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Ionospheric photoelectrons at Venus: Initial observations by ASPERA-4 ELS

Research output: Contribution to journalJournal article


<mark>Journal publication date</mark>1/05/2008
<mark>Journal</mark>Planetary and Space Science
Issue number6
Number of pages5
Pages (from-to)802-806
Early online date31/12/07
<mark>Original language</mark>English


We report the detection of electrons due to photo-ionization of atomic oxygen and carbon dioxide in the Venus atmosphere by solar helium 30.4 nm photons. The detection was by the Analyzer of Space Plasma and Energetic Atoms (ASPERA-4) Electron Spectrometer (ELS) on the Venus Express (VEx) European Space Agency (ESA) mission. Characteristic peaks in energy for such photoelectrons have been predicted by Venus atmosphere/ionosphere models. The ELS energy resolution (ΔE/E~7%) means that these are the first detailed measurements of such electrons. Considerations of ion production and transport in the atmosphere of Venus suggest that the observed photoelectron peaks are due primarily to ionization of atomic oxygen