Some major guiding principles to make future manned missions to mars safe and reliable

Some major risks-of-failure issues for the future manned missions to Mars are addressed. The specific complexity of the mission with the necessity of new and important technological developments has considerable implications in terms of risk estimation and management. The latest NASA reference mission is addressed and is commented on. It is concluded that the present design strategies are unable to provide sufficiently high reliability for the success of the mission. Several recommendations are proposed in this paper. The focus is on two categories of reliability problems. The first category concerns systems without clear accelerated testing capabilities, such as those for nuclear propulsion or entry-descent-and-landing. Several expensive precursor missions will have to be implemented to increase the maturity of the systems and to achieve the required level of reliability. Since cost is an important decision making parameter, it is suggested to determine the relationships between the different maturity models and their costs. For the entry-descent- and-landing phase, the proposed approach suggests a clear advantage of the 70° sphere cone heat shields. The second category concerns human-in-the-loop systems. Though different situations exist (e.g., maintenance, manual control, repairing), the same predictive model can be used to determine the probability of failure. The specific example of an ISRU option with robotic excavators and the possible intervention of astronauts is suggested. The preliminary conclusion is that astronauts with appropriate tools can be trained to increase the human capacity factor and reach an acceptable reliability level for the fueling process.