How Space Travel Affects the Human Body

What challenges does the human body face in space? For over 50 years, NASA’s Human Research Program (HRP) has explored how space travel impacts the human body, paving the way for the future of space travel. Despite substantial research, many unknowns exist about the human body’s challenges during extended space travel.

Radiation exposure is a significant concern after being in space for long periods. Earth has a magnetic field that provides natural protection, but only if you are in the atmosphere. Still, space exposes crews to elevated radiation levels from particles trapped in Earth’s magnetic field, solar energetic particles, and galactic cosmic rays (NASA, 2024). These exposures could lead to both short- and long-term health consequences, including cancer and degenerative diseases. NASA is actively improving shielding, real-time radiation monitoring, and developing procedures to mitigate radiation effects on missions and Earth. For instance, they use advanced materials and technologies to enhance spacecraft shielding, and they have systems in place to monitor radiation levels in real-time during space missions (NASA, 2024). NASA collaborates with medical and scientific experts to develop countermeasures, such as drugs and dietary supplements, to protect astronauts from radiation exposure. NASA also uses cosmic rays in ground-based experiments to simulate space radiation and better understand the radiation risks astronauts face in space. This is crucial because it allows researchers to develop and test countermeasures to protect astronauts from harmful radiation. By replicating the space radiation environment on Earth, scientists can study its effects on biological systems and validate protective strategies before astronauts embark on their missions. 

Another effect comes from isolation and confinement during space missions, as they can create psychological and social challenges. The limited space and close-quarter living can affect mental health, team dynamics, and morale. To combat this, NASA has introduced innovative tools such as sleep monitors, LED (light-emitting diode) lighting systems to help regulate circadian rhythms, and self-assessment vigilance tests to counter these effects. (NASA, 2024). Additionally, virtual reality for relaxation and activities such as maintaining space gardens is beneficial for mental well-being. This helps because training focusing on communication and cross-cultural understanding further aids astronauts in coping with the stresses of long-term mission isolation.

By addressing physical and mental health challenges, NASA aims to ensure astronauts can thrive and complete their missions safely and effectively. Factors like noise exposure during launch, flight, and landing can lead to hearing loss, and the absence of standing causes the soles of the feet to lose calluses, becoming softer and more sensitive to pressure. Astronauts at the International Space Station (ISS) develop calluses on the tops of their feet due to the frequent use of footholds. Additionally, the confined and controlled environment of the ISS can lead to the growth of microbes on surfaces and astronauts’ skin. This microbial growth and a potentially weakened immune system in space can cause skin irritation, rashes, or infections. Maintaining hygiene and regularly cleaning the living space is essential to mitigate these issues and ensure the health and comfort of astronauts (Baylor College Of Medicine, 2023). To combat noise exposure, which can lead to hearing loss, space organizations like NASA have implemented strict acoustic guidelines for the ISS, limiting continuous noise levels to 72 dBA during work periods. The 72 dBA limit set by NASA on the ISS measures sound intensity in decibels adjusted for the sensitivity of human hearing (dBA). This level protects astronauts from potential hearing damage from prolonged noise exposure (NASA, 2023). For context, 72 dBA is roughly equivalent to the noise level of a busy office or a quiet vacuum cleaner, which is loud enough to be noticeable but not excessively harmful over short periods. Measures include using acoustic dosimeters (devices used to measure and monitor noise exposure over time), improving equipment insulation, and installing quieter ventilation systems​. To mitigate hearing loss from noise during launch and flight, NASA’s Acoustics Office focuses on reducing sound at its source and using sound-dampening materials in spacecraft design (NASA, 2023).

The distance from Earth is another major challenge for space travel, particularly for missions that venture beyond low orbit, 1,200 miles above Earth (NASA, 2024). While the ISS orbits at a height of just 240 miles, Mars is about 140 million miles away, leading to communication delays of up to 22 minutes for messages sent one way. This vast distance necessitates astronauts to be exceptionally self-reliant regarding medical procedures and problem-solving. To equip them for these challenges, NASA provides training in various skills, including how to create IV solutions and perform ultrasounds to assess organ health. Additionally, advanced tools and the potential use of artificial intelligence are being explored to aid real-time medical assistance decision-making.

Adjusting to different gravity environments adds further complications. The spacecraft’s harsh and confined environment presents risks such as changes in microbial behavior and increased stress hormone levels, which can weaken the immune system. Missions to Mars will involve experiencing weightlessness during transit, adapting to Mars’ one-third gravity, and eventually returning to Earth’s full gravity. These changes can influence coordination, muscle strength, and bone density. Extended time in microgravity (such as on the ISS) can lead to fluid shifts that may affect vision and increase the likelihood of kidney stones. While these effects are temporary, they are still dangerous if not tended to correctly. To mitigate these risks, rigorous exercise routines, compression garments, and continuous medical monitoring are implemented to promote bone and muscle health (JAXA n.d.).

Finally, NASA implements thorough air quality monitoring, microbial assessments, and sanitation protocols to safeguard astronaut health. Preventative strategies, including pre-mission quarantines and flu vaccinations, further enhance crew protection (NASA, 2023).

As NASA prepares for its Artemis mission to the Moon in September 2025, these efforts will provide critical data to help prepare for an even more ambitious Mars expedition. Through ongoing research and technological innovation, NASA is laying the groundwork for a safe and sustainable future in deep space exploration.

References

Baylor College of Medicine. www.bcm.edu/academic-centers/space-medicine/translational-research-institute/space-health-resources/how-the-body-changes-in-space.

GCELT. 4 Oct. 2024, gcelt.org/is-72db-loud-a-comprehensive-guide-to-decibel-levels-in-everyday-life/?form=MG0AV3.

JAXA. 2021, humans-in-space.jaxa.jp/en/life/health-in-space/body-impact/#:~:text=Bones%20and%20muscles%20weaken,muscles%20of%20your%20lower%20body. Accessed 21 Nov. 2024.

NASA. 7 Apr. 2024, www.nasa.gov/humans-in-space/leo-economy-frequently-asked-questions/#:~:text=Low%20Earth%20orbit%20(LEO)%20encompasses,(2%2C000%20km)%20or%20less. Accessed 21 Nov. 2024.

NASA. 2 Feb. 2021, www.nasa.gov/humans-in-space/the-human-body-in-space/. Accessed 21 Nov. 2024.

NASA. 23 Jan. 2023, www.nasa.gov/humans-in-space/experiments-to-unlock-how-human-bodies-react-to-long-space-journeys/.

NASA. 28 June 2023, www.nasa.gov/general/galactic-cosmic-ray-simulator-brings-space-down-to-earth/?form=MG0AV3.