Knowledge / Space Science & Astronomy

Space Propulsion

Methods for changing spacecraft momentum, including chemical, electric, and emerging propulsion concepts.

By Siddhant Krishna · Published 2026-10-06 · Updated 2026-10-06

Rocket Propulsion

Rockets generate thrust by expelling mass and conserving momentum. They can operate in vacuum because they do not require atmospheric oxygen for the fundamental momentum-exchange mechanism.

F ≈ ṁv_e + (p_e-p_a)A_e

Specific Impulse

I_sp = F/(ṁg₀)

Specific impulse is a measure of propulsion efficiency in terms of thrust produced per unit weight-flow rate of propellant.

Electric Propulsion

Electric propulsion accelerates propellant using electrical energy and can achieve high exhaust velocities. Its limitation is generally low thrust compared with chemical propulsion, making it useful primarily for gradual trajectory changes.

References

NASA technical and educational material covering spacecraft motion, orbits, trajectories, and mission fundamentals.
https://solarsystem.nasa.gov/basics/chapter1-1/
NASA science resources covering astrophysics, Earth science, heliophysics, planetary science, and exploration.
https://science.nasa.gov/

Orbital MechanicsThe dynamics of spacecraft and celestial bodies under gravity.Spacecraft EngineeringThe engineering of vehicles capable of surviving, navigating, communicating, and operating in space.

Rocket Propulsion

Specific Impulse

Electric Propulsion

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