🛸 Ion Thruster — Electric Propulsion

Ion thrusters accelerate charged particles (usually xenon) using electric fields to generate thrust. They produce very low force but achieve extremely high specific impulse (Isp), making them ideal for long-duration deep-space missions where propellant mass must be minimized.

Ion Thruster

Power (kW) 5 kW Isp (s) 3 000 s Efficiency η 0.65

Mission ΔV Planner

Spacecraft mass (kg) 500 kg Mission ΔV (km/s) 6 km/s

Thruster Stats

Thrust—

Exhaust velocity—

Mass flow rate—

Propellant needed—

Wet/Dry ratio—

Burn time—

vs Chemical Rocket

🛸 Ion (this)

Isp = — s

Prop = —

🔥 Chemical

Isp = 310 s

Prop = —

Physics:
F = 2ηP / (Isp·g₀)
v_e = Isp·g₀
ΔV = Isp·g₀·ln(m₀/m₁)
m_p = m_dry·(e^ΔV/ve−1)

How Ion Thrusters Work

A neutral propellant gas (typically xenon) is ionized by electron bombardment or RF energy. The ions are then accelerated by a strong electric field to exhaust velocities of 20–80 km/s — compared to 3–4 km/s for chemical rockets. This gives ion thrusters a 10-30× higher Isp, meaning far less propellant is needed for the same ΔV. The tradeoff: thrust is extremely low (millinewtons to tens of millinewtons) and requires continuous power. NASA's Dawn spacecraft used ion thrusters to orbit both Vesta and Ceres; JAXA's Hayabusa used them for asteroid sample return. Modern Hall-effect thrusters and gridded ion engines are now standard for GEO satellite station-keeping.