Three astronauts have returned to earth after spending more than a year on the International Space Station.
Russian cosmonauts Oleg Kononenko and Nikolai Chub, as well as Nasa astronaut Tracy Dyson, have returned to earth in the Soyuz space capsule, which landed in Kazakhstan.
Russia has broken the record for longest stay on the ISS, with a total of 374 days.
Tracy has spent about six months on the ISS, and the bell for departure was rung by Suni Williams, another Nasa astronaut who is currently stranded on the space station after arriving on the Boeing Starliner.
Oleg also holds the record for the longest cumulative time in space, having been in orbit for 1,111 days over five trips.
But when the astronauts get used to Earth’s gravity and return to normal, the impact of living in low gravity on the human body is immediately clear.
Oleg, Nikolai and Tracy all had to be ejected from the spacecraft after landing in the Kazakhstan Steppe, as the toll of time in orbit had taken on their bodies.
Tracy was seen sitting in a wheelchair with a blanket over her legs after being lifted from the capsule, as staff wiped her face with cloths.
As astronauts spend longer and longer periods in orbit, research into the effects of low gravity on the human body is still in its early stages, the BBC reports.
To begin with, it’s difficult for astronauts to stay fit because they don’t need to use a lot of muscle.
He does two and a half hours of exercise and training on the ISS every day in the ‘gym’, including squats, deadlifts, rows and bench presses, and eats dietary supplements to try and preserve his bones – but even this is not enough.
Without gravity constantly affecting the body, muscle and bone mass quickly begin to decrease.
Most affected are the muscles in the back, neck, calves and quadriceps, AKA the muscles that help maintain posture.
Muscle mass can decrease up to five times in two weeks, increasing up to 30% in three to six months.
Bone mass also decreases, with astronauts losing 1-2% of bone mass for every month they spend in space – compared to Earth where people lose bone mass at a rate of 0.5-1% per year.
This can increase the risk of fractures as the bones become weaker, and it can take up to four years for bone mass to return to normal.
For the short kings out there, there is still hope because astronauts can grow taller during their time in space, because their spines elongate because there is no gravity pulling them down.
But this doesn’t come with the risk of back pain and slipped discs when back on earth.
And the lack of gravity can also impair an astronaut’s eyesight, as gravity helps force the blood in the body downwards as the heart pumps again.
This process will be chaotic in place, which means that blood can accumulate in the head more than usual, potentially pooling behind the eyes and around the optic nerve.
This can cause edema, which can affect visual acuity and structural changes in the eye itself. These changes begin after just two weeks in space – but while some changes reverse after about a year on Earth, others can be permanent.
Viewing galactic cosmic rays and energetic solar particles without the protection of the Earth’s atmosphere can also damage your eyes.
Contact the news team by emailing webnews@metro.co.uk.
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