This might remind you of the Interstellar movie, but wait it is not fictional! Yes, astronauts age slowly when they are in space.
As Sunita Williams and Barry ‘Butch’ Wilmore prepare to return to the earth after their prolonged stay in space, everyone’s concerned about how earth’s gravity will welcome them. Both the astronauts have been living in microgravity for the last nine months and sudden exposure to gravity might affect their health.
Astronauts on space stations age a bit slower than the rest of us. The European Space Agency had said this to a post on X. “Funny you should say that… astronauts actually age more slowly in orbit than on Earth (because of the Station’s speed and time dilation due to special relativity) BUT the effect is very small – after spending six months on the ISS, astronauts have aged about 0.005 seconds less than the rest of us,” the agency had replied to a post.
How will earth’s gravity act on Sunita Williams and Barry Wilmore’s health after they return to earth
NASA’s famous twins study sheds more light on how the human body reacts in space. For the twins’ study, NASA compared retired astronaut Scott Kelly while he was in space, to his identical twin brother, retired astronaut Mark Kelly, who remained on Earth.
NASA found that Scott, who stayed in space, experienced a change in telomere length; telomeres protect our chromosomes and tend to get shorter as we age. Scott had some changes in gene expression, which changed after returning to the earth but a small subset of it persisted after six months.
“Scott’s cognitive performance (such as mental alertness, spatial orientation, recognition of emotions) remained largely unchanged during his time in space, and relative to Mark on the ground. This is important as it suggests that astronauts can maintain high levels of cognitive performance for longer durations in space. However, a more pronounced decrease in speed and accuracy was observed after he landed and persisted for six-months,” NASA’s findings about the cognitive health of astronauts say.
“His bone breakdown and bone reformation cycle occurred at a faster rate during the first six months he was in space, but slowed down in the second half when his exercise volume was lower,” NASA found.
In space, astronauts experience thickening of the carotid artery, which is either of the two large tubes in the neck (arteries) that carry blood to the head. Spaceflight conditions can elevate oxidative stress and inflammatory responses, leading to vascular endothelial dysfunction and structural changes in arteries which return to preflight levels.
“By imaging the carotid artery using ultrasound and from sampling blood and urine, the researchers found indications of inflammation and carotid artery wall thickening in Scott during and immediately after his mission,” the NASA report says.
“NASA recognizes the Twins Study as the first study of its kind to compare molecular profiles of identical twin astronauts, and a methodology to integrate research from the ten teams was established. Because identical twins share the same genetic makeup, twin studies provide a way for scientists to explore how our health is impacted by the environment around us, independent of the physical variations that naturally occur between most of us as individuals,” NASA had said about this study.
In microgravity, the lack of gravitational force leads to reduced muscle use, resulting in muscle atrophy. Astronauts can experience up to a 20% loss in muscle mass during missions lasting between five to eleven days. This reduction in muscle strength poses challenges upon return to Earth’s gravity, affecting posture and movement.
Long-duration spaceflight has been linked to visual acuity issues, such as optic disc edema and globe flattening. These changes are associated with increased intracranial pressure in microgravity, potentially leading to long-term vision problems.
The sterile environment of the ISS may lack beneficial microbes essential for a healthy immune system. This absence can lead to immune dysregulation, making astronauts more susceptible to infections and allergic reactions upon return.
What medical tests astronauts undergo after returning to the earth?
Dual-energy X-ray absorptiometry (DEXA) scans measure bone mineral density to detect bone loss resulting from prolonged weightlessness.
Assessments of muscle strength and endurance identify atrophy and functional impairments due to reduced muscle use in microgravity.
Echocardiograms and MRIs evaluate heart structure and function, monitoring changes such as cardiac atrophy or altered function.
Postural stability assessments detect impairments in balance and coordination due to vestibular system adaptations in microgravity.
Eye movement tests identify spaceflight-associated neuro-ocular syndrome (SANS), which can affect vision.
Evaluations of memory, attention, and executive function identify cognitive changes resulting from extended space missions.
When are Sunita Williams, Butch Wilmore returning to earth?
Sunita Williams and Butch Wilmore are expected to return on March 19 or 20. As of December 2024, plans were in place for Williams and Wilmore to return to Earth no earlier than late March 2025 on a new SpaceX Dragon capsule.