Spacecraft study of the Solar system is one of humanity's most outstanding achievements. Thanks to this study, our present knowledge of properties of and conditions on the planets exceeds many-fold that of 20 years ago: planets have been rediscovered. This is especially the case for planetary atmospheres, whose properties were for the most part either not at all or only erroneously known. Much research has been invested in the study of the atmospheres of Mars and Venus, and their chemical composition and photochemistry are basic problems in these studies. In the present publication I have tried to summarize all findings in this field. The English version of the book includes new data in the field from the last 3 years since the book was published in Russian. I wish to thank U. von Zahn, who initiated my talks with Springer-Verlag and acted as technical editor. December 2, 1985 V. A. KRASNOPOLSKY Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 Chemical Composition and Structure of the Martian Atmosphere 4 1. 1 Carbon Dioxide and Atmospheric Pressure . . . . . . . . . . . . . . . . . . . 4 1. 2 CO and O Mixing Ratios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2 1. 3 Ozone. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1. 4 Water Vapor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 1. 5 Composition of the Upper Atmosphere as Determined from Airglow Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 1. 6 Mass Spectrometric Measurements of the Atmospheric Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 1. 7 Ionospheric Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 1. 8 Temperature Profile of the Lower Atmosphere. . . . . . . . . . . . . . . . 36 1. 9 Temperature of the Upper Atmosphere . . . . . . . . . . . . . . . . . . . . . . 40 1. 10 Eddy Diffusion Coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 2 Photochemistry of the Martian Atmosphere . . . . . . . . . . . . . . . . . .

Inhalt

1 Chemical Composition and Structure of the Martian Atmosphere.- 1.1 Carbon Dioxide and Atmospheric Pressure.- 1.2 CO and O2 Mixing Ratios.- 1.3 Ozone.- 1.4 Water Vapor.- 1.5 Composition of the Upper Atmosphere as Determined from Airglow Spectroscopy.- 1.6 Mass Spectrometric Measurements of the Atmospheric Composition.- 1.7 Ionospheric Composition.- 1.8 Temperature Profile of the Lower Atmosphere.- 1.9 Temperature of the Upper Atmosphere.- 1.10 Eddy Diffusion Coefficient.- 2 Photochemistry of the Martian Atmosphere.- 2.1 Ionosphere.- 2.2 Photochemistry of Nitrogen.- 2.3 H2 Dissociation and Escape of Atomic Hydrogen.- 2.4 Nonthermal Escape and Isotopic Composition of Oxygen and Nitrogen.- 2.5 Dissociation of C02: Atomic Carbon in the Upper Atmosphere.- 2.6 Diffusion and Photolysis of Water Vapor.- 2.7 Photochemistry of the Lower Atmosphere (Global Average Conditions).- 2.8 Diurnal Variations of Minor Components in the Low Latitude Atmosphere.- 2.9 Latitudinal Distribution of Ozone in Different Seasons.- 2.10 Seasonal Variations of Atmospheric Composition at a Latitude of 65 °N.- 3 Chemical Composition and Structure of the Yenusian Atmosphere and Cloud Layer.- 3.1 Properties of Aerosol in the Upper Part of the Cloud Layer Deduced from Polarization Measurements.- 3.2 Interpretation of Spectroscopic Measurements of Escaping Radiation.- 3.3 Spectroscopy in Visible and Infrared Ranges.- 3.4 Remote Sounding of Water Vapor and Carbon Monoxide in Far Infrared and Microwave Regions. Radio Spectrum.- 3.5 Optical Measurements in the 0.45-1.2 ?m Range from Venera Landers.- 3.6 Mass Spectrometric and Gas Chromatographic Measurements in the Lower Atmosphere.- 3.7 Physical Characteristics of the Cloud Layer.- 3.8 Ultraviolet Absorption in the Cloud Layer.- 3.9 Investigation of a Cloud Layer Elemental Composition by X-Ray Fluorescent Spectroscopy in the Region of 1 to 20 Å (0.6-13 keV).- 3.10 Summary of the Data on the Tropospheric and Cloud Layer Composition.- 3.11 The Upper Atmosphere.- 3.12 Ionosphere.- 3.13 Temperature, Eddy Mixing, Atmospheric Dynamics, and Lightning.- 4 Photochemistry of the Venusian Atmosphere.- 4.1 Day Side Ionosphere.- 4.2 Nighttime Ionosphere.- 4.3 Metastable Species in the Venusian Ionosphere. Nitric Oxide, Atomic Nitrogen, and Atomic Carbon.- 4.4 Light Components of the Upper Atmosphere (H, H2, He). "Hot" Atoms and Nonthermal Escape of H, He, and O.- 4.5 Thermospheric Models.- 4.6 Lightning and Lower Atmospheric Chemistry. Nitric Oxide in the Lower Atmosphere.- 4.7 Lower Atmospheric and Surface Rock Compositions (0 - 50 km).- 4.8 Neutral Atmospheric Photochemistry Above 50 km. Main Problems, Previous Results, Main Chemical Reactions.- 4.9 Radiative Transfer and Aerosol Transport in the Cloud Laye.- 4.10 Boundary Conditions.- 4.11 Atmospheric Composition at 50 to 200 km (Results of Calculations).- 4.12 O2 1.27 µm and O (1D) 630 nm Airglow. Photolytic Rates.- 4.13 The Influence of Some Reaction Rate Coefficients on the Results of Calculations.- 4.14 Photochemistry of the Venusian Mesosphere as Considered by Winick and Stewart (1980).- 4.15 Analysis of Atmospheric Photochemistry on Venus by Yung and DeMore (1982).- 4.16 Loss of Water from Venus and Its Atmospheric Evolution.- 4.17 Conclusions.- References.