10 weird things that happen to the human body from extended space travel
From "puffy face" to heart shrinkage
NASA’s Butch Wilmore and Suni Williams originally launched on Boeing’s Starliner on June 5, 2024, for a planned 10-day test flight.
They remained in orbit for approximately 287 days due to spacecraft issues, returning today via a SpaceX Crew Dragon. Their extended time in space ranks them just below NASA’s Peggy Whitson (289 days) but well short of the U.S. record held by Frank Rubio (371 days in 2022–2023) and the global record by Russia’s Valeri Polyakov (437 days in 1994–1995 on Mir).
Below is a list of ten scientifically documented short- and long-term effects on the human body from extended space travel.
Short-Term Effects (Within Days to Weeks)
Fluid Shifts and Puffy Faces
What Happens: In microgravity, bodily fluids shift upward, causing facial swelling and a sensation akin to a constant head cold. Blood volume in the lower body decreases by about 10% (1–2 liters).
During his first days aboard the International Space Station (ISS) in 2015, Scott Kelly reported feeling congested and noticed his face puffing up, a common "puffy face–bird leg" syndrome, as he described in interviews post-mission. John Glenn also reportedly suffered from puffy face syndrome after he flew on the Space Shuttle Discovery during the STS-95 mission, which launched on October 29, 1998, and landed on November 7, 1998. At age 77, Glenn became the oldest person to travel to space, returning 36 years after his historic Mercury-Atlas 6 orbital flight in 1962. The nine-day mission studied aging and microgravity effects. His participation was partly scientific—testing how space affects older bodies—and partly symbolic, cementing his legacy as a space pioneer and then-U.S. Senator.
Space Motion Sickness
What Happens: Microgravity disrupts the vestibular system, leading to nausea, vomiting, and disorientation as the brain struggles with no "down" reference. Symptoms typically subside within 2–3 days.
Jake Garn, a U.S. Senator on a 1985 Space Shuttle mission, suffered such severe space sickness that NASA informally named a sickness scale after him, with "one Garn" being the maximum level of misery.
Muscle Atrophy
What Happens: Without gravity, muscles, especially in the legs and back, weaken rapidly, losing up to 20% of mass within days if not exercised aggressively.
Peggy Whitson, after her 2007–2008 ISS stay, noted her legs felt "like jelly" upon return, requiring assistance to walk despite her rigorous in-flight workouts.
Vision Impairment (SANS)
What Happens: Fluid shifts increase intracranial pressure, flattening the eyeball and causing Spaceflight-Associated Neuro-Ocular Syndrome (SANS), affecting near vision within weeks.
John Phillips, after six months on the ISS in 2005, returned with a 20/100 vision drop from 20/20, prompting NASA to investigate SANS extensively.
Immune System Suppression
What Happens: Spaceflight stresses the immune system, reducing white blood cell function and increasing infection risk shortly after launch.
During the Apollo 7 mission in 1968, Wally Schirra developed a head cold in orbit, worsened by microgravity, which he famously grumbled about over the radio.
Long-Term Effects (Months to Years)
Bone Density Loss
What Happens: Bones lose density at 1–2% per month in microgravity, risking osteoporosis-like conditions; recovery can take years.
After 437 days on Mir in 1994–1995, Valeri Polyakov lost significant bone mass but walked off the Soyuz capsule unaided, stunning doctors who expected him to be carried.
Cardiovascular Changes
What Happens: Blood volume drops, and the heart weakens and rounds over months, reducing its efficiency; some effects persist post-flight.
Scott Kelly’s heart shrank slightly after his 340-day ISS mission (2015–2016), a change tracked in the Twins Study, contrasting with his brother Mark on Earth.
Radiation-Induced DNA Damage
What Happens: Cosmic radiation damages DNA over months, elevating cancer risk and causing cellular changes that may persist lifelong.
Scott Kelly’s telomeres lengthened in space during his year-long mission but shortened rapidly upon return, with some DNA damage lingering, as noted in the 2019 Twins Study.
Cognitive and Psychological Strain
What Happens: Isolation and confinement over months can lead to depression, cognitive deficits, and altered neuroplasticity, with recovery varying.
Frank Rubio, after 371 days on the ISS in 2023, admitted to mental fatigue from prolonged isolation, despite staying upbeat for his crew.
Spinal Elongation and Back Issues
What Happens: The spine stretches up to 3% (about an inch) in microgravity over months, risking back pain and disc herniation post-flight.
Frank Rubio, before his 2023 return, quipped during an ISS briefing that his elongated spine wedged him into his seat, potentially preventing neck injury on landing.
Very fascinating! Thank you for the report and summary!
So if man landed on the moon, where are all the medical reports for Aldren and Armstrong?