The Truth About Cryosleep
Is it possible to dream our way to new stars?
In one of the darkest science fiction stories I’ve ever read, the crew of a space station comes upon a derelict ship with which they struggle to communicate. Nobody aboard the old vessel responds to the crew’s messages. The spaceship is a crowded, rusty hunk of metal poorly built out of spare parts and with winding tubes slithering along the ceiling and throughout the hallways as if it were a nesting ground for tattered and hungry snakes. After the space station’s crew docks on the vessel and attempts to find any people onboard, they come to a cryosleep chamber just beyond a damaged bulkhead. In the cryosleep chamber the remaining people are found — male twins and a female, sleeping amongst the hissing pipes and disorder of their ship. Vitals are displayed on terminals connected to the cryobunks. It’s uncertain how long they’ve been asleep.
It’s only after the cryobunks are opened and the spaceship’s members are brought back to the station that the real astro-nightmare begins. It’s a violent, discomforting tale about the odds one crew faces when marooned out in interstellar waters.
The cryosleep chambers are something that’s seen repeatedly in the best science fiction stories — from adventurous tales like the Alien series to introspective masterpieces such as Interstellar and 2001: A Space Odyssey. When making long voyages to another planet it’d be dreamy to lay down and sleep, having onboard computers take care of all your body’s needs and then wake you up months or years later, never having aged a day and with your sanity fully intact. These chambers are like glimpses of immortality for us. We can use them to fast forward on our journeys and extend our lives far beyond their original 80 or so years. As we begin considering manned missions to Mars and beyond, cryosleep is one of the most important technologies in ferrying humans from this planet to another.
One of their biggest advantages lies in reducing a mission’s mass by almost 50%. During the crew’s hibernation (or “torpor”) they wouldn’t need as much food, water, or oxygen compared to when they’re awake. Less mass means it’s less expensive to launch and the money can go to reinforcing the ship against radiation. States of hibernation have been shown to better naturally protect the body against radiation as it is. In addition, hibernating animals don’t suffer from weakened muscles and bones, another major concern in the low gravity of space travel. Cryosleep concepts by NASA and SpaceWorks include artificial gravity in the chambers where the astronauts will be asleep. These cryosleep rooms are called stasis chambers.
To induce something similar to hibernation in humans our body temperature must be lowered 8 degrees from its usual 98° F (36.6° C to 32° C). This cooling process is the key difference between hibernation and hypothermia. During hibernation the body accommodates the lower temperatures and naturally keeps itself cold. But the body fights this cold during hypothermia and it tries to raise the temperature back to normal, not without damage to the skin and nerves. A hypothermic body will shiver in attempt to warm itself back up. A hibernating body will not.
And it is possible to place people in a therapeutic hypothermic state. It’s a medical treatment that takes advantage of the fact that chemical reactions slow during lower temperatures.The patient’s body is cooled down using icepacks, intravenous solutions, coolants, and water pads. The slower heart rate and slower metabolism help people to recover from events like cardiac arrest. When put into this state of purposeful hypothermia there is also a reduced rate of brain damage in patients. Some doctors will use powerful drugs to try to suppress shivering, but cooled bodies can only be kept that way for 3 days at a time.
Hibernation in humans has, arguably, only occurred once.
In a picturesque autumn field in Japan’s Rokko Mountains, an injured man was able to survive 24 days without food or water. His body had gone into a mode of energy conservation that the doctors called “hibernation”. After being exposed to the the mountain’s sharp 50° F (10° C) weather, the man’s body was just 72° F (22° C) when found. Far below the temperature required to enter a state of torpor. After being taken to a hospital the man made a full recovery in the following days with the medical reports claiming that there was no permanent damage. His organs slowed, and his brain remained unharmed.
That is the ideal picture of cryosleep or, as it’s sometimes called, suspended animation. Except that suspended animation suggests something that isn’t necessarily true.
When the term “suspended animation” is used it implies that there’s an agelessness to the procedure. In our ambitious science fiction stories — such as the movie Passengers where travelers were placed in suspended animation for over 100 years — people go to sleep and are frozen in time. They awake looking just as young as when they went to sleep, regardless of how much time has passed. This isn’t something we can achieve with hibernation alone. While there is some evidence that animals which hibernate live longer than those that don’t, they still age all the same.
The only way to prevent aging and preserve a body in the flowery, springy midst of youth is for it to undergo vitrification. Any natural fluids are leached from the body and replaced with medical grade antifreeze that would protect the cells from the damage of freezing and crystallization. Some cryonics companies specialize in offering this service to the dead: they preserve and protect your body until it can be revived at a future date. The hope behind this is that we’ll become technologically advanced enough to reanimate dead bodies.
But this is why we will never be ageless during sleep. In order to preserve ourselves, we would already be dead.
Space agencies are looking to induce human hibernation for a few weeks at a time, after which crew members can wake up and take a small break before going back to sleep. These stacked periods of torpor will help them slumber most of the way to their destination while machines and attached catheters take care of nourishing the body and getting rid of waste. The preliminary studies will be made in pigs. Pigs don’t naturally hibernate but if scientists are able to induce it during the studies then there is hope for inducing it in humans as well, possibly for months at a time.
It’s an optimistic but slippery slope. Even with therapeutic hypothermia it’s not clear if there are any lasting side effects. People undergoing the treatment are already in bad health to begin with. Erratic heartbeats, blood clotting, impaired brain function, and an increased rate of infection are just a few of the risks involved with the procedure, though the negatives of not having cryosleep available during space travel seem just as dire: increased need for life-support resources, less protection from radiation, larger power consumption, and emotional and mental tension from the long journey. All this while confined in close quarters with other members of the crew. It’s a situation ripe for cabin fever.
When we think about confronting space travel we consider its enormity — it is so vast. The cosmos stretches on forever all around us as we hunker down away from the radiation which would corrupt our very cells. We imagine traveling out beside beauties like Saturn and then passing by true giants like billowing, great, swollen stars. But what about time which itself is an entity that can horrify and control us, showing us with its distinctive ticking of the seconds that it is the one with all the power? Time brings us to our destination and yet it itself is something to overcome.
It would help for us to get some sleep on this journey. Let’s slip into a world that we’ve imagined, a world on which time has far less of a hold.
