The TLE handling method was improved according to the description below:

- The meanOE of the TLE are converted to osculationg elements with the
  SPG4 mentod
- Coordinate conversion added to (and from) TEME to J2000/ICRS
- When converting the osculationg elements to a TLE, the mean OE are
  generated using SPG4
- The unit test was updated accordingly

Author: OliverHasle

src/tests/test_readTLE.py

@@ -6,83 +6,82 @@
 import Basilisk.utilities.orbitalMotion as om
 from datetime import datetime, timedelta, timezone
 
-A_TOL = 1e-14 #[-]
+A_TOL = 1e-9 #[-]
+A_TOL_ROUNDTRIP = 1e-4 #[-] Tolerance for eccentricity (roundtrip error)
+A_TOL_DEG_ROUNDTRIP = 1.5  # [deg] Tolerance for angles in degrees (roundtrip error)
+
 DATA_DIR = pathlib.Path(__file__).parent / 'data'
 
 ###################################################################
 # Expected orbital elements for oneWeb (if testing multiple satellites)
 EXPECTED_OE_ONE_WEB = {
     'a': [
-        7575817.78380046,  # 0
-        7575897.531671279, # 1
-        7575896.775957426, # 2
-        7579911.683283668, # 3
-        7579911.241546285, # 4
-        7579912.336286875 # 5
-    ],
+              np.float64(7578544.80840588),
+              np.float64(7581725.314320893),
+              np.float64(7581725.090937277),
+              np.float64(7585736.508260437),
+              np.float64(7585735.9677996775),
+              np.float64(7585737.120163768)
+         ],
     'e': [
-        0.000175,   0.0001764, 0.0002086, 0.0001581, 0.0001714,
-        0.0002029
-    ],
+              np.float64(0.0008817590462989669),
+              np.float64(0.001210093768077448),
+              np.float64(0.001258633728769965),
+              np.float64(0.0011981313722308415),
+              np.float64(0.001206952489243135),
+              np.float64(0.001239828742668404)
+         ],
     'i': [
-        1.534083325979196,  1.5340868166376997, 1.534083325979196,
-        1.5341409218445117, 1.5341496484907717, 1.5341409218445117
-    ],
-    'f': [
-        2.2017240215026246, 4.489410705143804, 4.744271057621696,
-        4.549972500184758, 4.511343702990637, 4.567673118903615
-    ],
+              1.531618126589653,
+              1.5316291459001932,
+              1.5316258452568352,
+              1.5322241554919225,
+              1.5322307739504486,
+              1.5322225935006697
+             ],
     'Omega': [
-        4.888890636980372, 4.888930779553168, 4.889318242647111,
-        5.4216838070781765, 5.420380046126938, 5.4207134040140685
-    ],
+              4.8831623958720565,
+              4.883186443196075,
+              4.883574022425417,
+              5.415984679757847,
+              5.414680762509103,
+              5.415014177551135
+             ],
     'omega': [
-        1.372734617949328, 1.7957483234259417, 1.5408883647327218,
-        1.7351853983817387, 1.773814770716129, 1.717484269108012
-    ]
+              1.4377465022195557,
+              1.2801901375990692,
+              1.2537640336417852,
+              1.2645835093359827,
+              1.2744200510794836,
+              1.278331704552413
+         ],
+    'f': [
+              2.1381866215235528,
+              5.002606275268809,
+              5.029031746586543,
+              5.017006771870916,
+              5.0071733437393355,
+              5.003259952527291
+          ],
 }
 
 EXPECTED_OE_2LE = {
-    'a': [
-        6796012.0083837,
-        6763487.620700561,
-        6796034.881033647
-    ],
-    'e': [
-        0.0001066,
-        0.0001842,
-        0.0001045
-    ],
-    'i': [
-        0.9011588713652241,
-        0.7236833210469288,
-        0.9011606166944762
-    ],
-    'f': [
-        3.019032029543272,
-        3.4280122815833245,
-        3.0304383654813503
-    ],
-    'Omega': [
-        2.3957855389445846,
-        1.6320242222841097,
-        2.4180821201388114
-    ],
-    'omega': [
-        3.2658775496243098,
-        2.8566379826044352,
-        3.2544735682917785
-    ]
+    'a': [np.float64(6802505.842859207), np.float64(6770009.6048538275), np.float64(6802528.7123854)],
+    'e': [np.float64(0.0011264735370325686), np.float64(0.0011530055595853114), np.float64(0.001128835473051786)],
+    'i': [0.903248948599224, 0.7265482390037918, 0.9032099423215613],
+    'Omega': [2.3886009471482503, 1.6261518262462817, 2.410867356948434],
+    'omega': [0.8571434002531804, 0.7478010900864719, 0.8567388460152983],
+    'f': [5.428341410047342, 5.535537401708238, 5.428797206538743],
 }
 
 # Values to generate TLE for HYPSO 1
 oeHypso1 = om.ClassicElements()
-oeHypso1.i = np.deg2rad(97.3197)
-oeHypso1.e = 0.0004257 # [-]
-oeHypso1.a = (om.RP_EARTH + 445.195971181338)*1e3 # [m]
-oeHypso1.Omega = np.deg2rad(349.0390) # [rad]
-oeHypso1.omega = np.deg2rad(136.0807) # [rad]
-oeHypso1.f = np.deg2rad(224.04427854247686) # [rad]
+oeHypso1.i = 1.6979291907417804
+oeHypso1.e = 0.0013996087479637449
+oeHypso1.a = 6808434.893655814
+oeHypso1.Omega = 6.085804103135117
+oeHypso1.omega = 1.43544167146666
+oeHypso1.f = 4.845270389715793
 hypso1noradId = 51053 # [-]
 hypso1launch = datetime(2022, 1, 13, 0, 0, 0) # [UTC]
 hypso1tleEpoch = datetime(2025, 1, 1, tzinfo=timezone.utc) + timedelta(days=279.47924866 - 1) # [UTC]
@@ -153,7 +152,15 @@ def test_write_tle(satName, orbitalElements, noradID, launchDate, launch_Noyear,
     # String compaire (line 1)
     eCountTle += int((generatedTle.splitlines()[1] != expectedTLE.splitlines()[1]))
     # String compaire (line 2)
-    eCountTle += int((generatedTle.splitlines()[2][0:63] != expectedTLE.splitlines()[2][0:63])) # Ignore revolutions count and checksum
+    for i, (field_expected, field_generated) in enumerate(zip(expectedTLE.splitlines()[2].split(), generatedTle.splitlines()[2].split())):
+        if i in [4]: # 4 = eccentricity (leading decimal point assumed), 5 = argument of perigee, 6 = mean anomaly
+            # Eccentricity -> leading decimal point assume -> max tolerance is A_TOL_ROUNDTRIP * 1e7 => 1e-4 physical eccentricity tolerance
+            eCountTle += abs(float(field_expected) - float(field_generated)) > A_TOL_ROUNDTRIP * 1e7
+        elif i in [5,6]: # 5 = argument of perigee, 6 = mean anomaly (degrees)
+            eCountTle += abs(float(field_expected) - float(field_generated)) > A_TOL_DEG_ROUNDTRIP
+        else:
+            eCountTle += abs(float(field_expected) - float(field_generated)) > A_TOL_ROUNDTRIP
+
     assert eCountTle < 1, f"{eCountTle} functions failed in tleHandling.py script, generateTleDataString() method"
 
 @pytest.mark.parametrize("tlePath", [
@@ -174,7 +181,15 @@ def test_read_write_tle(tlePath):
     # String compaire (line 1)
     eCountTle += int((generatedTle.splitlines()[1] != tleToBeTested.splitlines()[1]))
     # String compaire (line 2)
-    eCountTle += int((generatedTle.splitlines()[2][0:63] != tleToBeTested.splitlines()[2][0:63])) # Ignore revolutions count and checksum
+    for i, (field_expected, field_generated) in enumerate(zip(tleToBeTested.splitlines()[2].split(), generatedTle.splitlines()[2].split())):
+        if i in [4]: # 4 = eccentricity (leading decimal point assumed), 5 = argument of perigee, 6 = mean anomaly
+            # Eccentricity -> leading decimal point assume -> max tolerance is A_TOL_ROUNDTRIP * 1e7 => 1e-4 physical eccentricity tolerance
+            eCountTle += abs(float(field_expected) - float(field_generated)) > A_TOL_ROUNDTRIP * 1e7
+        elif i in [5,6]: # 5 = argument of perigee, 6 = mean anomaly (degrees)
+            eCountTle += abs(float(field_expected) - float(field_generated)) > A_TOL_DEG_ROUNDTRIP
+        else:
+            eCountTle += abs(float(field_expected) - float(field_generated)) > A_TOL_ROUNDTRIP
+
     assert eCountTle < 1, f"{eCountTle} functions failed in tleHandling.py script, generateTleDataString() method"
 
 if __name__ == "__main__":