Artificial gravity for long-duration human spaceflight: physiological rationale, evidence gaps, risks, and research priorities

Long-duration missions beyond low Earth orbit will expose crews to prolonged microgravity during transit and partial gravity on the Moon or Mars. Existing exercise, nutritional, pharmacological, and sensorimotor countermeasures mitigate selected aspects of deconditioning but do not reproduce gravity’s continuous multisystem stimulus. Artificial gravity (AG), generated by rotation, is therefore a promising integrative countermeasure. This structured narrative review evaluates the physiological rationale for AG, evidence from human centrifugation and ground-based analog studies, human-factors and engineering constraints, and priorities for exploration missions. Evidence is strongest for the acute restoration of hydrostatic gradients and cardiovascular loading and is suggestive, although heterogeneous, for preserving orthostatic tolerance, muscle function, and selected sensorimotor outcomes. In the 60-day AGBRESA study (24 participants; eight per group), daily continuous or intermittent centrifugation attenuated the decline in time to presyncope relative to control but did not prevent several autonomic, ocular, balance, or mobility changes. Evidence for durable protection of bone, connective tissues, neuro-ocular health, immunity, endocrine and circadian regulation, cognition, sleep, and behavioural health remains insufficient. Interpretation is limited by small samples, overlapping cohort analyses, heterogeneous exposure geometries and schedules, and reliance on bed-rest analogs rather than in-flight trials. AG should therefore be regarded as a configurable intervention rather than a single countermeasure. Translation requires standardized reporting, adequately powered comparative studies, explicit safety and ethical governance, analyses of sex-related and individual responses, combined AG–exercise protocols, and phased validation from ground-based analogs to orbital demonstrators.