## 9 Practical Approach
Step 1: Determine the Criteria and Stakeholders: To apply the multi-criteria optimization model [104], we first identify the key criteria to be considered. These criteria are based on the goals of the mission, sustainability principles, and stakeholder requirements. In this case, the identified criteria include environmental impact, resource utilization, astronaut safety, scientific objectives, mission cost, international collaboration, and supply chain structure. Step 2: Establishing Weights and Limits: Once the criteria are identified, we assign weights to them based on their relative importance. For example, environmental impact and astronaut safety might have higher weights due to their criticality in ensuring long-term sustainability and protecting human life [105; 106; 107]. Constraints are also established to reflect specific limitations or guidelines, such as regulatory requirements or technological feasibility. Step 3: Develop Mission Scenarios: The multi-criteria optimization model allows for the generation of multiple mission scenarios by varying parameters, approaches, and trade-offs. These scenarios represent different combinations of mission design elements, such as propulsion systems, power generation methods, habitat structures, resource utilization strategies, and mission durations. Each scenario is evaluated based on the defined criteria, considering the weights and constraints assigned in Step 2. Step 4: Consider Scenarios and Trade-Offs: Using the multi-criteria optimization model, the generated mission scenarios are evaluated against the defined criteria. This evaluation involves assessing the performance of each scenario in terms of the identified criteria, taking into account the assigned weights and constraints. Trade-offs between criteria are analyzed, as optimizing one criterion may lead to compromises in others. Step 5: Identifying and Implementing Suboptimal Solutions in Practice: By analyzing the results of the evaluations, sub-optimal solutions that best align with the defined criteria and stakeholder requirements can be identified. These solutions represent mission strategies that strike a balance between minimizing risks, optimizing resource utilization, meeting sustainability goals, and optimizing supply chain efficiency. The sub-optimal solutions offer insights into the design choices and trade-offs necessary to achieve mission success while considering various factors. Step 6: Analysis and Refinement of Sensitivity: After identifying the optimal solutions, sensitivity analysis can be conducted to assess the robustness of the results. Sensitivity analysis helps understand the impact of changes in criteria weights, constraints, or underlying assumptions on the optimal solutions. This analysis allows for the refinement of the model and the mission strategies, ensuring a comprehensive understanding of the implications of different scenarios. In Table 6, the main steps of a space mission are defined. The application of the multi-objective optimization conceptual model in this practical approach yields valuable insights and design strategies for the space mission. The evaluation of the mission scenarios against the defined criteria provides a comprehensive understanding of the trade-offs involved. The model identifies mission strategies that balance risks, resource utilization, sustainability goals effectively, and supply chain efficient structure. For example, the evaluation may reveal that utilizing local resources, such as water ice on the Moon, for life support and propellant production significantly reduces the mission's reliance on Earth-based supplies. This approach minimizes environmental impact, optimizes resource utilization, and reduces mission costs. Additionally, the model may suggest the use of advanced propulsion technologies to minimize the mission's carbon footprint and mitigate the potential for space debris creation during the mission. The model can also assist in evaluating and addressing astronaut safety concerns.