The Venus ionosphere in the northern polar region

PLASLIFE is a computer simulation which assists in the interpretation of high latitude ionospheric observations and, in this study, is applied to the polar regions of Venus. The Venus Express spacecraft samples the high latitude ionosphere in the northern hemisphere of the planet. On 4 August 2008 it was inserted into a new orbit with pericentre located below 200 km close to 86° N. The ASPERA-4 instrument on the spacecraft records the first extended in situ data set of the plasma environment in this sector. The observed ionospheric ion and electron populations exhibit significant variation between orbits and, by compensating for the effects of solar zenith angle and altitude, the relative contributions of photoionisation and plasma transport can be investigated. These variations are discussed with respect to parameters including local time and solar flux. Comparisons are drawn with the terrestrial ionosphere

Plasma instabilities near Mars

Meeting abstract from the CDROM, #2338It has been suggested in the literature that the Kelvin-Helmholtz instability can be responsible for significant ion loss at Mars through the detachment of ionospheric plasma clouds Clouds of detached ionospheric plasma were observed at Venus by the Pioneer Venus orbiter The conditions at Mars differ somewhat from those at Venus The ratio between the ion gyro radius and the radius of the planet is larger at Mars than at Venus since Mars is a smaller planet and the solar wind magnetic field is weaker at Mars than at Venus It is therefore interesting to study instabilities at Mars and to compare the results from Mars with those from Venus We search the ion and electron data from the ASPERA-3 instrument on the Mars Express spacecraft for signatures of instabilities at Mars We present data indicative of instabilities in the magnetosheath and the induced magnetosphere boundary downstream of the plane