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Homework Help: [spacefight mechanics]how to find true anomaly and eccentricity?

  1. Feb 10, 2009 #1
    1. The problem statement, all variables and given/known data
    An earth satellite has a speed of 7km/s and a flight path angle of 15 degree when its radius is 9000km calculate the true anomaly and eccentricity of the orbit.

    2. Relevant equations

    r=h^2/u(1+ecostheta)

    3. The attempt at a solution
    The problem statement just doesn't seem provided enough information. The direction to the solution should deal with lagrange coefficients. Express r and v in the standard earth refrence frame using flight pitch angle, then transfer them to the perifocal fame.
    Then in perifocal fame:
    h=r cross v (in perifocal fame)
    e=1/u*(r cross v) -r(vector)/r
    But i don't know how to find the r and v vectors in the standard earth ref frame :(
    correct me if my approach is incorrect >.>

    the answer given is theta=83.35degree, e=0.2785
     
  2. jcsd
  3. Feb 10, 2009 #2

    D H

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    Staff Emeritus
    Science Advisor

    The problem does provide all the information needed. You do not need to find the r and v vectors in "the standard earth ref frame", just some earth-centered non-rotating reference frame.

    BTW, your equation for the eccentricity vector is incorrect.
     
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