Refactor TLE and related classes to streamline state vector conversion; remove unnecessary frame transformations and improve test assertions

Author: sylvain-guillet

IO.Astrodynamics.Net/IO.Astrodynamics.Performance/VelocityTLE.cs

@@ -7,6 +7,7 @@
 
 namespace IO.Astrodynamics.Performance;
 
+[MemoryDiagnoser]
 public class VelocityTLE
 {
     private Time _epoch;

IO.Astrodynamics.Net/IO.Astrodynamics.Tests/OrbitalParameters/TLETests.cs

@@ -54,9 +54,9 @@ public void ToStateVector()
             "2 25544  51.6423 353.0312 0000493 320.8755  39.2360 15.49309423 25703");
 
         TimeSystem.Time epoch = TimeSystem.Time.CreateTDB(664440682.84760022);
-        var stateVector = tle.AtEpoch(epoch).ToStateVector();
+        var stateVector = tle.AtEpoch(epoch).ToStateVector().ToFrame(Frames.Frame.ICRF) as StateVector;
 
-        Assert.Equal(stateVector, tle.ToStateVector(epoch));
+        Assert.Equal(stateVector, tle.ToStateVector(epoch).ToFrame(Frames.Frame.ICRF) as StateVector);
         // Adjusted tolerances to account for SGP4/SDP4 propagator differences
         // Position tolerance: ~30m (acceptable for orbital mechanics)
         Assert.True(System.Math.Abs(stateVector.Position.X - 4339206.6119421758) < 30.0,
@@ -81,7 +81,7 @@ public void Observation()
             "2 39348  20.0230 212.2863 7218258 312.9449   5.6833  2.25781763 89468");
 
         TimeSystem.Time epoch = new TimeSystem.Time("2024-08-26T22:34:20.00000Z");
-        var stateVector = tle.ToStateVector(epoch);
+        var stateVector = tle.ToStateVector(epoch).ToFrame(Frames.Frame.ICRF);
 
         // Assert.Equal(32718528.303724434, stateVector.Position.X, 1);
         // Assert.Equal(-17501136.957387105, stateVector.Position.Y, 1);
@@ -245,7 +245,7 @@ public void ToTLE_ValidOrbit_ReturnsValidTLE()
         var tle = sv.ToTLE(config);
         Assert.NotNull(tle);
         Assert.Equal("TestSatellite", tle.Name);
-        var computedSV = tle.ToStateVector();
+        var computedSV = tle.ToStateVector().ToFrame(Frames.Frame.ICRF).ToStateVector();
         Assert.Equal(sv.Position.X, computedSV.Position.X, (x, y) => System.Math.Abs(x - y) < 0.5);
         Assert.Equal(sv.Position.Y, computedSV.Position.Y, (x, y) => System.Math.Abs(x - y) < 2);
         Assert.Equal(sv.Position.Z, computedSV.Position.Z, (x, y) => System.Math.Abs(x - y) < 6);

IO.Astrodynamics.Net/IO.Astrodynamics/API.cs

@@ -824,7 +824,7 @@ public OrbitalParameters.OrbitalParameters ConvertTleToStateVector(string line1,
             var res = ConvertTLEToStateVectorProxy(line1, line2, line3, epoch.ToTDB().TimeSpanFromJ2000().TotalSeconds);
             return new OrbitalParameters.StateVector(res.Position.Convert(), res.Velocity.Convert(),
                 new Body.CelestialBody(PlanetsAndMoons.EARTH, Frame.ECLIPTIC_J2000, epoch), epoch,
-                new Frame(res.Frame)).ToFrame(Frame.ICRF);
+                new Frame(res.Frame));
         }
     }
 

IO.Astrodynamics.Net/IO.Astrodynamics/OrbitalParameters/TLE/MeanElementsConverter.cs

@@ -45,7 +45,7 @@ internal OrbitalParameters Convert(
                 var testTle = TLE.Create(currentKep, name, noradId, cosparId, revAtEpoch, Classification.Unclassified, bstar);
 
                 // Propagate the TLE to get osculating elements at the same epoch
-                var propagatedState = testTle.ToStateVector(targetState.Epoch).ToFrame(Frame.TEME);
+                var propagatedState = testTle.ToStateVector(targetState.Epoch);
                 var propagatedKep = propagatedState.ToKeplerianElements();
 
                 // Compute residuals (difference between target and propagated)

IO.Astrodynamics.Net/IO.Astrodynamics/OrbitalParameters/TLE/TLE.cs

@@ -462,7 +462,7 @@ public override OrbitalParameters AtEpoch(Time epoch)
     /// <returns>The state vector at the given epoch.</returns>
     public override StateVector ToStateVector(Time date)
     {
-        return API.Instance.ConvertTleToStateVector(Name, Line1, Line2, date).ToFrame(Frame.ICRF).ToStateVector();
+        return API.Instance.ConvertTleToStateVector(Name, Line1, Line2, date).ToStateVector();
     }
 
     /// <summary>