Venus: An ionospheric model with an exospheric temperature of 350°K

Abstract

The electron densities from Mariner 5 are fitted by an ionosphere based on a neutral composition (at the homopause) containing 1% O and 2 ppm H2. The corresponding exospheric temperature is 350°K. Ion-neutral reactions of the H2 give a large source of nonthermal H atoms that may explain the dual scale height of Lyman α.