Fall asleep for decades: man and hibernation
Now this sounds like the beginning of a science fiction novel - and indeed, the idea of "hibernation" was first voiced by science fiction writers. In their works, the artificial slowdown of metabolism with the ability to restart all biological processes at the right time has become one of the key technologies for long manned expeditions into deep space. In the fictional universe of the “Alien”, the period of its appearance is called exactly - May 20, 2028. This date looks quite likely for our real world: work is already underway.
In winter and in space
Even if bacterial spores and plant seeds are not taken into account, suspended animation is widespread in nature. Many mammals and birds are able to lower body temperature and slow down metabolism, falling into a state of torpor. As a rule, this allows them to survive unfavorable periods, be it daytime heat, night darkness or winter cold. Small rodents and almost a hundred species of birds, from hummingbirds and swifts to rather large kookabar kingfishers, “turn off” for 4–16 hours a day, most often at night.
Larger animals, ranging from hedgehogs to bears, plunge into hibernation for one or several months of winter (hibernation) or summer (estivation). This is usually due to a lack of food resources, however, certain species fall into torpor for other purposes. So, some bats mate in the fall, and then freeze in a daze in a cold cave. Only in the spring, when ovulation begins in females, sperm that have passed the winter fertilize them, and babies are born. Hibernation is the most famous type of suspended animation, and, apparently, that's why science fiction called it “space suspended animation”.
In reality, until very recently, it was believed that primates, including humans, are incapable of such hibernation. Only in 2004 it was discovered that Madagascan thick-tailed lemurs can remain in suspended animation for up to seven months a year. This (as well as the fact that such large animals as bears have mastered hibernation) suggests that people can also be introduced into torpor. Fortunately, the history of medicine knows several such cases. The most impressive example is the story of Mitsutaki Utikoshi, who, while spending time with friends in the mountains, lagged behind the company.
The poor thing quickly got lost, earned a pelvic fracture and disconnected from unbearable pain. Only after 24 days, the climber discovered his still unconscious body: the temperature dropped to 22 ° C, the pulse was almost not traced, the metabolism was practically at zero. However, Utikoshi survived and subsequently fully recovered. This incident caused a heated discussion among experts, which was also closely watched by the founder of the American startup SpaceWorks Enterprises John Bradford.
Education: Georgia Institute of Technology
Jobs: SpaceWorks Enterprises, Inc., President and CEO
“I am a big fan of science fiction, and I am always interested in the prospect of turning it into reality. But first of all, I am a space engineer, busy with the problem of manned flights to Mars and other bodies of the solar system. From both points of view, the hibernation of the crew is a suitable option. ”
Being engaged in technologies of manned space flights to other planets and bodies of the Solar system, the developer was well aware that the duration of such expeditions remains one of the most serious problems. Cassini probe reached Saturn seven years, New Horizons reached Pluto in 9.5. If we needed to supply the crew with water, oxygen and food for this entire period, such flights would hardly have taken place at all. And if we are really going to send people to other planets, we can hardly do without hibernation.
Wheel of dreams
SpaceWorks Enterprises engineers presented the technical design of the “space torpor system” in 2014. Unlike fantastic spaceships with straight rows of individual capsules, the concept uses a single cylindrical chamber, designed to accommodate several crew members. The robotic manipulators located in the center will automatically carry out the necessary injections, install catheters and breathing tubes, and monitor the status of their wards. It is assumed that the camera will rotate, creating artificial gravity, necessary to maintain the tone of the musculoskeletal system, blood vessels, and other body systems.
However, over such long periods, even the action of artificial attraction may not be enough. Therefore, the muscles of the astronauts will be additionally stimulated by weak electricity - since such therapy has already been developed on Earth and is used to prevent muscle atrophy in paralyzed patients. In addition, when you need to remove the crew from hibernation, you can make the muscles contract with increased activity, making it easier to warm up the body and wake up.
But to begin with, suspended animation will need to be induced, and this can be done in two ways: thermal and chemical. Therapeutic hypothermia is used in medicine, for example, for cardiac arrest: strong cooling and slowing down metabolism can to some extent protect the brain from quick and irreversible damage caused by a lack of oxygen.
Introducing a catheter into the large femoral artery, blood is pumped through the refrigerator, lowering the body temperature to 32−34 ° C for a day or even several. For future flights, such an operation can be carried out in a more gentle way, using heat-removing gel mats and a cooling spray, which can be supplied through breathing tubes supplied to the nasopharynx. But nutrition, as in patients, will have to be administered intravenously, along with drugs to prevent natural cold tremors.
Cold and injections
In such an environment, the medical risks are most unexpected. Say, to prevent blood clots, astronauts will need to inject heparin - but then any careless manipulation of catheters or needles can result in dangerous bleeding. In addition, hypothermia contributes to the development of infectious diseases, so the crew will have to administer antibiotics and antiviral drugs from time to time, and long-term complete parenteral (intravenous) nutrition can lead to liver failure. Such problems can be called more than a dozen, and so far there is no solution to them.
However, the chemical methods for inducing suspended animation are worked out even worse than thermal. Cooling allows experimenters to immerse large animals such as dogs and pigs into the torpor - and without consequences to return to life. The use of hydrogen sulfide vapors and other chemicals is limited to much smaller rodents, mice and gophers. However, no one ever sent people to sleep for months or years. Three-plus weeks that Mitsutaka Utikoshi spent “off” remain a record. Even in nature, mammals remain in this state for more than 8–9 months, and it is still unclear whether it is possible to count on the dates necessary for flights.