Spacecraft Propulsion Systems: Types and Functions

This page describes different types of Spacecraft Propulsion Systems, including their classification and functions.

Definition: Propulsion systems are the mechanisms used to apply forces and torques to a spacecraft in space in order to transfer, position, and orient it.

Functions of Spacecraft Propulsion Systems

As mentioned in the definition, the functions of spacecraft propulsion systems include:

• Transfer: Used for interplanetary travel.
• Position: Used for orbit control.
• Orientation: Used for attitude control.

Characteristics of Spacecraft Propulsion Systems

These characteristics are essential for attitude and orbit operational requirements of the spacecraft or satellite:

• Very high velocity increment capabilities.
• Low thrust levels with lower acceleration levels.
• Continuous operation mode for orbit control.
• Pulsed operation mode for attitude control.
• Predictable, accurate, and repeatable performance.
• Reliable, Leak-free long time operation
• Minimum and predictable thrust exhaust impingement effects

Types of Propulsion Systems | Classification of Propulsion Systems

The following are the types of propulsion systems used in a Spacecraft. These types are based on the source of energy used for the ejection of the propellant.

The figure-1 depicts a tree chart of the classifications.

• Chemical Propulsion: This type uses heat energy produced due to a chemical reaction. It produces gases at high temperature and pressure in a combustion chamber. These gases are accelerated through a nozzle device and ejected from the spacecraft system at high exit velocity in order to produce thrust force.
• Electric Propulsion: This type uses electric or electro-magnetic energy to eject matter at a higher velocity in order to produce thrust force.
• Nuclear Propulsion: This type uses energy from a nuclear reactor to heat gases. These gases are accelerated through the nozzle and consecutively ejected from the spacecraft system at a very high exit velocity in order to produce thrust force.