named its first astronaut crew bound for the moon in more than 50 years. 鈥淭here are three words that we keep saying in the Artemis program and they are 鈥榳e are going鈥�,鈥� said commander Reid Wiseman last April. Promising advances in rocket technology are ushering in exciting opportunities for space exploration. But, as a cognitive neuroscientist focusing on the effects of non-terrestrial gravity on the human brain and behaviour, I have to ask: are we ready to take on the challenges to human health posed by this new age of space travel?
Let鈥檚 be clear 鈥� going to space isn鈥檛 like taking a transatlantic flight. Space is a hostile environment for us. Ionising radiation, the lack of atmospheric pressure, extreme temperatures, confinement and isolation are just some of the stressors that space travellers encounter.
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Another is exposure to non-terrestrial gravitational environments, such as weightlessness or partial gravity on the moon or Mars, which leads to dramatic changes in human physiology. While the detrimental effects of such gravity on and systems are well-documented, very little is known about its impact on the human brain and behaviour.
Upon entry into weightlessness, pressure is removed from bodily tissues, causing a migration of fluids from the legs towards the upper part of the body and head. Neuroimaging studies have demonstrated structural changes after weightlessness exposure, including an upwards shift of the brain, an enlargement of the ventricles in this organ and differences in its white matter.
These lead to behavioural alterations. Astronauts have anecdotally reported shifts in their spatial orientation, perception, postural control and balance. Changes in psychological, cognitive and socio-emotional abilities have also been . Recent , including my own, have described effects of non-terrestrial gravities on decision-making, risk-taking behaviour and even aesthetic preferences.
How does gravity influence human behaviour more generally? It is hard to imagine a more ubiquitous aspect of life on Earth than gravity. The vestibular otoliths, which are sophisticated organs in the inner ear, detect gravitational acceleration. When the head moves with respect to gravity, the otoliths shift with the direction of gravitational acceleration, moving the vestibular receptors and signalling to the brain where the head is with respect to the direction of gravity.
The brain then combines the vestibular signals with sensory inputs from vision, visceral organs and skin, forming an internal representation of Earth鈥檚 gravity, known as a gravity prior. Our lifelong experience with terrestrial gravity makes the gravity prior highly reliable and optimal for Earth. Put simply, we can lift a glass of water with no effort because our brain knows exactly how to overcome the 9.8 metres per second squared of gravitational acceleration we experience on Earth. During space flight, conflicts arise between the unusual gravitational information sensed by the vestibular otoliths and the gravity prior, leaving astronauts disoriented and cognitively debilitated.
A huge gap in human preparation for space flight is evident. It is time to reconsider our sci-fi-based idea of astronauts: they are humans, and their brains demand time and effort to adapt to different gravity environments.
Our commitment to space exploration shouldn鈥檛 merely focus on improving rockets and flight manoeuvres. A clear understanding of how gravity affects human psychology and cognition is key to space success. Let鈥檚 use our brains to get ready for the next 鈥溾��.
Elisa Raffaella Ferr猫 is聽a聽reader in cognitive neuroscience at Birkbeck, University of London
