Ionospheric Ambipolar Electric Fields of Mars and Venus: Comparisons Between Theoretical Predictions and Direct Observations of the Electric Potential Drop
| Autor: | Joseph M. Grebowsky, Shaosui Xu, Glyn Collinson, Alex Glocer, David L. Mitchell, Bruce M. Jakosky, Laila Andersson, R. A. Frahm |
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| Rok vydání: | 2019 |
| Předmět: |
Physics
Atmospheric escape biology Field line Ambipolar diffusion Venus Mars Exploration Program Atmosphere of Mars biology.organism_classification Article Computational physics Geophysics Physics::Space Physics General Earth and Planetary Sciences Astrophysics::Earth and Planetary Astrophysics Ionosphere Pressure gradient |
| Zdroj: | Geophys Res Lett |
| ISSN: | 1944-8007 0094-8276 |
| Popis: | We test the hypothesis that their dominant driver of a planetary ambipolar electric field is the ionospheric electron pressure gradient (∇P(e)). The ionospheres of Venus and Mars are mapped using Langmuir probe measurements from NASA’s Pioneer Venus Orbiter (PVO) and Mars Atmosphere and Volatile Evolution (MAVEN) missions. We then determine the component of the ionospheric potential drop that can be explained by the electron pressure gradient drop along a simple draped field line. At Mars, this calculation is consistent with the mean potential drops measured statistically by MAVEN. However, at Venus, contrary to our current understanding, the thermal electron pressure gradient alone cannot explain Venus’ strong ambipolar field. These results strongly motivate a return to Venus with a comprehensive plasmas and fields package, similar to that on MAVEN, to investigate the physics of atmospheric escape at Earth’s closest analog. |
| Databáze: | OpenAIRE |
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