In recent decades, the number of orbital launches has significantly increased due to commercial, scientific, and technological drivers. As access to space becomes more frequent and affordable, the environmental impact of rocket emissions is receiving increasing attention. However, the specific interactions between rocket exhaust plumes and the atmosphere, especially in terms of chemical reactions and pollutant formation, are not yet fully understood. One of the key phenomena in this context is afterburning, defined as the post-combustion of unburned species in the plume due to mixing with atmospheric gases. This thesis presents the development of a simplified model aimed at studying the afterburning process in rocket plumes and estimating the resulting nitrogen oxide (NO) emissions.