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The Human Body in Space
NASA monitors the bodies of animals and humans to see how they react to extended periods in space. When the body is in space, it no longer has the strong pull of Earth’s gravity on it. Because the body’s systems normally function in the presence of gravity, NASA has been studying the effects of weightlessness on the body.
Weightlessness Takes a Toll
On Earth, the heart naturally pumps blood more forcefully to the upper body than to the lower body, where gravity helps the blood flow down. In space, the heart continues to pump the blood more forcefully to the upper body, but the balancing force of gravity does not pull the blood to the lower body. This uneven blood flow causes astronauts’ faces to become puffy and their lower bodies to become thin.
The shape of the spine also changes in space. Without the force of gravity pushing the vertebrae closer together, the spine stretches out and causes pain in some cases.
Another system affected in space is the body’s balancing system. To balance itself, the brain acquires information from the eyes, muscles and tendons, and a set of sensors (called the vestibular apparatus) in the inner ear. In space, the only balancing information that can be relied on enters through the eyes, so astronauts have difficulty moving around.
The most serious problem for astronauts, however, is bone loss. In space, the bones lose minerals, such as calcium, potassium, and sodium. The bone loss in the legs can be as high as ten percent, and even exercise does not completely solve the problem.
Laboratory in Space
With the completion of the International Space Station (ISS), NASA will be able to study some of the effects of long-term exposure to weightlessness. NASA also plans to expand its studies to better understand how the immune system is affected and how radiation, which is much greater in space,
affects humans. Radiation can pose serious health threats, including cancer and neurological damage.
Because people working together on the ISS will be in small spaces for long periods of time, NASA also plans to study how working in confined spaces affects astronauts’ personalities.
Infer What does NASA expect to gain by studying the effects of long-term space travel on the human body?