Mars exploration rovers entry, descent, and landing trajectory analysis

The Mars Exploration Rover mission successfully landed two rovers “Spirit” and “Opportunity” on Mars on January 4 and 25 of 2004, respectively. The trajectory analysis performed to define the entry, descent, and landing (EDL) scenario is described. The entry requirements and constraints are presented, as well as uncertainties used in a Monte Carlo dispersion analysis to statistically assess the robustness of the entry design to off-nominal conditions. In the analysis, six-degreeof-freedom and three-degree-of-freedom trajectory results are compared to assess the entry characteristics of the capsule. Comparison of the pre-entry results to preliminary post-landing reconstruction data shows that all EDL parameters were within the requirements. In addition, the final landing location for both “Spirit” and “Opportunity” were within 15 km from the target.