diff --git a/src/test/java/org/orekit/rugged/errors/RuggedMessagesTest.java b/src/test/java/org/orekit/rugged/errors/RuggedMessagesTest.java
index 67cb079fc52713eeae77625f7ed98777f7e33290..7f7d7afa4ddcd0399ebae2cbedbbe979b6a44aa5 100644
--- a/src/test/java/org/orekit/rugged/errors/RuggedMessagesTest.java
+++ b/src/test/java/org/orekit/rugged/errors/RuggedMessagesTest.java
@@ -96,6 +96,18 @@ public class RuggedMessagesTest {
         }
     }
 
+    @Test
+    public void testMissingLanguageMissingTranslation() {
+        Assert.assertEquals(RuggedMessages.INTERNAL_ERROR.getSourceString(),
+                            RuggedMessages.INTERNAL_ERROR.getLocalizedString(Locale.KOREAN));
+        Assert.assertEquals(RuggedMessages.NO_DEM_DATA.getSourceString(),
+                            RuggedMessages.NO_DEM_DATA.getLocalizedString(Locale.KOREAN));
+        Assert.assertEquals("ABCDEF {0}",
+                            RuggedMessages.UNKNOWN_SENSOR.getLocalizedString(Locale.KOREAN));
+        Assert.assertEquals(RuggedMessages.EMPTY_TILE.getSourceString(),
+                            RuggedMessages.EMPTY_TILE.getLocalizedString(Locale.KOREAN));
+    }
+
     @Test
     public void testVariablePartsConsistency() {
         for (final String language : LANGUAGES_LIST) {
diff --git a/src/test/java/org/orekit/rugged/linesensor/SensorMeanPlaneCrossingTest.java b/src/test/java/org/orekit/rugged/linesensor/SensorMeanPlaneCrossingTest.java
index 5a0d7670a843f4f5eea088d8ba8cf1d7ef772ba5..753d103f0412d5986370dc00d694ccc6aac153a0 100644
--- a/src/test/java/org/orekit/rugged/linesensor/SensorMeanPlaneCrossingTest.java
+++ b/src/test/java/org/orekit/rugged/linesensor/SensorMeanPlaneCrossingTest.java
@@ -46,6 +46,8 @@ import org.orekit.orbits.PositionAngle;
 import org.orekit.propagation.Propagator;
 import org.orekit.propagation.analytical.KeplerianPropagator;
 import org.orekit.rugged.TestUtils;
+import org.orekit.rugged.errors.RuggedException;
+import org.orekit.rugged.errors.RuggedMessages;
 import org.orekit.rugged.linesensor.SensorMeanPlaneCrossing.CrossingResult;
 import org.orekit.rugged.los.LOSBuilder;
 import org.orekit.rugged.utils.SpacecraftToObservedBody;
@@ -146,8 +148,7 @@ public class SensorMeanPlaneCrossingTest {
 
     private void doTestDerivative(boolean lightTimeCorrection,
                                   boolean aberrationOfLightCorrection,
-                                  double tol)
-        {
+                                  double tol) {
 
         final Vector3D position  = new Vector3D(1.5, Vector3D.PLUS_I);
         final Vector3D normal    = Vector3D.PLUS_I;
@@ -215,6 +216,20 @@ public class SensorMeanPlaneCrossingTest {
                             Vector3D.distance(result.getTargetDirectionDerivative(), dirDer),
                             tol * dirDer.getNorm());
 
+        try {
+            mean.getScToBody().getBodyToInertial(refDate.shiftedBy(-Constants.JULIAN_CENTURY));
+            Assert.fail("an exception should have been thrown");
+        } catch (RuggedException re) {
+            Assert.assertEquals(RuggedMessages.OUT_OF_TIME_RANGE, re.getSpecifier());
+        }
+        try {
+            mean.getScToBody().getBodyToInertial(refDate.shiftedBy(Constants.JULIAN_CENTURY));
+            Assert.fail("an exception should have been thrown");
+        } catch (RuggedException re) {
+            Assert.assertEquals(RuggedMessages.OUT_OF_TIME_RANGE, re.getSpecifier());
+        }
+        Assert.assertNotNull(mean.getScToBody().getBodyToInertial(refDate));
+
     }
 
     @Test
diff --git a/src/test/resources/assets/org/orekit/rugged/RuggedMessages_ko.utf8 b/src/test/resources/assets/org/orekit/rugged/RuggedMessages_ko.utf8
new file mode 100644
index 0000000000000000000000000000000000000000..ab4e739779cb393190efdf1a20b26bb440e08f1b
--- /dev/null
+++ b/src/test/resources/assets/org/orekit/rugged/RuggedMessages_ko.utf8
@@ -0,0 +1,8 @@
+# no Digital Elevation Model data at latitude {0} and longitude {1}
+NO_DEM_DATA = <MISSING TRANSLATION>
+
+# unknown sensor {0}
+UNKNOWN_SENSOR = ABCDEF {0}
+
+# tile is empty: {0} ⨉ {1}
+EMPTY_TILE =
\ No newline at end of file