Affordable Human Moon and Mars Exploration Through Hardware Commonality

Abstract

The Vision for Space Exploration calls for the safe, affordable, and sustainable human exploration of the Moon and Mars. In order to achieve exploration affordability and sustainability, the Mars -back approach was developed. The fundamental principle of the Mars -back approach is that the syste m elements used for lunar exploration are a subset (in terms of design) of those used for Mars exploration; thereby the lunar exploration hardware is directly relevant to the exploration of Mars. After systematic qualitative and quantitative analysis of ov er 1000 lunar and over 1000 Mars exploration architectures using a discrete event simulation tool, two architectures were chosen for further analysis based on overall mission mass, mission risk, and cost: a direct return architecture for lunar exploration, and an architecture similar in concept to the 1993 NASA Mars Design Reference Mission for conjunction -class Mars exploration. Employing the Mars -back approach, the Mars exploration hardware can enable a crewed lunar direct return architecture along with o ne way cargo -delivery capability, such as for a long -duration surface habitat, without the need for additional hardware development. Common system elements include the CEV for short term habitation and Earth entry, long -term in -space and planetary surface habitats, and propulsion stages for Earth departure, deep -space maneuvers, and planetary descent / ascent. Commonality was introduced through design for the most stressing case, typically Mars, when requirements were similar, and through modular, extensibl e solutions when requirements differed more widely. Based on the commonality concept, a hardware development roadmap was laid out for phased development of the hardware; each phase provides increasing mission capability. Hardware development with commonali ty eliminates the need for any significant “development gap” between lunar and Mars exploration missions. The development approach ensures that technology and hardware development for lunar missions is directly relevant to Mars exploration. Also, extensive testing of Mars hardware can be carried out during long -stay lunar missions, thereby increasing operational experience with the equipment to be used for Mars missions and reducing Mars mission risk. As identical hardware is used, lunar missions could stil l be executed during Mars exploration because the production and assembly lines would still be running. Most importantly, the overall lifecycle cost for exploration of the Moon and Mars is significantly reduced by limiting the amount of hardware that must be developed. The drawback of Mars -back commonality is a certain non -optimality in the common system design which leads to increased system dry and wet mass and therefore to a potential increase in recurring cost, mainly in launch and production. Quantitat ive analysis of this commonality penalty shows a modest growth of Initial Mass in LEO, which appears acceptable when set against the significant savings in overall lifecycle cost that would be achieved.