Slopes along Apollo EVAs: Astronaut experience as input for future mission planning

One major factor for operational safety and planning of human extravehicular activities (EVAs) is the topography of the landing region. During planning for EVAs for future crewed missions, digital elevation models (DEMs) and derived slope maps are often used to place constraints on proposed EVA paths to minimize the slopes and vertical meters traveled. However, the specification of these constraints has not yet been studied in detail and has to date relied on generalized assumptions. The Apollo program was the subject of meticulous planning and execution over an extended period. Our study concentrated on the pivotal aspect of mission planning, namely the topographic conditions of all Apollo landing sites. Furthermore, there are numerous conditions of lunar exploration whose "ground truth" can only be fully comprehended by astronauts who have personally visited the Moon. Certainly, there are technical constraints for the use and operation of equipment and tools, such as suits and instrument carts. However, astronaut observational physiological and psychological experiences and constraints are need to be considered for the planning of successful EVAs. In this study, we examined a variety of data sources, including topographic data, Apollo astronaut reports, audio and video recordings, in order to assess their experience and performance in relation to the topography and slopes along each Apollo extra vehicular activity (EVA). The ability of the astronauts to accurately perceive distances, slopes, and to move with confidence is contingent upon topographic and illumination conditions, as well as the specific equipment that they are required to carry. Future mission planning must take realistic traverse speeds into account, as well as the perception of both real and perceived hazards on challenging traverses.