diff --git a/tests/test_cartesian_to_elements_quadrature.cpp b/tests/test_cartesian_to_elements_advanced.cpp
similarity index 50%
rename from tests/test_cartesian_to_elements_quadrature.cpp
rename to tests/test_cartesian_to_elements_advanced.cpp
index 73076d4..edfeeee 100644
--- a/tests/test_cartesian_to_elements_quadrature.cpp
+++ b/tests/test_cartesian_to_elements_advanced.cpp
@@ -9,12 +9,257 @@
 
 using Catch::Matchers::WithinAbs;
 
-TEST_CASE("Cartesian to Elements - Quadrature Points", "[orbital_mechanics]") {
+TEST_CASE("Cartesian to Elements - Advanced Tests", "[orbital_mechanics]") {
     const double G = 6.67430e-11;
     const double M_sun = 1.989e30;
     const double mu = G * M_sun;
 
-    SECTION("Quadrature point ν=π/2 (90°) preserves orbital elements") {
+    SECTION("Circular orbit conversion preserves exact circular parameters") {
+        double r = 1.496e11;
+        double v_circular = sqrt(mu / r);
+        Vec3 position = {r, 0.0, 0.0};
+        Vec3 velocity = {0.0, v_circular, 0.0};
+
+        OrbitalElements elements = cartesian_to_orbital_elements(position, velocity, M_sun);
+
+        REQUIRE_THAT(elements.eccentricity, WithinAbs(0.0, 1e-10));
+        REQUIRE_THAT(elements.semi_major_axis, WithinAbs(r, 1e3));
+
+        Vec3 converted_position, converted_velocity;
+        orbital_elements_to_cartesian(elements, M_sun, &converted_position, &converted_velocity);
+
+        REQUIRE(compare_vec3(position, converted_position, 1e3));
+        REQUIRE(compare_vec3(velocity, converted_velocity, 1e-3));
+    }
+
+    SECTION("Near-circular orbit (e=0.001) recovers small eccentricity") {
+        OrbitalElements elements = {
+            .semi_major_axis = 1.496e11,
+            .eccentricity = 0.001,
+            .true_anomaly = 0.5,
+            .inclination = 0.0,
+            .longitude_of_ascending_node = 0.0,
+            .argument_of_periapsis = 0.0
+        };
+
+        Vec3 position, velocity;
+        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
+
+        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
+
+        REQUIRE_THAT(recovered.eccentricity, WithinAbs(0.001, 1e-6));
+        REQUIRE_THAT(recovered.semi_major_axis, WithinAbs(1.496e11, 1e3));
+    }
+
+    SECTION("Elliptical orbit (e=0.5) preserves orbital shape") {
+        OrbitalElements elements = {
+            .semi_major_axis = 1.0e11,
+            .eccentricity = 0.5,
+            .true_anomaly = 0.8,
+            .inclination = 0.0,
+            .longitude_of_ascending_node = 0.0,
+            .argument_of_periapsis = 0.0
+        };
+
+        Vec3 position, velocity;
+        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
+
+        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
+
+        REQUIRE_THAT(recovered.eccentricity, WithinAbs(0.5, 1e-4));
+        REQUIRE_THAT(recovered.semi_major_axis, WithinAbs(1.0e11, 1e6));
+    }
+
+    SECTION("Highly elliptical orbit (e=0.95) preserves extreme eccentricity") {
+        OrbitalElements elements = {
+            .semi_major_axis = 1.0e11,
+            .eccentricity = 0.95,
+            .true_anomaly = 0.1,
+            .inclination = 0.0,
+            .longitude_of_ascending_node = 0.0,
+            .argument_of_periapsis = 0.0
+        };
+
+        Vec3 position, velocity;
+        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
+
+        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
+
+        REQUIRE_THAT(recovered.eccentricity, WithinAbs(0.95, 1e-3));
+        REQUIRE_THAT(recovered.semi_major_axis, WithinAbs(1.0e11, 1e6));
+    }
+
+    SECTION("Near-parabolic orbit (e=0.999) recovers near-escape trajectory") {
+        OrbitalElements elements = {
+            .semi_major_axis = 1.0e11,
+            .eccentricity = 0.999,
+            .true_anomaly = 0.05,
+            .inclination = 0.0,
+            .longitude_of_ascending_node = 0.0,
+            .argument_of_periapsis = 0.0
+        };
+
+        Vec3 position, velocity;
+        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
+
+        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
+
+        REQUIRE_THAT(recovered.eccentricity, WithinAbs(0.999, 1e-3));
+    }
+
+    SECTION("Parabolic orbit (e=1.0) recovers escape trajectory") {
+        OrbitalElements elements = {
+            .semi_latus_rectum = 1.0e11,
+            .eccentricity = 1.0,
+            .true_anomaly = 0.5,
+            .inclination = 0.0,
+            .longitude_of_ascending_node = 0.0,
+            .argument_of_periapsis = 0.0
+        };
+
+        Vec3 position, velocity;
+        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
+
+        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
+
+        REQUIRE_THAT(recovered.eccentricity, WithinAbs(1.0, 1e-2));
+        REQUIRE_THAT(recovered.semi_latus_rectum, WithinAbs(1.0e11, 1e3));
+    }
+
+    SECTION("Hyperbolic orbit (e=2.0) preserves unbound trajectory") {
+        OrbitalElements elements = {
+            .semi_major_axis = -1.0e11,
+            .eccentricity = 2.0,
+            .true_anomaly = 0.5,
+            .inclination = 0.0,
+            .longitude_of_ascending_node = 0.0,
+            .argument_of_periapsis = 0.0
+        };
+
+        Vec3 position, velocity;
+        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
+
+        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
+
+        REQUIRE_THAT(recovered.eccentricity, WithinAbs(2.0, 1e-3));
+        REQUIRE_THAT(recovered.semi_major_axis, WithinAbs(-1.0e11, 1e6));
+    }
+
+    SECTION("Highly hyperbolic orbit (e=10.0) preserves extreme unbound trajectory") {
+        OrbitalElements elements = {
+            .semi_major_axis = -1.0e10,
+            .eccentricity = 10.0,
+            .true_anomaly = 0.8,
+            .inclination = 0.0,
+            .longitude_of_ascending_node = 0.0,
+            .argument_of_periapsis = 0.0
+        };
+
+        Vec3 position, velocity;
+        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
+
+        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
+
+        REQUIRE_THAT(recovered.eccentricity, WithinAbs(10.0, 1e-3));
+        REQUIRE_THAT(recovered.semi_major_axis, WithinAbs(-1.0e10, 1e8));
+    }
+
+    SECTION("Zero inclination (i=0) preserves equatorial orbit") {
+        OrbitalElements elements = {
+            .semi_major_axis = 1.0e11,
+            .eccentricity = 0.3,
+            .true_anomaly = 0.5,
+            .inclination = 0.0,
+            .longitude_of_ascending_node = 0.0,
+            .argument_of_periapsis = 0.0
+        };
+
+        Vec3 position, velocity;
+        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
+
+        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
+
+        REQUIRE_THAT(recovered.inclination, WithinAbs(0.0, 1e-6));
+        REQUIRE_THAT(recovered.eccentricity, WithinAbs(0.3, 1e-4));
+    }
+
+    SECTION("90-degree inclination (i=pi/2) preserves polar orbit") {
+        OrbitalElements elements = {
+            .semi_major_axis = 1.0e11,
+            .eccentricity = 0.2,
+            .true_anomaly = 0.6,
+            .inclination = M_PI / 2.0,
+            .longitude_of_ascending_node = 0.5,
+            .argument_of_periapsis = 0.3
+        };
+
+        Vec3 position, velocity;
+        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
+
+        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
+
+        REQUIRE_THAT(recovered.inclination, WithinAbs(M_PI / 2.0, 1e-4));
+        REQUIRE_THAT(recovered.longitude_of_ascending_node, WithinAbs(0.5, 1e-4));
+        REQUIRE_THAT(recovered.argument_of_periapsis, WithinAbs(0.3, 1e-4));
+    }
+
+    SECTION("180-degree inclination (i=pi) preserves retrograde orbit") {
+        OrbitalElements elements = {
+            .semi_major_axis = 1.0e11,
+            .eccentricity = 0.2,
+            .true_anomaly = 0.6,
+            .inclination = M_PI,
+            .longitude_of_ascending_node = 0.5,
+            .argument_of_periapsis = 0.3
+        };
+
+        Vec3 position, velocity;
+        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
+
+        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
+
+        REQUIRE_THAT(recovered.inclination, WithinAbs(M_PI, 1e-4));
+    }
+
+    SECTION("Periapsis (nu=0) recovers true anomaly correctly") {
+        OrbitalElements elements = {
+            .semi_major_axis = 1.0e11,
+            .eccentricity = 0.5,
+            .true_anomaly = 0.0,
+            .inclination = 0.0,
+            .longitude_of_ascending_node = 0.0,
+            .argument_of_periapsis = 0.0
+        };
+
+        Vec3 position, velocity;
+        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
+
+        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
+
+        REQUIRE_THAT(recovered.true_anomaly, WithinAbs(0.0, 1e-6));
+        REQUIRE_THAT(recovered.eccentricity, WithinAbs(0.5, 1e-4));
+    }
+
+    SECTION("Apoapsis (nu=pi) recovers true anomaly correctly") {
+        OrbitalElements elements = {
+            .semi_major_axis = 1.0e11,
+            .eccentricity = 0.5,
+            .true_anomaly = M_PI,
+            .inclination = 0.0,
+            .longitude_of_ascending_node = 0.0,
+            .argument_of_periapsis = 0.0
+        };
+
+        Vec3 position, velocity;
+        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
+
+        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
+
+        REQUIRE_THAT(recovered.true_anomaly, WithinAbs(M_PI, 1e-6));
+        REQUIRE_THAT(recovered.eccentricity, WithinAbs(0.5, 1e-4));
+    }
+
+    SECTION("Quadrature point nu=pi/2 (90 deg) preserves orbital elements") {
         OrbitalElements elements = {
             .semi_major_axis = 1.0e11,
             .eccentricity = 0.5,
@@ -34,7 +279,7 @@ TEST_CASE("Cartesian to Elements - Quadrature Points", "[orbital_mechanics]") {
         REQUIRE_THAT(recovered.true_anomaly, WithinAbs(M_PI / 2.0, 1e-6));
     }
 
-    SECTION("Quadrature point ν=-π/2 (-90°) preserves orbital elements") {
+    SECTION("Quadrature point nu=-pi/2 (-90 deg) preserves orbital elements") {
         OrbitalElements elements = {
             .semi_major_axis = 1.0e11,
             .eccentricity = 0.5,
@@ -54,7 +299,7 @@ TEST_CASE("Cartesian to Elements - Quadrature Points", "[orbital_mechanics]") {
         REQUIRE_THAT(recovered.true_anomaly, WithinAbs(-M_PI / 2.0, 1e-6));
     }
 
-    SECTION("Quadrature point ν=3π/2 (270°) preserves orbital elements") {
+    SECTION("Quadrature point nu=3pi/2 (270 deg) preserves orbital elements") {
         OrbitalElements elements = {
             .semi_major_axis = 1.0e11,
             .eccentricity = 0.5,
@@ -74,7 +319,7 @@ TEST_CASE("Cartesian to Elements - Quadrature Points", "[orbital_mechanics]") {
         REQUIRE_THAT(recovered.true_anomaly, WithinAbs(-M_PI / 2.0, 1e-6));
     }
 
-    SECTION("Quadrature point ν=-3π/2 (-270°) preserves orbital elements") {
+    SECTION("Quadrature point nu=-3pi/2 (-270 deg) preserves orbital elements") {
         OrbitalElements elements = {
             .semi_major_axis = 1.0e11,
             .eccentricity = 0.5,
@@ -134,7 +379,7 @@ TEST_CASE("Cartesian to Elements - Quadrature Points", "[orbital_mechanics]") {
         REQUIRE_THAT(recovered.true_anomaly, WithinAbs(M_PI / 2.0, 1e-6));
     }
 
-    SECTION("Large true anomaly ν=5.0 rad (≈286°) preserves accuracy") {
+    SECTION("Large true anomaly nu=5.0 rad (approx 286 deg) preserves accuracy") {
         OrbitalElements elements = {
             .semi_major_axis = 1.0e11,
             .eccentricity = 0.5,
@@ -154,7 +399,7 @@ TEST_CASE("Cartesian to Elements - Quadrature Points", "[orbital_mechanics]") {
         REQUIRE_THAT(recovered.true_anomaly, WithinAbs(-1.28318530717958623, 1e-6));
     }
 
-    SECTION("Large negative true anomaly ν=-5.0 rad (≈-286°) preserves accuracy") {
+    SECTION("Large negative true anomaly nu=-5.0 rad (approx -286 deg) preserves accuracy") {
         OrbitalElements elements = {
             .semi_major_axis = 1.0e11,
             .eccentricity = 0.5,
@@ -174,7 +419,7 @@ TEST_CASE("Cartesian to Elements - Quadrature Points", "[orbital_mechanics]") {
         REQUIRE_THAT(recovered.true_anomaly, WithinAbs(1.28318530717958623, 1e-6));
     }
 
-    SECTION("Very large true anomaly ν=10.0 rad (≈573°) preserves accuracy") {
+    SECTION("Very large true anomaly nu=10.0 rad (approx 573 deg) preserves accuracy") {
         OrbitalElements elements = {
             .semi_major_axis = 1.0e11,
             .eccentricity = 0.5,
@@ -241,7 +486,7 @@ TEST_CASE("Cartesian to Elements - Quadrature Points", "[orbital_mechanics]") {
         }
     }
 
-    SECTION("Hyperbolic orbit at quadrature point ν=π/2") {
+    SECTION("Hyperbolic orbit at quadrature point nu=pi/2") {
         OrbitalElements elements = {
             .semi_major_axis = -1.0e11,
             .eccentricity = 2.0,
diff --git a/tests/test_cartesian_to_elements_extreme.cpp b/tests/test_cartesian_to_elements_extreme.cpp
deleted file mode 100644
index 1877c11..0000000
--- a/tests/test_cartesian_to_elements_extreme.cpp
+++ /dev/null
@@ -1,262 +0,0 @@
-#include <catch2/catch_test_macros.hpp>
-#include <catch2/matchers/catch_matchers_floating_point.hpp>
-#include <cmath>
-#include "../src/orbital_mechanics.h"
-#include "../src/spacecraft.h"
-#include "../src/test_utilities.h"
-#include "../src/config_loader.h"
-#include "../src/simulation.h"
-
-using Catch::Matchers::WithinAbs;
-
-TEST_CASE("Cartesian to Elements - Edge Cases", "[orbital_mechanics]") {
-    const double G = 6.67430e-11;
-    const double M_sun = 1.989e30;
-    const double mu = G * M_sun;
-
-    SECTION("Circular orbit conversion preserves exact circular parameters") {
-        double r = 1.496e11;
-        double v_circular = sqrt(mu / r);
-        Vec3 position = {r, 0.0, 0.0};
-        Vec3 velocity = {0.0, v_circular, 0.0};
-
-        OrbitalElements elements = cartesian_to_orbital_elements(position, velocity, M_sun);
-
-        REQUIRE_THAT(elements.eccentricity, WithinAbs(0.0, 1e-10));
-        REQUIRE_THAT(elements.semi_major_axis, WithinAbs(r, 1e3));
-
-        Vec3 converted_position, converted_velocity;
-        orbital_elements_to_cartesian(elements, M_sun, &converted_position, &converted_velocity);
-
-        REQUIRE(compare_vec3(position, converted_position, 1e3));
-        REQUIRE(compare_vec3(velocity, converted_velocity, 1e-3));
-    }
-
-    SECTION("Near-circular orbit (e=0.001) recovers small eccentricity") {
-        OrbitalElements elements = {
-            .semi_major_axis = 1.496e11,
-            .eccentricity = 0.001,
-            .true_anomaly = 0.5,
-            .inclination = 0.0,
-            .longitude_of_ascending_node = 0.0,
-            .argument_of_periapsis = 0.0
-        };
-
-        Vec3 position, velocity;
-        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
-
-        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
-
-        REQUIRE_THAT(recovered.eccentricity, WithinAbs(0.001, 1e-6));
-        REQUIRE_THAT(recovered.semi_major_axis, WithinAbs(1.496e11, 1e3));
-    }
-
-    SECTION("Elliptical orbit (e=0.5) preserves orbital shape") {
-        OrbitalElements elements = {
-            .semi_major_axis = 1.0e11,
-            .eccentricity = 0.5,
-            .true_anomaly = 0.8,
-            .inclination = 0.0,
-            .longitude_of_ascending_node = 0.0,
-            .argument_of_periapsis = 0.0
-        };
-
-        Vec3 position, velocity;
-        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
-
-        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
-
-        REQUIRE_THAT(recovered.eccentricity, WithinAbs(0.5, 1e-4));
-        REQUIRE_THAT(recovered.semi_major_axis, WithinAbs(1.0e11, 1e6));
-    }
-
-    SECTION("Highly elliptical orbit (e=0.95) preserves extreme eccentricity") {
-        OrbitalElements elements = {
-            .semi_major_axis = 1.0e11,
-            .eccentricity = 0.95,
-            .true_anomaly = 0.1,
-            .inclination = 0.0,
-            .longitude_of_ascending_node = 0.0,
-            .argument_of_periapsis = 0.0
-        };
-
-        Vec3 position, velocity;
-        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
-
-        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
-
-        REQUIRE_THAT(recovered.eccentricity, WithinAbs(0.95, 1e-3));
-        REQUIRE_THAT(recovered.semi_major_axis, WithinAbs(1.0e11, 1e6));
-    }
-
-    SECTION("Near-parabolic orbit (e=0.999) recovers near-escape trajectory") {
-        OrbitalElements elements = {
-            .semi_major_axis = 1.0e11,
-            .eccentricity = 0.999,
-            .true_anomaly = 0.05,
-            .inclination = 0.0,
-            .longitude_of_ascending_node = 0.0,
-            .argument_of_periapsis = 0.0
-        };
-
-        Vec3 position, velocity;
-        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
-
-        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
-
-        REQUIRE_THAT(recovered.eccentricity, WithinAbs(0.999, 1e-3));
-        // Semi-major axis poorly conditioned for e≈1, skip test
-    }
-
-    SECTION("Parabolic orbit (e=1.0) recovers escape trajectory") {
-        OrbitalElements elements = {
-            .semi_latus_rectum = 1.0e11,
-            .eccentricity = 1.0,
-            .true_anomaly = 0.5,
-            .inclination = 0.0,
-            .longitude_of_ascending_node = 0.0,
-            .argument_of_periapsis = 0.0
-        };
-
-        Vec3 position, velocity;
-        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
-
-        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
-
-        REQUIRE_THAT(recovered.eccentricity, WithinAbs(1.0, 1e-2));
-        REQUIRE_THAT(recovered.semi_latus_rectum, WithinAbs(1.0e11, 1e3));
-    }
-
-    SECTION("Hyperbolic orbit (e=2.0) preserves unbound trajectory") {
-        OrbitalElements elements = {
-            .semi_major_axis = -1.0e11,
-            .eccentricity = 2.0,
-            .true_anomaly = 0.5,
-            .inclination = 0.0,
-            .longitude_of_ascending_node = 0.0,
-            .argument_of_periapsis = 0.0
-        };
-
-        Vec3 position, velocity;
-        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
-
-        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
-
-        REQUIRE_THAT(recovered.eccentricity, WithinAbs(2.0, 1e-3));
-        REQUIRE_THAT(recovered.semi_major_axis, WithinAbs(-1.0e11, 1e6));
-    }
-
-    SECTION("Highly hyperbolic orbit (e=10.0) preserves extreme unbound trajectory") {
-        OrbitalElements elements = {
-            .semi_major_axis = -1.0e10,
-            .eccentricity = 10.0,
-            .true_anomaly = 0.8,
-            .inclination = 0.0,
-            .longitude_of_ascending_node = 0.0,
-            .argument_of_periapsis = 0.0
-        };
-
-        Vec3 position, velocity;
-        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
-
-        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
-
-        REQUIRE_THAT(recovered.eccentricity, WithinAbs(10.0, 1e-3));
-        REQUIRE_THAT(recovered.semi_major_axis, WithinAbs(-1.0e10, 1e8));
-    }
-
-    SECTION("Zero inclination (i=0) preserves equatorial orbit") {
-        OrbitalElements elements = {
-            .semi_major_axis = 1.0e11,
-            .eccentricity = 0.3,
-            .true_anomaly = 0.5,
-            .inclination = 0.0,
-            .longitude_of_ascending_node = 0.0,
-            .argument_of_periapsis = 0.0
-        };
-
-        Vec3 position, velocity;
-        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
-
-        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
-
-        REQUIRE_THAT(recovered.inclination, WithinAbs(0.0, 1e-6));
-        REQUIRE_THAT(recovered.eccentricity, WithinAbs(0.3, 1e-4));
-    }
-
-    SECTION("90-degree inclination (i=π/2) preserves polar orbit") {
-        OrbitalElements elements = {
-            .semi_major_axis = 1.0e11,
-            .eccentricity = 0.2,
-            .true_anomaly = 0.6,
-            .inclination = M_PI / 2.0,
-            .longitude_of_ascending_node = 0.5,
-            .argument_of_periapsis = 0.3
-        };
-
-        Vec3 position, velocity;
-        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
-
-        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
-
-        REQUIRE_THAT(recovered.inclination, WithinAbs(M_PI / 2.0, 1e-4));
-        REQUIRE_THAT(recovered.longitude_of_ascending_node, WithinAbs(0.5, 1e-4));
-        REQUIRE_THAT(recovered.argument_of_periapsis, WithinAbs(0.3, 1e-4));
-    }
-
-    SECTION("180-degree inclination (i=π) preserves retrograde orbit") {
-        OrbitalElements elements = {
-            .semi_major_axis = 1.0e11,
-            .eccentricity = 0.2,
-            .true_anomaly = 0.6,
-            .inclination = M_PI,
-            .longitude_of_ascending_node = 0.5,
-            .argument_of_periapsis = 0.3
-        };
-
-        Vec3 position, velocity;
-        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
-
-        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
-
-        REQUIRE_THAT(recovered.inclination, WithinAbs(M_PI, 1e-4));
-    }
-
-    SECTION("Periapsis (ν=0) recovers true anomaly correctly") {
-        OrbitalElements elements = {
-            .semi_major_axis = 1.0e11,
-            .eccentricity = 0.5,
-            .true_anomaly = 0.0,
-            .inclination = 0.0,
-            .longitude_of_ascending_node = 0.0,
-            .argument_of_periapsis = 0.0
-        };
-
-        Vec3 position, velocity;
-        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
-
-        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
-
-        REQUIRE_THAT(recovered.true_anomaly, WithinAbs(0.0, 1e-6));
-        REQUIRE_THAT(recovered.eccentricity, WithinAbs(0.5, 1e-4));
-    }
-
-    SECTION("Apoapsis (ν=π) recovers true anomaly correctly") {
-        OrbitalElements elements = {
-            .semi_major_axis = 1.0e11,
-            .eccentricity = 0.5,
-            .true_anomaly = M_PI,
-            .inclination = 0.0,
-            .longitude_of_ascending_node = 0.0,
-            .argument_of_periapsis = 0.0
-        };
-
-        Vec3 position, velocity;
-        orbital_elements_to_cartesian(elements, M_sun, &position, &velocity);
-
-        OrbitalElements recovered = cartesian_to_orbital_elements(position, velocity, M_sun);
-
-        REQUIRE_THAT(recovered.true_anomaly, WithinAbs(M_PI, 1e-6));
-        REQUIRE_THAT(recovered.eccentricity, WithinAbs(0.5, 1e-4));
-    }
-}