Project Hail Mary: Could Coma or Hibernation Save Interstellar Travelers?

The allure of interstellar travel, once confined to the realm of science fiction, is increasingly prompting serious scientific inquiry. Andy Weir’s novel, Project Hail Mary, and its recent film adaptation, have sparked a renewed debate about the very real challenges of keeping humans alive during voyages spanning years, even decades. While the story centers on a desperate mission to save Earth, a compelling question arises: how do you survive a journey to another star?

One of the proposed solutions within the narrative – placing astronauts in medically induced comas – is, according to experts, fraught with peril. Dr. Haig Aintablian, an emergency physician and flight surgeon at UCLA’s space medicine program, acknowledges the appeal. “How cool would it be if you went to sleep a few hours after launch, and you woke up right as you arrived on the planet or the celestial body that you’re approaching?” he muses. However, he cautions that maintaining human life in a comatose state for extended periods is far from a simple undertaking.

The human body, Dr. Aintablian explains, is not designed for prolonged inactivity. A comatose state carries significant risks, including the development of dangerous blood clots, debilitating muscle atrophy, and increased susceptibility to infections stemming from the necessary medical equipment. “The human body is not designed to just be a stagnant blob,” he states, highlighting the physiological demands of even passive survival.

This leads to consideration of more radical approaches, such as induced hibernation or even cryopreservation – essentially, freezing astronauts for the duration of the trip. Dr. Aintablian suggests that the ability to safely freeze and thaw a human would “solve the issue” of long-duration space travel. However, this solution remains firmly in the realm of theoretical possibility.

The fundamental challenge lies in the physiological toll of extreme temperature changes. While some animals, like wood frogs, can survive freezing and thawing, the mechanisms that allow them to do so are not fully understood, and it’s unclear if they could be replicated in humans. Integrative biologist Matthew Regan of the University of Montreal points out that human hearts struggle to function below approximately 28° Celsius (around 82° Fahrenheit). While some individuals have survived temporary dips to lower temperatures, these instances are far removed from the years-long cryogenic sleep required for interstellar voyages.

A more plausible, though still complex, alternative may lie in mimicking the hibernation patterns of certain mammals. Animals like arctic ground squirrels can dramatically slow their metabolism during torpor, reducing it to as little as 2% of its normal rate. This “pilot light” level of activity allows them to conserve energy while minimizing the negative effects of inactivity. Bears, while not entering as deep a state of torpor, also experience a significant metabolic slowdown, dropping their body temperatures by several degrees.

The benefits of such a strategy for space travel are potentially significant. A reduced metabolic rate would translate to lower resource consumption – less food, water, and oxygen needed to sustain the crew. It might also offer some protection against the damaging effects of ionizing radiation, a major concern for long-duration space missions. However, even this approach isn’t without its challenges.

Hibernating animals periodically arouse from their torpor, rewarming their bodies and engaging in brief periods of activity. The purpose of these awakenings remains a mystery, but neurochemist Kelly Drew of the University of Alaska Fairbanks suggests they may be crucial for muscle regeneration and maintaining brain health. Humans, too, might require periodic awakenings to prevent muscle atrophy and cognitive decline.

preparing astronauts for such a state requires careful consideration. Hibernation biologist Hannah Carey of the University of Wisconsin–Madison cautions against simply “fattening up” astronauts before a long voyage. Bears that accumulate excessive fat reserves before hibernation can develop high cholesterol levels, which, while recoverable for the bears, could pose a significant cardiovascular risk for humans. Carey’s research with captive ground squirrels has revealed that even maintaining sufficient body fat doesn’t guarantee successful hibernation; some animals died mysteriously despite having ample reserves, potentially due to cardiac stress.

the fate of the astronauts in Project Hail Mary wasn’t determined by the limitations of human physiology, but by a “tech failure.” According to Weir, the deaths were not a result of inherent biological incompatibility with long-term coma, but rather a consequence of the inherent risks associated with maintaining life support systems for such extended periods. “It was a tech failure,” he explained. “Being in a coma for four years is a dangerous proposition in the best of times. So a small tech failure can lead to catastrophic results. Which it did in this case.”

As we continue to contemplate the possibility of interstellar travel, it’s clear that overcoming the biological hurdles will require innovative solutions and a deep understanding of the intricate mechanisms that govern life itself. While the dream of reaching distant stars remains a significant challenge, the ongoing research into hibernation, cryopreservation, and metabolic control offers a glimmer of hope for future explorers.