diff --git a/tests/configs/earth_circular.txt b/tests/configs/earth_circular.txt
new file mode 100644
index 0000000..4c08845
--- /dev/null
+++ b/tests/configs/earth_circular.txt
@@ -0,0 +1,11 @@
+# Test Configuration: Sun + Earth (circular orbit)
+# Earth at 1 AU with circular orbit
+# Expected orbital period: ~365 days
+#
+# Format: name mass(kg) radius(m) x(m) y(m) z(m) parent_index r g b eccentricity semi_major_axis(m)
+
+# Sun at origin (index 0)
+Sun 1.989e30 6.96e8 0 0 0 -1 1.0 1.0 0.0 0 0
+
+# Earth at 1 AU - circular orbit (index 1, parent Sun)
+Earth 5.972e24 6.371e6 1.496e11 0 0 0 0.0 0.5 1.0 0 1.496e11
diff --git a/tests/configs/mars_circular.txt b/tests/configs/mars_circular.txt
new file mode 100644
index 0000000..e09492d
--- /dev/null
+++ b/tests/configs/mars_circular.txt
@@ -0,0 +1,11 @@
+# Test Configuration: Sun + Mars (circular orbit)
+# Mars at 1.5 AU with circular orbit
+# Expected orbital period: ~687 days
+#
+# Format: name mass(kg) radius(m) x(m) y(m) z(m) parent_index r g b eccentricity semi_major_axis(m)
+
+# Sun at origin (index 0)
+Sun 1.989e30 6.96e8 0 0 0 -1 1.0 1.0 0.0 0 0
+
+# Mars at 1.5 AU - circular orbit (index 1, parent Sun)
+Mars 6.39e23 3.3895e6 2.244e11 0 0 0 0.8 0.3 0.1 0 2.244e11
diff --git a/tests/test_energy.cpp b/tests/test_energy.cpp
index eea84c4..6e9b421 100644
--- a/tests/test_energy.cpp
+++ b/tests/test_energy.cpp
@@ -1,6 +1,7 @@
 #include <catch2/catch_test_macros.hpp>
 #include "../src/physics.h"
 #include "../src/bodies.h"
+#include "../src/config_loader.h"
 #include "../src/test_utilities.h"
 #include <cmath>
 
@@ -11,13 +12,7 @@ TEST_CASE("Energy conservation - Earth circular orbit", "[energy][rk4]") {
 
     SimulationState* sim = create_simulation(10, TIME_STEP);
 
-    Vec3 sun_pos = {0, 0, 0};
-    Vec3 sun_vel = {0, 0, 0};
-    add_body(sim, "Sun", 1.989e30, 6.96e8, sun_pos, sun_vel, -1, 1.0, 1.0, 0.0, 0, 0);
-
-    Vec3 earth_pos = {1.496e11, 0, 0};
-    Vec3 earth_vel = {0, 29800, 0};
-    add_body(sim, "Earth", 5.972e24, 6.371e6, earth_pos, earth_vel, 0, 0.0, 0.5, 1.0, 0, 1.496e11);
+    REQUIRE(load_system_config(sim, "tests/configs/earth_circular.txt"));
 
     double initial_energy = calculate_system_total_energy(sim);
 
diff --git a/tests/test_orbital_period.cpp b/tests/test_orbital_period.cpp
index 73cc91f..609c651 100644
--- a/tests/test_orbital_period.cpp
+++ b/tests/test_orbital_period.cpp
@@ -1,6 +1,7 @@
 #include <catch2/catch_test_macros.hpp>
 #include "../src/physics.h"
 #include "../src/bodies.h"
+#include "../src/config_loader.h"
 #include "../src/test_utilities.h"
 #include <cmath>
 
@@ -12,13 +13,7 @@ TEST_CASE("Orbital period - Earth (RK4)", "[period][rk4]") {
 
     SimulationState* sim = create_simulation(10, TIME_STEP);
 
-    Vec3 sun_pos = {0, 0, 0};
-    Vec3 sun_vel = {0, 0, 0};
-    add_body(sim, "Sun", 1.989e30, 6.96e8, sun_pos, sun_vel, -1, 1.0, 1.0, 0.0, 0, 0);
-
-    Vec3 earth_pos = {1.496e11, 0, 0};
-    Vec3 earth_vel = {0, 29789, 0};
-    add_body(sim, "Earth", 5.972e24, 6.371e6, earth_pos, earth_vel, 0, 0.0, 0.5, 1.0, 0, 1.496e11);
+    REQUIRE(load_system_config(sim, "tests/configs/earth_circular.txt"));
 
     OrbitTracker* tracker = create_orbit_tracker(1);
 
@@ -51,13 +46,7 @@ TEST_CASE("Orbital period - Mars (RK4)", "[period][rk4]") {
 
     SimulationState* sim = create_simulation(10, TIME_STEP);
 
-    Vec3 sun_pos = {0, 0, 0};
-    Vec3 sun_vel = {0, 0, 0};
-    add_body(sim, "Sun", 1.989e30, 6.96e8, sun_pos, sun_vel, -1, 1.0, 1.0, 0.0, 0, 0);
-
-    Vec3 mars_pos = {2.244e11, 0, 0};
-    Vec3 mars_vel = {0, 24323, 0};
-    add_body(sim, "Mars", 6.39e23, 3.3895e6, mars_pos, mars_vel, 0, 0.8, 0.3, 0.1, 0, 2.244e11);
+    REQUIRE(load_system_config(sim, "tests/configs/mars_circular.txt"));
 
     OrbitTracker* tracker = create_orbit_tracker(1);