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Space Propulsion - IAP/TU Wien

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<strong>Space</strong> <strong>Propulsion</strong><br />

Total impulse<br />

Total impulse is the total momentum gained during the burn time t b of a thruster<br />

definition<br />

I<br />

tb<br />

= ∫Tdt<br />

[ N.<br />

s]<br />

0<br />

When thrust is constant over time, or at least during thruster – on time intervals,<br />

total impulse can be written as<br />

I = T τ.<br />

τ τ<br />

τ<br />

= ⎛ dm ⎞<br />

∫Tdt<br />

= ∫ ⎜ ⎟Ve<br />

dt = Ve<br />

dt<br />

∫<br />

0 0 ⎝ ⎠<br />

0<br />

I dm = V . m<br />

e<br />

p<br />

m p … propellant mass used during mission time τ<br />

V e … exhaust velocity, assumed to be constant during mission

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