State of Anabiosis for Astronauts in Long-Duration Interplanetary Flights: Science Fiction or Future Medicine?

The concept of putting astronauts into a state of artificial anabiosis (or stasis) for multi-month or multi-year interplanetary missions has long moved from the pages of science fiction to serious research programs by NASA, the European Space Agency (ESA), and private companies (such as SpaceX). This idea is no longer seen as a plot device but as a potentially decisive technology for manned missions to Mars and other planets, allowing to overcome key physiological, psychological, and logistical barriers.

1. Technological and Medical Challenges of Long-Duration Flights.

Traveling to Mars under the classic scenario with an active crew takes 6-9 months one way. This creates a complex of problems:

Resource consumption: The crew consumes oxygen, water, food, generates waste. For a long-duration mission, this requires an enormous mass of cargo, making it economically and technically unfeasible.

Body degradation in weightlessness: Despite the physical exercise system, astronauts develop muscle atrophy, demineralization of bones (up to 1-2% per month), cardiovascular changes, and vision impairments.

Psychological stress: Long-term stay in a confined space, monotony, removal from Earth, social isolation, and potential interpersonal conflicts pose a serious risk to mental health.

Radiation exposure: In deep space, outside the protection of Earth's magnetosphere, the crew is exposed to galactic cosmic rays and solar proton events, increasing the risks of oncological diseases and CNS damage.

The state of controlled stasis theoretically can mitigate all these problems.

2. Prototypes in Nature: Hibernation and Torpor.

Scientists are not inventing anabiosis from scratch but strive to reproduce and improve mechanisms that exist in nature:

True hibernation in squirrels, ground squirrels, and bats: radical reduction of metabolism by 85-99%, body temperature to levels close to zero, heart rate and breathing rate. The key drawback is the cycles of spontaneous awakenings, energy-intensive for the body.

Winter sleep in bears: Less deep but longer (up to 6 months) state with moderate reduction in body temperature and metabolism, without food, drinking, and excretion of waste, maintaining muscle and bone mass due to unique biochemical adaptations (urea recycling).

Torpor (oцепенение) in hummingbirds and small mammals: short-term daily reduction in temperature and metabolism to save energy.

The ideal prototype for humans is the bear's state, as more manageable and safe for a large mammal.

3. Technologies of Induced Stasis: Main Approaches.

Modern research focuses on several directions:

Pharmacological hibernation: Search and synthesis of substances capable of "switching" human metabolism to a conservation mode. The study of hydrogen sulfide (H2S) and adenosine, which can induce a state of torpor in animals, is considered promising. In 2005, American scientists were able to induce reversible metabolic anabiosis in mice by inhaling air with a small addition of hydrogen sulfide, reducing oxygen consumption by 90%.

Therapeutic hypothermia (targeted controlled cooling): This is an existing clinical practice used after cardiac arrest or head and brain injuries to protect the brain. The body temperature of the patient is reduced to 32-34°C for several days. For space stasis, much more prolonged and deeper cooling (up to 32°C, and potentially below) with the use of complex external heat exchange and monitoring systems will be required.

Stimulation of hibernation centers in the brain: In 2020, Japanese scientists from the University of Tsukuba, by stimulating certain neurons (Q neurons) in the hypothalamus of mice, induced a state similar to hibernation in them for several days with reversible reduction in body temperature and metabolism. This breakthrough discovery indicates the possibility of direct neural control of this state.

Interesting fact: In 2014, SpaceWorks Enterprises received a grant from NASA to develop the concept of "torpor for Mars flight" (Torpor Inducing Transfer Habitat). Their project proposes to put the crew into a state of therapeutic hypothermia (32-34°C) for 14-day cycles with short periods of awakening for food intake and system checks. According to calculations, this could reduce the mass of the spacecraft by 30-50% due to the reduction in life support volume.

4. Advantages and Unresolved Issues.

Advantages of stasis:

Reduction of crew needs: A significant reduction in resource consumption, minimalization of waste.

Protection from weightlessness: In a state of hypothermia and reduced metabolism, the processes of muscle and bone atrophy should slow down significantly.

Reduction of radiation risk: Metabolically inactive cells are less susceptible to radiation damage.

Resolution of psychological issues: Time flies subjectively for the crew, the stress from isolation is minimized.

Critical Unresolved Issues:

Long-term muscle atrophy and osteoporosis: Even in stasis, these processes, although slowed down, will progress. Technologies for muscle stimulation in a unconscious state are needed.

Nutrition and hydration: How to deliver nutrients and maintain water-electrolyte balance? Options for complete parenteral (intravenous) nutrition or periodic awakenings are being considered.

Risks of thrombosis and infections: The risk of thrombosis and immunosuppression increases significantly in conditions of hypothermia and immobility.

Long-term effects on the brain: Are there irreversible cognitive impairments after months in a hypometabolic state? The protective effect of hypothermia for the brain is known, but not studied at such scales.

Reliability of systems: A technical failure of the life support system of the stasis capsule will be fatal. Absolutely reliable, duplicated systems with artificial intelligence for monitoring are required.

Conclusion.

The state of anabiosis for astronauts is no longer pure science fiction but a multidisciplinary scientific and technical task of extreme complexity. Its solution lies at the intersection of neurobiology, cryobiology, life support systems, and space engineering. Although practical implementation is still decades away, the first steps have already been made. Success in this area will not only be a breakthrough in cosmonautics but also the greatest achievement in medicine, capable of saving lives on Earth by managing metabolism in critical states. Pioneers here will not only be engineers and astronauts but also biologists who have studied the sleeping bear in the den and the squirrel in the frozen burrow for years.

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