Understanding Electric Propulsion
Types of Electric Propulsion
| Type | How It Works | Isp (s) | Example Use |
|---|---|---|---|
| Gridded Ion | Ions accelerated through electrostatic grids | 2,000–5,000 | NASA Dawn, DART |
| Hall-Effect | Ions accelerated by crossed electric/magnetic fields | 1,500–3,000 | Starlink, Eutelsat GEO sats |
| Pulsed Plasma | Electromagnetic pulses ablate solid propellant | 600–2,000 | CubeSats |
| Electrospray | Electric field extracts and accelerates ions from liquid | 500–5,000 | Accion TILE thrusters |
Why Electric Propulsion Is Growing
As launch costs have fallen, the economics of satellite operations have shifted. EP allows satellites to be launched into lower, cheaper orbits and then slowly spiral up to their operational altitude under their own power — saving on launch costs at the expense of weeks or months of transit time. This approach, called electric orbit raising, is now standard for large GEO communications satellites and is used by every Starlink satellite for orbit raising, station-keeping, and end-of-life deorbit.
Deep Space Applications
Electric propulsion shines on long-duration deep-space missions. NASA's Dawn spacecraft accumulated over 11 km/s of delta-v using its three NSTAR ion thrusters — more than any spacecraft in history. ESA's BepiColombo is using ion thrusters for its 7-year journey to Mercury. Future missions to the outer solar system and asteroid belt will rely increasingly on solar or nuclear electric propulsion to achieve trajectories that chemical rockets cannot.