It’s a storyline worthy of a sci-fi movie: hibernate a full crew of six astronauts from Earth to Mars. In the context of the race to explore the red planet, the European Space Agency is exploring this unusual avenue, which would facilitate space travel, and is considering it within the next two decades.
“Hibernation in astronauts would be a great advantage for long-duration space missions, as it would make travel safer, reduce the degradation of body tissues and allow great savings in terms of mass and costs”, explain to Press Alexander Choukèr, physicist at Ludwig Maximilian University Hospital in Munich, Germany, and member of the European Space Agency’s hibernation committee.
During distant space travel, engineers face an important logistical problem: the limited space in space shuttles for equipment and food.
A very large part of the mass in space travel is spent on basic living needs like food, water, air and waste disposal, details Jürgen Bereiter-Hahn, retired professor of the Institute of Cell Biology and Neuroscience at Goethe University in Frankfurt, Germany, and Human Hibernation Research Coordinator.
This is how hibernation derives its full meaning, since in a state of torpor, astronauts would not need to drink or eat. All the energy required for the body to function would be extracted from fat, just as hibernating animals do.
“In the animal kingdom, hibernation is very common. The common goal is to save energy and resources. It’s the same thing in the space sector, ”says Mr. Choukèr.
The only resource that would be consumed by astronauts would be oxygen, and the only waste produced, carbon dioxide. The energy requirements of their metabolism would be reduced by 75%.
180 days in torpor
The scenario described by the researchers is ambitious: at the time of their departure for the red planet, the members of the crew would lie down in their respective capsules. The ambient temperature would drop to 18 ° C. This temperature, combined with a drug administered to astronauts, would stabilize their body temperature at 32 ° C, a decrease of 5 ° C compared to normal.
“In our research, we draw a lot from hibernation in bears. The hibernation temperature of this animal is approximately 31 ℃. It is estimated that a similar temperature would be sufficient in humans, ”says Choukèr.
Drugs that alter brain activity would put astronauts into a state of torpor. The decrease in temperature in the capsule would allow astronauts to maintain an inactive stage similar to hibernation in animals.
“This temperature would achieve a slowing down of the metabolism, while avoiding the problems associated with a too low body temperature, such as heart problems”, explains Gerhard Heldmaier, professor of biology at the Philipps University in Marburg, Germany, and member of the European Space Agency’s hibernation committee.
During the entire journey between Earth and Mars, approximately 180 days, no communication would be possible between the crew and the team on Earth. The mission must therefore be designed to operate in a largely autonomous manner, thanks to artificial intelligence.
ILLUSTRATION FROM THE WEBSITE OF THE EUROPEAN SPACE AGENCY
During space travel, crew members would lie down in their respective capsules and their health would be monitored and controlled through a medical interface.
A medical interface would make it possible to monitor their state of health during the trip.
When they arrive on Mars, the astronauts would regain consciousness. Experts fear no memory loss or skill degradation.
Challenge: activate the right region of the brain
In order to achieve the state of torpor in humans, scientists wish to draw inspiration from hibernation in animals.
The fact that many animals are able to hibernate suggests that humans may have the ability to hibernate as well. You just have to find a way to activate it.
Alexander Choukèr, physicist and member of the European Space Agency’s hibernation committee
In recent years, researchers have observed that mice can enter torpor only hours after being starved and exposed to the cold. This hibernation seems to be triggered by neurons in the hypothalamus, a region of the brain that notably controls hunger, stress or arousal.
In humans, successfully altering the activity of hypothalamus neurons is a challenge, says Bereiter-Hahn. This region of the brain cannot be easily reached by injecting a drug, because the human body, in order to protect itself, blocks access to the brain to several molecules.
“The biggest challenge will be to be able to activate and deactivate the right region of the brain capable of making us go into hibernation,” adds the researcher.
Over the next few years, the Agency will continue its research to better understand hibernation in animals, with the goal of applying these same practices to humans.
“We need more basic research to explore the essential elements of metabolic control,” says Professor Heldmaier.
In the next decade, researchers hope to develop precise protocols for the hibernation of humans. The team wants to launch its first missions involving hibernation within the next 20 years.
“The essence of human life is adaptation. Hibernation is only one way of adapting to new hostile environments, ”summarizes Mr. Choukèr.
54.6 million kilometers
Minimum distance between Earth and Mars
Source: NASA
175 to 225 days
The duration of the trip to Mars, which may vary depending on the date of the mission.
Source: European Space Agency
Hibernation to the rescue of patients
Hibernation would not only be beneficial in the field of space exploration. It could also have wide medical applications. An American doctor is studying the possibility of placing patients in a state of torpor by replacing their blood with ice-cold saline solution.
“Patients who experience cardiac arrest as a result of trauma, such as a gunshot wound or stab wounds, rarely survive,” explains Press Samuel Tisherman, professor at the University of Maryland School of Medicine, United States. Irreversible damage is done to vital organs before surgeons can control the bleeding. Replacing the blood with ice-cold fluid decreases the oxygen and blood flow requirements of vital organs to protect them while surgeons operate to stop the bleeding. After the operation is completed, the saline solution is removed and replaced with the patient’s blood.
Until now, the method would have been carried out a few times by Dr Tisherman in patients who had little chance of survival with traditional medical methods. The number of patients who survived and the details of the operations will be released in a scientific article when the study is completed.