diff --git a/tests/orbit_test.cpp b/tests/orbit_test.cpp
index 21df5a4..8247377 100644
--- a/tests/orbit_test.cpp
+++ b/tests/orbit_test.cpp
@@ -19,42 +19,37 @@ TEST_CASE("orbit construction", "[orbits]")
 // NOTE: example 4.6 in "Space Flight Dynamics" by Craig A. Kluever
 TEST_CASE("orbit propagation", "[orbits]")
 {
-	orbital_elements orbit = {};
-	double a = 26564.5; // kilometers
-	double e = 0.7411;
-	ellipse_parameters ep = ellipseInitAE(a, e);
-	orbit.ep = ep;
-	double initial_anom = 260 * M_PI / 180; // radians
-	unsigned int time_step = 60 * 50; // seconds
-
-	// NOTE: solve for gravitational parameter from mean motion
-	double mean_motion = 0.00014582; // rad/s
-	orbit.mu = pow(mean_motion, 2) * pow(ep.a, 3);
-
-
-	double E1 = getEccAnomFromTrueAnom(ep.e, initial_anom);
+	double a = 26564.5;		// NOTE: semi-major axis in km
+	double e = 0.7411;		// NOTE: eccentricity
+	double mu = 398601.68;	// NOTE: gravitational parameter
+	double r = 6378;		// NOTE: body radius in km
+	double initial_anom = 260 * M_PI / 180; // NOTE: radians
+	unsigned int time_step = 60 * 50; // NOTE: seconds
+	system_2body sys = systemInit(gravBodyInit(mu, r), orbitInit(a, e));
+
+	double E1 = getEccAnomFromTrueAnom(sys.ep.e, initial_anom);
 	REQUIRE_THAT(E1, WithinAbs(-0.8615, 1e-4));
 
-	double M1 = getMeanAnomFromEccAnom(E1, ep.e);
+	double M1 = getMeanAnomFromEccAnom(E1, sys.ep.e);
 	REQUIRE_THAT(M1, WithinAbs(-0.2992, 1e-4));
 
-	double n = getMeanMotion(orbit.mu, orbit.ep.a);
+	double n = getMeanMotion(sys.body.mu, sys.ep.a);
 	REQUIRE_THAT(n, WithinAbs(0.00014582, 1e-8));
 
 	double M2 = getPropagatedMeanAnom(M1, n, time_step);
 	REQUIRE_THAT(M2, WithinAbs(0.1383, 1e-5));
 
 	// TODO: could also test for the other trial values listed in table 4.1
-	double E2_1 = getInitialTrialValue(M2, ep.e);
+	double E2_1 = getInitialTrialValue(M2, sys.ep.e);
 	REQUIRE_THAT(E2_1, WithinAbs(0.315452, 1e-5));
 
-	double ecc_anom = getPropagatedEccAnomaly(orbit, initial_anom, time_step);
+	double ecc_anom = getPropagatedEccAnomaly(sys, initial_anom, time_step);
 	REQUIRE_THAT(ecc_anom, WithinAbs(0.481518, 1e-5));
 
-	double true_anom = getPropagatedTrueAnomaly(orbit, initial_anom, time_step);
+	double true_anom = getPropagatedTrueAnomaly(sys, initial_anom, time_step);
 	REQUIRE_THAT(true_anom, WithinAbs(1.1339, 1e-4));
 
-	double r2 = getRadialDistance(ep.e, ep.p, true_anom);
+	double r2 = orbitGetRadialDistance(sys.ep.e, sys.ep.p, true_anom);
 	REQUIRE_THAT(r2, WithinAbs(9116.1, 0.1));
 
 	glm::vec2 pos = polarToRect(true_anom, r2);