OASIS

Presentation Abstract

Title	The Ionospheres of Venus and Mars - a Comparison of Venus Express and Mars Express Observations
Author Block	Martin Pätzold¹, B. Häusler², S. Tellman¹, M. Bird³, D. Hinson⁴, G. Tyler⁴, P. Withers⁵ ¹Rheinisches Institut Für Umweltforschung, Germany, ²Universität der Bundeswehr München, Germany, ³Universität Bonn, Germany, ⁴Stanford University, ⁵Boston University.
Abstract	The radio science experiments VeRa on Venus Express and MaRS on Mars Express sound the ionospheres of Venus and Mars at microwavelengths. They cover the full ionospheric electron density profile from the base of the ionosphere at 115 km (80 km at Mars) to the ionopause at altitudes between 300 km and 600 km. Both ionospheres consists of a lower layer, V1 at Venus at about 125 km and M1 at Mars at 110 km, and the main layer, V2 at Venus at 140 km and M2 at Mars at about 135 km altitude, formed mainly by solar radiation at X-ray and EUV, respectively. The peak altitudes and densities of both layers depend on the solar zenith angle and change with daytime. VEX and MEX observations will be compared with past observations and models. Occasionally, a region of enhanced ionisation below the lower layer (V1 or M1) can be observed which is caused by the infall of meteors into the atmosphere. These occurrences are sporadic or correlated with crossings of the planets with cometary orbit planes creating meteor showers in the atmospheres. Occurrence rates, morphology, repeatability of the ionospheric meteor layers shall be discussed.