The research of space traces back to ancient times, so a dream of thousands of years became reality in 1961 with the first spaceflight completed by Gagarin on Vostok 1. Many other astronauts have followed him since then; mankind has conquered the Moon, and maybe Mars will come next. According to Elon Musk’s plans, we will be spending our holidays in space in a few years time.
However, scientists had to face lots of challenges and difficulties to reach success – not just in the field of engineering and physics, but also in the field of medicine, since space is extraordinarily dangerous for the human body.
The change of gravity fields makes spatial orientation, finding balance, and head and eye coordination difficult, and it can also cause motion sickness. During a Mars mission, our body has to get used to the difference between Earth’s gravity field and weightlessness, and also to the gravity field on the surface of Mars (which is approximately one-third of Earth’s gravity). Without gravity, our bones lose minerals, their density dropping at over 1% per month (!), increasing the risk of osteoporosis-related fractures. (For comparison: the rate of bone density reduction for elderly people is 1-1,5% per year.) The increased excretion of calcium and dehydration augment the risk of developing kidney stones. In case of a lack of exercise and proper nutrition, muscle strength and endurance decrease. Moreover, because of the absence of effort during levitation, cardiovascular deconditioning can occur. Astronauts can also experience vision problems, because of the pressure of fluids on the eyes.
The most dangerous aspect of space travel is space radiation. The astronauts on the space station receive over ten times more radiation than on Earth. This increased radiation exposure causes problems in the long term, but it can also have acute effects. It increases the risk of cancer, can cause reduced cognitive- and motor functions and behavioral changes. Many people experience the symptoms of radiation sickness; nausea, vomiting, anorexia and fatigue. The development of different degenerative tissue diseases like cataracts and cardiovascular diseases increases as well. Interestingly, the International Space Station is just within Earth’s protective magnetic field, but radiation exposure is still ten times higher than what we receive on Earth. During a Mars mission, the shielding of spacecrafts will be extremely important to reduce the radiation risks to an acceptable level.
In space, microorganisms change as well. In a closed habitat, like a spaceship, microbes are transferred easier from person to person. Since the immune system is altered, the susceptibility to allergies and illnesses is increased. On the space station, NASA is monitoring the quality of air continuously to ensure that the air is not contaminated by toxic gases like formaldehyde or ammonia. The analysis of the astronaut’s blood and urine samples ensures the monitoring of their immune systems.
Beside physical symptoms, psychological problems can also occur during a spaceflight. The feeling of confinement and isolation might be familiar to all of us in this current pandemic situation. A spaceflight means a six-month long isolation, spent with the same few colleagues. Along with a general decline in mood and enthusiasm, cognitive functions and interpersonal interactions diminish as well. On Mars, there are 38 extra minutes each day, which could increase the risk of developing sleep disorders caused by the changes in our circadian rhythm. The lack of fresh food can further reduce the physical and mental performance. Sleep disorders, decline in mood or depression cause more and more severe physical symptoms, which can eventually risk the success of the expedition. Therefore psychological training is extraordinarily important before space travel.
(Source: nasa.gov)