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H 2 abundance in the atmosphere of Venus
Author(s) -
Kumar Shailendra,
Hunten Donald M.,
Taylor Harry A.
Publication year - 1981
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl008i003p00237
Subject(s) - venus , atmosphere of venus , exosphere , atmosphere (unit) , orbiter , mixing ratio , ion , flux (metallurgy) , altitude (triangle) , ionosphere , astrobiology , physics , atmospheric sciences , mass spectrometry , environmental science , astrophysics , astronomy , materials science , meteorology , geometry , mathematics , quantum mechanics , metallurgy
The in situ measurements from the Pioneer Venus Orbiter (PVO) Ion Mass Spectrometer have led to the detection of H 2 + ions in the Venus ionosphere. Although H 2 + is a minor ion, its measurement provides the first direct clue for determining the H 2 abundance in the upper atmosphere of Venus. A photochemical model using PVO measurements is used to derive an H 2 mixing ratio of 10 ppm below 140 km altitude. The presence of this much H 2 confirms our previous prediction that the reactions of O + with H 2 and subsequent recombination of OH + provide an important source of nonthermal H observed in the Venus exosphere. The estimated escape flux for H is ∼10 8 cm −2 s −1