Flying beacon aided entry navigation for mars orbiter-lander integrated mission

The Mars orbiter-lander integrated exploration has its attractiveness on better economy and more scientific return, for which the human’s first successful Mars landing exploration, Viking 1, exactly selected this pattern and so will the Chinese planning first Mars mission. This paper proposes an innovative entry navigation concept for the integrated exploration to acquire a precise state estimation which plays a fundamental part in the high-precision soft landing. Radio communication, regarded as the near-future EDL navigation strategy surpassing dead reckoning, is the basic technology of the navigation scheme in which the orbiter works as the navigation reference owing to its precise determined orbit. However, the one orbiter based entry navigation makes no accuracy improvement in some cases blamed on the terrible geometric configuration. Thus, the flying beacon is introduced to ameliorate the geometric configuration instead of providing another radio reference. As for the details of the navigation scheme, the position and velocity of both the lander and the flying beacon are combined into the estimated state space; the relative range and line-of-sight velocity among the three vehicles are measured and inputted into a nonlinear filter to obtain the optimal state estimation. To verify the advancement of the proposed concept, observability degree is exploited to quantify the navigation performance and the Monte Carlo simulation is performed to obtain the statistical estimation accuracy. Analysis indicates that the observability degree is significantly improved and performance sensitivity to the orbiter-lander geometric configuration is greatly reduced. Therefore, all states can be estimated accurately under various orbiter-lander geometric configurations.