Java tutorial
/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */ package lambertmrev; import org.orekit.frames.*; import org.orekit.time.*; import org.orekit.utils.*; import org.orekit.orbits.*; import java.io.PrintWriter; import java.io.BufferedWriter; import java.io.File; import java.io.FileNotFoundException; import java.io.FileWriter; import java.io.IOException; import org.orekit.orbits.KeplerianOrbit; import org.orekit.propagation.analytical.*; import org.orekit.propagation.SpacecraftState; import org.orekit.propagation.analytical.KeplerianPropagator; import org.apache.commons.math3.geometry.euclidean.threed.*; import org.orekit.data.DataProvidersManager; import org.orekit.time.TimeScalesFactory; import org.apache.commons.math3.linear.MatrixUtils; import org.apache.commons.math3.util.FastMath; import org.apache.commons.math3.linear.*; import org.apache.commons.math3.random.*; import org.orekit.orbits.PositionAngle; import java.util.Random; import java.util.logging.Level; import java.util.logging.Logger; /** * * @author zittersteijn */ public class LambertMRev { /** * @param args the command line arguments */ public static void main(String[] args) { // Want to test the Lambert class so you can specify the number of revs for which to compute //System.out.print("this is the frames tutorial \n"); try { Frame inertialFrame = FramesFactory.getEME2000(); TimeScale utc = TimeScalesFactory.getTAI(); AbsoluteDate initialDate = new AbsoluteDate(2004, 01, 01, 23, 30, 00.000, utc); double mu = 3.986004415e+14; double a = 24396159; // semi major axis in meters double e = 0.72831215; // eccentricity double i = Math.toRadians(7); // inclination double omega = Math.toRadians(180); // perigee argument double raan = Math.toRadians(261); // right ascension of ascending node double lM = 0; // mean anomaly Orbit initialOrbit = new KeplerianOrbit(a, e, i, omega, raan, lM, PositionAngle.MEAN, inertialFrame, initialDate, mu); //KeplerianPropagator kepler = new KeplerianPropagator(initialOrbit); // set geocentric positions Vector3D r1 = new Vector3D(-6.88999e3, 3.92763e4, 2.67053e3); Vector3D r2 = new Vector3D(-3.41458e4, 2.05328e4, 3.44315e3); Vector3D r1_site = new Vector3D(4.72599e3, 1.26633e3, 4.07799e3); Vector3D r2_site = new Vector3D(4.70819e3, 1.33099e3, 4.07799e3); // get the topocentric positions Vector3D top1 = Transform.geo2radec(r1.scalarMultiply(1000), r1_site.scalarMultiply(1000)); Vector3D top2 = Transform.geo2radec(r2.scalarMultiply(1000), r2_site.scalarMultiply(1000)); // time of flight in seconds double tof = 3 * 3600; // propagate to 0 and tof Lambert test = new Lambert(); boolean cw = false; int multi_revs = 1; RealMatrix v1_mat; Random randomGenerator = new Random(); PrintWriter out_a = new PrintWriter("out_java_a.txt"); PrintWriter out_e = new PrintWriter("out_java_e.txt"); PrintWriter out_rho1 = new PrintWriter("out_java_rho1.txt"); PrintWriter out_rho2 = new PrintWriter("out_java_rho2.txt"); // start the loop double A, Ecc, rho1, rho2, tof_hyp; long time1 = System.nanoTime(); for (int ll = 0; ll < 1e6; ll++) { rho1 = top1.getZ() / 1000 + 1e-3 * randomGenerator.nextGaussian() * top1.getZ() / 1000; rho2 = top2.getZ() / 1000 + 1e-3 * randomGenerator.nextGaussian() * top2.getZ() / 1000; //tof_hyp = FastMath.abs(tof + 0.1*3600 * randomGenerator.nextGaussian()); // from topo to geo Vector3D r1_hyp = Transform.radec2geo(top1.getX(), top1.getY(), rho1, r1_site); Vector3D r2_hyp = Transform.radec2geo(top2.getX(), top2.getY(), rho2, r2_site); // System.out.println(r1_hyp.scalarMultiply(1000).getNorm()); // System.out.println(r2_hyp.scalarMultiply(1000).getNorm()); // System.out.println(tof/3600); test.lambert_problem(r1_hyp.scalarMultiply(1000), r2_hyp.scalarMultiply(1000), tof, mu, cw, multi_revs); v1_mat = test.get_v1(); Vector3D v1 = new Vector3D(v1_mat.getEntry(0, 0), v1_mat.getEntry(0, 1), v1_mat.getEntry(0, 2)); // System.out.println(v1); PVCoordinates rv1 = new PVCoordinates(r1_hyp.scalarMultiply(1000), v1); Orbit orbit_out = new KeplerianOrbit(rv1, inertialFrame, initialDate, mu); A = orbit_out.getA(); Ecc = orbit_out.getE(); // System.out.println(ll + " - " +A); out_a.println(A); out_e.println(Ecc); out_rho1.println(rho1); out_rho2.println(rho2); } long time2 = System.nanoTime(); long timeTaken = time2 - time1; out_a.close(); out_e.close(); out_rho1.close(); out_rho2.close(); System.out.println("Time taken " + timeTaken / 1000 / 1000 + " milli secs"); // get the truth test.lambert_problem(r1.scalarMultiply(1000), r2.scalarMultiply(1000), tof, mu, cw, multi_revs); v1_mat = test.get_v1(); Vector3D v1 = new Vector3D(v1_mat.getEntry(0, 0), v1_mat.getEntry(0, 1), v1_mat.getEntry(0, 2)); PVCoordinates rv1 = new PVCoordinates(r1.scalarMultiply(1000), v1); Orbit orbit_out = new KeplerianOrbit(rv1, inertialFrame, initialDate, mu); //System.out.println(orbit_out.getA()); } catch (FileNotFoundException ex) { Logger.getLogger(LambertMRev.class.getName()).log(Level.SEVERE, null, ex); } } }