Fast O(sup +) ion flow observed around Venus at low altitudes

Technical Report · Thu Dec 01 04:00:00 EST 1988

OSTI ID:6274880

Kasprzak, W T; Niemann, H B

The Pioneer Venus Orbiter Neutral Mass Spectrometer (ONMS) has observed fast O(+) ions with an energy exceeding 40 eV in the spacecraft reference frame. The orbit of the spacecraft is nearly polar with periapsis near the equator. The ONMS is mounted at an angle to the spin axis which, in turn, is perpendicular to the ecliptic plane. From the spin modulated data the direction of the ion flow in that plane can be determined. Data from the first 11 diurnal cycles (orbits 1 to 2475) are vector averaged in order to display the general flow pattern. Plots of the averaged data are presented. On the dayside and near the terminators, where fast O(+) is observed near the ionopause, the directions are more or less parallel to the planet's surface with evidence of an asymmetry about the Sun-Venus line. On the nightside below 2000 km and near the equator there is a preferred dawn to dusk direction while at higher altitudes (lower solar zenith angles and higher latitudes) the flow direction is more antisunward. The averaged flux for this time period is 8x10 to the 5th/sq cm/s with a maximum of 5x10 to the 8th.

• Research Organization: National Aeronautics and Space Administration, Greenbelt, MD (USA). Goddard Space Flight Center
• OSTI ID: 6274880
• Report Number(s): N-89-15847; NASA-TM-100717; REPT-89B0053; NAS-1.15:100717
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHARGED PARTICLES
DATA
EXPERIMENTAL DATA
INFORMATION
ION MOBILITY
IONS
MASS SPECTROMETERS
MEASURING INSTRUMENTS
MOBILITY
NUMERICAL DATA
OXYGEN IONS
PARTICLE MOBILITY
PLANETARY IONOSPHERES
PLANETS
SPECTROMETERS
VENUS PLANET