Human hibernation?

If humans are to ever leave Earth in search of a new home, it is likely we’d need to travel quite a distance to our new planet. It takes 6 months to reach Mars – with Mars not even being a good candidate to host us in the first place. Then if you go beyond Mars you reach the Jovian system planets, Jupiter, Saturn, Uranus and Neptune. Being composed mostly of gas and only a small portion of solid surface, it would be an impossibility to live on these planets. Beyond Neptune, there are numerous Pluto-sized dwarf-planets which are mostly covered in ice and would take around 10 years of travelling just to reach. So this poses two problems, other new-earth candidates in our solar system are (1) very difficult to live on and (2) quite a distance away.

But hey, maybe we could try a new galaxy? As beautiful as our Milky way Galaxy is, it is not the only galaxy in the Universe and if we can one day leave Earth, intergalactic travel would have to be on the cards. Our nearest galactic neighbour is the Canis Major Dwarf (CMD) Galaxy which hosts about 1 billion stars and can been in the southern night sky as it is located in the same place as the Canis Major constellation:

Canis Major Dwarf Galaxy in relation to our Sun and the Milky Way galaxy. The CMD galaxy is so small that the gravity of our galaxy is slowly tearing it apart and creating these long streams that you can observe in the image. Credit: NASA

Problem is, the CMD Galaxy is about 25 000 light years or 2.4×10^17 Km from Earth. If you’re not familiar with light years (ly), a light year is a measure of distance, not time. It is the distance a photon of light travels in one Earth calendar year:

The Speed of light = 300 000 km/s

Speed = Distance ÷ Time, Therefore, the distance light travels in one year is approximately: 9 460 000 000 000 kilometres

*9 trillion, 460 billion kilometres!*

So, what i’m trying to say, is that the distances in space are huge, even to our closest galactic neighbour. The Voyager 1 spacecraft that recently passed into the interstellar medium (outside our solar system) is shooting through space at ~17 km/s. If we got on a space ship and flew towards the CMD galaxy at this speed, it would take us about 450 million years to reach it. Even travelling at the speed of light, it would still take 25 000 years! This is quite a problem… Although, most Sci-Fi movies combat this by using Einstein’s theory of relatively by being able to travel at near the speed of light thereby slowing time in the travellers frame of reference, though I won’t address that in this post.

Having to travel such large distances in space means a team of scientists (and passengers) onboard would need to have a way to stay alive on these extremely long journeys. The solution, human hibernation! Or the deep sleep. This sort of scenario has been seen in numerous films such as: Event horizon (1997), Interstellar (2014), 2001: A Space Odyssey (1968) and the recent Alien: Covenant (2017). The main objective is to put the crew of a spacecraft into a deep sleep so that they can slow their ageing process and awake at a much later date so that they can continue to perform their duties. But is such a thing possible?

A similar idea you’re probably familiar with is cryogenic freezing, which basically involves cooling an individual in an ice bath, then draining the blood from the body and replacing it with anti-freeze liquid to prevent cell-destroying ice crystals forming.  The individual is then cooled over a couple of weeks with nitrogen gas and eventually suspended in a liquid nitrogen bath. The problem with cryogenic freezing is that scientists know how to freeze someone, but aren’t sure how to defrost them and bring them back to life. As a result, people wanting to go through cryogenic freezing must already have died, with the hope that when the science advances in the future, they can be brought back to life via cloning or even have the head attached to a new body. So this isn’t a viable idea, we need another way.

How do they do it in Sci-Fi? Well, most of the films that incorporate human hibernation have scenes where we see the individual come out of their sleep chamber, with evidence of some sort of cryogenic fluid. Though, not all films use this method, some just use basic dry sleeping pods. As it’s a close representation of cryogenic freezing, I will focus on the methods in films that utilise some sort of preservation fluid. Furthermore, this is not a type of cryogenic freezing but instead a state of stasis, whereby the individual’s metabolic rate is slowed dramatically, but not frozen. Slowing of the metabolic rate results in hibernation which is common in the animal kingdom. Northern-most bears can hibernate for 8 months, which means they can slow their metabolic rate such that their body uses built-up fat reserves and their kidneys recycle urine to put it back into the body. This is an extremely low energy state which is great for conserving resources but based on evolutionary theory, hibernating animals do not have longer life spans than non-hibernating animals. So theoretically, if a human could hibernate during a long space flight, it wouldn’t aid in dramatically slowing (or stopping) the ageing process. This would defeat the purpose of going into stasis in the first place. 

In films such as Event Horizon (1997), the crew members would enter into a vertical chamber, attached to a breathing apparatus and then the chamber would fill with, lets call, stasis fluid. Upon awakening, the crew members would fall out of the pod and the fluid would drain away. As this process does not involve freezing, it’s safe to assume that the purpose of the fluid is not to freeze but to aid in cooling the body temperature (and slowing the metabolic rate) and potentially preserving the physical body. This particular scenario sets up a hibernation-like state which, as I mentioned above, will likely not extend the life of the individual. So some future science must be present which allows the body to almost completely shut-down before being woken up again, ultimately freezing the ageing process. This is only one example for which there are numerous in Sci-Fi, but the main goal of all stasis pods is to slow the ageing process so that crew members can awake, years or even hundreds or thousands of years later.

This kind of technology isn’t a reality yet, but it’s a vital part of future space travel and intergalactic space travel. An aerospace engineering firm SpaceWorks is currently working to solve the problem of human stasis. They are researching the effects of stasis on the physical and mental human body with a hope to determine the best way to keep a human in stasis for a trip to Mars. If we are to reach the sights of the Canis Major Dwarf Galaxy, 25 000 light years away, we need some way to shut-down our bodies into low power mode or even freeze, so that our journey won’t result in the birth and death of multiple generations on the space craft!

References and further reading:

Smith, R. (2016, November 18). What is cryogenics and how does freezing bodies work? Retrieved May 28, 2017, from

NASA. (n.d.). The nearest galaxies. Retrieved May 28, 2017, from

Turbill, C., Bieber, C., & Ruf, T. (2011, March 30). Hibernation is associated with increased survival and the evolution of slow life histories among mammals. Retrieved May 28, 2017, from

Marder, J. (2011, February 17). Hibernating Bears Slow Down More, Cool Down Less. Retrieved May 28, 2017, from

SpaceWorks. (n.d.). Retrieved May 30, 2017, from

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