A space propulsion system is a technology or set of technologies used to propel spacecraft through outer space. These systems are crucial for enabling spacecraft to move, change their velocity, and travel to different destinations in space. The choice of propulsion system depends on the mission requirements, spacecraft design, and the specific goals of the mission. There are various types of space propulsion systems, each with its own advantages and limitations.

• Chemical Propulsion: This is one of the most traditional and widely used forms of propulsion. Chemical rockets use the reaction between propellants (usually a fuel and an oxidizer) to produce high-speed exhaust gases, creating thrust that propels the spacecraft. The Space Shuttle, for example, used chemical propulsion.
• Electric Propulsion: Electric propulsion systems use electric power to accelerate propellants to high speeds, providing greater efficiency compared to chemical rockets. Ion thrusters and Hall effect thrusters are examples of electric propulsion systems. These systems are often used for deep space missions and satellite station-keeping.
• Nuclear Propulsion: This concept involves using nuclear reactions, typically nuclear fission or, in the future, possibly nuclear fusion, to generate thrust. Nuclear thermal propulsion and nuclear electric propulsion are two potential types. While not yet widely implemented, nuclear propulsion systems could offer higher efficiency for certain long-duration missions.
• Solar Sails: Solar sails utilize the pressure of sunlight to propel a spacecraft. These large, lightweight sails capture photons from the Sun, imparting momentum to the spacecraft. While the acceleration is very gradual, solar sails can provide a continuous thrust without the need for propellant.