Astronauts return from space with big physical changes
Muscle atrophy
In the microgravity environment of space, muscles do not need to support the body’s weight in the way that they do on Earth. If you were to travel to space, you would find your muscle fibers weakening due to muscle atrophy. All astronauts are subject to rigorous exercise regimes to mitigate these effects.
Fluid redistribution
In microgravity, bodily fluids shift upwards towards the head, which causes puffiness in the face, nasal congestion, and increased intracranial pressure.
Peripheral edema
The head isn’t the only place where fluid goes. While in space, bodily fluid flows to other extremities like the hands and feet, causing them to swell. This condition is known as peripheral edema, and can be truly uncomfortable.
Cardiovascular deconditioning
The heart and blood vessels also undergo changes in space. If regular exercise is not maintained, the heart may shrink, and the efficiency of blood circulation can decrease, leading to potential cardiovascular problems.
Radiation exposure
Space travel exposes astronauts to higher levels of cosmic radiation than on Earth, since our atmosphere protects us from this. Higher radiation increases the risk of cancer and acute radiation syndrome.
Immune system reactivation
Interestingly, spaceflight can also reactivate dormant viruses in the body (such as the herpes virus) due to changes in the immune system. If treatment measures aren’t put in place, this reactivation can lead to outbreaks of conditions like shingles.
Vestibular system adaptations
The human vestibular system, which helps maintain balance and spatial orientation, is extremely disrupted in microgravity, which can result in space motion sickness and impair an astronaut’s balance and orientation, especially upon reentry to Earth’s gravity.
Dental health issues
The unique conditions of space can even impact dental health. Changes in saliva production, diet, and oral hygiene routines can increase the risk of dental problems, which means that astronauts must maintain proper dental care and preventive measures in space.
Microbial changes
The confined environment of a spacecraft can alter the microbiome of both astronauts and their surroundings. This change can increase the risk of infections and impact overall health, which means that there are stringent protocols on spacecraft to ensure proper hygiene.
Decompression sickness
Astronauts may face the risk of decompression sickness–which can cause neurological issues–during spacewalks due to changes in atmospheric pressure between the outside and inside of the spacecraft. Space agencies have put proper protocols in place to prevent this.
Weight loss
Space missions often result in a loss of body mass due to changes in metabolism and diet, not to mention the lack of gravity that causes muscle to weaken.
Hearing loss
Sometimes, it isn’t microgravity that causes health issues for astronauts. The increased noise levels within a space craft can lead to hearing loss if a person is exposed to it for a prolonged period.
Decreased lung function
Changes in gravity can also have an effect on the body’s respiratory mechanics, which is why spacecraft is generically equipped with state-of-the-art air quality control systems.
