Java tutorial
/* Copyright 2002-2015 CS Systmes d'Information * Licensed to CS Systmes d'Information (CS) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * CS licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package fr.cs.examples.frames; import java.io.File; import java.io.IOException; import java.io.PrintStream; import java.util.Locale; import org.apache.commons.math3.exception.util.LocalizedFormats; import org.apache.commons.math3.geometry.euclidean.threed.Vector3D; import org.apache.commons.math3.util.FastMath; import org.orekit.attitudes.NadirPointing; import org.orekit.attitudes.YawSteering; import org.orekit.bodies.BodyShape; import org.orekit.bodies.CelestialBodyFactory; import org.orekit.bodies.OneAxisEllipsoid; import org.orekit.errors.OrekitException; import org.orekit.errors.PropagationException; import org.orekit.frames.Frame; import org.orekit.frames.FramesFactory; import org.orekit.frames.Transform; import org.orekit.orbits.CircularOrbit; import org.orekit.orbits.Orbit; import org.orekit.orbits.PositionAngle; import org.orekit.propagation.Propagator; import org.orekit.propagation.SpacecraftState; import org.orekit.propagation.analytical.EcksteinHechlerPropagator; import org.orekit.propagation.sampling.OrekitFixedStepHandler; import org.orekit.time.AbsoluteDate; import org.orekit.time.DateComponents; import org.orekit.time.TimeComponents; import org.orekit.time.TimeScalesFactory; import org.orekit.utils.Constants; import org.orekit.utils.IERSConventions; import org.orekit.utils.PVCoordinatesProvider; import fr.cs.examples.Autoconfiguration; /** Orekit tutorial for computing spacecraft related data. * @author Pascal Parraud * @author Luc Maisonobe */ public class Frames3 { public static void main(String[] args) { try { // configure Orekit and printing format Autoconfiguration.configureOrekit(); // Initial state definition : // ========================== // Date // **** AbsoluteDate initialDate = new AbsoluteDate(new DateComponents(1970, 04, 07), TimeComponents.H00, TimeScalesFactory.getUTC()); // Orbit // ***** // The Sun is in the orbital plane for raan ~ 202 double mu = 3.986004415e+14; // gravitation coefficient Frame eme2000 = FramesFactory.getEME2000(); // inertial frame Orbit orbit = new CircularOrbit(7178000.0, 0.5e-4, -0.5e-4, FastMath.toRadians(50.), FastMath.toRadians(220.), FastMath.toRadians(5.300), PositionAngle.MEAN, eme2000, initialDate, mu); // Attitude laws // ************* // Earth Frame earthFrame = FramesFactory.getITRF(IERSConventions.IERS_2010, true); BodyShape earth = new OneAxisEllipsoid(Constants.WGS84_EARTH_EQUATORIAL_RADIUS, Constants.WGS84_EARTH_FLATTENING, earthFrame); // Target pointing attitude provider over satellite nadir at date, without yaw compensation NadirPointing nadirLaw = new NadirPointing(eme2000, earth); // Target pointing attitude provider with yaw compensation final PVCoordinatesProvider sun = CelestialBodyFactory.getSun(); YawSteering yawSteeringLaw = new YawSteering(eme2000, nadirLaw, sun, Vector3D.MINUS_I); // Propagator : Eckstein-Hechler analytic propagator Propagator propagator = new EcksteinHechlerPropagator(orbit, yawSteeringLaw, Constants.EIGEN5C_EARTH_EQUATORIAL_RADIUS, Constants.EIGEN5C_EARTH_MU, Constants.EIGEN5C_EARTH_C20, Constants.EIGEN5C_EARTH_C30, Constants.EIGEN5C_EARTH_C40, Constants.EIGEN5C_EARTH_C50, Constants.EIGEN5C_EARTH_C60); // Let's write the results in a file in order to draw some plots. propagator.setMasterMode(10, new OrekitFixedStepHandler() { PrintStream out = null; public void init(SpacecraftState s0, AbsoluteDate t) throws PropagationException { try { File file = new File(System.getProperty("user.home"), "XYZ.dat"); System.out.println("Results written to file: " + file.getAbsolutePath()); out = new PrintStream(file); out.println("#time X Y Z Wx Wy Wz"); } catch (IOException ioe) { throw new PropagationException(ioe, LocalizedFormats.SIMPLE_MESSAGE, ioe.getLocalizedMessage()); } } public void handleStep(SpacecraftState currentState, boolean isLast) throws PropagationException { try { // get the transform from orbit/attitude reference frame to spacecraft frame Transform inertToSpacecraft = currentState.toTransform(); // get the position of the Sun in orbit/attitude reference frame Vector3D sunInert = sun.getPVCoordinates(currentState.getDate(), currentState.getFrame()) .getPosition(); // convert Sun position to spacecraft frame Vector3D sunSat = inertToSpacecraft.transformPosition(sunInert); // and the spacecraft rotational rate also Vector3D spin = inertToSpacecraft.getRotationRate(); // Lets calculate the reduced coordinates double sunX = sunSat.getX() / sunSat.getNorm(); double sunY = sunSat.getY() / sunSat.getNorm(); double sunZ = sunSat.getZ() / sunSat.getNorm(); out.format(Locale.US, "%s %12.3f %12.3f %12.3f %12.7f %12.7f %12.7f%n", currentState.getDate(), sunX, sunY, sunZ, spin.getX(), spin.getY(), spin.getZ()); if (isLast) { out.close(); } } catch (OrekitException oe) { throw new PropagationException(oe); } } }); System.out.println("Running..."); propagator.propagate(initialDate.shiftedBy(6000)); } catch (OrekitException oe) { System.err.println(oe.getMessage()); } } }