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Study of planetary atmospheres by absorptive occultations

1990; Wiley; Volume: 28; Issue: 2 Linguagem: Inglês

10.1029/rg028i002p00117

8755-1209

Gerald R. Smith, D. M. Hunten,

Atmospheric Ozone and Climate

As a spacecraft observes the setting or rising of the Sun or a star behind the limb of a planet, the absorption spectrum of the upper atmosphere can be observed as a function of height. This powerful method can give the composition and the vertical distribution of individual gases, from which temperatures can be derived. This review describes the technique and methods of data reduction. Early experiments on the Earth's atmosphere (many from sounding rockets) are briefly summarized; many of them were compromised by the need to use instruments not designed for the purpose. Emphasis is placed on observations of the other planets, by ultraviolet spectrometers able to look at the Sun as well as stars. Mariner 10 set tight upper limits on the atmosphere of Mercury (and also found tiny quantities of H and He). The Voyager instruments defined the upper atmospheres of all four Jovian planets, as well as the satellites Titan and Triton. The potential for future measurements is at least as rich as the history, especially by use of instruments and platforms optimized for the purpose.