In terms of performance, what does a higher specific impulse indicate?

A higher specific impulse is a crucial indicator of the efficiency with which a rocket or propulsion system uses its fuel. It effectively measures the amount of thrust produced per unit of fuel consumed over time. Therefore, a higher specific impulse signifies that the engine generates more thrust relative to the amount of fuel being expended. This directly translates to greater fuel efficiency, as the system can achieve more propulsion for less fuel, enabling it to operate for longer periods or travel further distances without needing to carry an excessive amount of fuel.

Specific impulse is typically expressed in seconds and gives a clear idea of performance in the context of space propulsion systems, where optimizing fuel usage is critical due to the substantial cost and logistics involved in carrying fuel into orbit or beyond. As a result, when evaluating propulsion systems or rocket engines, a focus on specific impulse helps identify the most efficient technologies.