An overview of the environmental impact of solid propulsion

Solid propulsion is one of the most studied rocket technologies from an environmental perspective. Despite being widely documented since the early flights of NASA's Space Shuttle (STS), its effective impact on the global and local environment remains unclear. Studies in this field have always blamed solid rockets for emitting hydrogen chloride and solid aluminum oxide particles, contributing to the global ozone depletion. However, the rate of launches and the quantity of propellant consumed do not support this kind of urgent concern. New models and experimental evidence have emerged over the last 20 years regarding the potential effects of exhaust gases, but knowledge gaps still exist. This document presents an overview of the subject, focusing on chlorine-based combustion products. The paper concludes that solid propulsion does not pose a global environmental problem due to its HCl emissions, being effects on the atmosphere rather confined in space and time. However, questions remain regarding other types of emissions, such as aluminum oxide and soot.