Space Propulsion - IAP/TU Wien
Space Propulsion - IAP/TU Wien
Space Propulsion - IAP/TU Wien
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Repositioning, cont‘d<br />
<strong>Space</strong> <strong>Propulsion</strong><br />
The elements of a geosynchronous orbit are<br />
r =<br />
42,164.17 km (circular)<br />
P =<br />
86,164.09 s<br />
V =<br />
3.07466 km/s<br />
ΔP is equal to the time required for 2 deg<br />
of motion on a geosynchronous orbit<br />
0<br />
Δϕ<br />
2 *86,164.09<br />
ΔP = P =<br />
=<br />
360 360<br />
478.689<br />
[ s]<br />
The period for the spacecraft on the<br />
elliptical reposition orbit is<br />
semimajor axis of the reposition orbit<br />
P = 86,164.09 + 478.689 = 86,642.78 [s]<br />
2<br />
2<br />
P μ (86,642.78) (398,600)<br />
a = 3 = 3<br />
= 42,320<br />
2<br />
2<br />
4π<br />
4π<br />
[ km]<br />
velocity at periapsis of an elliptical orbit<br />
with semimajor axis a<br />
V 2μ<br />
μ 2(398,600) 398,600<br />
= − =<br />
− 3.08032<br />
r a 42164 42320<br />
=<br />
[ km / s]<br />
velocity change to place the spacecraft<br />
on the reposition ellipse<br />
3.08032km/s - 3.07466km/s = 5.66 m/s<br />
The same velocity change (in the opposite direction<br />
is necessary for recirculation of repositioning orbit<br />
Propellant consumption under<br />
assumption of negligible mass change<br />
⎡ ⎛ V ⎞ ⎤ ⎧ ⎡11.32⎤<br />
⎫<br />
m<br />
p<br />
m<br />
f ⎢exp⎜<br />
Δ<br />
=<br />
⎟ −1⎥<br />
= 1000⎨exp<br />
−1⎬<br />
= 3.66<br />
I<br />
⎢<br />
sp<br />
⎩ ⎣ 3100 ⎥<br />
⎢<br />
⎣ ⎝ ⎠ ⎥⎦<br />
⎦ ⎭<br />
[ kg]