Terrestrial analogs for Spaceflight Associated Neuro-Ocular Syndrome

Given the unique challenges of conducting research in space, sophisticated platforms known as “microgravity analogs” are used on earth to closely mimic outer space. This chapter illustrates the three main terrestrial analogs for the study of Spaceflight Associated Neuro-Ocular Syndrome (SANS): parabolic flight, dry immersion, and head-down tilt bed rest (HDTBR). While brief periods of microgravity can only be experienced during parabolic flight, HDTBR remains the most popular terrestrial analog. SANS signs and symptoms have not been fully replicated on earth; however, analog-based research may be used to generate pathophysiological hypotheses, validate and test new instrumentation, and evaluate candidate SANS countermeasures.