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Initial observations of the nightside ionosphere of Venus from Pioneer Venus Orbiter radio occultationsResults of radio occultation measurements of electron density profiles of the nightside ionosphere of Venus at solar zenith angles from 90 to 164 deg, obtained from the Pioneer Venus Orbiter, are reported. Data were derived from closed-loop S- and X-band signals received by the Deep Space Network upon ionospheric entry and exit of the spacecraft. Nightside electron density profiles are found to be rather uniform in the solar zenith angle range of from 95 to 107 deg, with peak electron densities ranging from 23,000 to 40,000/cu cm, while between 110 and 164 deg, profiles exhibit a high degree of variability and peak electron densities vary from 7,600 to 31,800/cu cm. A possible mechanism for the maintenance of the nightside Venus ionosphere during the long Venus night, which is consistent with the observed spatial and temporal variability of deep ionospheric electron density profiles, is proposed to be impact ionization by precipitating particles, although transport processes from the dayside may also be important.
Document ID
19790056816
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Kliore, A. J.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Patel, I. R.
(California Institute of Technology, Jet Propulsion Laboratory, Pasadena Calif., United States)
Nagy, A. F.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Cravens, T. E.
(Michigan, University Ann Arbor, Mich., United States)
Gombosi, T. I.
(Michigan, University Ann Arbor, Mich.; Magyar Tudomanyos Akademia, Kozponti Fizikai Kutato Intezet, Budapest, Hungary)
Date Acquired
August 9, 2013
Publication Date
July 6, 1979
Publication Information
Publication: Science
Volume: 205
Subject Category
Lunar And Planetary Exploration
Accession Number
79A40829
Funding Number(s)
CONTRACT_GRANT: NAS2-9130
CONTRACT_GRANT: NAS7-100
CONTRACT_GRANT: NGR-23-005-015
Distribution Limits
Public
Copyright
Other

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