Real Time Trajectory Generation of Mars Entry using Legendre Pseudo-Spectral Method

A real-time trajectory generation methodology for the atmospheric entry phase of Mars Entry, Descent and Landing (EDL) missions is developed in this paper. The proposed algorithm can handle large initial conditions errors and deliver the spacecraft precisely to the landing interface. In order to obtain the solution to entry guidance problem in real-time, the state equations are discretized using Legendre-Pseudospectral method. A simple, but effective methodology has been developed as part of this paper which uses a modified Newton-Raphson method for obtaining the solution to the entry guidance problem. The algorithm developed in this work is least sensitive to initial guess profiles and the results show good convergence properties. Reliability and robustness of the proposed scheme is demonstrated with respect to both initial guess profiles and initial conditions errors using Monte Carlo simulations.