies, we recommend that you contact us to inquire about possible subtleties that might not be covered adequately in our documentation. If these data are used in a scientific publication, please acknowledge their source (the Ames Plasma Group), the ARC Pioneer Project, and the National Aeronautics and Space Administration. We would appreciate receiving copies (including pre-publication material) of any scientific papers that make use of these data sets.

Pioneer 10 are available until late 1995 and Pioneer 11 data are available until mid-1992. After those dates, declining spacecraft power made further operation of the plasma analyzers impossible. Pioneer Venus Orbiter data is available for the entire mission including the cruise phase.

Data Sets:

For further information contact:

Dr. Paul R. Gazis, SJSU Research Associate
phone: (415) 604-5704
fax:   (415) 604-6779

Go to Top of page.

Go to The Pioneer Data Sets.

Go to Pioneer Project Home Page.

Go to NASA Space Physics Data System (SPDS) Home Page.

Go to NASA / Ames / Space Science Division / Planetary Systems Branch.

Go to Other space physics related links
Last modified: 27 March 1997