Cryonicist's Horizons

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Cryogenic Sleep for Space Travel

Apart from the future, cryogenic technology could also allow us to explore distant planets.

Between five and seven million years ago, the first human ancestors appeared when some apelike animals in the Afar Triangle in East Africa began to walk on two legs. From there, they started expanding and exploring the world around them. They migrated to other continents, populating what is now Europe, Asia, and the Americas. Some of them built boats and sailed tremendous distances to islands they didn’t know existed. 


Today, we know (almost) everything about Earth. Now,we’re looking at space. More than 50 years ago, we set foot on the Moon. Now, our next goal is Mars. After that, we might move on to other planets in our solar system. We may look to explore further into the Milky Way. Perhaps, we will eventually travel to other galaxies. However, for this to be possible, humanity must first develop technologies such as cryosleep and human cryopreservation.

Why We (Might) Need Cryogenic Sleep

A big problem connected to space travel is speed and distance. Since planets are so far away from each other, it may take years, even centuries, to get from one planet to another. Let’s consider interstellar space travel within our solar system. 

According to NASA, on average and with the current technologies, it would take about 7 months to get to Mars, which it's placed at a distance of 480 million km from Earth along its orbit. A spacecraft would need around 6 years to get to Jupiter and 9.5 years to get to Pluto. If you’ve ever been bored on a long-haul flight, imagine spending years waiting inside a spacecraft.


How long would it take to travel between galaxies instead? For example, if we wanted to go to the Andromeda Galaxy, the closest large spiral galaxy, how much time would that take? The distance to cover is 2.537 million light-years which is about 22.833.000.000 million km. If we compare this number with the seven months needed to land on Mars, we can see that it would take about 28 million years to reach the Andromeda Galaxy. This figure is not exact but it can give us an idea of how much time one would need for intergalactic travels. Since no human can live that long and our consciousness is still perishable, how can we solve this problem?


Many sci-fi movies, such as 2001: Space Odyssey, Interstellar, or Passengers, have already shown us one possible option: induced cryogenic sleep, also known as (incorrectly!) suspended animation! To be exact, “cryogenic sleep” implies very low temperatures, whereas “suspended animation” is usually achieved by a reduction of only a few degrees. However, in popular media, the terms are usually used interchangeably.

andromeda galaxy
The Andromeda Galaxy is the most distant thing we can see with the unaided eye - Image credits: Peter Forister

Cryogenic Sleep: Pros and Cons

Cryogenic sleep can be seen as a sort of artificially-induced human hibernation. In nature, there are several animals that can decrease their metabolism by reducing the temperature of their bodies. In this state of biostasis, they can go on for months with limited food and water. 


To give an example, ground squirrels spend 8 months in a hibernation state called torpor, during which their heart rate, metabolism, and body temperature are incredibly low. After these months, their body warms up and they “come back to life” without any damage. While humans can’t naturally decide to hibernate themselves, medical technology might be able to induce this state. Several researchers are currently studying how to put humans into something similar to cryosleep. From a medical point of view, this could help treat diseases such as heart disease, diabetes, and Alzheimer's.


But What Are the Pros of Cryogenic Sleep for Space Travel?

  • First of all, astronauts would be able to travel for months without noticing it. Mental health is a problem when having to spend so much time locked inside a limited space with other individuals - as we all noticed very well during the recent lockdown for COVID-19!
  • Additionally, they would need lower quantities of food and water. By carrying less cargo, a ship would use less fuel.
  • The cryosleep chambers could protect astronauts more efficiently from harmful cosmic radiation. On Earth, the atmosphere and magnetic shield of our planet protect us. In space, however, astronauts are exposed to radiation.
  • The chambers could have an artificial Earth-like gravitational force that would keep astronauts’ bodies in shape. In fact, due to the lack of gravity, astronauts have to fight against muscle atrophy or bone degeneration by exercising on average for two hours per day. The technology necessary to produce artificial gravity in a space as wide as a spacecraft would be extremely complex and expensive. On the other hand, cryosleep chambers are small in size and studies are underway to make gravity possible inside them.
  • Finally, cryosleep (compared to cryopreservation) can be reverted relatively easily by simply bringing an astronaut back to their normal temperature without damaging the body.

What Are The Cons Instead?

  • The first one is that this technique hasn’t been successfully perfected yet.
  • Secondly, hibernation doesn’t completely stop aging. The metabolic reduction achieved through the use of low temperatures slows down the aging process. With advanced technology, aging could be significantly slowed down perhaps even for centuries. Yet, cryosleep alone will unfortunately not allow us to travel to the Andromeda Galaxy.

cryogenic sleep pods in passengers
Cryosleep pods from the movie “Passengers” (2016)

Cryopreservation for Space Travel

If we want to eventually reach extragalactic planets, cryonics aka human cryopreservation may be the solution we are looking for. This is a procedure a patient undergoes after legal death that allows it to be preserved for as long as it’s needed with the use of cryogenic temperatures (-196 °C). In fact, through vitrification, all biological processes stop. The astronauts could be preserved even up to 28.000 years, without virtually any change or degradation.


Clearly, researchers will have to develop the necessary technology for revival before even considering how cryopreservation can be applied to space exploration. In any case, we still have quite a few planets to explore in our galaxy.

Current Cryosleep Research

Are there any researchers trying to achieve cryosleep for space travel? The answer is yes. Engineers and scientists at the aerospace company SpaceWork Enterprises are working on a project called Torpor Inducing Transfer Habitat For Human Stasis To Mars for NASA.


The idea is to use a medical practice called Therapeutic Hypothermia (TH) which is commonly applied for traumatic injuries. The metabolic rate is reduced significantly by cooling the body down by only 5 to 7 degrees Celsius. In fact, this decreases by 5% to 7% per 1°C less in core body temperature.


Astronauts will go through several two-week cycles of suspended animations. During that time they will receive intravenous feeding and their waste will be removed through catheters.

cryogenic sleep chambers spacework 1
cryogenic sleep chambers spacework 2
WorkSpace design for NASA’s Stasis chamber


Considering what is already being developed for cryogenic sleep, this technology being used in space flight might not be so distant. Certainly there are still many problems that need to be solved. Space travel presents numerous difficulties. For some of them, we still haven't found a solution. However, if we look back to the past, even sailing presented several difficulties when the technology available to us was still in its infancy.


At Tomorrow Bio, we are excited to have a chance to witness future developments of aerospace technology. Revival technology would allow us to save lives and give our members a chance to live an extended life. Who knows if cryopreservation will also be used for intergalactic travel in the future?


Interested in learning more about cryonics? Take a look at our online editorial Tomorrow Insight. Don’t forget to download the ebook below that can give you an overview of the human cryopreservation procedure and its life-saving possibilities!

Tomorrow Bio is the worlds fastest growing human cryopreservation provider. Our all inclusive cryopreservation plans start at just 31€ per month. Learn more here.