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Brandeis researchers explore solutions for spatial disorientation of astronauts

On Nov. 10, 2023, Vivekanand Pandey Vimal, GSAS PhD’17, a research scientist at Brandeis University’s Ashton Graybiel Spatial Orientation Lab, published an article in the explanatory journalism outlet “The Conversation” detailing his team’s work on countermeasures for spatial disorientation in spacefight. 

 

In the field of aeronautics, spatial disorientation is a deadly threat. Between 1993 and 2013, spatal disorientation led to the deaths of 101 people and 65 aircraft totalling 2.32 billion in damages. When it comes to the much more complex and dangerous field of space travel, spatal disorientation is an even larger concern. During scenarios without familiar gravitational cues, such as landing on the Moon, astronauts may completely lose track of their spatial orientation, which boosts the likelihood of fatal accidents.

 

Vimal, together with his collaborators Alexander Panic, James Lackner and Paul DiZio, conducted experiements using a multi-axis rotation device (MARS). The MARS, as Vimal explained, is “a machine containing a chair that’s programmed to behave like an inverted pendulum. Like a pencil falling left or right as you try to balance it on your fingertip, the multi-axis rotation device tilts to the left or right.​​” Participants in the experiments were strapped into the chair and tasked with using a joystick to keep the chair upright and balanced. To further simulate spatial disorientation, the participants were blindfolded.

 

When the MARS chair was placed upright, simulating conditions on Earth, the participants were all able to keep themselves balanced. This is because they were able to use gravitation cues to tell if they were tilted away from the vertical. However, when the MARS chairs were tilted back 90 degrees, simulating spaceflight, the participants showed poor results. This was because, since they were lying on their backs, they could no longer locate the vertical axis using their natural gravitational cues. “[E]ven though the balance point they were trying to find was the same, they could no longer use gravity to determine how much they were tilted from the balance point,” Vidal noted.

 

Next, the research team experimented with countermeasures to reduce the impact of the observed spatial disorientation. Specifically, the team used small vibrating devices called vibrotactors, which have been found to enhance performance for airplance and helicopter pilots. Since vibrotactors send signals via touch and vibration, rather than visual cues, they have the potential to keep pilots from being overwhelmed with visual information and thus getting disoriented.

 

The research team attached four vibrotactors on each arm for participants in the research group. Whenever a participant titled out of balance, the vibrotactors on the appropriate arm would vibrate proportionaly to the degree of tilt. When the researchers repeated the experiments with the vibrotactors attached, they discovered some interesting results. Although having vibrotactors did improve the subject’s performance in the spaceflight simulation, it was still not as good as their performance during the Earth simulation. The team discovered that this was because participants felt conflicted between their own incorrect perceptions of their orientation and what the vibotactors were telling them—even though they all reported high levels of trust in the vibrotactors to give them correct information. Vidal wrote, “This suggests that cognitive trust, or their self-reported level of trust, may differ than their gut-level trust—and cognitive trust alone does not ensure people will be able to rely on the vibrotactors when disoriented.”

 

To get around this shortcoming, Vidal and his team conducted two more experiments. In the first one, participants were given 40 minutes in the MARS to play around with the vibrotactors using the Earth gravity simulation and see how they worked. On the next day, they were then tested in the spaceflight simulation, but they showed only a modest improvement in their performance. 

 

In the second experiment, participants were given a specialized training program. “Participants spent the first day in the Earth analog condition, where they had to stabilize themselves while searching for hidden balance points that were different than the upright, or gravitational vertical,” Vidal wrote. This exercise taught them to focus solely on the vibrotactor inputs rather than their own senses. On the second day, they were tested on the spaceflight simulation. Compared to participants who had the vibrotactors, but did not go through the specialized training, they showed a significant improvement in performance.

 

In the end, Vidal’s team concluded that, while using vibrotactors did improve participant’s sense of spatial orientation, they still remained insufficient on their own. “Our findings suggest that simple exposure to sensory augmentation devices will be not be enough training for astronauts to rely on the device when they cannot rely upon their own senses. Also, cognitive trust in the device may not be enough to ensure reliance,” Vidal concluded. The researchers recommended that astronauts be given “specialized training that requires disengaging from one sense while focusing on feedback from the device” in order to realize the full potential of the vibrotactors in reducing disorientation while in space.

In addition to the article in “The Conversation,” Vidal’s team had previously published their research in the journal “Frontiers in Physiology” on Nov. 3.

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