Group Captain Shubhanshu Shukla is all set to become the second Indian in space with the launch of Axiom-4, scheduled for Wednesday 05:30 pm. He will spend 14 days in the International Space Station (ISS) conducting experiments, one of them being on whether people with diabetes can be considered for space travel. His own body will be undergoing changes brought on by floating in microgravity. Space travel -- which now includes orbital flights with private civilians -- presents an extraordinary challenge to the human body. The absence of gravitational forces affects nearly every physiological system. How does space impact human health? Since the 1961-foray of Yuri Gagarin into outer space, we have gathered a lot of information on the immediate and chronic impact of space on the health of astronauts. Space sickness: After reaching the microgravity environment of outer space, astronauts report symptoms of space sickness such as headaches, nausea, and vomiting. This is because the brain gets confused with the gravity and acceleration information it receives from the inner ear — the information that is essential for maintaining balance on Earth. This does not last long as the brain gets used to the new information in a couple of days. When they come back to Earth, they are forced to re-adjust again, and can initially experience difficulty in standing, walking, turning, or fixing their gaze. Fluid accumulation: During the initial days in space, astronauts may also experience swelling of their face. This is because all the bodily fluids that are pulled down to the lower body due to gravity on Earth rush to the upper body. The distribution of fluids, however, balances out in some days. After returning to Earth, astronauts may experience dizziness while standing up because in the presence of gravity, the heart has to pump harder to send blood to the brain. Bone and muscles: Without the need to carry the body’s weight when in space, astronauts start experiencing bone and muscle loss. This decrease in load-bearing can result in decreasing bone density, especially in the lower body such as legs, hips and spine. It also results in an increase in mineral content elsewhere in the body, leading to an increased risk of stones. The reduced muscle strength could result in falls when they are back on Earth. Eyes: When in space, the eyes experience several changes such as flattening of the globe and swelling in the back of the eye where the retina and optic nerve connect. These changes in the eye and brain structures is referred to as Space Associated Neuro-Ocular Syndrome, which has no equivalent on Earth. This is experienced by nearly 70% of the astronauts on the space station, with the impact intensifying during longer stays. The upward shift of fluids is thought to be the reason. Heart health: With the body not requiring the heart to pump as hard in space, long duration stays there may decrease the size of the heart. On return to earth, the smaller, weaker heart may over-exert itself. Astronauts experience a decline in their blood volume, their aerobic capacity and experience more arrhythmias or irregular heartbeats. The space radiation also impacts the lining of blood vessels, which can initiate or accelerate heart diseases. What is the diabetes research that Shubhanshu and his crew mates will conduct? With rising incidence of diabetes on earth, one of the Axiom-4 experiments will investigate whether those who depend on regular insulin shots can opt for space travel. At present, such people are disqualified. While the Galactic 07 sub-orbital flight last year confirmed that the commercially available insulin-pens can effectively deliver insulin, the current experiment will focus on blood sugar level monitoring. The experiment will use Continuous Glucose Monitors (CGMs) to see whether accurate sugar level reading is possible in space. It will also check the efficacy of insulin that has been exposed to space. Why do we need to study human health in space? The study of human health in space can help researchers improve comfort during space travel — such as designing ways to maintain a normal sleep-wake-up cycle, providing better nutrition and exercise guidelines and more comfortable suits. It is extremely important with several countries now looking at sustained presence in space as well as long-duration space travel to planets such as Mars. India plans to set up its own space station called Bharatiya Antariksh Station by 2035 and send man to the moon by 2040. Many studies on human health conducted in space also have implications for developing new therapies on Earth.
