Canadian medical experiments on Shuttle flight 41-G

Area of Science:

• Human physiology
• Neuroscience
• Space medicine

Background:

• Understanding the human nervous system's adaptation to microgravity is crucial for astronaut health and mission success.
• Space motion sickness remains a significant challenge for spaceflight participants.
• Previous research indicates various sensory and motor functions are affected by spaceflight.

Purpose of the Study:

• To investigate the adaptation of the human nervous system to weightlessness during the 41-G mission.
• To assess the contribution of these adaptations to space motion sickness.
• To examine the re-adaptation process to Earth's gravity.

Main Methods:

• Six Canadian medical experiments were conducted on two payload specialist astronauts.
• Pre-flight tests established baseline data for comparison.
• Post-flight experiments evaluated the astronauts' re-adaptation to the ground environment.

Main Results:

• No changes were observed in the vestibulo-ocular reflex during the 8-day mission.
• Astronauts reported significant proprioceptive illusions, particularly after landing.
• Tactile acuity remained normal, but limb position sense was impaired.
• Visual target localization was distorted without visual cues.
• Taste and olfaction thresholds showed no significant differences.
• The Canadian payload specialist exhibited reduced susceptibility to space motion sickness on-orbit, contrary to pre-flight predictions.

Conclusions:

• The human nervous system undergoes notable sensory alterations in microgravity, impacting proprioception and spatial orientation.
• Re-adaptation to Earth's gravity is rapid, occurring within the first day post-flight.
• Individual susceptibility to space motion sickness may not be accurately predicted by pre-flight testing.