Health hazards after 9 months of space travel

NASA astronauts Barry Wilmore and Sunita Williams launched into space from Florida in June last year. The mission was supposed to last eight days. However, they returned after nine months. The Americans were testing Boeing’s new Starliner on its maiden crewed voyage, but technical problems with the spacecraft caused it to return to Earth without them. They’ve been living inside the International Space Station (ISS) ever since. Now, after nine months in orbit, the astronauts are returning home. Experts say they face a long and intense recovery due to both the physiological and psychological impacts of space travel. Nine months may sound like a long time, but some astronauts stay in orbit for up to a year. ISS missions typically last six months. Still, experts say prolonged time in the low gravity environment of space, known as microgravity, takes a toll on the body.

Dr Rebecca Allen, the co-director of the Space Technology and Industry Institute at Swinburne University of Technology, has been quoted as saying: “Our most important muscle, our heart, pumps blood differently in space because fluids don’t flow, of course, without gravity there.” She explains: “Our immune system functions, our gut microbiome and even our very DNA changes.” Allen also added that without the constant tug of gravity, muscle mass and bone density start to deplete. “Our muscles get strong because they’re used to holding us up against gravity. When you take that away, they no longer have that resistance to really build up strength, and so they very quickly deteriorate,” she said. “But also the bones that they’re attached to, they don’t have that continuous pull of the muscles on them, so our bones also start to break down.” Gravity eases off the pressure on the legs, hips and spine and as a result of them being used less, this can lead to a loss of bone density.

Dr Brad Tucker, an astrophysicist and cosmologist at The Australian National University, has also been quoted as saying that studies have shown that six months in space can result in the equivalent of 20 years’ worth of bone density loss. “So [Wilmore and Williams] being in their late fifties, early sixties, they’re going to have the bones of an 80-year-old now, coming down,” he said. If astronauts don’t keep up their fitness while in space, their muscle mass can decrease as a result of gravity taking away the effort needed to move about and use their legs and back. If muscle mass has decreased in space, this could increase the risk of astronauts having a fall back on Earth and sustaining fall-related injuries. Usually, they are put under strength training, high calcium and vitamin D diet. Prolonged exposure to microgravity also affects the vestibular system, located in the inner ear and is crucial for maintaining balance and spatial orientation. That can cause balance and coordination issues, Tucker said. He said eyesight can also be impacted. “The ocular nerve, through pressure changes in space, creates a vision distortion. So when [the astronauts] come back down, their vision will be distorted.” A common effect on the eyes after being in space for a bit is “swelling in the back of the eye”. Baylor College of Medicine’s Centre for Space Medicine details certain ways the human body changes in space and some of the potential health challenges the NASA astronauts face after their return. The Centre notes: “Not standing on your feet causes them to lose callouses and become soft from disuse and less sensitive to pressure variations. Instead, astronauts on the International Space Station (ISS), have developed callouses on top of their feet from using footholds on the station.”

Astronauts’ skin elsewhere on their body may also get more easily irritated as a result of their immune system being lowered while away in space alongside microbial growth. The Centre explains the lack of gravity experienced when in space can alter the way the brain feeds certain signals. While astronauts may feel space motion sickness and a ‘loss of sense of direction’ when they first go into space, Williams and Wilmore will have adjusted during their long stay. However, Baylor College’s Medicine Centre warns: “Once the astronaut returns to Earth, they are immediately forced to readjust again, back to Earth’s gravity, and can experience issues standing, stabilizing their gaze, walking, and turning. “For their safety, returning astronauts are often placed in a chair immediately upon return to Earth.” Astronauts may also feel the impact of ‘The Overview Effect’. The ‘Overview Effect’ often takes place when astronauts go into space and look down and see Earth from that perspective for the first time. The experience ‘shift[s] [...] the way astronauts view and think about our planet and life itself,’ NASA explains. Ex-NASA astronaut and author Ron Garan spent a whopping 178 days in space and when he looked down at Earth he was hit with a “sobering realization” of how fragile Earth is.

Garan was hit by the realisation that our planet — and every living thing on it — is being kept alive by a “paper thin layer”. “I saw an iridescent biosphere teaming with life, I didn’t see an economy, but since our human-made systems treat everything including the very life-support systems of our planet as the [...] subsidiary of the global economy, it’s obvious from the vanish point of space that we’re living a lie,” he has been quoted as saying. In space, astronauts are exposed to ‘about 100 times’ the amount of radiation the rest of us are here on Earth. They can experience radiation sickness, central nervous system effects, degenerative diseases, and most notably, an increased lifetime risk of cancer. In nine months, Williams would have been exposed to radiation levels equal to almost 270 chest X-rays. The human heart, brain and circulatory system are also affected due to a prolonged stay in space. In microgravity, fluids from the rest of the body that tend to shift upward toward the head result in facial puffiness, nasal congestion, and increased pressure inside the skull. This makes the head appear bigger, and the legs smaller and weaker. This phenomenon is called “puffy-head bird-legs syndrome”. The increase of fluid in the brain can also lead to hearing loss, vision loss and a disorder known as Spaceflight Associated Neuro-ocular Syndrome (SANS), which is caused by added pressure to the brain. The heart in space changes from an oval shape to a round shape, and muscle atrophy constricts blood vessels, which causes damage to the circulatory system. So, technically speaking, the two astronauts are now on another adaptation journey, followed by rigorous training, rehabilitation, and NASA’s support systems helping them transition smoothly.

Views expressed are personal