urn:nasa:pds:context:instrument:pvo.omag 2.0 1.20.0.0 Product_Context 2020-08-26 1.0 extracted metadata from PDS3 catalog and modified to comply with PDS4 Information Model 2024-04-02 2.0 Updated to IM 1.20.0.0 urn:nasa:pds:context:instrument_host:spacecraft.pvo instrument_to_instrument_host Busse, F., 'Generation of planetary field by convection', Phys. Earth Planet. Int., vol. 12, p. 350, 1976. reference.BUSSE1976 Dolginov, S.S., Y.G. Yeroshenko and L. Davis, 'On the nature of the magnetic field near Venus', Kosmich. Issled., vol. 7, p. 747, 1969. reference.DOLGINOVETAL1969 [see ELPHICETAL1980A] reference.ELPHICETAL1979 Gordon, D.I., and R.E. Brown, Recent Advances in Fluxgate Magnetometry, IEEE Trans. on Magnetics, Vol. MAG-8, 76, 1972. reference.GORDONETAL1972 Russell, C.T., 'The magnetic moment of Venus: Venera-4 measurements reinterpreted,' Geophys. Res. Lett., vol. 3, p. 125, 1976. reference.RUSSELL1976 Russell, C.T., The ISEE 1 and 2 fluxgate magnetometers, IEEE Trans. Geosci. Electro., GE-16, P. 239, 1978. reference.RUSSELL1978 Russell, C.T., R.C. Elphic, and J.A. Slavin, 'On the strength of the Venus bow shock', Nature, 1979. reference.RUSSELLETAL1979A Russell, C.T., R.C. Elphic, and J.A. Slavin, 'Initial Pioneer Venus magnetic field results: Dayside observations', Science, vol. 203, p. 745, 1979. reference.RUSSELLETAL1979B Russell, C.T., and R.C. Elphic, 'Observation of magnetic flux ropes in Venus ionosphere', Nature, vol. 279, p. 616, 1979. reference.RUSSELLETAL1979C Russell, C.T., R.C. Elphic, and J.A. Slavin, 'Initial Pioneer Venus magnetic field results: Nightside observations', Science, vol 205, p. 114, 1979. reference.RUSSELLETAL1979D Russell, C.T., R.C. Snare, J.D. Means, and R.C. Elphic, 'Pioneer Venus Orbiter Fluxgate Magnetometer', Ieee Trans. Geo. Elec., Vol. GE 18, No. 1 p. 32, 1980. reference.RUSSELLETAL1980 Slavin, J.A., R.C. Elphic, and C.T. Russell, 'A comparison of Pioneer Venus and Venera bow shock observations: Evidence for a solar cycle variation', Geophys. Res. Lett., 1979. reference.SLAVINETAL1979A Slavin, J.A., R.C. Elphic, C.T. Russell, J.H. Wolfe, and D.S. Intriligator, 'Position and shape of the Venus bow shock: Pioneer Venus orbiter magnetometer observations', Geophys. Res. Lett., 1979. reference.SLAVINETAL1979B Smith, E.J., L. Davis, Jr., P.J. Coleman, Jr., and C.P. Sonett, Science, vol. 139, p. 909, 1963. reference.SMITHETAL1963 Snare, R.C. and J.D. Means, A Magnetometer for the Pioneer Venus Orbiter, IEEE Trans. Magnetics, vol. MAG-13(5), 1107, (REPLACED BY SNARE&MEANS1977), 1977. reference.SNAREETAL1977 FLUXGATE MAGNETOMETER (OMAG) for PIONEER VENUS Magnetometer not applicable not applicable INSTRUMENT OVERVIEW =================== This experiment used a triaxial fluxgate magnetometer with two ring-core sensors at the end of a magnetometer boom and one ring-core sensor, at 45 degrees to the spin axis, partway down the boom. The drive and electronics design had been used on the Apollo 15 and 16 subsatellites. The objectives of this investigation were to: (1) determine any planetary and remnant magnetic fields; (2) deduce the location and strength of the ionospheric current system; (3) determine the energy and mass balance in the upper atmosphere of Venus; (4) examine the nature of the solar wind interaction with Venus; and, (5) study the near-wake region of Venus and the structure of the Venusian bow shock. Additional objectives for interplanetary (solar wind) studies were to determine the perturbation of the near-planet region by Venus and to compare the properties of the average field at 0.7 and 1.0 AU. The magnetometer consists of three basic units, the electronics unit mounted inside the main spacecraft bus, an inboard sensor assembly mounted about one-third of the way from the end of a 4.7 meter boom, and an outboard assembly mounted on the end of the boom. The electronics box is magnesium, 15 x 22 x 15 cm in size, and has a mass of 1,7 kg. It includes a 12-bit analog to digital converter. the inboard sensor is 6 x 7 x 6 cm, with a mass of 110 g. It holds a single magnetometer oriented at 45 degrees to the orbiter spin axis. The outboard sensor is 8 x 5 x 4.5 cm, with a mass of 170 g. It comprises two magnetometers, one parallel to the spin axis and one perpendicular. Total mass including wiring is 2 kg, and the system uses 2.2 W at 27 V DC. The magnetometers are triaxial fluxgate type with large loop gain and feedback. The core of the magnetometer is a ring wrapped with permeable metal. The core is surrounded by drive, sense, and feedback coils. A sinusoidal drive voltage with a 7.25 kHz frequency is used, 4 V peak-to-peak and 150 mA. The sense circuit detects the second harmonic of the drive frequency, which is a function of the external magnetic field along the sense axis of the magnetometer ring core. The feedback circuit acts to conceal the field and the output is the measured input to the feedback circuit required to cancel the field. The range of the instrument is 128 gamma, which remains constant, but the resolution can change from 1/16 gamma to 1/2 gamma. The sampling rate can vary by more than two orders of magnitude. The signals flow to the data handling assembly, where it is digitized to 12 bits for each of the three sensors. The 36 bits are compressed to a single 32 bit word by conversion to floating point words. The instrument was intended to, in the worst case of low-bit and low-sample rates, measure one vector per 32 s. While in Venus orbit, when the spacecraft was coasting through the interplanetary region in the apoapsis mode, the sample rate was one vector per 8 s. While the spacecraft was passing through Venus' ionosphere in the periapsis mode, the sample rate was four vectors per second. The last full orbit of three-axis data was 3602, which ended on 16 Oct. 1988 at 14:30 UT. After this time, only one-axis data were available.