private double getSimpleMass(Body body1, Body body2) {
		double mass = 0;
		Body ancestor = body1.parent;
		while (ancestor != null) {
			if (ancestor == body2) {
				return body2.mass;
			}
			ancestor = ancestor.parent;
		}
		if (body1.parent == body2.parent
		// Sibling case: bundle niblings with siblings
				|| body1 == body2.parent
		// Child case: bundle grandchildren with child
		) {

			return body2.systemMass;
		}
		if (body1.parent != null) {
			if (body1.parent.parent == body2.parent) {
				// Aunt/Uncle case: bundle cousins with aunt/uncle
				return body2.systemMass;
			}
		}
		return mass;
	}