Human System Interactions in the Design of an Interplanetary Mission

It has been suggested that the design of the last NASA reference mission for the human exploration of Mars is lacking sufficient considerations for human factors and human machine interactions. The NASA team examined many different options, long or short stay, chemical or nuclear thermal propulsion, pre-deploy or all-up, in situ resource utilization (ISRU) or not, etc. The decision process was based on a bottom-up approach, which led to local optimizations but to unpractical solutions in certain domains. For instance, the optimal number of astronauts has been determined according to skills requirements and organizational issues but no attention has been paid to its impact on the payload, on the mass of the landers, on the volume of the habitat and on the overall risks of the mission. A human centered design approach is proposed here, with a particular focus on interdependencies and human systems interactions. Following the guiding principles of human rated space systems, it is suggested that different choices may be more appropriate. The main ones are a reduction of the size of the crew, the entire duplication of the mission and a trade-off between "pre-deploy" and "all-up".