The effects of a long stay in space is a theme on which it recently rekindled after the return to the earth of astronauts Sunita Williams and Butch Wilmore After more than 9 months in the International Space Station, in the face of the only 8 days expected initially. In fact, the images of the two astronauts on the return to Earth have aroused a certain amazement, particularly those of Sunita Williams who appeared visibly aged compared to his departure in June.
This is not unusual, in reality: the conditions of microgravity experienced on the International Space Station (ISS) bring a series of effects on the body of astronauts including decalcification of bones, loss of muscle mass, redistribution of body fluids and so -called baby feet (“Feet as a child”), that is, the loss of the callous and corneous layer at the base of the feet. On the other hand, astronauts are also on the ISS as a sort of “guinea pigs” To study the effects of microgravity on the human body, of which, all in all, there is still little known.
Effects of microgravity on the human body
Effects on muscles and bones
Perhaps the best known effect of the conditions of microgravity in space are the loss of muscle tone (after 6 months in orbit muscle mass also decreases by 20% and muscle strength even 40%) and the Decalcification of bones With a decrease in bone density, even 1-1.5% for each month spent in space.
Although astronauts practice a lot of exercise in orbit and take vitamin D, the loss of muscle tone is felt especially in the legs and in the lumbar region, since the muscles must not support the weight of the body due to the terrestrial gravity.
Once you return to the ground, however, the bone density is not immediately recovered, but they are necessary months of rehabilitation to approach the pre-party conditions. In fact, some studies have shown how even after a year the astronauts are unable to fully recover the original bone density.
In space you become higher
It has been discovered that astronauts who remain in space for 6 months or more on the return appear higher and slimming. The studies have calculated, for an 180 cm high human being, 6 months of stay in space can Increase the height from 3 to 5 cm. This is due to the fact that without the weight that “crushes” the body down, the spine is stretched and stretches because the intervertebral discs tend to expand and relax.
Effects on body fluids
The permanence in orbit also change the internal fluids, including blood. It has been found that the conditions of microgravity have a deleterious effect on the heart and circulation. The heart, in fact, having to pump less blood in the absence of gravity, can incur arrhythmiaswhile the blood itself can slow down and station in some parts of the body by bringing to clot.
Microgravity also causes one redistribution of body fluidswhich in apparent absence of weight are no longer “forced” to accumulate in the lower part of the body and consequently move towards the head, which exerts pressure on the eyes, being able to cause damage to the vision.
Life in orbit also brings changes to the intestinal microbiota and severe damage to the kidneys, so much so that some scientists have hypothesized that the astronauts who will go to Mars may need the dialysis Once back to the ground.
Effects on DNA
Perhaps the most worrying effect of the permanence in orbit is however the Possible DNA damage. Without the terrestrial atmosphere to protect them, astronauts are subject to high levels of radiation coming from the sun and outside the solar system due to cosmic rays. It is estimated that at the share of the International Space Station the astronauts absorb a quantity of radiation 10 times higher than that on earth. Radiation can alter DNA and cause carcinogenic mutations that increase the risk of developing cancer.
Aesthetic effects
The conditions of microgravity also have an effect aesthetic on the human body. For example, on their return, astronauts can suffer from a condition known as baby feet (“Feet as a child”). This condition rises due to the Loss of the Callosa and thick part of the feet in orbit. The skin of the sole of the feet, in fact, is thicker than that of the rest of the body since on earth it must support the pressure of the entire body weight. In conditions of microgravity, missing this solicitation, the skin tends to soften, losing the callous and corneous layer. The feet essentially become soft and sensitive like those of a child, requesting several weeks or months to reform a callose layer on the ground.
Other aesthetic effects include pallor of the skindue to the artificial lights of the ISS, and a deterioration of the scalp. One of the most obvious effects of the 9 -month stay in orbit for Sunita Williams was precisely the modification of his hair, which appear significantly more gray than 9 months ago. The absence of gravity deduced the scalp, ruining the crown of astronauts.
