The Efficacy of VR as a Countermeasure for Astronaut Motion Sickness in Post-Flight Water Landings

Astronauts returning from long-duration missions in microgravity often experience motion sickness upon return to Earth. This is due to a reinterpretation of cues, particularly from the vestibular system, while in microgravity and thus experiencing “sensory conflict” after being re-exposed to Earth gravity. Motion sickness symptoms such as nausea and vertigo can be further exacerbated by the wave-like motion the astronauts experience in the capsule as they await recovery. Astronauts experiencing motion sickness symptoms may be unable to respond to emergencies should they arise while they are waiting. Pharmacological countermeasures have proven effective in mitigating effects of motion sickness, but there are a variety of side effects, such as drowsiness. This study evaluated the efficacy of virtual reality as a medium for reducing the effects of motion sickness during wave-like motions following gravity transitions. Gravity transitions were simulated using the “sickness induced by centrifugation” (SIC) paradigm in which subjects were placed in a centrifuge and exposed to hyper-gravity for an extended duration. Our experiment used the Human Eccentric Rotator Device (HERD) at U of Colorado to expose subjects to a net 2G (centripetal acceleration and Earth gravity) into the negative body-centered x-axis for one hour with their head fixed, habituating the subject's otolith organs to hyper-gravity. Following the hour on the HERD, subjects were transitioned to the Tilt-Translation Sled (TTS) where they experienced roll-tilt and lateral translation meant to simulate the motion astronauts undergo following a water landing. The control group was provided with a stationary fixation point in virtual reality while the countermeasure group was provided a visual scene with cues of self-motion. Results suggest that the severity of motion sickness was slightly reduced in the countermeasure group and subjects in the countermeasure group had considerably better balance than those in the control group.