1. A method of autonomous space navigation, comprising: from a tracker space vehicle in a first trajectory through a gravitational field about a gravitational body, making a series of angle-only line-of-sight (LOS) measurements of a target space vehicle in a second trajectory through the gravitational field producing a unique inertial angle LOS history, wherein said angle-only LOS measurements are made in an inertial frame of reference centered about the gravitational body; providing an extended Kalman filter (EKF) based on a gravity model for said gravitational body and including a first set of states including position, velocity and acceleration for the target space vehicle in the inertial frame of reference centered about the gravitational body and a second set of states including position, velocity and acceleration for the tracker space vehicle in the inertial frame of reference centered about the gravitational body; inputting only the unique inertial angle LOS history and time into the EKF that updates said first and second sets of states to simultaneously infer position and velocity for both the target and tracker space vehicles in the inertial frame of reference centered about the gravitational body; and outputting the position and velocity for at least one of said target and tracker space vehicles.