Sunita Williams and Barry Wilmore are back on Earth after 286 days in space — but the challenges aren’t over yet. Readjusting to gravity can be tough, as long missions take a serious toll on the human body.
Sunita Williams and Barry Wilmore returned to Earth aboard a SpaceX Crew Dragon capsule, alongside astronauts Nick Hague and Alexander Gorbunov. After splashing down off the coast of Tallahassee, both were immediately placed on reclining stretchers and taken for medical evaluations.
After spending over nine months in microgravity, the returning astronauts will face significant physical changes and potential health risks — some of which could become permanent without proper care and rehabilitation.
Here are a few common effects astronauts experience after extended time in space:
‘Baby feet,’ bone loss, and weakened muscles
In microgravity, bones and muscles weaken from lack of use. Back on Earth, this can make simple tasks like standing, walking, or even holding objects surprisingly difficult.
In the weightlessness of space, the spine stretches, temporarily increasing an astronaut’s height. But there’s a downside — the cells responsible for building bone slow down, while the cells that break down bone keep working at their usual rate, accelerating bone loss. Muscles also weaken, as they no longer have to work against gravity.
Each month spent in space causes an astronaut’s weight-bearing bones to lose about 1% of their density, leaving them weaker and more fragile. At the same time, as calluses wear away and the body grows unaccustomed to using leg muscles and bones, astronauts can develop what’s known as “baby feet” — a condition where the thick, protective padding under the feet disappears, making walking difficult and uncomfortable.
Puffy-head, bird-legs syndrome
A prolonged stay in space affects the heart, brain, and circulatory system in surprising ways. In microgravity, bodily fluids shift upward toward the head, causing facial puffiness, nasal congestion, and increased pressure inside the skull. Meanwhile, the legs lose fluid, making them appear thinner and weaker — a condition nicknamed “puffy-head, bird-legs syndrome.”
This buildup of fluid around the brain can also lead to hearing and vision problems, and in some cases, a disorder called Spaceflight Associated Neuro-ocular Syndrome (SANS), caused by excess pressure on the brain.
Even the heart changes shape in space, shifting from its natural oval form to a rounder one. Muscle weakening and restricted blood vessels put additional stress on the circulatory system. When astronauts return to Earth, the loss of blood volume makes it harder for the body to regulate blood pressure, often leading to dizziness, nausea, and fainting spells.
While conditions like “baby feet,” facial puffiness, and bone loss can be painful and challenging, most astronauts recover with time, exercise, and proper medical care. However, some changes can be permanent — and far more serious.
Permanent Risks
Astronauts are exposed to intense solar and cosmic radiation during their time in space, putting them at long-term risk for cancer, degenerative diseases, and central nervous system disorders. In just nine months, Sunita Williams would have absorbed radiation equal to nearly 270 chest X-rays.
Combined with ongoing bone density loss and weakened immunity, this exposure increases the likelihood of osteoporosis and makes long-term recovery even harder.
NASA’s 2019 Twins Study revealed that while the majority of genes return to normal after an astronaut’s return to Earth, about 7% remain altered, indicating lasting genetic changes caused by space travel.
Space travel can also have lasting effects on an astronaut’s mental health. Disrupted sleep cycles, altered circadian rhythms, isolation, and the constant stress of living in space all contribute to a higher risk of depression, anxiety, and even cognitive decline. These mental health challenges can persist long after returning to Earth.
