Revisiting the needs for artificial gravity during deep space missions

In the past 15 years, several group studies have identified the need to validate the role of artificial gravity (AG) as countermeasure to physiological deconditioning during long duration space missions. AG during centrifugation can be adjusted by varying the rotation rate of the vehicle or the distance of the habitat relative to the axis or rotation. These AG parameters have an impact on vehicle design and on human activities associated with the mission. Mission designers are presently reviewing the technologies and habitats necessary to maintain optimal health, safety, and performance of the crewmembers for missions to destinations beyond the Earth–Moon system. New health concerns during space flight have now emerged, such as the Vision Impairment and Intracranial Pressure (VIIP) syndrome, which appears to be caused by prolonged cranial fluid shifts that persist in the presence of currently available countermeasures. The notion of AG research therefore needed to be revisited to consider what role, if any, AG should play in these missions. This paper describes the engineering aspects of human spacecraft providing AG, what is known of the effects of AG on humans, and the research needed to answer the questions raised by mission designers.