Recently a ram source of N2 Lyman-Birge-Hopfield (LBH) emission has been reported on S3-4 satellite. An investigation of likely chemical processes responsible has identified a gas phase reaction involving ram atmosphere and the ram-side cloud of gas leading the satellite. The process produces large quantities of fast N that impinge on low-altitude spacecraft. Subsequent surface recombination produces excited N2 which results in the emission with predictions of altitude variation similar to that measured by other investigators. ¿ American Geophysical Union 1988