Atmospheric interaction radiation from high altitude rocket exhausts

Abstract

A model for calculating the infrared radiation from rocket exhaust gases at high altitudes (typically above 200 km), caused by collisions between exhaust molecular species and atmospheric species is presented. At altitudes where the atmospheric mean free path is larger than a typical rocket exhaust plume lenght scale, the evolution in space and time of the exhaust gases is described by the kinetic theory of gases. In addition, the collision frequency between exhaust and atmospheric species is sufficiently low that excited molecules have time, on the average, to loose thsis excitation energy via radiative emission before experiencing another collision. Thus, the distribution of excited molecular states is nonthermal in this model. Two examples of such radiation are presented: one for the radiation from the CO 2 (υ 3) mode and the other for the H 2O(υ 3) mode. The atmospheric collision partner for excitation of both of these exhaust species is taken to be atomic oxygen, the dominant atmospheric constituent at high altitudes.