DEEP SPACE SLEEP

Hi-tech pods that allow human beings to hibernate for long-distance space travel are about to become a reality

On Oct. 7, 2006, Mitsutaka Uchikoshi left a barbecue on Mt. Rokko in western Japan, deciding to walk down the mountain rather than taking a cable car with his friends. He lost his way, slipped, broke his pelvis and, with nobody around to help, eventually lost consciousness. Twenty-four days later, a passing climber found Uchikoshi. His body temperature had fallen to 22 degrees Celsius (normal is around 37), his pulse was barely discernable, and his metabolism was almost at a standstill. But despite multiple organ failures and significant blood loss, with no food nor water, he survived somehow, and fully recovered.

Uchikoshi was declared the first documented case of human hibernation. His story instantly drew the attention of the medical community, which hoped it would give rise to new therapies.

Among those interested was John A. Bradford, president of Spaceworks, a US company developing technologies for space exploration based in Atlanta, Georgia. Bradford, however, didn’t want to develop treatments for medical conditions; he wanted to find a way to hibernate crews on long-distance spaceflights.

“I’m a big science fiction fan, so it was a little bit about making science fiction a reality,” says Bradford. “But first and foremost, I’m a space engineer working with manned missions to Mars and other destinations within our solar system on my mind. And from that perspective, human stasis makes a lot of sense.” If the crew is asleep, that makes reduces amount of food and life support systems needed, thus bringing down overall ship mass—and costs—significantly.

Bradford and his team focused their efforts on “therapeutic hypothermia”, a well-established procedure used in hospitals all over the world, performed on thousands of patients to treat cardiac arrest or traumatic brain injury. It amounts to slowly cooling the body to 32-34 C, usually one degree per hour, which slows down heart rate and lowers blood pressure to give medical teams more time to work on treating acute heart and brain issues. Typically, a patient stays in stasis for 2-4 days, though there have been instances where doctors chose to keep their patient in this state for as long as two weeks—without any complications. And the Uchikoshi case showed it’s possible to survive an even longer cooling procedure.

“Our goal is to get from days and weeks to months,” says Bradford, who says the medical equipment used for therapeutic hypothermia can easily be automated and made space-ready. It’s already small, low-powered, easy to use, and portable enough to be carried in ambulances.

Spaceworks’ stasis chamber will probably look much like they usually do in science fiction movies—with a few key differences. “Personal stasis pods have some advantages. You can control everyone’s ambient temperature individually. They also come in handy in case of breakdown or an emergency like pathogen,” says Bradford. But that sort of design would add lots of weight to the spaceship. That’s why Spaceworks’ engineers are leaning toward an open, shared stasis chamber. “There would be some robotic arms and monitoring systems taking care of [the passengers]. They’d have small transnasal tubes for the cooling and some warming systems as well, to bring them back from stasis,” says Bradford.

Spaceworks
An artist’s rendering of what Spaceworks’ human stasis pods would look like.

The real-world stasis will also differ from Hollywood visions in that the crew won’t sleep through the whole flight. Spaceworks’ team has interviewed several medical experts and most of them agree that shorter, repeat cycles of going in and out of stasis would be safer than a single, long-term cycle. One reason is that would ensure one crewmember would always be awake as a caretaker, taking his or her watch monitoring the spaceship’s systems and responding to emergencies. “So, for the near term—the next 20, 30, 40 years—we can work with something like two weeks’ stasis capability,” says Bradford.

But there are a few obstacles to overcome. Our bodies are not designed for low-gravity environments: Bones and muscles, relieved from their usual duty of supporting our weight, gradually lose mass up to the point where people become partially crippled. The heart, designed to pump blood up to the brain against the gravity, does its job a bit too well in space. That’s why astronauts suffer from increased intracranial blood pressure, which leads to vision impairment. One solution would be to build a spaceship with artificial gravity, but that’s probably prohibitively costly. Another is to make sure the crew exercises a lot, like those onboard the International Space Station do today. But a crew wouldn’t be able to exercise while in the stasis. Or would they?

“We have ideas how to exercise them,” says Bradford. One is called “neuromuscular electrical stimulation,” which entails sending small electrical impulses through the body, triggering muscles to contract. “There are very promising results in using this technique on comatose patients to prevent muscle atrophy,” Bradford says. In space, that could be accompanied by administering drugs to mitigate the effects of microgravity on bone mass.

As for increased intracranial pressure, therapeutic hypothermia is specifically used today as a countermeasure to that exact condition.

Spaceworks wants to start animal testing in 2018, then proceed to tests with healthy human subjects and, possibly, perform experiments onboard the ISS. But the team’s vision goes much further than just flying to Mars, or even to the Jupiter system. They are already thinking about how to support hundreds of passengers on an interstellar mission. Bradford believes it’s realistic to imagine a system that brings core body temperature down by a few degrees, metabolic rate by 50% to 70%, and extends the stasis period from weeks to months.

An artist's rendering of what Spaceworks' human stasis pods would look like.
Spaceworks human stasis system would use sleep cycles; some crewmembers would be asleep while others kept the ship running. (Spaceworks)

But what about those cryo-chambers in Hollywood’s vision of interstellar travel, that let space voyagers sleep for hundreds of years? After all, real deep space travel will take a least dozens of years, if not hundreds and thousands, right?

Well, Hollywood got it all wrong. The reality is way crazier.

“Our way to colonize the universe is open, and we don’t need fancy things defying known physics to do this,” says John Ellis, a physicist working at CERN in Geneva, Switzerland. As he told me at a conference back in 2015:

Einstein’s relativity makes that perfectly possible. Let’s take Alpha Centauri, a little more than 4.3 light years away from us. If only we could accelerate a spaceship to, say, 0.8 the speed of light, the time dilation would really kick in. The journey would last more than five years, as measured by clocks on Earth, but only few months, as measured by clocks onboard the spaceship. And the journey will get shorter for the crew, the closer they get to the speed of light. A few months of flight is all the future astronauts will need.

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