The visible airglow experiment—a review

Contributions of the Visible Airglow Experiment (VAE) to the understanding of thermospheric aeronomy are summarized and discussed. The importance of instrumental design and operation is considered and particular attention is given to the relationship between observation and inversion for optical measurements of light emissions from a diffuse medium. The specific influence of the VAE investigation on the present understanding of the physical mechanisms which produce and destroy the excited species, O + ( 2P), O( 1D), O( 1S), N( 2D), N 2 + (B 2 Σ u +), N 2(C 3 π u ) and Mg + ( 2 P 1 2 ) , is discussed in detail.