ISP (Specific Impulse)

Specific impulse (ISP) measures how efficiently a rocket engine uses its propellant to produce thrust. Think of it as the engine’s fuel efficiency, indicating how many seconds the engine can generate a certain amount of thrust with a specific quantity of fuel. Higher ISP means the engine can accelerate a spacecraft more effectively, using less fuel for the same amount of thrust. It is usually expressed in seconds, representing the effective exhaust velocity of the propellant. In essence, ISP helps compare rocket engines' performance, with higher values indicating more efficient propulsion systems.