The ‘human’ barrier we must overcome for space travel

By Devanshi Saxena

Space is altogether a dangerous, unfriendly place. Besides being unwelcoming, it imposes upon a rigorous schedule on the astronauts with a carefully scripted high-tempo work routine. Daily exercise is also required to prevent degradation of muscles and bones during an astronaut’s stay in space. Quoting Star Trek’s legendary doctor, Leonard ‘Bones’ McCoy, “Space is disease and danger, wrapped in darkness and silence.” On the positive side, however, NASA’s Human Research Program has been diligently looking into the effects of space travel on the human body and possible ways to overcome the negative after-effects of space travel.

Effects of space travel on the human body

As elucidated by Kevin Fong, founder of the Centre for Altitude, Space and Extreme Environment Medicine at University College London and author of “Extremes: Life Death and the Limits of the Human Body: “Space isn’t an environment we’ve evolved to survive in. It’s wrong to conceive space travel as this long-haul flight with some floating around thrown in – it’s an expedition, like any other expedition.” It is interesting to delve deeper into the intricacies of what happens when human bodies are pushed to the limit, and what are the most reliable methods to deal with it.

One of the first things that astronauts complain about is nausea or vomiting due to lack of gravity. Balance, coordination and spatial orientation are negatively affected by the lack of gravity which impacts the sensitive inner ear. Inability to track moving objects as a result of disorientation proves detrimental to essential piloting skills. When in micro gravity, the body fluids are pushed to the upper part of the body, unopposed by gravity, leading to swelling of tissues in the head. A recent study undertaken by the researchers at the University of Texas suggests that spaceflight may lead to optic nerve swelling, retinal changes, changes in the shape of the eye with an increase in intracranial pressure. As the effect of gravity drips, it also leads to bone and muscle deterioration.

Struggling to adapt to artificial night times and arduous work shifts, astronauts’ circadian rhythms, and the biological clock is messed up which interferes with the sleep-wake cycle. In a set of studies conducted by NASA, it has been concluded that spaceflight has a detrimental effect on the immune system. Even more concerning is the harmful effect of cosmic radiations which in lethal doses may adversely affect the neurological functioning of the body making long-duration missions too dangerous.

Besides physical well-being, another very important aspect is the psychological health of the astronauts. The challenges posed by isolation and long-duration spaceflight are potent enough to render the victim powerless. Taking into account the dangers associated with stress and depression, the space agencies are diligently working in the areas of behavioral health training, improvements in communication technology and research to forestall any potential problems.

Paramount importance of an exercise regime

According to Don Hagan, director of exercise physiology at Johnson Space Centre, regular exercise is of utmost priority in space, and two and a half hours each day are devoted to fitness. Regular exercise becomes all the more important in space as the bones and muscles of the astronauts start degenerating in the absence of any specialized workout. Bone and muscle loss implies decreased size and strength which can inhibit an astronaut’s potential and vigor to work for long hours in the space station. Also, in case of an emergency, it is important for astronauts to remain fit in order to get out of the Space Shuttle quickly. It has been proven through researches that exercise increases the amount of plasma in the body thus, making more red blood cells for oxygen transportation. In micro gravity, where fluids such as plasma are lost throughout the body, a systematic workout routine is the only way out.

Microgravity also brings about “orthostatic intolerance.” With no gravity and less blood volume, astronauts are more prone to fainting. Here, exercise can help increase blood volume and circulation that helps to prevent blackouts and disorientation.

The main components of a workout regime

In space, three pieces of exercise equipment are used by astronauts, each designated for a specific purpose.  

Cycle Ergometer: This is like a bicycle, and the main activity is pedaling. It is used to keep a tab on heart rate while measuring the amount of work done.

Treadmill: Walking or jogging on the treadmill is akin to walking on Earth. It is the most efficient way to keep bones and muscles healthy. Harnesses are attached to the astronauts to hold them to the walking surface in a zero-gravity environment.

Resistance Exercise Device (RED): To use it, astronauts pull and twist the cords attached to the pulleys. The RED is used for a total body workout. From squats and bending exercises for the legs to arm exercises and heel raises, RED is an integral part of an astronaut’s routine.

Russians and Americans have different exercise routines on the Space Station. But maintaining the health of their astronauts and cosmonauts in the physically and psychologically taxing conditions of space is the prime objective of all the meticulously designed exercise regimens.

The challenges of a post space travel recovery

Although floating in micro gravity may appear harmless at the first glance, yet the rigors of spaceflight leave a lasting mark on the health which is never positive in any sense. As the space-shuttle plummets towards the earth on its return journey, an astronaut is most likely to suffer from Entry Motion Sickness (EMS) with symptoms including a headache, pallor sweating, dizziness, nausea, and vomiting.

Once back on Earth, the body readjusts to the crushing force of normal gravity. Astronauts experience weightlessness because the space station is in continual free-fall as it orbits the planet. This period of getting used to Earth’s gravitational pull is known as ‘re-adaptation’ and this phase may last from six weeks to three years as the body adapts itself to return to pre-flight normality. After landing, an astronaut has to deal with dizziness and vertigo while the brain tries to familiarize itself with the functions of balance and orientation.

About 80 percent of astronauts experience low blood pressure upon return which hinders their ability to participate in mundane, everyday things, like walking or driving a car. The risk of cardiac ailments also increases as the arteries stiffen post space travel. Because of bone degradation in space, long rehabilitation periods are required to restore the body to normalcy.

The health issues are causing concern for scientists aiming for longer space missions and therefore exclusive researches are being undertaken to minimize the risks associated with space travel. Currently, these researchers are focusing on three major health hazards: The long-term effects of space radiation, the Visual Impairment Syndrome which is caused due to the increased pressure on the brain and could lead to optic nerve damage and loss in peripheral vision if left untreated. Another issue is the consequences on mental health from the isolation depression which may render a complete recovery almost impossible.

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