Navigation analysis and design for Mars entry

Abstract

This thesis presents a navigation system design for a lander module during entry at Mars. The system estimates the state vector with an extended Kalman filter, which utilizes update information provided by the following measurement types: two-way range with orbiting satellites, two-way Doppler with orbiting satellites, two-way range with surface beacons, two-way Doppler with surface beacons, altitude, and relative surface velocity. Filter performance of the navigation design is analyzed using a computer simulation of such a spacecraft during Mars entry. Simulation results are presented to evaluate the effectiveness of the filter using each of the individual measurement types. In addition, the sequence in which the measurements are filtered that yields the most favourable results is determined. Using this optimal sequence, the simulation produces a final standard deviation of 105.25 m for the lander position and 0.168 m/s for the lander velocity, compared to final standard deviations of 1218.85 m and 3.700 m/s for a case where no measurements are processed.