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guidance, flight mechanics and trajectory optimization

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Now, the,magnitude of the required velocity, V, can be determined from the<br />

energy equation<br />

This magnitude- can be associated with a velocity component normal to the<br />

radius (V,) which is found from the conservation of angular momentum<br />

x =pz<br />

<strong>and</strong> a radial component (V ) found from<br />

Finally, the required velocity vector can be written as<br />

r (0)<br />

-R V -y - r(0)<br />

+v (GX!p_r,<br />

* I(J x r$xql<br />

A variation of this procedure called 'miss distance <strong>guidance</strong>' <strong>and</strong> is<br />

described by Gunckel in Reference 2.8. In this method, both the target <strong>and</strong><br />

rendezvous vehicle orbits are integrated forward to the rendezvous time.<br />

The difference in their positions, at this time, is the -miss distance. The<br />

velocity required for rendezvous is then found by operating on the miss<br />

distance with the transition matrix.<br />

where<br />

s_v = pJ ( c (Tl) - c ( 7))<br />

VR = velocity vector required of the<br />

rendezvous vehicle at t = 0<br />

yto1 = velocity of the rendezvous vehicle at t = 0<br />

= transition matrix relative variations in<br />

position at t = T to velocity at t = 0<br />

51

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