/// <summary>
/// Parent ralitive velocity vector.
/// </summary>
/// <returns>The orbital vector ralitive to the parent</returns>
/// <param name="orbit">Orbit.</param>
/// <param name="atDateTime">At date time.</param>
public static Vector3 InstantaneousOrbitalVelocityVector_m(OrbitDB orbit, DateTime atDateTime)
{
var position = GetPosition_m(orbit, atDateTime);
var sma = orbit.SemiMajorAxis;
if (orbit.GravitationalParameter_Km3S2 == 0 || sma == 0)
{
return(new Vector3()); //so we're not returning NaN;
}
var sgp = orbit.GravitationalParameter_m3S2;
double e = orbit.Eccentricity;
double trueAnomaly = GetTrueAnomaly(orbit, atDateTime);
double aoP = orbit.ArgumentOfPeriapsis;
double i = orbit.Inclination;
double loAN = orbit.LongitudeOfAscendingNode;
return(OrbitMath.ParentLocalVeclocityVector(sgp, position, sma, e, trueAnomaly, aoP, i, loAN));
}