Relationship between selected orientation rest frame, circular vection and space motion sickness

Area of Science:

• Human physiology and neuroscience
• Space medicine and astronaut health

Background:

• Space motion sickness (SMS) and spatial disorientation affect a majority of astronauts.
• Subjective spatial orientation relies on 'rest frames,' which in microgravity may be visual or based on the body's internal axis.

Purpose of the Study:

• To investigate the relationship between astronauts' orientation rest frames and variables like circular vection response latencies and SMS.
• To determine if rest frame selection influences susceptibility to space motion sickness.

Main Methods:

• Astronauts' microgravity spatial orientation rest frames were identified through verbal reports.
• Circular vection responses were measured by exposing astronauts to a rotating virtual room.
• Vection onset latency was recorded, and SMS symptom scores were analyzed using negative binomial regression.

Main Results:

• Astronauts using visual cues for orientation had significantly shorter vection latencies compared to those using internal z-axis cues.
• Reliance on visual cues was associated with an estimated three-fold increase in SMS scores on the first flight day.
• A clear relationship was established between astronaut rest frames, circular vection sensitivity, and SMS.

Conclusions:

• Astronauts' rest frames can be meaningfully classified, impacting their susceptibility to motion sickness.
• Vection latencies show potential as a predictive measure for SMS severity and duration.
• Understanding rest frames may aid in developing countermeasures for space motion sickness.