Atmosphere and Ionosphere of Venus from the Mariner V S-Band Radio Occultation Measurement

Abstract

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. Profiles of refractivity, temperature, pressure, and density in the neutral atmosphere, as well as electron density in the daytime ionosphere, are presented. A constant scale height was observed above the tropopause, and the temperature increased with an approximately linear lapse rate below the tropopause to the level at which signal was lost, presumably because heavy defocusing attenuation occurred as critical refraction was approached. An ionosphere having at least two maxima was observed at only 85 kilometers above the tropopause.

Venus Atmospheric Thermal Structure and Radiative Balance

“…The feasibility of the radio occultation technique to obtain atmospheric profiles of temperature and density with altitude was first demonstrated by Mariner 4 at Mars (Kliore et al 1965) and then at Venus by Mariner 5 (Kliore et al 1967) using both one way (spacecraft to Earth), and two way (Earth to spacecraft to Earth) occultations (Howard et al 1974), generally at two frequencies (X and S band). Venera 9/10 occultations at 32 cm (Kolosov et al 1978;) and 15/16 at 5 and 13 cm wavelengths (Yakovlev et al 1987) orbiters also obtained radio occultation profiles by using these radio frequencies.…”

“…The radio occultation technique X and S band frequencies was used to obtain temperature profiles of the upper atmosphere (35 to 90 km) of Venus for the first time from Mariner 5 (Kliore et al 1967). These were followed by Mariner 10 (Fjeldbo et al 1971), Pioneer Venus orbiter (Kliore and Patel 1980), Magellan (Jenkins et al 1994;Jenkins 1998), Venus Express (Tellmann et al 2009) and now Akatsuki .…”

Satellite Atmospheres and Magnetospheres

“…This technique has been used very successfully to measure the characteristics of the ionospheres and atmospheres of Venus (Kliore et al, 1967;Fjeldbo et al, 1971;Kliore and Patel 1980); Mars (Kliore et al, 1965;Kliore et al, 1972a;Lindal et al, 1979); Mercury (Howard et al, 1974); Jupiter (Fjeldbo et al, 1975;Eshleman et al, 1979;Lindal et al, 1981;Hinson et al, 1997); Saturn Tyler et al, 1981;Lindal et al, 1985); Uranus (Lindal et al, 1987); Neptune (Tyler et al, 1989;Lindal 1992); Saturn's rings (Marouf and Tyler 1985); as well as Saturn's satellite Titan (Lindal et al, 1983); Neptune's Triton (Tyler et al, 1989); and Jupiter's satellites Io (Kliore et al, 1975) and Europa (Kliore et al, 1997).…”

The Atmospheres of Mars and Venus

“…From these studies it is also possible to determine the total pressure from the broadening of spectral lines, and it appears that CO2 is the major constituent of the Mars atmosphere as well. Total pressure is also determined from the surface refractivity obtained during the Mariner 4, 6, and 7 flybys (Kliore et al 1969a, and these results fall in the range 4.9-7.6 mb. Here the spread of values is real, and is probably due to topographic differences at the entrance and exit points for the different spacecraft (Pettengill et al 1969, Goldstein et al 1970.…”