Propulsion

Thrusters and engines that burn propellants for high thrust — the standard means of orbit insertion and large manoeuvres, using monopropellants (hydrazine) or bipropellants.

The simplest thruster — it just releases a stored, pressurised gas through a nozzle. Low-performance but reliable, used for fine attitude control and on small spacecraft.

A type of electric propulsion that traps electrons in a magnetic field to ionise and accelerate propellant. Widely used for satellite station-keeping and, increasingly, for deep-space missions — NASA's Psyche is the first to fly Hall-effect thrusters beyond lunar orbit.

A gridded electrostatic thruster that ionises a propellant (usually xenon) and accelerates it with electric-field grids to very high exhaust velocity. It delivers tiny thrust but sips fuel, enabling missions like Deep Space 1 and Dawn.

A propulsion concept that heats a propellant with a nuclear reactor for high thrust and efficiency. Long studied and tested on the ground, it is a candidate for future fast crewed trips to Mars.

The subsystem that changes a spacecraft's velocity — for orbit insertion, trajectory corrections, and station-keeping — using chemical, electric, or cold-gas thrusters.

A set of small thrusters arranged around a spacecraft for precise control of orientation and small translations — used for pointing, docking, and stabilisation.