On Earth, people grip objects to ensure they don't fall. In space, this process changes: when astronauts hold an object without moving it and then let go, the object doesn't fall because there is no gravity. But when astronauts move an object in any direction, inertia takes it up, down, left, or right if the hand grip is not steady.
Philippe Lefevre and colleagues at Universite catholique de Louvain and Ikerbasque explored how astronauts adapt their hand grip when transitioning between environments with and without gravity.
The researchers discovered that gravity has a lasting imprint on the brain even after people are in gravity-free environments for several months. Astronauts overcompensated with their hand grip on objects in space because their brains anticipated gravity's pull. This overcompensation was especially pronounced when astronauts were moving objects around.
Similarly, after returning to Earth, astronauts initially made incorrect predictions about how they were holding and manipulating objects, but progressively adjusted their grip over time.
According to the researchers, this work suggests that the brain adapts to different gravitational environments gradually, and that control strategies for grip strength often depend on the brain's predictions about the risk of making accidents. Lefevre noted the intense preparation and work required to coordinate with the space agency and await successful spacecraft flight - a process that spanned close to 20 years when combined with data compilation and analyses.
The researchers look forward to publishing further data collected from astronauts on point-to-point movement accuracy with objects, adjustments following object collision, and adjustments based on skin friction with objects.
Research Report:Effect of Risks, Consequences, and Gravitational Priors on Sensorimotor Coordination: Insights from Weightlessness
Related Links
Universite catholique de Louvain and Ikerbasque
Space Medicine Technology and Systems
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