Jupiter's ionosphere: Results from the First Galileo Radio Occultation Experiment

Abstract

The Galileo spacecraft passed behind Jupiter on December 8, 1995, allowing the first radio occultation measurements of its ionospheric structure in 16 years. At ingress (24°S, 68°W), the principal peak of electron density is located at an altitude of 900 km above the 1‐bar pressure level, with a peak density of 105 cm−3 and a thickness of ∼200 km. At egress (43°S, 28°W), the main peak is centered near 2000 km altitude, with a peak density of 2×104 cm−3 and a thickness of ∼1000 km. Two thin layers, possibly forced by upwardly propagating gravity waves, appear at lower altitudes in the ingress profile. This is the first in a two‐year series of observations that should help to resolve long‐standing questions about Jupiter's ionosphere.

The structure of Titan’s atmosphere from Cassini radio occultations

“…It has been successfully used for many bodies in the solar system, including Jupiter and its satellites (Eshleman, 1975;Hinson et al, 1997), Saturn (Lindal et al, 1985), Uranus (Lindal et al, 1987), Neptune and Triton (Lindal, 1992), Mars (Cahoy et al, 2006), and Venus (Jenkins et al, 1994;Hinson and Jenkins, 1995). Prior to Cassini, the Voyager 1 spacecraft was occulted by Titan in 1979, early in Titan's northern spring (Lindal et al, 1983).…”

Consideration of the Jovian S-bursts and NB-emission Based on the Parametric Model

“…Hinson et al [1997] reported on the peak electron density n e ≈ 10 5 cm −3 located at the altitude h m ≈ 900 km with thickness H ≈ 200 km in the evening sector, in the morning sector these parameters are n e ≈ 2×10 4 cm −3 , h m ≈ 2000 km, and H ≈ 1000 km. The directivity pattern of the Jovian decametric radiation source represents a hollow cone, which is magnetic field aligned and has an angular aperture 2θ s ≈ 120…”

ARTS, the Atmospheric Radiative Transfer Simulator – version 2.2, the planetary toolbox edition

“…An example is the addition of radio occultation measurements and radio link budget estimations (Sect. 3.1), which is of particular interest for the planetary toolbox since such measurements are relevant for planetary exploration (e.g., Eshleman et al, 1987;Hinson et al, 1997;Oschlisniok et al, 2012). Some physical processes affect both passive and active measurements.…”