Specific Impulse (Isp)

Specific impulse (Isp) measures a rocket engine's efficiency, indicating how much thrust it produces per unit of propellant consumed over time. Think of it as the engine's "fuel efficiency"—a higher Isp means the engine gets more push (thrust) for each kilogram of propellant burned, allowing spacecraft to travel farther or faster with less fuel. It is typically expressed in seconds and helps compare the effectiveness of different propulsion systems. In essence, Isp tells us how efficiently a rocket uses its fuel to generate motion, directly impacting mission range and payload capacity.