Análise comparativa entre propulsão química e nuclear para missões tripuladas interplanetárias para Marte

Abstract

Considering the various risks to life on Earth and the planet's limited resources to sustain a growing population, space presents itself as a way to ensure the survival of mankind, by making the species multiplanetary. Manned interplanetary missions are essential to this goal, providing experience for a future colonization of space and other celestial bodies, as well as enabling various advances in science. The present work aims to compare chemical and nuclear propulsion, analyzing manned interplanetary missions in relation to astronauts’ radiation exposure, cost, reliability and risk. Discussions were held on the advantages and disadvantages of the propulsive methods, as well as their feasibility and challenges, outlining the best application for each propulsion system. The study was based on the NASA Design Reference Architecture 5 reference missions (using nuclear propulsion) and SpaceX Mars Program (using chemical propulsion), both bound for Mars. There was a very similar exposure to radiation in both missions, a significantly lower cost in the mission with chemical propulsion, while a higher reliability and lower risk in the mission with nuclear propulsion. Challenges were observed to make the cases studied viable, both common to the two missions – such as the need for high reliability on-orbit assembly and refuel – and characteristic of each propulsion – such as improvements in the aerocapture process for chemical propulsion and mitigation of catastrophic failures for nuclear propulsion. Based on the analyses, it was possible to conclude that chemical propulsion has better application in unmanned interplanetary missions or near-space missions, being limited due to its lower performance, but attractive due to its cost. It was also concluded that, by presenting greater safety to astronauts and better performance, nuclear propulsion is more suitable for manned interplanetary missions.