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Impact of Extended Space Missions on Astronaut Health
On March 14, NASA astronauts Suni Williams and Butch Wilmore concluded a mission that was intended to last just over a week but ultimately extended to nine months. Initially part of the first crewed test flight for Elon Musk’s Starliner to the International Space Station (ISS), their return was delayed due to serious issues, including helium leaks and problems with the propulsion system, prompting NASA to opt for an empty return spacecraft instead.
Unlike a cinematic scenario where travelers find themselves in bureaucratic limbo, the reality of prolonged space missions presents significant health risks to astronauts. The extended duration in space raises concerns about the physiological effects on their bodies, which can be profound and lasting.
The initial launch experience subjects astronauts to intense g-forces, described by former NASA astronaut Dr. Sandy Magnus as akin to a “70-pound gorilla” pressing on their chests. This sensation precedes a relative absence of gravity once in orbit, where astronauts spend the majority of their time in a weightless environment.
The absence of gravity affects the body in numerous ways, from vision deterioration to genetic mutations, as well as unique physical sensations, including adjustments to fabric on skin. “Space causes an accelerated model for disease and aging,” explained Dr. Afshin Beheshti, director of the Center for Space Biomedicine. The physiological stressors present in space may heighten risks associated with aging-related health conditions.
Recently, four astronauts launched to the ISS, scheduled to return Williams and Wilmore to Earth. As of their lengthy nine-month stay, they join a small group of eight astronauts who have spent over 200 days in space, a record held by NASA astronaut Frank Rubio at 371 days. Evidence suggests they will face a lengthy recovery process upon returning.
Reflecting on their upcoming return, Wilmore remarked in a CNN interview about the re-acclimation process, noting, “Even to lift a pencil we will feel the weight. That’s the transition back.”
On Earth, gravitational forces stimulate bone maintenance through osteoblast activity, crucial for bone density. In microgravity, however, astronauts can experience approximately 1% bone density loss per month without sufficient countermeasures.
Despite engaging in daily exercise, the astronauts will likely face some degree of bone density loss. Following their landing, they will enter a 45-day recovery program supervised by medical professionals, as outlined by NASA’s Lead Flight Surgeon Dr. Stevan Gilmore.
“They work closely with trainers, dedicating two hours daily to restore their pre-flight health and fitness baseline,” Gilmore indicated. “Generally, most crew members’ physiological systems recover within this timeframe.”
In a related case, astronaut Scott Kelly, who spent a year aboard the ISS, faced extensive physical rehabilitation, needing to relearn basic movements like walking. Dr. Beheshti discussed Kelly’s experience, highlighting the significant recovery process following such a prolonged mission.
Kelly was a participant in NASA’s Twin Study, in which components of his health were compared to those of his twin brother, Sen. Mark Kelly, who remained on Earth. The findings revealed that Scott exhibited more heart disease indicators upon return and experienced a condition known as Spaceflight Associated Neuro-ocular Syndrome (SANS). This condition is marked by fluid redistribution affecting vision due to the absence of gravity.
Post-mission, Scott Kelly required corrective lenses, a change from his pre-mission eyesight noting a significant alteration in his vision following extended space exposure.
Sleep disturbances and altered eating patterns also affect astronauts in space. Research has shown that cognitive processing speeds may decline, albeit returning to baseline after they come back to Earth. Some studies examining civilian space passengers revealed similar cognitive impacts.
“Some individuals perform better in space and exhibit increased focus,” noted Dr. Chris Mason from Weill Cornell Medicine, “while others may experience slowdowns in cognitive functions.” Varied outcomes suggest individual differences significantly influence astronauts’ adaptations to their environments.
In addition, exposure to heightened radiation levels beyond Earth can lead to cellular damage, including increased risks of heart disease and cancer, among other degenerative conditions impacting eye health. Astronauts experience radiation exposure on the ISS significantly higher than on Earth, accumulating radiation equivalent to one year of Earth exposure for every week spent in orbit.
This radiation is known to impair mitochondrial function, thus disrupting energy production vital for cellular health. Mitochondria play crucial roles in both energy metabolism and the immune response, indicating that prolonged exposure in space can have extensive effects.
Recent studies, including one published in Communications Biology, found that astronauts exhibited longer telomeres, potentially tied to both rejuvenating effects and cancer risks. Additionally, some immune-related genes are activated during spaceflight as a response to environmental stress.
“Anti-inflammatory markers get activated in almost every mission, showcasing the body’s adaptive responses to challenges in space,” Mason remarked, emphasizing the intricate nature of astronaut health.
While the majority of physiological changes return to normal within weeks of returning to Earth, the depth of individual variability reinforces the need for ongoing research into astronaut health risks.
Efforts to safeguard astronauts from radiation effects are ongoing; scientists are exploring potential breakthroughs, including small molecules that may enhance resistance, which could extend beyond space missions to benefit patients undergoing radiation treatments for cancer.
Research into artificial hibernation techniques, similar to phenomena observed in winter mammals, may also offer ways to diminish radiation-related damage. Preliminary findings indicate that inducing a state of dormancy could mitigate some of the adverse effects associated with radiation exposure.
As the era of commercial space travel grows, spearheaded by innovators like Elon Musk, these health challenges underscore the critical understanding required to support human life in the cosmos.
Though their extra time in space may have been unexpected, Williams and Wilmore’s years of preparation reflect their commitment to the mission. They seem unfazed by the extended duration, with Williams noting in her CNN interview an anticipation of how odd it will feel to adjust back to Earth, stating, “I think both of us will be a little bit sad when that feeling of space leaves us after about 24 hours.”
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