Sunitha Williams: Sunita, who returned safely from space, will have to face difficulties on Earth for some time

Astronauts floating weightlessly in the International Space Station (ISS) 400 kilometers above the ground face many problems after returning to Earth. Sunita Williams, who returned to Earth after spending a long time in gravity-free space, may also face health problems. She may face problems like loss of bone and muscle density.

After Sunita Williams returns to Earth from space, it will not be easy for her to get re-acclimatized to gravity. In this sequence, she will have difficulty in standing, keeping her eyes steady, walking and turning sides. It will take a few weeks for Sunita Williams and other astronauts to get accustomed to life on the ground.

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Bones and muscles

Due to the lack of gravity, astronauts do not have to work hard to walk and move in orbit. As a result, there is no strain on their bones and muscles. Bone tissue changes its shape in space. The cells that form new bone tissue slow down. The process of breaking down old bone tissue continues as usual. Therefore, astronauts' bone density decreases. If proper precautions are not taken, astronauts' bones lose 1-2 percent of their density every 30 days in orbit. This can increase to 10 percent in six months. A similar decline occurs in the elderly on Earth at a rate of 0.5 to 1 percent annually. Due to this problem, astronauts' bones are at a higher risk of breaking. They also take longer to recover. After returning to Earth, it can take up to four years for astronauts' bone density to return to normal levels. To reduce bone loss, astronauts do rigorous exercises on the ISS. They exercise on a treadmill or stationary bicycle for at least two hours a day.

Muscles also become weak

Without the force of gravity on the body, muscles also weaken. The muscles of the back, neck and shoulders that support our posture while sitting and standing are more affected. Muscle deterioration can be up to 20 percent after spending two weeks in space. If you spend 3-6 months it can reach 30 percent. After returning to Earth, the effect of gravity on astronauts begins again. As a result, they sometimes develop 'gravity sickness'. The symptoms of this disorder are similar to space sickness.

Eye vision

Some fluid that accumulates on the astronauts' scalp may also accumulate behind the eye, around the optic nerve. This can cause blurred vision. There is scope for structural changes in the eye.

Heart, brain, circulatory system

On Earth, gravity pulls blood and other fluids to the lower parts of the body. The heart pumps them. This process goes awry in rhododendrons. As a result, more blood and fluids than normal accumulate in the upper part of the body. This makes some astronauts' stomachs look a little bloated. Blood and fluid accumulate in the head. This can cause hearing problems.

The shape of the heart also changes

The shape of the heart also changes in space. Muscle atrophy can cause contraction of blood vessels. It becomes difficult to control blood pressure after returning to Earth. In 2013, Canadian astronaut Chris Hadfield, who returned to Earth after serving on the ISS, developed a 'weightless tongue' and had to change his way of speaking. Astronauts lose the thick skin on their feet. This makes their feet soft and difficult to walk like babies. Astronauts are at risk of having fewer white blood cells due to radioactivity in Earth orbit. As a result, their immune system may weaken. Astronauts may have long-term problems due to excessive exposure to radioactivity. The risk of cancer and neurodegenerative diseases may increase.

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