This is what a year in space does to the body as NASA astronaut returns home after 371 days

As an astronaut returns to Earth after a lengthy period up in space, scientists have explained what that sort of time up away from our home planet does to the body of a normal human.

Obviously, very few people ever manage to go up to space so there’s not a huge sample size for what happens when people come back.

Even fewer are up there for prolonged periods of time, meaning that when they come back, the scientists are presumably extra keen to find out what effect the sudden return to Earth from space has on the human body.

There are mental and physical effects of the return to Earth as gravity begins to take hold once again, and astronauts return to society from the isolation above the atmosphere.

NASA astronaut Frank Rubio came back from that isolation on Wednesday, having spent 371 days up in space, the most ever by a US astronaut.

NASA

The 47-year-old was supposed to be up on the International Space Station for six months but that was later extended, meaning he spent over a year up there.

At around 7:00am, he arrived back on Earth.

And now, he’s set to be assessed and studied by the NASA medical team as he’ll need a bit of time to get used to things down here again.

Even everyday tasks like standing up and walking around will be new to him after that time, and there’ll be psychological challenges to deal with too.

The lack of gravity up in space means that muscle mass decreases as it is simply not being used, as well as bone loss.

That starts off early in the mission before tailing off after a bit.

One of the biggest issues is with balance, as Dr Jennifer Fogarty – chief scientific officer at Baylor College of Medicine's Translational Research Institute for Space Health – told ABC News: "How do you coordinate movement like walking, which you haven't done for a long period of time, and then the idea of balance?

“When you put those two together, it can kind of create a little bit of a precarious situation and something that's very well-monitored with the crew members when they land on Earth.”

She also pointed out that longer missions will take astronauts longer to acclimatise back to Earth conditions.

Weightlessness does a lot to the body and can cause structural changes to the eyes and brain, known as Spaceflight Associated Neuro-Ocular Syndrome.

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Being in an enclosed and isolated environment can also cause fatigue, stress, and loss of sleep.

Basically, there are all sorts of things to consider.

Scientists will be assessing how Rubio has held up over his 371 days up in space, checking his mental and physical health, as well as his immune system, and for changes to his genes.

Space is obviously a tough place to go, but Fogarty said that these changes and effects aren’t unaccounted for and are the sort of things that NASA prepares for before sending anyone out there.

She said: “We can select people, train them and make sure they're very healthy before they go.

"We do the research to understand where we can make different choices with the environments we build for these people to live and work in, so that we are not tapping into those reserves…and compromising them."