Instrument Information
IDENTIFIER urn:nasa:pds:context:instrument:pvo.oims::2.2
NAME Ion Mass Spectrometer (OIMS) for Pioneer Venus
TYPE Mass Spectrometer
DESCRIPTION The Pioneer Venus Orbiter Ion Mass Spectrometer (OIMS) was used to analyze the composition and concentration of thermal positive ions in Venus's ionosphere. This data helped interpret solar wind interactions with Venus, upper atmosphere photochemistry, and atmospheric mass and heat transport. The OIMS, designed similarly to instruments on previous missions, operates within a mass range of 1-56 amu and utilizes a Bennett radio-frequency mass spectrometer. Comprising an analyzer tube and an electronics package, the instrument weighs 3.0 kg and functions using 1.5 W of power for data processing and telemetry. The analyzer tube includes tungsten mesh grids and can measure 16 common ion masses. The instrument operates in 6.3-second cycles, alternating between an explore phase (measuring the selected masses) and an adapt phase (repeated measurements of detected ions).
MODEL IDENTIFIER
NAIF INSTRUMENT IDENTIFIER
SERIAL NUMBER not applicable
REFERENCES Brinton, H.C., L.R. Scott, M.W. Pharo, III, and J.T.C. Coulson, The Bennett ion-mass spectrometer on Atmosphere Explorer-C and -E, Radio Sci., vol. 8, 323, 1973.

Taylor, H.A., Jr., H.C. Brinton, S.J. Bauer, R.E. Hartle, T.M. Donahue, P.A. Cloutier, F.C. Michel, R.E. Daniell, Jr., B.H. Blackwell, Ionosphere of Venus: First observations of the dayside ion composition near dawn and dusk, Science, vol. 203, 752, 1979.

Taylor, H.A., Jr., H.C. Brinton, S.J. Bauer, R.E. Hartle, P.A. Cloutier, F.C. Michel, R.E. Daniell, Jr., T.M. Donahue, R.C. Maehl, Ionosphere of Venus: First observations of the effects of dynamics on the dayside ion composition, Science, vol. 203, 755, 1979.