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Space Propulsion - IAP/TU Wien

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

Spiraling up<br />

Δ<br />

V = v c , 0<br />

− v c , r<br />

ΔV<br />

v<br />

c,0<br />

= 1−<br />

r<br />

0<br />

r<br />

I sp<br />

>> ΔV<br />

τ =<br />

m<br />

0<br />

I<br />

sp<br />

T<br />

I<br />

−ΔV<br />

/ Isp<br />

sp ΔV<br />

/ Isp<br />

[ 1−<br />

e ] = m ( e −1)<br />

f<br />

T<br />

→<br />

m<br />

f<br />

ΔV<br />

T<br />

m<br />

p<br />

⎡ ⎛ V ⎞ ⎤<br />

m<br />

f ⎢ ⎜<br />

Δ<br />

= exp ⎟ −1⎥<br />

→ m<br />

⎢<br />

⎣<br />

I<br />

⎝ sp ⎠ ⎥⎦<br />

f<br />

ΔV<br />

I<br />

sp<br />

m<br />

∞<br />

= 100.<br />

5<br />

10<br />

100<br />

5x10<br />

τ ∞<br />

=<br />

−3<br />

5<br />

7809<br />

( e 1) 2 /10 − ≅ 11.7 [ kg]<br />

5<br />

7809<br />

( e 1) 2 /10 − ≅ 5.1 [ y]<br />

Example<br />

Electric propulsion: T = 5 mN, I sp<br />

= 10 5 m/s;<br />

Time and propellant mass required for spiraling<br />

up a 100 kg payload from 300 km LEO (v =<br />

7730 m/s) to escape velocity?

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