Dayside pickup oxygen ion precipitation at Venus and Mars: Spatial distributions, energy deposition and consequences

Journal Article · Mon Apr 01 00:00:00 EST 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/90JA01753· OSTI ID:5225078

Luhmann, J G ^[1]; Kozyra, J U ^[2]

---

1. Univ. of California, Los Angeles (USA)
2. Univ. of Michigan, Ann Arbor (USA)

The fluxes and energy spectra of picked-up planetary O{sup +} ions incident on the dayside atmospheres of Venus and Mars are calculated using the neutral exposure models of Nagy and Cravens (1988) and the Spreiter and Stahara (1980) gasdynamic model of the magnetosheath electric and magnetic field. Cold ({approximately}10 eV) O{sup +} ions are launched from hemispherical grids of starting points covering the daysides of the planets and their trajectories are followed until they either impact the dayside obstacle or cross the terminator plane. The impacting, or precipitating, ion fluxes are weighted according to the altitude of the hemispherical starting point grid in a manner consistent with the exosphere density models and the local photoion production rate. Maps of precipitating ion number flux and energy flux show the asymmetrical distribution of dayside energy deposition expected from this source which is unique to the weakly magnetized planets. Although the associated heating of the atmosphere and ionsphere is found to be negligible compared to that from the usual sources, backscattered or sputtered neutral oxygen atoms are produced at energies exceeding that needed for escape from the gravitational fields of both planets. These neutral winds, driven by pickup ion precipitation, represent a possibly significant loss of atmospheric constituents over the age of the solar system.

• OSTI ID: 5225078
• Journal Information: Journal of Geophysical Research; (United States), Vol. 96:A4; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
MARS PLANET
SOLAR WIND
INTERACTIONS
VENUS PLANET
CHARGED-PARTICLE PRECIPITATION
COMPARATIVE EVALUATIONS
ELECTRIC FIELDS
ENERGY SPECTRA
ENERGY TRANSFER
IONS
LOSSES
MAGNETIC FIELDS
MASS TRANSFER
MATHEMATICAL MODELS
OXYGEN IONS
PLANETARY ATMOSPHERES
SPATIAL DISTRIBUTION
ATMOSPHERES
CHARGED PARTICLES
DISTRIBUTION
EVALUATION
PLANETS
SOLAR ACTIVITY
SPECTRA
640107* - Astrophysics & Cosmology- Planetary Phenomena