Imagine awakening, disoriented and with a beard, aboard a spaceship far from Earth. This is the scenario for Ryland Grace, portrayed by Ryan Gosling, in the new space drama Project Hail Mary. The audience quickly discovers that Grace, a middle school science teacher, has been dispatched on a mission to save the sun from dying.
The film is heavily grounded in scientific concepts, from the real star Tau Ceti to its portrayal of artificial gravity. While some aspects like quantum physics and fictional sun-eating microbes called Astrophage are speculative, “everything else just follows established physics and science,” according to Andy Weir, the author of the novel Project Hail Mary and a producer of its film adaptation, in an interview with Scientific American.
But how scientifically accurate is the movie’s opening scene? The answer is both yes and no.
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In the novel, Grace perceives his sleep condition as resembling a medically induced coma or a form of “suspended animation.” He is connected to an IV and feeding tubes and receives “constant medical care” from an onboard robot. “Everything a body needs,” Weir notes in the book.
However, inducing a pharmacological coma for extended space travel is challenging, says Matteo Cerri, an associate professor of physiology at the University of Bologna in Italy. Such a coma wouldn’t significantly slow metabolism, thus not affecting the body’s need for food or oxygen. Additionally, “at a certain point, the drugs become toxic,” Cerri explains.
Cerri suggests an alternative: reducing metabolism in a state akin to hibernation, or “synthetic torpor.” Many animals, like bears and hamsters, lower their metabolic rate and oxygen use during torpor. Ground squirrels, for instance, experience prolonged torpor known as true hibernation, allowing them to survive without eating or drinking for months. “Life is moving but very slowly. It’s like you slow down the clock of life, and every second lasts longer,” he adds.
While no human has been put into such a state, Cerri believes synthetic torpor could be possible. He chairs a European Space Agency research group investigating human hibernation for space travel, which could reduce metabolic demands, increase lifespans, and offer radiation protection. Lower tissue oxygen levels may enhance radiation resistance. “Radiation is the number one problem for space exploration,” Cerri states. “There is no solution at the moment.”
Although no one has induced hibernation in humans yet, Cerri and his colleagues have successfully induced torpor in rats, which don’t naturally enter this state. They achieved this by administering drugs to the brain stem, “tricking” the rat brain into synthetic torpor. Replicating this in humans remains unsafe.
Another possibility often depicted in science fiction, including films like Alien, Avatar, and Futurama, is “cryosleep,” which involves freezing a person to later revive them unharmed. While not yet achieved, some scientists believe it’s theoretically possible.
“I believe reversible human cryostasis will become technically possible,” says Alexander German, a molecular neurology researcher at the Friedrich-AlexanderUniversity of Erlangen-Nuremberg in Germany. He observes that in nature, tardigrades can “vitrify” into a glasslike state, Siberian salamanders can endure years frozen in permafrost, and Arctic ground squirrels can survive weeks at subfreezing body temperatures. This suggests that humans might also have such potential if the right methods are applied, according to German.
In a recent paper, German and his team successfully restored brain activity in mouse brain slices after vitrification at –196 degrees Celsius. “This provides evidence that reversible cryostasis may be possible in principle, although we still have a long way to go in practice,” he says.
The challenge with cryonics is that as water freezes, it expands into a crystal form that can burst cells, much like a “blade in a balloon,” Cerri explains. If scientists can overcome this and other issues, like the toxicity of vitrification chemicals, cryosleep could revolutionize space travel by enabling extremely long journeys, he suggests.
Interestingly, Cerri notes that science-fiction films, including Project Hail Mary, often inaccurately portray the awakening process in suspended animation. “The thing that every movie gets wrong, usually, is the arousal. Waking up is too immediate,” he says. In reality, safely emerging from hibernation or cryosleep would likely require hours or days for the body and mind to return to normal function. “Every organ has to ‘go back to work,’” Cerri concludes.
