Astronauts have become very different from space after a long period outside the planet

In June 2024, NASA Astronauts Butch Wilmore and Suni Williams arrived at the International Space Station for a mission of 8 to 10 days. However, the Starlliner ship problems They delayed their return Until March 2025286 days later.

What began as a short stay became more than nine months of microgravity, which It can have deep effects In the body of astronauts: muscle atrophy, loss of bone density, cardiovascular alterations, vision and stress problems.

This was its appearance before being thrown into the space in the Starliner ship:

And this is its appearance when returning in the Crew Dragon ship that rescued them:

Decades of aging

Both NASA Like ESA They have studied in depth the effects of exposure to space and microgravity on the human body. One of the most common is the loss of muscle and bone mass.

In the International Space Station there is no severity that forces the muscles and bones to work to sustain the body, so the tissues begin to weaken due to disuse. Astronauts lose about 1% bone mineral density for each month that pass in space. Their muscles, especially those of the legs and back, end up atrophy, hence they have trouble standing after landing on earth.

To mitigate this effect, the ISS crew are subjected to railway routines: two hours a day on the running tape, static bicycle or resistance exercises. But it is not enough: a study published in Scientific Reports revealed that a stay of more than six months in space can cause bone losses equivalent to decades of aging on Earth.

It is common for astronauts to have a greater risk of fractures due to the lower resistance of their bones, as if they were elderly. For Butch and Suni, with an expected bone loss of 9-10%, NASA has established An intensive 45 -day physical rehabilitation program. Even so, for many astronauts the recovery is incomplete even one year after returning. It is lacking two to four years for the muscles of a person to fully recover their original strength after a prolonged mission.

Effects of microgravity

Upon floating, body fluids are redistributed to the upper body, since gravity does not throw them towards the feet. This causes the swollen face feature seen in astronauts aboard the ISS. But it also has internal consequences: the body interprets that there is excess fluid and reduces total blood volume.

With less blood volume and without the need to pump against gravity, the cardiovascular system relaxes. The heart can lose weight of its muscle walls and blood pressure tends to fall. Upon returning to the ground, this adjustment sometimes cause dizziness or even fainting (orthostatic hypotension), since gravity takes the blood again to the legs, and the body
It takes time to fall.

Astronauts often use special compression suits or increase fluid and salt intake before the reentry to minimize these symptoms. Even so, it is common for them to remain seated, as happened with Butch and Suni when you get off the Crew Dragon, waiting for your body to be rebuilt.

Another important physical effect discovered in the last decades of space exploration It is the so-called neuro-ocular syndrome associated with space flights (Sans). Without gravitational attraction, the displacement of fluids to the head can increase intracranial pressure, which in turn slightly deforms eye balloons and compresses the optic nerve. Many astronauts in prolonged stays report changes in their visual acuity: they can develop temporary farsightedness (difficulty seeing closely), which means that their eyes change under internal pressure.

In long -term missions, More than 70% of astronauts They have come to suffer Sans. NASA Astronaut Scott Kelly, who spent a year in space and then be compared to his twin brother Markdeveloped an edema of the optic nerve and changes in the retina.

Prolonged ungrampidity and the closed environment of the ISS also They affect the immune system of astronautscausing changes in the distribution of white blood cells and in the Expression of certain immune genes In response to the extreme environment. Paradoxically, living in the sterilized environment of ISS can weaken the immune response over time: by not exposing yourself to so many everyday pathogens, the immune system lowers the guard. Cutaneous eruptions, allergies and even reactivation of latent viruses (such as herpes) have been observed due to the decrease in defenses.

Radiation and nine months of stress

At the same time, prolonged missions astronauts accumulate significant exposure to Solar radiation and cosmic raysnot having the atmosphere as a protective shield. However, a nine -month stay is within the acceptable limits of NASA, since the ISS orbit the Earth only 400 km of altitude. Cell damage It will be a much greater problem In future long -term space flights to the moon and Mars.

More worrying are the Psychological effects of prolonged confinement in a space station that orbits the earth 16 times a day. The schedules are not a problem because the ISS follows a strict time routine with the time of the Greenwich meridian. But the lack of natural cycles of light and dark can alter biological rhythms, cause sleep deprivation or reduce cognitive performance.

In the end, what can happen more invoice is the psychological experience of being working in a confined environment, far from the family and with a handful of classmates from different countries. In the case of Butch Wilmore and Suni Williams, this situation was aggravated by uncertainty: its mission was extended due to technical problems, for a long time without a clear return date. Hence Wilmore’s daughter will mention stress Like a problem.

The good news is that most body changes in space are not permanent. Approximately 95% of physiological alterations return to normal in the weeks after return. Astronauts typically recover their balance and ability to walk in a few days, fluid distribution is rapidly normalized and sleep disorders tend to improve by reestablishing terrestrial cycles.

As for psychological sequelae, career astronauts are chosen for their predisposition to be rendered under situations of great stress without getting nervous. It is your work and your passion. They do not charge extra hoursbut whenever they have opportunity they are willing to return to their favorite place: space.

Images | NASA, Spacex

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