



Science fiction is shifting into reality. With humanity’s plans to return to the moon this decade and further ambitions to travel to Mars in the next, we need to figure out how to keep astronauts healthy for these years-long missions. One solution long championed by science fiction is suspended animation, or putting humans in a hibernation-like sleep for the duration of travel time.

We can turn to nature for guidance and a potential solution to this challenge.

A squirrel monkey sits on top of a model rocket.
Primates have been used in space research for decades. Space pioneer Miss Baker, a squirrel monkey, rode a Jupiter IRBM into space in 1959 and returned safely. (NASA/Marshall Space Flight Center)

It’s cold and dark out there

Space is unforgiving. In this freezing void of darkness there is no oxygen, no gravity and no protection against the constant shower of cosmic radiation. Humans have evolved under a constant gravitational pull — so when you put people into space, strange and dangerous things happen to their bodies.

However, scientists and engineers working with astronauts on the International Space Station have innovated and continue to address these problems. For example, we know that spaceflight leads to loss of muscle and bone density, since our bones and muscles do not need to work against the pull of gravity to move us around.

But we still do not know how to address other space-related medical issues, including immune system alterations, problems with vision and bombardment with hazardous cosmic radiation.

These physiological challenges are combined with the technological difficulties of sending multiple humans on these long missions where they face logistical complications of packing and allocating enough provisions and supplies, as well as social issues of coping with extreme isolation in deep space.

Putting the body on pause

Suspended animation and biostasis may elicit science fiction images of humans in cryosleep pods. If we could put humans in a state of suspended animation by greatly slowing or even fully halting metabolic activity, we could alleviate issues surrounding space travel: time, health concerns, spacecraft size and supply allocation.

WIRED takes a look at the science behind suspended animation.

But how can we safely ease humans into hibernation and then bring them back when the time is right, without risking muscle and bone wasting, to name a few challenges? These are questions that the United States Department of Defense and other space agencies are actively exploring.

Animals who spend the winter in states of suspended animation — hibernation — don’t experience significant muscle and bone wasting. Their existence and ability to reversibly turn off biological processes seemingly necessary for life may well hold the key to creating the conditions required for the human hibernation strategy that could pave our way to surviving long interstellar voyages to distant stars.

In fact, the use of biostasis has already been proposed for the transport of large numbers of travellers to Mars, where crew members will be sustained with specially formulated total nutrition liquids while they “sleep.”

Model animals?

How do we translate hibernation in animals to hibernation in humans? Recent work has uncovered such an ability in animals that are evolutionarily similar to humans: hibernating primates. What is unique about these primates is that they can enter a state of hibernation when resources are scarce and temperatures become cold, and do so without seriously dropping their body temperature.

One of the driving forces behind this extreme ability is microRNAs — short pieces of RNA that act as molecular gene silencers. MicroRNAs can regulate gene expression without altering the genetic code itself. By studying the microRNA strategy these animals use, we can exploit this genetic on/off switch for rapid, reversible changes that could aid hibernation in humans.

Our work on gray mouse lemurs (Microcebus murinus) shows how microRNAs control which biological processes remain on to protect the animal and which ones are switched off to save energy. Some of these microRNAs were found to combat muscle wasting during hibernation. Other roles seem to involve preventing cell death, slowing down or stopping unnecessary cell growth, and switching fuel stores from quickly consumed sugars to slower-burned fats.

While microRNAs are a promising avenue of research, they are just one piece of the puzzle. Our lab is also looking into other aspects of how primates hibernate, such as how these lemurs protect their cells from stress, control global gene levels and how they store enough energy to survive hibernation.

Mouse lemurs are more closely related to humans than mice, which are more typically used for research.

Our lab also looks at how microRNAs are helping animals survive other extreme environmental stresses including freezing, oxygen-deprivation and hot, dry climates. There is no stress more extreme than the vacuum of space, and we hope our research will contribute to the new RNA-based interventions that are gaining attention and emerging as viable human therapeutics.

Space is within our reach, and studying what’s already on Earth will help get us there.

Hanane Hadj-Moussa, PhD Candidate in Molecular Biology, Carleton University; Aline Ingelson-Filpula, M.Sc. Candidate in Biochemistry and Molecular Biology, Carleton University, and Kenneth B. Storey, Professor of Biochemistry, Carleton University


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dodgy geezer
January 24, 2021 2:05 am

Perhaps this would also be a good way to spend time in lockdown during pandemics?

Peta of Newark
January 24, 2021 2:53 am

We’re all going to Mars anyway, unless a few folks come out of their slumbers and realise what is actually going on in The Real World
Mars being the perfect realisation of an endless Ice Age – and over the last million or so years they’ve been coming, getting closer together and progressively deeper and longer.
Learn about ‘Weathering’

Am in 2 minds about signing up to this hibernation lark myself and certainly not least, wouldn’t it be a great way of us humans surviving normal winters?

Questions are:
1) Would I, you or anyone actually trust the technology?
2) Would this hideous nightmare vision of what happens inside Chemically Disabled ## and Magically Thinking minds of other people all be over when me, you, whoever were awoken?
is it worth the risk, or should we ‘Take A few Risks Right Now’ and hopefully avoid those 2.

Woody Allen took the optimist’s view in Sleeper.
Very very prescient, because when he awoke, he found that all the things he remembered as being ‘Bad For You’ were in fact ‘Good’
Namely and (##) Saturated Fat as a dietary staple. NOT Cooked Starch.

I’d assert along with a few folks from round here who’ve Been There Done That and Bought the Ketogenic T-Shirt, that it Really Is That Simple.

And just Get A Load Of This:

Doctors are actually saying that it’s OK, if not actually good, to chemically trash your mind, personality, science, economies, education, your own children, politics, souls and bodies in order to cope with Government Induced Stress.

Remember, Human Animals always give away the things they try to hide – thus – Alert Minds, what few there are left, conclude that our medics are all dipsomaniacs & drunks.

Look out Mars! Here we come – 8 Billion of us and counting.
And, we’re bring all of Planet Earth along for the ride.

Last edited 8 months ago by Peta of Newark
Tom in Florida
Reply to  Peta of Newark
January 24, 2021 6:39 am

Except that Mars ain’t the kind of place to raise your kids

Bill Powers
Reply to  Tom in Florida
January 24, 2021 7:10 am

Well as Huxley pointed out, the Government will be making the kids in a lab very soon and once that happens the Government will be raising them to fulfill the role they were created to fulfill. Worker drones will be the first to Mars to colonize, build and maintain human habitats. The Central Authoritarians will come once it has been made safe for travel and use of the privileged .

In this Brave New World, normal human pregnancies will be outlawed (with the exception of the Faceless Cultural elite who run the world in the background and are not subject to the laws made for the great unwashed). Any accidental unwashed pregnancy will be subject to abortion upon discovery up to and including the moment of birth and beyond.

Hush little baby don’t you cry..

Big Al
Reply to  Bill Powers
January 24, 2021 8:02 am

It was not movie. Prophecy PS … By Jan, 30th looking for NEW, revised ending. Section. 11.3 …. Military Control.

Reply to  Peta of Newark
January 24, 2021 6:53 am

What i found most interesting about this, was the they slow down cell growth. Isn’t that what makes us age? Wouldn’t it be nice to live as long as you want and not lose muscle or bone mass 🙂

Reply to  Terry Dean Roehrig Sr
January 24, 2021 12:26 pm

Calorie restriction will prolong most organisms normal life spans. So put down that cupcake and live longer. Unless the cupcake is what makes life worth living.

Last edited 8 months ago by joelobryan
Michael S. Kelly
Reply to  Joel O'Bryan
January 24, 2021 8:22 pm

As one of my mentors used to observe, back in the 1980s, “If you don’t smoke, don’t drink, don’t eat meat, eggs, and ice cream, you’ll live for 100 years – but it will seem like 200 years.”

Julian Flood
Reply to  Joel O'Bryan
January 25, 2021 2:09 am

Watch the videos by Cynthia Kenyon on this. Summing them up — avoid insulin spike by eating non-sugary food, the insulin triggers aging by engaging the aging mechanism. See you for the birthday celebration in 2050.

There’s one problem, I think beer may have the same effect and there are limits.


Mark - Helsinki
January 24, 2021 4:54 am

To put it simply, human DNA will have to be altered in order for us to be able to survive any of this without severe permanent health impacts.

Cryo sleep for healthy humans without severe damage to the human body and brain is still purely the realm of science fiction

Steve Taylor
Reply to  Mark - Helsinki
January 24, 2021 11:08 am

No, the whole point of the article is that it could be possible to do that by sending the right messages to the cells in the body.

Reply to  Mark - Helsinki
January 24, 2021 11:50 am

There is the issue of what age the person is & what physical condition they are in. It is our histone de-acetyl-ase silent information regulator proteins Sirtuin 1 that, among other things, holds back programmed cell death (apoptosis) & Sirtuin 3 that, among other things, allays apoptosis. Natural hibernators’ skeletal muscles are crucial for bringing them back functionally & in the low metabolic state their skeletal muscle level of Sirtuin 3 is elevated.

Mark - Helsinki
January 24, 2021 4:57 am

If you went into cryo sleep for 3 years, you will be a different person when you come out of it

People who go into multi year comas and come out, don’t just resume who they were at the point of going in

John Tillman
Reply to  Mark - Helsinki
January 24, 2021 6:14 am

A friend of mine, formerly a hard-charging DA, was put in an induced coma after a botched operation. She suffered continuous violent nightmares for a month. After being awakened, she has been afraid to leave her house for years.

Ron Long
January 24, 2021 6:11 am

Who needs lemurs, there’s already thousands of government employees that have been hibernating for years.

Reply to  Ron Long
January 24, 2021 9:37 am

comment image

We call that “functionary pick-up sticks” in German, the first who moves has lost 😀

Last edited 8 months ago by Krishna Gans
John Tillman
January 24, 2021 6:35 am

I hope that hibernating humans won’t have to imitate pregnant polar bears and pack on hundreds of pounds of fat prior to denning up. Ditto black and brown bears, but not male and non-pregnant female polar bears, which benefit from a mutation in a nitric oxide metabolism gene permitting them to stay warm in winter.

Tom in Florida
January 24, 2021 6:37 am


“Animals who spend the winter in states of suspended animation — hibernation — don’t experience significant muscle and bone wasting”

So it appears that it is the lack of gravity that causes the loss of muscle and bone density, not the hibernation.

Reply to  Tom in Florida
January 24, 2021 9:39 am

right on, Tom.
The reason hibernation stops the loss of bone and muscle mass is…..hmmm…..well they really don’t know, its a supposition….the ISS experiments with hibernating bears were cancelled /s

Tom Abbott
Reply to  Tom in Florida
January 26, 2021 12:34 pm


That is a good question. We need to put a hibernating animal in orbit for a period of months and see how they fare.

I suppose the hibernating part would have about the same effect in space as on Earth. The animal would not be moving much and would not be exercising its muscles in either situation, so gravity or no gravity would not be a factor.

I’ll have to think about this more.

January 24, 2021 6:43 am

Remember what happened on Red Dwarf when Lister emerged from stasis after 3 million years… Last human in the universe with a Hologram and humanized Cat for sanity.

Climate believer
January 24, 2021 7:18 am

I can understand why Martians might want to come to Earth, but why would we want to go there? We already have the best planet.

Tom Abbott
Reply to  Climate believer
January 26, 2021 12:40 pm

Because it’s there. I forget who said that first. 🙂

Giordano Milton
January 24, 2021 7:34 am

Maybe we should just send lemurs to other planets, instead.

January 24, 2021 7:39 am

There was excitement years ago about the potential of hydrogen sulfide to induce a “suspended animation.” Instead, it appears results were misinterpreted and the real cause was induced hypoxia.


Last edited 8 months ago by Scissor
Gordon A. Dressler
January 24, 2021 8:01 am

There is a world of difference between hibernation (as we know it today in some animals, bacteria and viruses) and putting any living organism, let alone humans, through a cryogenic freeze-thaw cycle.

The biggest problem with the latter is that ice crystals that form in body liquids (mostly water content) expand upon formation and destroy cell walls and the nucleus of cells. I think the common phrase here is “freezer burn”.

Biophysics 101.

Steve Taylor
Reply to  Gordon A. Dressler
January 24, 2021 11:12 am

Its possible to induce something called vitrification, freezing without crystals, under some circumstances.

Gordon A. Dressler
Reply to  Steve Taylor
January 24, 2021 5:38 pm

Steve, uhhhhh . . . yeah, but any conditions applicable to the physical size of a human body? I think not.

Of course, you are free to cite an appropriate scientific (not science fiction) paper that corrects me on this.

Max More
Reply to  Gordon A. Dressler
February 3, 2021 8:49 am

Not yet. But there has been some success reversibly cryopreserving rabbit kidneys. It seems to be a matter or time and more research to succeed with something the size of a human brain. You can cryopreserve them today successfully, but will have to wait for better rewarming technology to reverse the process.

Max More
Reply to  Gordon A. Dressler
February 3, 2021 8:47 am

This is incorrect, although a view I encounter often. What actually happens is that cells dehydrate and ice forms between cells, not inside them. They do not blow up cells. Damage is done to the cell membranes from outside. But that can be prevented by replacing the water in the body with a cryoprotectant. Instead of freezing, the cells vitrify, preserving structure. We know this works because we can cryopreserve then rewarm and use eggs, sperm, skin, heart valves, etc. Of course, we are still a way off from reversibly cryopreserving whole humans.

Neil Jordan
January 24, 2021 10:10 am

The bad news is in the first paragraph – cosmic radiation. Unless hibernation stops radiation damage, high-energy particles producing skid marks in the retina will cause irreparable damage. To paraphrase my grad advisor, you can send your astronauts to the stars but they will come back blind.

Reply to  Neil Jordan
January 24, 2021 10:14 am

Couldn’t they be protected in a lead case ?

Michael T
Reply to  Krishna Gans
January 24, 2021 12:18 pm

Water and plastic are much better.

Tom Abbott
Reply to  Michael T
January 26, 2021 12:43 pm

A one-meter-thick coating of water ice on the outside (or inside) of your habitat module will stop the radiation from penetrating.

January 24, 2021 10:28 am

Put me down as a neanderthal when it comes to space travel. Colonizing the moon would be a huge waste of time and money. Sending men to Mars (even a quick fly by) will never happen. The I S S is pointless already.

Rory Forbes
Reply to  Dave
January 24, 2021 10:54 am

I’m afraid I agree with you on that one. Hell we haven’t even managed to fix jet lag or the bad effects of shift work, not to mention the lack of gravity.

Tom Abbott
Reply to  Rory Forbes
January 26, 2021 12:53 pm

I’m glad you brought that up. Here’s a link to show us a way to produce artificial gravity in orbit.


I think NASA ought to be fully funding these guys. This is the future of human space travel and living.

A little artificial gravity and a nice coating of ice on the module, and we’re in business in space!

Rory Forbes
Reply to  Tom Abbott
January 26, 2021 2:25 pm


I hope you’re being facetious, because what I saw at that site is hardly novel or ground breaking conceptually. That sort of artificial gravity has been around for generations. As for “a nice coating of ice on the module”, ice sublimes to a gas at far warmer temperatures than in deep space.

I frankly don’t seem much practical reason for space travel. Hell, we need to work out how to run a proper election first.

Julian Flood
Reply to  Dave
January 25, 2021 2:11 am

Musk wants to colonise Mars. Bezos is the man to bet on, he has his eyes on the asteroid belt, much more sensible.


Tom Abbott
Reply to  Julian Flood
January 26, 2021 1:20 pm

Bezos has his eye on building a large, O’Neill-Cylinder-type human habitat that can house thousands and even millions of people in space with artificial gravity and radiation protection provided and land area for growing food.

I imagine Bezos will start out small and work his way up to bigger and bigger habitats, or his successors will.

Jeff Bezos was a student of Gerard K. O’Neill, so he is very familiar with human space development of this type. And now he has money coming out his ears! 🙂

That’s good for human space development and the survival of the human race.

Tom Abbott
Reply to  Dave
January 26, 2021 12:49 pm

There are now people on Earth with the means and the methods, and the desire to get to other planets, so barring a totalitarian takeover of access to space, or some other catastrophy, humans *will* be walking on the Moon and Mars in the lifetime of many of us living today, imo.

I think we are going to see a whole lot of human space exploration in the next 25 years.

January 24, 2021 11:17 am

Not just gravity has all life on this planet evolved to survive. Everything living thing on this planet deals with some amount of genetic damage from natural ionizing radiation. The entire hypothesis of hormesis to ionizing radiation, for which there is considerable evidence, predicts a beneficial response to very low doses of radiation. Above a certain limit, DNA damage repair pathway capabilities and processes are exceeded and deleterious,
irreparable genome damage accumulates with resulting mutations to genes and genetic -controlled biological processes.

DNA damage repair mechanism require energy. ALot onf energy in the form of GTP and ATP production to power the enzymes involved in DNA damage detection, the helicases (unwinding, dealing with super-twisting), mis-aligned nucleotides forming chemical adducts, cyclo-butane rings between cytidines, detecting uracil in DNA, endo- and exonucleases for excision repair, insertion of and polymerization of new bases to replace damaged nucleotides. All very metabolic energy intensive. The cell cannot go to sleep if substantial DNA damage is being done by radiation, as when it tries to restart, – genome damage may be too great, and the cell dies through apoptosis.

see more here:

People like to point to tardigrades as being demonstrated to be able to go into hundreds of years of dormancy, only to reawaken, and start “living” again after being in cold protected conditions for a such a long period. Tardigrades have evloved that capability here on Earth, inside our protective geomagnetic shield, protected by Earth’s thick atmosphere and magnetic shield from higher levels of genetic damage that higher doses of ionizing radiation would bring.

But with bioloigical dormancy in space, where cellular activity and metabolism is greatly slowed or stopped, either in tissues or in whole bodies, the DNA damage from the much higher levels of ionizing radiation would continue. With any dormancy in space, the required shielding levels from ionizing radiation would be very high, probably 10x to 100x higher than “normal” for spacefarers who remain awake. Without that very high shielding levels, passengers would awaken (if at all), only to quickly die of too much un-repaired radiation damage to their cellular genomes.

Last edited 8 months ago by joelobryan
Michael S. Kelly
Reply to  Joel O'Bryan
January 24, 2021 8:38 pm

One of the advantages of hibernation is that the person would be isolated in a small volume, which could be heavily shielded without adding the catastrophic dead weight of an extended shielded habitat. Further, a 1 g environment would be easier to establish – via centrifuge – for people in repose rather than people attempting to move about normally.

The real question is whether humans could adapt to the 1/6 g of the Moon or the 1/3 g of Mars. Colonization of those worlds depends on the answer.

For just the sake of exploration, I would gladly spend the rest of my years on Mars, even if it meant having fewer of those years than I might on Earth. But then, I’m 66, and don’t have many left on either…

Tom Abbott
Reply to  Michael S. Kelly
January 26, 2021 1:45 pm


A 2001: A Space Odyssey-type space station one mile in diameter when rotated around its center, at one revolution per minute, would produce artificial gravity inside the rim of the space station that is equivalent to gravity on the surface of the Earth.

If we had an access tunnel that connected one side of the rotating space station to the other side, and was situated so it passed through the center of the rotating space station, then a person could walk from the rim which is at one Earth gravity (1 g) towards the center, and you could experience any level of gravity from 1 g to near zero at the center. Put a habitat module at the 1/6 g position or the 1/3 g position and put people in them and you can duplicate the gravity situation on the Moon and Mars.

Julian Flood
January 25, 2021 2:05 am

Genetically engineer the trehalose gene into your sleepers. Then you can freeze dry them without damage. Reversing the process might be a bit difficult but [handwave handwave] and there you have your interstellar travellers.

I’ve an SF short, Boat of a Thousand Days, around this concept. It’s in one of my online shorts collections — anyone with Hollywood connections who manages to sell it to hot-shot producer can have ten percent.

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