Specific Impulse

Specific impulse is a number that measures how much thrust (power) a rocket engine produces. It is used by engineers to compare different rocket engines and decide which one to use.

The number is calculated by measuring how much fuel is used for each pound of thrust (power) produced. A higher number means the engine uses less fuel for the same amount of power, so it is more efficient.

Think of it like a race. The engine with a higher specific impulse number is like a race car that can travel farther with the same amount of gas.