The Human Body in Space: Pushing the Limits of Physiological Adaptation

The United States' announcement of its "Vision for Space Exploration" in 2004 paved the way for Nasa's Artemis program to return astronauts to the Moon and eventually send humans to Mars. As astronomers prepare for the long-duration spaceflight, physiologists are working to understand the effects of space on the human body. Research has revealed the "space exposome," a comprehensive map of everything that stresses the human body in space, from radiation and weightlessness to disrupted sleep and isolation. By studying these effects, scientists aim to uncover the "space integrome," the complete network of physiological connections that keeps an astronaut alive in extreme environments.

Key Takeaways:

• The human body is pushed to its limits in space, experiencing radiation, isolation, weightlessness, and confinement, which create stresses unlike any encountered by astronauts before.
• Physiologists are mapping the "space exposome," a comprehensive map of everything that stresses the human body in space, to understand how these factors combine to affect the body.
• Each factor is harmful on its own, but combined they amplify one another, pushing the body to its limits and revealing how it truly works.
• The "space integrome" is emerging, revealing the complete network of physiological connections that keeps an astronaut alive in the most extreme environment known.
• The body as a biosphere is connected through a complex network of physiological systems, influencing each other in continuous biological feedback loops.
• Astronauts' lives depend on the compatibility of their spacesuits, which shield the body from the lethal physics of space, protecting against vacuum, radiation, and extreme temperatures.
• Digital physiology is enabling real-time tracking of heart rate, brain activity, and chemical changes in the blood, allowing scientists to simulate how the body will react to stressors such as radiation or microgravity.
• Research on spaceflight is already helping shapes treatments for osteoporosis, cardiovascular disease, and age-related muscle loss, and improving our understanding of intracranial hypertension and mental health.
• The ultimate test of our biology will be Mars, where every gram of muscle preserved, every synapse protected, and every cell repaired will be a triumph of physiology.

Statistics:

• Astronauts lose 1-1.5% of their bone mass each month in microgravity.
• Astronauts undergo intensive resistance workouts and sessions in lower-body negative pressure chambers to maintain healthy circulation.
• There are over 2 hours of "countermeasures" per day to counteract the effects of microgravity.
• Galatic cosmic rays can cause DNA damage and chromosomal rearrangements that raise the risk of cancer.
• The International Space Station crew spends over 2 hours a day performing "countermeasures".
• Astronauts eat carefully planned diets to stabilise their metabolism.

Sources:

• Damian Bailey, Professor of Physiology and Biochemistry, University of South Wales
• European Space Agency, CC BY-NC-ND (http://creativecommons.org/licenses/by-nc-nd/4.0/)
• Angelique Van Ombergen, Chief Exploration Scientist for the Directorate of Human and Robotic Exploration at the European Space Agency
• The Conversation -- UK