Long journeys in space can severely impact health. Exposure to high radiation and prolonged microgravity can affect various organ systems, including muscles and bones. Additionally, spending extended periods in cramped conditions poses serious psychological risks.
A possible solution to these challenges might be rooted in a physiological strategy, observed in animals for around 250 million years: hibernation. During hibernation, animals essentially power down, shutting down eating, drinking, and moving, and they don’t feel hunger or cold. This remarkable adaptation could be vital for human missions to Mars and beyond, and it may even have benefits for Earth.
Interestingly, hibernation could counteract many issues associated with long space flights—like muscle and bone deterioration and radiation damage. By inducing a long-term state of unconsciousness, fewer resources like food and water would be needed, which could shorten missions significantly.
“Protecting humans from radiation in space is very challenging. We haven’t yet found an effective shield,” notes Christiane Hahn.
However, there’s a hitch: humans aren’t naturally equipped for hibernation. Unlike bears or bats, we haven’t evolved to drastically reduce our metabolism in times of scarcity. To tackle this, an increasing number of scientists are attempting to find methods to safely induce hibernation in humans.
With backing from organizations like the European Space Agency and NASA, researchers are delving into the mechanics of how animals shut down their systems and then reactivate without negative repercussions after long periods without food or water.
“This is a very promising area,” Hahn states, emphasizing its potential to revolutionize space travel.
The dangers of space radiation
Radiation presents a critical risk for long-duration space travel. On Earth, our atmosphere shields us from most radioactive particles, but in space, that protection is absent. Over extensive trips, astronauts would face constant exposure to harmful particles, which can accumulate inside spacecraft and exacerbate risks. “We haven’t yet found an effective shield,” Hahn reiterates.
Research indicates that hibernation might offer protection against this radiation damage. Hibernating animals tend to lower their metabolic rates, consume less oxygen, and compact their DNA, which shields them from harm. Additionally, these animals possess robust mechanisms for DNA repair.
According to Elena Gracheva at Yale University, “It’s incredible what they can do.” She’s studying 13-lined ground squirrels, which hibernate in a controlled environment, highlighting that these creatures undergo drastic physiological changes, surviving for months without food or water. A specific brain region linked to thirst regulation might also provide insights valuable for non-hibernators, including humans.
Now, efforts are underway to manipulate human biological processes to gain similar benefits. Researchers are testing various methods, from drugs to ultrasound, to induce a “synthetic torpor” state. While “torpor” typically refers to short stints of metabolic slowdown, hibernation lasts much longer, making this area of study both intriguing and critical.
“It is definitely feasible,” comments Kelly Drew, who has researched arctic ground squirrels that hibernate from late summer to spring. Her studies explore how these animals manage to protect their vital organs in freezing conditions.
Understanding key mechanisms
Recently, advancements have allowed scientists to provoke synthetic torpor in different animal species, usually through invasive techniques. For instance, researchers have pinpointed certain brain cells that help govern temperature and energy expenditure. Efforts are now centered around employing non-invasive methods, such as ultrasound, for triggering torpor in future human trials.
However, hibernation’s complexity cannot be understated—it encompasses all bodily processes. Thus, various biological switches likely play a role. For example, recent studies have suggested a brain area may be pivotal in metabolic regulation. By activating neurons in this region, researchers have been able to induce torpor, lowering body temperatures in hamsters significantly.
Exploring whether similar circuits exist in humans is a next step; no one has yet investigated that, but researchers plan to do so.
Some studies have already looked at sedatives that can lower metabolic rates in humans. These investigations indicate a modest reduction in metabolism might offer some protection against space travel hazards—especially when considering the potential for food conservation on missions to Mars.
Potential applications beyond space
Synthetic torpor’s promise goes beyond just space exploration; it’s being examined for various health issues, like cancer and Alzheimer’s disease. Hibernation appears to kick-start repair mechanisms across numerous cell types and can inhibit cancer growth, increasing vulnerability to treatments.
“This has so much therapeutic potential,” Cerri states, noting the excitement around these findings. Drew and colleagues believe this could even impact weight management by adjusting metabolic rates upward.
There’s also ongoing research into specific molecules that arise during hibernation that could help treat diseases such as Parkinson’s. A group in the Netherlands has isolated a molecule that holds promise in combating various health conditions and has begun their first human trial.
Callaway, an emergency room physician, envisions synthetic torpor being helpful in urgent medical scenarios where slowing metabolism could offer crucial time for treatment. Unlike those in medically induced comas, those in synthetic torpor wouldn’t require life support, as their brains would remain active.
While this technique has many potential benefits, challenges remain. For example, traditional hypothermia treatments prompt the body to shiver in response to cold, which can increase heart rates and inflammation. This response could detract from the therapy’s efficacy. Hibernating animals manage to avoid this excessive reaction, making synthetic torpor a promising alternative.
Experts generally believe that the initial application of hibernation-like states will be in medicine. Organ preservation stands out as a strong candidate because harnessing some hibernation pathways could help extend organ viability. Preliminary tests have indicated positive results in this realm.
There’s a range of outlooks on when we might see synthetic torpor utilized in humans. Some, like Cerri, are optimistic for a timeframe of 10 to 15 years, while others suggest it could take longer. Hahn, for one, points out the necessity for a deeper understanding of the processes involved before implementation. “We need to ensure accuracy in both inducing and reversing torpor to avoid potential pitfalls,” she concludes.
