Abstract: Based on lightofsight (LOS) vector measurement, an autonomous navigation algorithm is developed to realize the first autonomous navigation mission of China during the phase of approaching Mars. On the basis of orbital dynamics and the geometric relationship between Mars and the spacecraft, the equation with respect to the norm of the position vector is derived in detail, with the Mars LOS serving as the only measurement. The equations of position vector and velocity vector are further developed. Finally, simulations and comparative analysis on the autonomous navigation algorithm are directed under orbits of ellipse and hyperbola respectively.

Key words: 3lightofsight vector measurement, autonomous navigation, hyperbolic orbit