ENERGETIC ELECTRONS IN THE DAYSIDE MANTLE OF VENUS

The purpose of the current study is to review the available and releva nt experimental data in order to examine whether there is any evidence of accelerated electrons above the dayside ionosphere of Venus, where the shocked solar wind encounters the planetary plasma, that is in th e dayside mantle. Such energetic electrons were seen around Mars in th e corresponding region, and theoretical studies also predict their exi stence at Venus. Direct measurements, however, are not available, beca use the retarding potential analyzer (ORPA) onboard the Pioneer Venus Orbiter had an upper energy limit of 60 eV. Therefore we were forced t o look for indirect evidences. We have reexamined the ORPA data and th e magnetic field measurements in the dayside mantle. We have concluded , using these indirect indicators, that this energetic electron popula tion is very likely to be present in the dayside mantle of Venus.