The Interplanetary Transport Network (ITN) is a collection of gravitationally determined pathways through the solar system that require very little energy for an object to follow. The ITN makes particular use of Lagrange points as locations where trajectories through Outer space are redirected using little or no energy. These points have the peculiar property of allowing objects to orbit around them, despite the absence of any material object therein. While they use little energy, the transport can take a very long time.