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
Rok vydání: 2019
Předmět:
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