TLE_APOAPSIS_PERIAPSISCALC.cs

class Program
{

    private const double mu = 398600.4418;
    private static void printDatasSats(double meanMotion, double excentricity)
    {
        double SemiMajorAxis = Math.Pow(mu / Math.Pow(meanMotion * (double)2 * Math.PI / 86400, (double)2), (double)((double)1 / (double)3));
        double Apoapsis = (SemiMajorAxis * ((double)1 + excentricity)) - 6378.135;
        double Periapsis = (SemiMajorAxis * ((double)1 - excentricity)) - 6378.135;
        Console.WriteLine(string.Format("SemiMajorAxis = {0}\nApoapsis = {1}\nPeriapsis = {2}", SemiMajorAxis, Apoapsis, Periapsis));
    }


    /*
     * 1 25544U 98067A   19029.92277616  .00001044  00000-0  23727-4 0  9995
     * 2 25544  51.6423 328.8640 0004868 330.0424 140.1326 15.53206111153771
     *
     * MeanMotion = 15.53206111
     * Excentricity = 0.0004868 
     */

    static void Main(string[] args)
    {
        printDatasSats(15.53206111, 0.0004868);
        /*
         * It outputs 
         * SemiMajorAxis = 6785.50926153916
         * Apoapsis = 410.677447447682 km
         * Periapsis = 404.071075630646 km
         */
    }
}