diff --git a/src/orbits.cpp b/src/orbits.cpp
index a6e8e15..123d615 100644
--- a/src/orbits.cpp
+++ b/src/orbits.cpp
@@ -24,13 +24,16 @@ constructEllipseAE(double a, double e)
 }
 
 bool
-validateEllipse(const ellipse_parameters ep)
+validateEllipse(const ellipse_parameters& ep)
 {
+	// TODO: find out why satellite position gets wonky with orbit
+	// 	eccentricity > 0.995 while passing through true anom = 0.
+	// 	maybe divide by 0, or some floating point error?
 	return (ep.a > 0 &&
 		ep.b > 0 &&
 		ep.a >= ep.b &&
 		ep.e >= 0 &&
-		ep.e < 1);
+		ep.e < 0.995);
 }
 
 bool
diff --git a/src/orbits.h b/src/orbits.h
index eee3503..4012431 100644
--- a/src/orbits.h
+++ b/src/orbits.h
@@ -27,8 +27,12 @@ struct orbital_elements
 	double mu;		// NOTE: (μ) gravitational parameter
 	double nu;		// NOTE: (ν) true anomaly
 
+	double epsilon;	// NOTE: (ε) specific orbital energy, MJ/kg
+	double h;		// NOTE: angular momentum
+
 	glm::vec3 pos;	// NOTE: true anomaly in 3d with ep.f2 at origin
-	double radial_velocity;
+	double vr;		// NOTE: radial velocity
+	double gamma;	// NOTE: (γ) flight path angle
 };
 
 struct ellipse_3d
@@ -46,7 +50,7 @@ ellipse_parameters
 constructEllipseAE(double a, double e);
 
 bool
-validateEllipse(const ellipse_parameters);
+validateEllipse(const ellipse_parameters& ep);
 
 bool
 ellipsesEqual(ellipse_parameters& e1, ellipse_parameters& e2);