Astronauts could one day be put into artificial hibernation for deep space trips to Mars and beyond, scientists suggest.
From films such as Aliens to Interstellar, Hollywood has long used suspended animation for its space men and women on a mission to far flung parts of the Galaxy.
But this once-fanciful sci-fi staple could become a reality in spaceflight, a meeting of scientists suggested.
They are meeting to understand the physiology and potential for hibernation and the related process, torpor, to aid human health in spaceflight and back on Earth.
Humans do not hibernate like bears and some other animals when food is scarce and temperatures low.
These animals survive by entering hibernation, a physiological process that reduces their normal metabolism to low levels for days or weeks at a time.
These periods of low metabolism, known as torpor, allow the animal’s body temperature to fall to just above the surrounding air temperature, thus conserving energy.
Humans do not naturally undergo torpor, but scientists are interested in the idea of producing states of “synthetic” torpor for spaceflight and treating serious illnesses.
Postdoctural Fellow Dr Matthew Regan the University of Wisconsin School of Veterinary Medicine explained: “Synthetic torpor could protect astronauts from space-related health hazards and simultaneously reduce demands on spacecraft mass, volume and power capacities.”
The theory is hibernating crew are kept alive over vast cosmic distances reducing the need to take along huge stocks of food and water.
This means spacecrafts do not have to be so big and missions are cheaper while astronauts don’t get bored as they traverse long distances of space.
The symposium in New Orleans will explore how synthetic torpor might be induced by the brain, its similarities and differences to sleep, and how it could benefit astronauts.
And studying hibernation in mammals, how they are able to safely lower their body temperature and metabolism for extended periods of time, may also aid treatment of people experiencing traumatic medical events, such as stroke, cardiac arrest and severe blood loss.
Animals that use torpor have a natural resistance to various injuries that can happen due to lack of blood flow.
They are also resistant to radiation injury and decoding this resistance would be especially beneficial to protecting humans from space radiation.
Professor Hannah Carey of the University of Wisconsin said the synthetic torpor based on the biology of natural hibernators was preferable to current medical practices that use hypothermia-based methods to treat trauma patients.
And studying hibernation could be key on how to create synthetic torpor for space travel.
Yet how the nervous system reduces metabolic activity during torpor remains unknown.
Assistant Professor of Physiology Dr Matteo Cerri from the University of Bologna in Italy explained many of the organs that regulate metabolism are controlled by nerve cells (neurons) located in the raphe pallidus, an area of the brainstem that controls the production of heat in mammals.
Prof Cerri added: “For an animal to enter torpor, the neurons within the raphe pallidus have to be inhibited
“If function in these cells is not suppressed their activity would counteract the hypothermia induced by torpor.”
He will present preliminary results identifying neurons projecting to the raphe pallidus and involved in torpor-related activity.
Associate Professor of Neuroscience Dr Vladyslav Vyazovskiy of the University of Oxford added defining the relationship between sleep and torpor has been fraught with controversy.
But the two states appear to be intimately linked because of the neuronal connections they share.
A lack of available food sources may cause mammals to conserve energy and lower their body temperature, two hallmark characteristics of torpor, research showed.
Prof Vyazovskiy said: “Less is known about the specific fasting-related signals which initiate entry into torpor.
He will discuss the connection between sleep and torpor and why more research is needed to determine how torpor affects brain function in animals.
Some of the physiological adaptations that animals exhibit, such as the low-oxygen environments that seals and penguins experience with deep diving or that birds experience on a high-altitude flight, are impossible for humans.
Yet understanding how animals adapt in extreme conditions may play a positive role in human medical science, especially in the “extreme environment of space.
The increasingly real possibility of travelling to Mars, once just a science fiction story, emphasises the need to resolve factors that have hampered the feasibility of long-duration spaceflight, including having an ample supply of food, water and breathable air.
Finding a way to induce torpor in humans could help eliminate limiting factors as well as protect astronauts from harmful radiation.
The symposium was part of the American Physiological Society’s Comparative Physiology: Complexity and Integration conference.
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