Merge branch 'issue-859' into release-11.0

pom.xml

@@ -269,6 +269,9 @@
     <contributor>
       <name>Lars N&#230;sbye Christensen</name>
     </contributor>
+    <contributor>
+      <name>Emmanuel Papanagiotou</name>
+    </contributor>
     <contributor>
       <name>Thomas Paulet</name>
     </contributor>

src/main/java/org/orekit/propagation/conversion/TLEPropagatorBuilder.java

@@ -46,12 +46,24 @@ import org.orekit.utils.ParameterDriversList;
  */
 public class TLEPropagatorBuilder extends AbstractPropagatorBuilder implements OrbitDeterminationPropagatorBuilder {
 
+    /** Default value for epsilon. */
+    private static final double EPSILON_DEFAULT = 1.0e-10;
+
+    /** Default value for maxIterations. */
+    private static final int MAX_ITERATIONS_DEFAULT = 100;
+
     /** Data context used to access frames and time scales. */
     private final DataContext dataContext;
 
     /** Template TLE. */
     private final TLE templateTLE;
 
+    /** Threshold for convergence used in TLE generation. */
+    private final double epsilon;
+
+    /** Maximum number of iterations for convergence used in TLE generation. */
+    private final int maxIterations;
+
     /** Build a new instance. This constructor uses the {@link DataContext#getDefault()
      * default data context}.
      * <p>
@@ -61,6 +73,9 @@ public class TLEPropagatorBuilder extends AbstractPropagatorBuilder implements O
      * classification, .... and is also used together with the {@code positionScale} to
      * convert from the {@link ParameterDriver#setNormalizedValue(double) normalized}
      * parameters used by the callers of this builder to the real orbital parameters.
+     * </p><p>
+     * Using this constructor, {@link #EPSILON_DEFAULT} and {@link #MAX_ITERATIONS_DEFAULT}
+     * are used for spacecraft's state to TLE transformation
      * </p>
      * @param templateTLE reference TLE from which real orbits will be built
      * @param positionAngle position angle type to use
@@ -83,6 +98,9 @@ public class TLEPropagatorBuilder extends AbstractPropagatorBuilder implements O
      * classification, .... and is also used together with the {@code positionScale} to
      * convert from the {@link ParameterDriver#setNormalizedValue(double) normalized}
      * parameters used by the callers of this builder to the real orbital parameters.
+     * </p><p>
+     * Using this constructor, {@link #EPSILON_DEFAULT} and {@link #MAX_ITERATIONS_DEFAULT}
+     * are used for spacecraft's state to TLE transformation
      * </p>
      * @param templateTLE reference TLE from which real orbits will be built
      * @param positionAngle position angle type to use
@@ -90,11 +108,65 @@ public class TLEPropagatorBuilder extends AbstractPropagatorBuilder implements O
      * (typically set to the expected standard deviation of the position)
      * @param dataContext used to access frames and time scales.
      * @since 10.1
+     * @see #TLEPropagatorBuilder(TLE, PositionAngle, double, DataContext, double, int)
      */
     public TLEPropagatorBuilder(final TLE templateTLE,
                                 final PositionAngle positionAngle,
                                 final double positionScale,
                                 final DataContext dataContext) {
+        this(templateTLE, positionAngle, positionScale, dataContext, EPSILON_DEFAULT, MAX_ITERATIONS_DEFAULT);
+    }
+
+    /** Build a new instance. This constructor uses the {@link DataContext#getDefault()
+     * default data context}.
+     * <p>
+     * The template TLE is used as a model to {@link
+     * #createInitialOrbit() create initial orbit}. It defines the
+     * inertial frame, the central attraction coefficient, orbit type, satellite number,
+     * classification, .... and is also used together with the {@code positionScale} to
+     * convert from the {@link ParameterDriver#setNormalizedValue(double) normalized}
+     * parameters used by the callers of this builder to the real orbital parameters.
+     * </p>
+     * @param templateTLE reference TLE from which real orbits will be built
+     * @param positionAngle position angle type to use
+     * @param positionScale scaling factor used for orbital parameters normalization
+     * (typically set to the expected standard deviation of the position)
+     * @param epsilon used to compute threshold for convergence check
+     * @param maxIterations maximum number of iterations for convergence
+     * @since 11.0.2
+     * @see #TLEPropagatorBuilder(TLE, PositionAngle, double, DataContext, double, int)
+     */
+    @DefaultDataContext
+    public TLEPropagatorBuilder(final TLE templateTLE, final PositionAngle positionAngle,
+                                final double positionScale, final double epsilon,
+                                final int maxIterations) {
+        this(templateTLE, positionAngle, positionScale, DataContext.getDefault(), epsilon, maxIterations);
+    }
+
+    /** Build a new instance.
+     * <p>
+     * The template TLE is used as a model to {@link
+     * #createInitialOrbit() create initial orbit}. It defines the
+     * inertial frame, the central attraction coefficient, orbit type, satellite number,
+     * classification, .... and is also used together with the {@code positionScale} to
+     * convert from the {@link ParameterDriver#setNormalizedValue(double) normalized}
+     * parameters used by the callers of this builder to the real orbital parameters.
+     * </p>
+     * @param templateTLE reference TLE from which real orbits will be built
+     * @param positionAngle position angle type to use
+     * @param positionScale scaling factor used for orbital parameters normalization
+     * (typically set to the expected standard deviation of the position)
+     * @param dataContext used to access frames and time scales.
+     * @param epsilon used to compute threshold for convergence check
+     * @param maxIterations maximum number of iterations for convergence
+     * @since 11.0.2
+     */
+    public TLEPropagatorBuilder(final TLE templateTLE,
+                                final PositionAngle positionAngle,
+                                final double positionScale,
+                                final DataContext dataContext,
+                                final double epsilon,
+                                final int maxIterations) {
         super(TLEPropagator.selectExtrapolator(templateTLE, dataContext.getFrames())
                         .getInitialState().getOrbit(),
               positionAngle, positionScale, false,
@@ -102,9 +174,10 @@ public class TLEPropagatorBuilder extends AbstractPropagatorBuilder implements O
         for (final ParameterDriver driver : templateTLE.getParametersDrivers()) {
             addSupportedParameter(driver);
         }
-        this.templateTLE = templateTLE;
-        this.dataContext = dataContext;
-
+        this.templateTLE   = templateTLE;
+        this.dataContext   = dataContext;
+        this.epsilon       = epsilon;
+        this.maxIterations = maxIterations;
     }
 
     /** {@inheritDoc} */
@@ -119,7 +192,7 @@ public class TLEPropagatorBuilder extends AbstractPropagatorBuilder implements O
         final TimeScale       utc   = dataContext.getTimeScales().getUTC();
 
         // TLE related to the orbit
-        final TLE tle = TLE.stateToTLE(state, templateTLE, utc, teme);
+        final TLE tle = TLE.stateToTLE(state, templateTLE, utc, teme, epsilon, maxIterations);
         final List<ParameterDriver> drivers = templateTLE.getParametersDrivers();
         for (int index = 0; index < drivers.size(); index++) {
             if (drivers.get(index).isSelected()) {

src/test/java/org/orekit/propagation/conversion/TLEConverterTest.java

@@ -17,10 +17,14 @@
 package org.orekit.propagation.conversion;
 
 import org.junit.Assert;
+import org.junit.Before;
 import org.junit.Test;
 import org.orekit.Utils;
+import org.orekit.errors.OrekitException;
+import org.orekit.errors.OrekitMessages;
 import org.orekit.orbits.PositionAngle;
 import org.orekit.propagation.analytical.tle.TLE;
+import org.orekit.propagation.analytical.tle.TLEPropagator;
 import org.orekit.utils.ParameterDriver;
 
 public class TLEConverterTest {
@@ -28,7 +32,6 @@ public class TLEConverterTest {
     @Test
     public void testDeselectOrbitals() {
 
-        Utils.setDataRoot("regular-data");
         final TLE tle = new TLE("1 27508U 02040A   12021.25695307 -.00000113  00000-0  10000-3 0  7326",
                                 "2 27508   0.0571 356.7800 0005033 344.4621 218.7816  1.00271798 34501");
         
@@ -41,4 +44,37 @@ public class TLEConverterTest {
             Assert.assertFalse(driver.isSelected());
         }
     }
+
+    @Test
+    public void testIssue859() {
+
+        // INTELSAT 25 TLE taken from Celestrak the 2021-11-24T07:45:00.000
+        // Because the satellite eccentricity and inclination are closed to zero, this satellite
+        // reach convergence issues when converting the spacecraft's state to TLE.
+        final TLE tle = new TLE("1 33153U 08034A   21327.46310733 -.00000207  00000+0  00000+0 0  9990",
+                                "2 33153   0.0042  20.7353 0003042 213.9370 323.2156  1.00270917 48929");
+
+        // Verify convergence issue
+        final TLEPropagatorBuilder propagatorBuilderError = new TLEPropagatorBuilder(tle, PositionAngle.MEAN, 1.);
+        try {
+            propagatorBuilderError.buildPropagator(propagatorBuilderError.getSelectedNormalizedParameters());
+        } catch (OrekitException oe) {
+            Assert.assertEquals(OrekitMessages.UNABLE_TO_COMPUTE_TLE, oe.getSpecifier());
+        }
+
+        // Now try using different convergence threshold
+        final TLEPropagatorBuilder propagatorBuilder = new TLEPropagatorBuilder(tle, PositionAngle.MEAN, 1., 2.0e-4, 10000);
+        final TLEPropagator propagator = propagatorBuilder.buildPropagator(propagatorBuilderError.getSelectedNormalizedParameters());
+        final TLE newTLE = propagator.getTLE();
+
+        // Verify
+        Assert.assertEquals(0.0, newTLE.getDate().durationFrom(tle.getDate()), Utils.epsilonTest);
+
+    }
+
+    @Before
+    public void setUp() {
+        Utils.setDataRoot("regular-data");
+    }
+
 }
\ No newline at end of file