NASA astronauts, back on Earth after nine months: Here's how space changes the body

It was a mission that lasted much longer than planned.

United States astronauts Sunita “Suni” Williams and Barry “Butch” Wilmore went into space aboard the Boeing Starliner Calypso on June 5, 2024. They were scheduled to spend eight days on the International Space Station (ISS).

But as the spacecraft approached the station, its thrusters failed, and NASA ordered the astronauts to stay on the ISS until they figured out how to return them.

This lasted nine months, or 288 days, and Williams and Wilmore are now among NASA astronauts with the longest stay in space on a single mission.

Who has spent the longest time in space?

The ISS orbits at an altitude of 354 kilometers, while the average distance from Mars to Earth is 225 million kilometers.

Astronaut Frank Rubio holds the record for NASA's longest space mission, spending more than a year on the ISS.

The overall record for a space flight belongs to Russian Valery Polyakov, who spent 437 days on the Mir space station.

When did the SpaceX Crew-9 mission return to Earth?

The SpaceX Dragon spacecraft, carrying Williams and Wilmore to Earth, returned at around 17:57 local time (21:57 GMT) near the coast of Florida, after separating from the ISS at 05:05 GMT.

Also with Wilmore and Williams was Russian Roscosmos astronaut Alexander Gorbunov.

Now that they are on the ground, the crew will have to adjust to returning to Earth, both physically and mentally.

How does life in space harm the body?

Spending months in microgravity is brutal on the body. Without the Earth's gravitational pull, muscles shrink, bones weaken, and body fluids shift.

Astronauts lose muscle mass quickly because they don't use their legs to support their weight. Their bones become brittle and they lose one percent of their bone mass per month—the equivalent of a full year of aging on Earth.

Radiation is another major concern. Although the ISS is protected by Earth's magnetosphere, astronauts on missions lasting six months or longer receive more than ten times the radiation that naturally occurs on Earth. Prolonged exposure is linked to a higher risk of cancer and possible cognitive decline.

Body mass and fluids : Astronauts lose about 20 percent of their body fluids and about five percent of their body mass while in space.

Muscles: Microgravity causes muscle atrophy, but exercising two hours a day, six days a week and taking supplements can reduce muscle loss.

Skin: The skin is thin, easily damaged, and heals more slowly in space.

Eyes: Microgravity damages vision, while radiation increases the risk of cataracts.

DNA: Most genes are restored upon return to Earth, but about seven percent remain disrupted.

Psychosomatics and cognitive functions: Radiation can cause brain damage and the onset of Alzheimer's disease. Space disrupts orientation, causing motion sickness.

Cardiovascular system: Blood circulation slows down and red blood cell production decreases. Cardiac arrhythmia is common.

Immune system: The immune system is weakened. Six months of radiation exposure in space is equivalent to ten times the annual exposure on Earth.

Bones: Skeletal deformity and bone loss are possible with a loss of one percent of bone mass each month. Astronauts become taller because their spines expand while in orbit.

How does the body recover on Earth?

Returning to Earth doesn't immediately undo the months of strain on an astronaut's body. As their bodies adjust to gravity, they experience balance problems, dizziness, and impaired cardiovascular function.

Even months after the landing, not everything is recovered. They face long-term health risks, including cancer, nerve damage and degenerative diseases.

Arriving from space: the spine returns to normal size. Abdominal bloating is no longer a problem and blood pressure is normalizing.

A week later: Motion sickness, disorientation, and balance problems disappear. Sleep returns to normal.

Two weeks later: The immune system recovers and lost body fluids are replaced. Red blood cell production returns to normal.

One month later: Muscle recovery is almost complete and close to pre-flight levels.

Three months later: Skin recovery is complete. Body mass returns to ground level and vision problems no longer exist.

Six months later: The risk of bone fractures remains, as does the increased risk of cancer; 93 percent of the genes return to normal, but seven percent remain switched off.

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