  This paper presents a navigation strategy to fly to the Moon along a Weak
Stability Boundary transfer trajectory. A particular strategy is devised to
ensure capture into an uncontrolled relatively stable orbit at the Moon. Both
uncertainty in the orbit determination process and in the control of the thrust
vector are included in the navigation analysis. The orbit determination process
is based on the definition of an optimal filtering technique that is able to
meet accuracy requirements at an acceptable computational cost. Three
sequential filtering techniques are analysed: an extended Kalman filter, an
Unscented Kalman filter and a Kalman filter based on high order expansions. The
analysis shows that only the unscented Kalman filter meets the accuracy
requirements at an acceptable computational cost. This paper demonstrates lunar
weak capture for all trajectories within a capture corridor defined by all the
trajectories in the neighbourhood of the nominal one, in state space. A minimum
f'v strategy is presented to extend the lifetime of the spacecraft around the
Moon. The orbit determination and navigation strategies are applied to the case
of the European Student Moon Orbiter.
