This is why hibernation in space may not be possible for humans

(ORDO NEWS) — Sending humans to virtually anywhere in space beyond the moon puts the logistics of health, nutrition and psychology in ways we are only just beginning to understand.

The main solution to these problems in science fiction is simply to put travelers in the void for a while to sleep. In a state reminiscent of hibernation or torpor, metabolism is reduced, and the mind gets rid of the boredom of endlessly waiting for empty hours.

Unlike FTL travel and wormholes, the idea of ​​hibernating astronauts seems to be quite feasible. So much so that even the European Space Agency is seriously studying the scientific basis for this idea.

The results of a new study by a trio of Chilean scientists have revealed a mathematical hurdle to turning the potential of prolonged human stasis into reality, which could mean it will forever remain out of our reach.

Roberto F. Nespolo and Carlos Mejias of the Millennium Institute for Integrative Biology and Francisco Bozinovic of the Pontifical Catholic University of Chile set out to investigate the relationship between body weight and energy expenditure in hibernating animals.

They found a minimal metabolic rate that allows cells to survive in cold, low oxygen environments. For relatively heavy animals like us, the energy savings that we might expect from falling into a state similar to deep hibernation would be negligible.

In fact, we’d probably be better off just napping the old fashioned way.

The word “hibernation” often conjures up the image of a bear hiding in a den for a long winter rest.

Although bears do close for several long cold months, their hibernation is not exactly like the real hibernation of small animals such as squirrels and bats.

In these animals, the body temperature drops sharply, the metabolism is reduced, and the heartbeat and breathing slow down. This process can reduce energy costs by up to 98 percent in some cases, eliminating the need to expend energy on hunting or foraging.

However, even in this state, the animal can lose more than a quarter of its body weight as it burns its fuel reserves.

If we apply the same math to a hibernating adult, then a daily food intake of about 12,000 kilojoules will be replaced by a need for just a couple hundred kilojoules of fat.

Continuing this scenario, we can imagine that our intrepid space tourist, sheltered in his specially equipped bed, will lose just over six grams of fat per day. For a year it will be about two kilograms of weight.

That might be fine for fast travel to Jupiter’s moons, but if the average adult wants to live decades flying through interstellar space to the nearest star, they’ll have to put on a few hundred more pounds of fat. Or waking up regularly to drink a lard milkshake or three.

These calculations are based on many assumptions, not the least of which is how hibernation can be scaled. After all, there is probably a good reason for the lack of massive hibernating mammals our size (or larger).

Therefore, the researchers conducted a statistical analysis of the various hibernating species, as described in previous studies.

Based on this, they concluded that the daily energy expenditure of hibernating animals is sufficiently balanced that a gram of tissue from a tiny mammal, such as a 25-gram eared bat, consumes as much energy as a gram of tissue from an 820-gram squirrel.

It can be assumed that if we ever learn how to hibernate as efficiently as a squirrel, then each gram of our tissue will require as much energy as each gram of their tissue.

However, when mammals are active, it’s a different story. Scaling the relationship between active metabolism and weight yields a slightly different plot that shows the point at which hibernation does not save much energy for larger animals.

This point is near our own mass, which means that our total energy requirements during hibernation will not differ significantly from those during rest.

Perhaps that’s why bears don’t hibernate the way smaller animals do. And for us humans, this means that cooling the body, lowering the heart rate and breathing rate, and artificially lowering the metabolism may not give the results we expect.

If we want to get rid of boredom and not swallow the ship’s supply of ice cream, we can watch the TV series “The Expanse”, take a bunch of sedatives and get to Mars in a nap.

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