A recent study published in Frontiers in Physiology examines how vibrating wearable devices, known as vibrotactors, can be used to help astronauts cope with spatial disorientation when in space, which results from the lack of gravitational cues, or natural sensory perceptions, they are accustomed to using when on Earth and despite the rigorous training the astronauts undergo to combat the symptoms of spatial disorientation. This study was conducted by a team of researchers at Brandeis University and holds the potential to help develop more efficient methods to combat spatial disorientation, especially with long-term missions to the Moon, and even Mars.
“Long-duration spaceflight will cause many physiological and psychological stressors, which will make astronauts very susceptible to spatial disorientation,” said Dr. Vivekanand P. Vimal, who is a research scientist at Brandeis University and lead author of the study. “When disoriented, an astronaut will no longer be able to rely on their own internal sensors, which they have depended on for their whole lives.”
Another name for spatial disorientation is “visual reorientation illusions” or VRIs, which is when astronauts are unable to determine what is “up” or “down” in while in space, and specifically during spacewalks. This proper orientation and knowing what is up or down is monitored by our body’s vestibular system, and specifically sensors within the inner ear that constantly send information about the motions of the head and body to the brain, telling it whether we are up or down. However, the weightlessness experienced by astronauts in space causes the vestibular system to incorrectly interpret the body’s proper orientation, but the central nervous system helps to reinterpret these signals, which is why most astronauts adapt to weightlessness after a few days in space.
For the study, the researchers enlisted 30 participants and were involved in using a multi-axis rotation device (MARS) and severely hampering their sensory perception to evaluate how the vibrotactors helped the participants with spatial disorientation. For the rotation device, the participants used a joystick to keep it balanced with the goal of keeping it as close to the balance point as possible throughout the 40 trials each participant was assigned to complete, with the first 20 trials consisting of an Earth analog on a vertical roll plane where the participants were able to use their sensory perception, and the second 20 trials consisting of a spaceflight analog on a horizontal roll plane where gravitational cues became harder, if not impossible, to use.
All 30 participants watched a video on the rotation device’s operations and were then split into three different study groups: 10 obtained additional training on how to use the vibrotactors without using their natural sensory perceptions, 10 used the vibrotactors, and 10 received both. The sensory perception hampering was conducted by blindfolding and providing earplugs and white noise to all participants throughout the trials, and the vibrotactors consisted of four wearable devices strapped to each arm, for a total of eight, and would vibrate if the participant moved away from the balance point during the trials.
Image of the multi-axis rotation device (MARS) used for this study, which participants used to remain balanced for an Earth analog in the vertical roll plane (left) and a spaceflight analog in the horizontal roll plane (right). (Credit: Vimal et al. (2023))
In the end, the researchers found that all participants experienced spatial disorientation during the spaceflight analogs, which the researchers anticipated prior to the study. Additionally, the researchers found the group who used only the vribrotactors and not the additional training performed better than the participants who received only the additional training and no vibrotactors. Participants who completed both were found to have performed the best among the three groups. Despite this, the participants were found to have performed far better in the Earth analog than the spaceflight analog, which the researchers determined could be from adjusting to the vibrotactors cues or from the vibrotactors themselves not buzzing enough to signal the participant they were veering away from the balance point.
“A pilot’s cognitive trust in this external device will most likely not be enough,” said Vimal. “Instead,
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