A subjective assessment of alternative mission architectures for the human exploration of Mars at NASA using multicriteria decision making

The primary driver for developing missions to send humans to other planets is to generate significant new scientific knowledge. NASA plans human planetary explorations with an acceptable level of risk consistent with other manned operations. Space exploration risks cannot be completely eliminated. Therefore, an acceptable level of cost, technical, safety, schedule, and political risks and benefits must be established for exploratory missions. This study uses a multicriteria decision model to identify the risks and benefits associated with three alternative mission architecture scenarios for the human exploration of Mars. The three alternatives identified by the Mission Operations Directorate at the Johnson Space Center include split, combo lander, and dual scenarios. The model considers seven phases of the mission: (1) Earth vicinity/departure, (2) Mars transfer, (3) Mars arrival, (4) planetary surface, (5) Mars vicinity/departure, (6) Earth transfer, and (7) Earth arrival. Analytic hierarchy process, subjective probability estimation, and the entropy method are used to capture experts' beliefs concerning the risks and benefits of the three alternative scenarios through a series of sequential, rational, and analytical processes.