Sending humans virtually anywhere in space beyond the Moon pushes the limits of health, food, and psychology.
In science fiction, the main solution to these problems is to put the void-travelers to bed. The mind is spared the boredom of waiting out endless empty hours when it is in a sleep-like state.
The idea of putting astronauts into a form of hibernation feels like it is within grasp, unlike faster-than-light travel and wormholes. Enough for the European Space Agency to seriously look into the science behind it.
A mathematical hurdle that might mean it is forever beyond our reach is the result of a new study by a trio of researchers.
Roberto F. Nespolo and Carlos Mejias from the Millennium Institute for Integrative Biology and Francisco Bozinovic from the Pontifical Catholic University of Chile set out to investigate the relationship between body mass and energy expenditure in animals.
Cells can persist under cold, low-oxygen conditions with a minimum level of metabolism. The energy savings we might expect from entering a deep state of sleep would be insignificant for animals like us.
We would probably be better off napping away the old fashioned way.
The word "hibernation" evokes images of a bear tucked away in a den for a long winter's rest.
While bears do shut down for several long, cold months, their dormancy is not quite like that of bats or ground squirrels.
Body temperature plummets, metabolism shrinks, and heart rate and breathing slow in these animals. The process can reduce energy expenditure by as much as 98 percent in some cases.
Even in this state, the animal can still lose 25% of its body weight as it burns through its fuel reserves.
If we applied the same basic mathematics to an adult human, a daily food intake of around 12,000 kilojoules would be replaced by a need for just a couple hundred kilojoules of body fat.
Our intrepid space tourist would lose over six grams of fat a day if they were in their bed. It would add up to around two kilograms of weight over the course of a year.
If the average adult wants to survive decades floating through space to a nearby star, they would need to pack on an additional few hundred kilograms of fat. That's how you wake to throw back a few.
Many assumptions are used in the back-of-the-envelope calculations. There is probably a good reason for the scarcity of large mammals.
The researchers did a statistical analysis of a variety of hibernating species.
They found that a gram of tissue from a small mammal, like a leaf-eared bat, consumes as much energy as a gram of tissue from a ground squirrel.
If we were to work out how to hibernate as efficiently as a dormouse, every gram of our tissue would need the same amount of energy.
When mammals are active, it is a different story. The scaling of the relationship between active metabolism and mass produces a slightly different graph that shows a point at which hibernating doesn't really save a lot of energy for bigger beasts.
Our total energy needs will not be different from those when we are merely at rest.
Smaller animals do the same thing as bears do. It also means that going to all the risk and trouble of cooling our bodies, dropping our heart rate and breathing, and artificially depressing our metabolism just might not give us the results we hope for.
If we want to save ourselves from boredom, we should binge The Expanse, take a bunch of sedatives, and go to Mars.
It isn't going to be worth the hassle to force humans to sleep.
The research was published in a journal.
All Rights Reserved © 2024
