Journal ArticleDOI
Solar cycle effects on the structure of the electron density profiles in the dayside ionosphere of venus
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The ionopause height for values of the solar zenith angle below about 50 deg regardless of the phase in the solar cycle was found to be generally low at times of solar minimum and intermediate solar activity as discussed by the authors.Abstract:
Results are presented of observations from the changes in the electron density structure of the dayside ionosphere of Venus that were brought about by changing solar activity. The ionopause height is generally low for values of the solar zenith angle below about 50 deg regardless of the phase in the solar cycle. At solar maximum, and at times of intermediate solar activity, the ionopause height for solar zenith angles greater than about 50 deg is highly variable, ranging from a minimum of about 200 km to a maximum of more than 1000 km. At times of solar minimum the great majority of all ionopause heights for all solar zenith angles are uniformly low, lying between 200 and 300 km. It is argued that the compressed nature of the Venus atmosphere at solar minimum is produced by permeation of the ionosphere by the solar wind magnetic field, which occurs when the solar wind dynamic pressure exceeds the ionospheric plasma pressure.read more
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Journal ArticleDOI
What makes a planet habitable
Helmut Lammer,Jan Hendrik Bredehöft,Athena Coustenis,Maxim L. Khodachenko,Lisa Kaltenegger,Olivier Grasset,Daniel Prieur,François Raulin,Pascale Ehrenfreund,M. Yamauchi,Jan-Erik Wahlund,Jean-Mathias Grießmeier,Günter Stangl,Charles S. Cockell,Yu. N. Kulikov,John Lee Grenfell,Heike Rauer +16 more
TL;DR: In this article, the authors discuss the geodynamical and geophysical environments which are necessary for planets where plate tectonics remain active over geological time scales and for planets which evolve to one-plate planets.
Journal ArticleDOI
Solar activity variations of the Venus thermosphere/ionosphere
Jane L. Fox,K. Y. Sung +1 more
TL;DR: In this article, the authors present models of the low and high solar activity thermospheres and ionospheres of Venus for a background atmosphere based largely on the VTS3 model of Hedin et al.
Journal ArticleDOI
The structure of Venus’ middle atmosphere and ionosphere
Martin Pätzold,Bernd Häusler,Mike Bird,Silvia Tellmann,R. Mattei,S. W. Asmar,Véronique Dehant,W. Eidel,Takeshi Imamura,Richard A. Simpson,G. L. Tyler +10 more
TL;DR: The fine structure in temperatures at upper cloud-deck altitudes is determined, a distinct day–night temperature difference in the southern middle atmosphere is detected, and day-to-day changes in Venus’ ionosphere are tracked.
Journal ArticleDOI
Cassini radio science
Arvydas J. Kliore,John D. Anderson,John W. Armstrong,S. W. Asmar,C. L. Hamilton,Nicole J. Rappaport,Hugo D. Wahlquist,R. Ambrosini,F. M. Flasar,Richard G. French,Luciano Iess,Essam A. Marouf,Andrew F. Nagy +12 more
TL;DR: Cassini radio science investigations will be conducted both during the cruise (gravitational wave and conjunction experiments) and the Saturnian tour of the mission (atmospheric and ionospheric occultations, ring occultation, determinations of masses and gravity fields) as mentioned in this paper.
Book ChapterDOI
Radio occultation observations of the ionospheres of Mars and Venus
TL;DR: The availability of a large body of radio occultation data for the Mars and Venus ionospheres makes possible comparative studies of their structures and temporal behavior as mentioned in this paper, and the results show that the Venus ionosphere at solar minimum, and that of Mars at all times, are not in a state of diffusive equilibrium above the chemical equilibrium regions.
References
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Journal ArticleDOI
The dynamic behavior of the Venus ionosphere in response to solar wind interactions
Larry H. Brace,R. F. Theis,Walter R. Hoegy,John H. Wolfe,John D. Mihalov,Christopher T. Russell,R. C. Elphic,Andrew F. Nagy +7 more
TL;DR: The dynamics of the Venus ionosphere relates to the variations in the solar wind and the ionosheath magnetic fields as demonstrated by the electron density and temperature measurements of the Pioneer Venus orbiter electron probe.
Journal ArticleDOI
The solar wind interaction with Venus
TL;DR: In this article, the relationship between the solar wind and the Earth's surface was analyzed, and the effects of the intrinsic field, neutral atmosphere, and ionosphere of the planet Venus on solar wind were examined.
Journal ArticleDOI
An observational study of the nightside ionospheres of Mars and Venus with radio occultation methods
TL;DR: In this article, the nightside electron density profiles obtained with radio occultation data from the Viking orbiters were investigated for Mars and Venus, and it was shown that the Mars nightside ionosphere is generally weaker than the Venus night side ionosphere, and when it is present, the peak altitude is higher.
Journal ArticleDOI
Atmosphere and ionosphere of venus from the mariner v s-band radio occultation measurement.
TL;DR: Measurements of the frequency, phase, and amplitude of the S-band radio signal of Mariner V as it passed behind Venus were used to obtain the effects of refraction in its atmosphere and ionosphere.
Journal ArticleDOI
Characteristics of the Marslike limit of the Venus-solar wind interaction
TL;DR: In this article, the response of the Venus ionosphere to the solar wind when the latter exceeds the peak thermal pressure in the planetary ionosphere is characterized on the basis of observations from the Pioneer Venus Orbiter.