Atmospheric densities from Explorer 17 density gages and a comparison with satellite drag data

Abstract

The purpose of this letter is to present the initial atmospheric densities directly measured by the ionization gages on the Explorer 17 satellite. The satellite has been described [Horowitz, 1963] and the gages and their response to the atmosphere have also been reported [Newton et al., 1963]. The data presented in this letter were obtained with two types of ionization vacuum gages, the hot-filament thermionic type (Bayard-Alpert) and the magnetron type (Redhead). The absolute accuracy of these data is believed to be ±35% and the repeatability is ±20%.