Missions   PVO

Pioneer Venus Orbiter (PVO)

PVO in orbit.


Evolution of PVO.


PVO entry into
Venus atmosphere.


(Close up) PVO entry into
Venus atmosphere.


Pioneer spacecraft.

The Pioneer Venus Orbiter (PVO) was launched on May 20, 1978, and was inserted into orbit around Venus on December 4, 1978. The spacecraft was on orbit acquiring data for nearly fourteen years, finally burning up in the atmosphere of Venus in October 1992. The PVO mission was primarily directed towards in situ and remote sensing of the atmosphere and ionosphere of Venus. The in situ instruments included: ion and neutral mass spectrometers, a Langmuir probe to measure thermal electrons, a retarding potential analyzer to measure thermal ions, a magnetometer, and a plasma wave electric field experiment. The remote sensing instruments included: an ultraviolet spectrometer, a cloud photopolarimeter, an infrared detector, and a radar experiment. Additional experiments included a solar wind plasma instrument, and a gamma-ray burst detector.

Data from many of these instruments have been submitted to the Planetary Data System.

Ten-minute averaged magnetic field and plasma data

Data from the Orbiter Magnetometer (OMAG) and the Orbiter Electric Field Detector (OEFD) were reduced and analyzed by the space physics group at UCLA. Prof. C. T. Russell is the Principal Investigator for the OMAG, while R. J. Strangeway is the Principal Investigator for the OEFD, which is the plasma wave experiment. The PVO Bibliography gives a list of all the publications arising from the data analysis of these two experiments.

Many of the papers involving the magnetometer data have been concerned with the solar wind interaction with an unmagnetized planet. Topics include the basic shape and structure of the bow shock, the magnetosheath, the ionosphere, and the magnetotail. At Venus the solar wind is in direct contact with the ionosphere, and the magnetic fields detected within the ionosphere of Venus are ultimately due to solar wind magnetic flux being convected and/or diffused into the ionosphere. The magnetic fields within the ionosphere are therefore highly variable, as changes in both the solar wind and ionosphere affect the processes which transport magnetic flux.

Most of the publications using data from the plasma wave instrument have addressed the issue of whether or not lightning occurs on Venus. It has been argued that Extremely Low Frequency (ELF) waves detected at low altitudes by PVO are due to atmospheric lightning. Because of the difficulty in identifying the wave modes, and the relative paucity of corroborating evidence, there is still some scientific debate about the nature of the plasma waves detected by PVO. Confirmation of the presence of lightning poses interesting questions concerning the means by which cloud electrification, and subsequent lightning discharges, occur because the atmosphere of Venus (sulfuric acid clouds in a carbon dioxide atmosphere) is quite different from the Earth (water clouds in an oxygen/nitrogen atmosphere).

Associated References


PVO Bibliography
The Pioneer Venus Mission
Orginally published in: Venus and Mars: Atmospheres, Ionospheres and Solar Wind Interactions. (edited by J.G. Luhmann, M. Tatrallyay and R.O. Pepin) 225-236, American Geophysical Union, Washington D.C., 1992.
The Pioneer Venus Fluxgate Magnetometer
Originally in: IEEE Trans. on Geoscience and Remote Sensing, GE-18, 32-36, 1980.



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Last updated: December 31, 1999