Researchers at York University, led by principle investigator Professor Laurence Harris, in collaboration with the Canadian Space Agency and NASA, published a study in Nature Microgravity investigating whether the distance humans perceive themselves to move changes in the microgravity of space.
On the International Space Station (ISS), Earth’s gravity is cancelled by the orbiting of the station. In the resulting microgravity, the way people move is more like flying, which can – potentially – make people feel like they are covering distances more quickly. What Harris and his collaborators wondered was, “Can humans adapt to this type of self-motion? Would their internal sense of distance travelled be the same or change?”
Their study to investigate further started as a proposal in 2014 and has since been tested on 12 astronauts who have been aboard the ISS. Harris, a professor in the Faculty of Health and Faculty of Science, and his team compared the performance of astronauts before, during, and after their year-long missions to the ISS and – to their surprise – found that the astronauts’ sense of how far they had travelled remained largely intact.
Despite existing research showing that perception of gravity influences our perception of distance, the York study’s findings suggest that humans are able to compensate adequately for the lack of an Earth-normal environment using vision. This means humans are able to manually operate machinery and accurately navigate around the spacecraft – without misjudging distance. That’s positive news for space flight and astronaut safety, but these findings may also have applications here on Earth. “Our discovery of the flexible response to changes in gravity may be useful to help understand a range of people’s balance disorders here on Earth,” says Harris.
Among the 12 astronauts tested for the study, six were men and six were women, which the research team notes is unusual. Equal numbers of men and women are not always represented in space studies, but the researchers felt it important to have for this study, to not only have equal representation but to identify whether there were any differences between genders (they found no gender-related effects).
The current study – titled “The Effects of Long-Term Exposure to Microgravity and Body Orientation Relative to Gravity on Perceived Traveled Distance” – represents the first of three that will be published arising from the study investigating the effects of microgravity exposure on different perceptual skills, including the estimation of body tilt, travelled distance and object size.