X-ray Pulsars Used for Interplanetary Navigation

This is a cool little link to an article on a new technology for interplanetary navigation. It proposes to use high power high precision x-ray pulsars to mimic a GPS-like system of navigation. It is accurate up to around 1km which is very good in terms of the vastness of space however that could only help you to avoid large objects such as planets and would be unsatisfactory for calculating exact orbits and trajectories to land something on another planet such as MARS! The project is being conducted by a firm called Microcosm and it is being done with funding from NASA. Its official name is X-Ray Pulsar Positioning System (XPPS).