I am trying to plot an orbit using gmat. I fixed apogee(RadApo) and perigee(RadPer) for the inner orbit(green) and inserted an impulsive burn.

I got the desired shape of the outer orbit but I am unable to know how do I find relation between the velocity on impulsive burn (element-1) and the apogee of the second orbit.

It would be very helpful of anyone if I can get this relation or If I can know what is the RadApo(apogee) for the second orbit(Red)

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1 Answer 1


Assume the velocity increment is at the perigee and along the velocity then the new velocity is $V$, calcualate the semimajor axis from the vis viva equation:

$V^2 = \mu (2/r - 1/a)$

The apogee distance is then $r_a = 2a-r_p$

If $1/a$ is zero you have a parabolic orbit, if negative it is hyperbolic.


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