The European Space Agency has looked at the science of hibernation. They potentially want to get people to hibernate for space travel.
Hibernation seems like the sensible solution in the absence of other possible theoretical space travel methods. Faster than light travel and going through wormholes isn’t an option for astronauts yet. The ESA didn’t think putting astronauts into hibernation for long journeys was a silly idea compared to the theoretical alternatives.
A Hollywood idea that has influenced the space industry
The idea of hibernating space travelers has been banded around in science fiction movies such as Star Wars, Empire Strikes Back, and Avatar. In Star Wars, Han Solo was frozen by a bounty hunter and delivered to Jabba the Hutt, and in Avatar, soldiers were hibernated in their travel from Earth to a mission on the planet Pandora. This Hollywood concept deserves serious consideration.
In these films, travelers are put in a sleep-like state akin to hibernation or torpor. The idea behind the science is to get a person’s metabolism to drop and spare the mind from the boredom of thousands of hours traveling in space.
An examination of the relationship between body mass and energy expenditure in animals that hibernate was done by Francisco Bozinovic (Pontifical Catholic University of Chile) and Roberto F. Nespolo and Carlos Mejias (Millennium Institute for Integrative Biology).
These researchers from Chile have now done the math of whether hibernation is possible for people, and at the moment, the math doesn’t look good.
Smaller animals hibernate more effectively
Their research indicates that there’s probably a reason why there is no abundance of hibernating mammals our size (or larger).
They discovered that hibernation for smaller animals is more effective than for bigger animals. Bears which are the stereotype that come to mind when we think of hibernation, hibernate a bit differently than smaller animals.
There is a minimum level of metabolism required for cells to persist under cold, low-oxygen conditions. The energy people would save from entering a deep, hibernation-like state would be negligible. Mike Mcrae writing for sciencealert.com, thinks astronauts would be better off napping the old-fashioned way.
Although it is believed that bears hibernate in the cold months, their hibernation isn’t what these researchers would describe as a true hibernation, like the hibernations of bats and ground squirrels.
When smaller animals go into hibernation, their body temperature plummets, reducing their metabolism, breathing, and heart rate.
When these smaller animals hibernate, they can reduce their energy expenditure by as much as 98 percent. In some cases, this negates their need to go foraging or hunting.
Even small animals saving up to 98% of their energy in hibernation can still lose more than a quarter of their body weight over their winter sleep.
Applying the same calculations to an adult human, a human needs around 50 calories worth of body fat to save a daily food intake of approximately 2868 calories required for an adult male.
Hibernating astronauts
A hibernating space traveler would lose over six grams of fat a day. In a year, this would add up to around two kilograms of weight.
Although space agencies could consider hibernating people on journeys to the Jovian moon Europa (which could take up to six years), if astronauts hibernate decades in space, they’d need to bulk up like a Sumo wrestler with an additional few hundred kilograms of fat.
Carrying out a statistical analysis of hibernation across various species, the researchers concluded that hibernating animals’ daily energy expenditure scales were pretty balanced.
The science is different for active mammals. There is a scaling relationship between active metabolism and mass. There is a point where hibernating doesn’t save much energy for larger animals.
If humans were to hibernate, there would not be a significant difference between the energy we would need while hibernating compared to how much energy we would use just resting.
Hibernating people is not worth the risk
This research indicates why bears don’t hibernate as smaller animals do. This research also demonstrates that it is not worth the risk of cooling our bodies, reducing our heart rate and breathing, and artificially experimenting with our metabolism to relieve travelers’ boredom in space.
Their research is published in Proceedings of the Royal Society B.
Different ideas need to be revolutionized for space travel
Hollywood should rethink how space travel is done in movie plots in light of this evidence. Perhaps Hollywood and science should focus more on Stargate and Star Trek, with scientists beginning to figure out the alternative theories of how astronauts can step through wormholes like Stargate or be beamed up into Space like Star Trek.
