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A recurring theme in science fiction is space travel. Beyond the famous ‘hyperspace jump’ of ships like the Enterprise of ‘Star Treck‘, some creators have explored the idea of putting their heroes to sleep for a long period of time to avoid the ‘hassle’ of traveling light years away (as in the ‘Alien‘ or in Kubrick’s work ‘2001: A Space Odyssey‘). But what if we might actually bring this mechanism to reality? This is what European researchers believe, suggesting that hibernation might actually become a viable technique for space travel not only to interstellar space, but also to our neighbor. Mars. The findings have just been published in the journal ‘
Neuroscience & Biobehavioral Reviews‘.
Go through the at least 55 million kilometers that do not separate from Red planet would carry a land ship 6 to 9 months. During that time, the astronauts on board would have to eat, drink and breathe, taking with them (or, in the best of cases, generating in situ) the necessary supplies of food, water and oxygen. “We are talking regarding 30 kilograms per astronaut per weekand on top of that we have to consider the radiation, as well as the mental and physiological challenges,” he sums up Jennifer Ngo-Anhresearch and payload coordinator for Human and Robotic Exploration at the European Space Agency (ESA) and one of the authors of the study.
All this without counting around 200 days living in a stressful environment, on the way to a new world quite hostile to life. And then another 200 back to Earth. “Where there is life, there is stress. This strategy would minimize the boredom, loneliness and levels of aggression linked to confinement in a spaceship”, adds the researcher.
space sleep capsules
The researchers suggest what the rooms might be like in which future astronauts will sleep during their ‘space sleep’. It would be capsules with a soft shell, in an environment with low light, low temperature (less than 10 ºC) and high humidity. The astronauts would move very little, but would not be restrained and would wear clothing that would prevent overheating.
Meanwhile, wearable sensors would measure your posture, temperature and heart rate, and the artificial intelligence would be in charge of ensuring that everything is in order (including all the operation of the ship). In addition, each capsule would be surrounded by water containers that act as a shield once morest radiation. “Away from Earth’s magnetic field, damage from high-energy particles can lead to cell death, radiation sickness or cancer,” Alexander notes.
Imitating tardigrades, bears, squirrels and mice
The hard part comes with the dream itself. Although the mechanism of hibernation is not something invented by humans, nor do we have to start from scratch to understand it. As is known, various species seclude themselves for months (or even years), slowing down your metabolism by up to 90%: some go from 200 beats per minute to no more than five; and from 100 breaths per minute to one every five. Others would even say that they are almost dead. A ‘suspended life’ which, in the case of astronauts, would have as a direct consequence the decreased volume of supplies necessary, as well as ship size reduction. And, the lower the weight of the ship, the more feasible the exploration of greater distances.
If we look at the terrestrial candidates that we might imitate, the tardigradesthose almost indestructible beings, are the champions: thanks to the cryptobiosis, also known as water bears can withstand extreme conditions until they are suitable once more. However, much separates us from these microscopic organisms that endure until they are shot with a gun.
That is why the researchers point to the Bears as the best model to follow: with a body mass similar to ours, they reduce their temperature by only a few degrees, a limit considered safe for humans. And astronauts might follow the same ‘trick’ as these animals to prepare for hibernation: acquire extra body fat before going to sleep. Thanks to this, brown and black bears retire to their dens and spend six months fasting and immobilization.
The problem is that if a person spends six months in bed, there is a great loss of muscle and bone strength, in addition to risk for the heart. “But research shows that bears emerge from their den healthy in the spring with only a marginal loss of muscle mass. It only takes regarding 20 days for them to get back to normal. This teaches us that hibernation prevents muscle and bone atrophy due to disuse, and protects once morest tissue damage,” he explains. Alexander ChoukerProfessor of Medicine at the Ludwig Maximilians University of Munich (Germany).
According to recent studies, lower testosterone levels they seem to aid prolonged hibernation in mammals, as their counterpart, estrogen, strongly regulates energy metabolism. “The very specific and different balance of hormones in women or men and their role in regulating metabolism suggests that female candida might be the ideal candidate for these tests,” adds Alexander.
Another option are the squirrels. A recent study published in ‘
Science‘ explains that microbes in their intestines recycle the nitrogen from urea and return it to the muscles, which do not lose tone despite hibernation. If this mechanism might be transferred in some way to the human metabolism, it would be a great step to use it in long-duration space travel, as its authors maintain. Tests have also been carried out with mice, a species that, although they do not have hibernation periods as such, can reduce their metabolic activity whenever food is not available and go into a kind of ‘sleep’ longer than usual (and much more profitable). Taking advantage of this characteristic, Japanese researchers activated a specific type of brain cells called ‘Q neurons‘ to induce that state of lethargy in which the mice experienced a drop in body temperature from 36 degrees to 27 degrees, as well as a drop in heart rate, low oxygen consumption and slow breathing.
“We do not know the exact mechanism behind the induction of torpor or hibernation, but through specific projects, the ESA would like to identify those neurons and their projections that are activated (or blocked) during the onset of torpor,” Ngo explains to ABC. -Anh. “To this end, we also support research investigating the role of the hypothalamus. Methods used in animal models have not yet been applied to humans, but work is underway to prepare initial evidence in this direction.”
However, some ‘ad hoc’ experiments have been carried out with humans. In fact, it has already been proven that the therapeutic torpor in people is feasible: since the 1980s, doctors have provoked hypothermia (decrease in body temperature below 35 degrees) to reduce metabolic activity during long and complex surgeries or to try to improve survival following episodes that require resuscitation techniques, such as out-of-hospital cardiac arrest. The problem is that it is not an active reduction of energy.
“We still don’t know when we will be able to apply these techniques in humans,” says Ngo-Anh. “It will not be today or tomorrow. But over time, they will become a reality on long-duration manned missions,” he says.
