We indicate how existing Pioneer Venus Orbiter (PVO) data might be used to gain a better understanding of nightward ion flow in the Venusian ionosphere. Calculations based on PVO measurements made at solar maximum suggest that the global nightward flow of O(+) may be signifcantly greater than is required to maintain the observed nightside ionosphere densities. The validity of this conclusion depends upon (1) the accuracy with which the flow can be determined from the PVO ion density and velocity measurements and (2) the validity of the ionosphere theory used to estimate the required downward O(+) flux on the night side. If the measurements and theory are assumed to be accurate, the excess nightward flow implies a significant rate of ion escape from the planet, particularly at times of low solar wind dynamic pressure, Psw, when the ionopause rises to allow increased nightward flow. To illustrate a potentially important mechanism for ion escape from Venus, we present Orbiter Electron Temperature Probe (OETP) observations of plasma clouds and scavenged ionospheric plasma observed above the ionopause. We then employ OETP and Orbiter Retarding Potential Analyzer (ORPA) data to reexamine the global ion flow for average Psw conditions.


    Access

    Access via TIB

    Check availability in my library


    Export, share and cite



    Title :

    The nightward ion flow scenario at Venus revisited


    Contributors:
    Brace, L. H. (author) / Hartle, R. E. (author) / Theis, R. F. (author)

    Published in:

    Publication date :

    1995-01-01



    Type of media :

    Miscellaneous


    Type of material :

    No indication


    Language :

    English




    The Nightward Ion Flow Scenario at Venus Revisited

    Brace, L.H. | Online Contents | 1995


    The Nightward Ion Flow Scenario at Venus Revisited

    Brace, L. H. / Hartle, R. E. / Theis, R. F. et al. | British Library Conference Proceedings | 1995


    Venus atmospheric platform options revisited

    Dorrington, G.E. | Elsevier | 2010


    Venus atmospheric platform options revisited

    Dorrington, G.E. | Online Contents | 2010


    Venus Express: Scientific goals, instrumentation, and scenario of the mission

    Titov, D. V. / Svedhem, H. / McCoy, D. et al. | Springer Verlag | 2006