S.1 Spacecraft Propulsion Systems Chapter 1: Introduction to ...

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S.6 Propulsion Performance Factors
Propulsion Performance is determined by ‘Specific Impulses’ which permits an objective and
comparative evaluation of thrust engines and propulsion systems of different designs and with
different propellants:
Thruster Performance Factor
The most useful parameter for determining thrust engine (or thruster) performance is
Thruster-specific Impulse:
F
I sp = [Ns/kg]
o
m
The Isp is defined as the impulse delivered per unit mass of propellant and which can be
easily obtained by Test.