**Abstract**

This chapter briefly introduces hybrid rocket propulsion for general audience. Advantageous of hybrid rockets over solids and liquids are presented. This chapter also explains how to design a test setup for hybrid motor firings. Hybrid propulsion provides sustainable, safe and low cost systems for space missions. Therefore, this chapter proposes hybrid propulsion system for Mars Ascent Vehicles. Paraffin wax is the fuel of the rocket. Propulsion system uses *CO*2*=N*2*O* mixture as the oxidizer. The goal is to understand the ignition capability of the *CO*<sup>2</sup> as an in-situ oxidizer on Mars. *CO*<sup>2</sup> is known as major combustion product in the nature. However, it can only burn with metallic powders. Thus, metallic additives are added in the fuel grain. Results show that *CO*<sup>2</sup> increase slows down the chemical kinetics thus reduces the adiabatic flame temperature. Maximum flammability limit is achieved at 75% *CO*<sup>2</sup> by mass in the oxidizer mixture. Flame temperature is 1700 K at 75% *CO*2. Ignition quenches below the 1700 K.

**Keywords:** hybrid rockets, *CO2* combustion, metallic additives, paraffin wax, mars ascent vehicle
