Yuri Gagarin was the first to prove that humans can survive in outer space. For 55 years since, humanity has been striving to adapt to life in space, but the questions of exploring our galaxy and taking a journey to other planets still remain open-ended. Can technology help our bodies withstand prolonged spatial voyages?

Running a kilometer in 3 minutes and 35 seconds, 14 pull-ups, jumping a distance of two meters, and the ability to withstand long periods in solitude and small spaces — these are just some of the requirements listed by Russia's space agency Roscosmos for their astronauts. After Russia announced less rigid criteria for entry into its team of astronauts in 2012, it has since been overwhelmed by the number of applicants.

Before and after flight

Georgy Samarin, deputy director at the Institute of Biomedical Problems, says that even with lower standards not everyone qualifies for a space mission, and certain procedures and testing must be followed. Today, having poor eyesight or even recovering from minor surgery are not disqualifying factors — recent adaptations as a result of "casual" cosmic tourists.

In the 1960's, the requirements for candidates in the first group of astronauts were quite strict: The pilots pushed their physique to the limits and endured extreme conditions, vibrations, and temperature drops. In the end, 20 individuals were selected, each one with a remarkable profile. Only two individuals made it to the final cut, and chief Soviet engineer and founder of practical astronautics, Sergey Korovlev, had to select one of the men for the mission. In his diary, he wrote about the choice: "It is difficult because you are sending a man either to his death, or to eternal glory."

One of the top candidates — astronaut Valentin Bondarenko died just 19 days prior to the launch. On the last day of training, before exiting the experiment chamber where Bondarenko spent 10 days in solitary confinement, he wiped his skin with an alcohol-soaked cotton ball and tossed it aside. It landed on an electric hot plate — instantly igniting the oxygen inside of the training simulator and showing that even the smallest mistake or careless action can be a matter of life and death.

Physicians were concerned that the state of weightlessness can cause disorientation and unpredictable reactions of the psyche. That is why Vostok-1 was equipped with a security system that required Yuri Gagarin, the man eventually chosen, to enter a code in order to confirm his adequate state of mind.

"Space Russian nesting dolls" on display at London's Science Museum — Photo: Veronika Lukasova/ZUMA

While everything went well with the preservation of sanity, soon after something else became very clear: The prolonged absence of gravity has a negative impact on almost all vital systems of the body. The musculoskeletal, immune, and cardiovascular systems all came under attack, eyesight and hearing suffered too. Moreover, in the last century we did not know that the absence of gravity, the absence of support under the feet, degrades not only the muscles — but also the brain. If it does not receive enough signals from the feet, the cells begin to self-destruct. A similar process happens to a body in old age. We can say that without preventative measures, a human on long-term missions in space would experience accelerated aging.

Samarin believes that our dreams of carefree space travel remain out of reach. "We are far from it. We see the astronauts being helped out of the spacecraft, they are tired, soaked in sweat, and they have difficulties simply standing up," he explains, referring to the effects of gravity on the human body. "They are helped to the tent, helped with a change of clothes."

With all of that in mind, the past Soviet instruction manual for astronauts stated that if you land in an unauthorized location, you are to leave the cabin, take out a pistol, and not permit anyone to approach the spacecraft. The instructions are still the same, says Samarin, who doubts any astronaut would be able to carry it out. "This is just to say that every human body is different, but what we need is for every astronaut to be in an adequate state after landing. Who will meet and help them on Mars?"

Ground under the feet

In the 1970's, the entire crew of Soyuz-9 nearly perished after an 18-day flight: The astronauts experienced muscular atrophy, as a result of which they could not move and could barely breathe. After the incident, the United States and the USSR held several scientific conventions, and determined that a human should not remain in space for more than 17 days, as after that period the astronauts will not be able to survive in Earth's conditions.

Since then, a rigorous testing and exercise system was developed by Soviet and American physicians. The Soviets used volunteers to test the effects of prolonged space travel and zero gravity: Some participants were asked to lie in bed with their legs raised for a year, and others lived a year of their lives entirely submerged under water.

"In the absence of gravity, all that nature evolved over the course of millions of years on Earth is no longer needed," says Inessa Kozlovskaya, one of the leading experts on flight preparation. "A strong skeleton and the muscular system that developed under the effect of gravity are not necessary. The system just turns off as soon as you lose stable footing."

Magical Boots

Russian Mikhail Kornienko and American Scott Kelly embarked on a training mission aboard the ISS in 2015, as part of the One Year Crew — the joint mission was aimed to help scientists understand how the human body reacts and adapts to the harsh environment of space for extreme lengths of time, and of course, see which nation's training system works better. For an entire year they followed their own regimen, and scientists analyzed the data.

Russian scientists believe that the best preventative measure against zero gravity is running, because it is primarily a gravitational function of the body and is entirely absent in zero gravity. The astronauts run, alternating between accelerated jogging and walking, and the treadmill must be self-powered, so that the astronaut moves the treadmill with his feet.

Astronaut Shannon Lucid exercising on a treadmill aboard the Russian Mir space station in 1998 — Photo: NASA/JSC/Unknown

According to scientific recommendations, an astronaut in orbit should run 30% of his waking hours. On the other hand, Americans prefer a more strength-based preventative regimen, like weightlifting.

"In recent years scientists are trying to solve a problem associated with changes to the visual system," mentions Samarin. "Our American colleagues have identified a number of eyesight complications among their astronauts, but ours do not exhibit such changes. We believe that this is due to the different nature of the preventative measures that the astronauts follow. It would be interesting to test our hypothesis."

In addition to that, astronauts in orbit wear weighted suits that imitate gravity, and special boots that create the illusion of walking. The insole of these shoes is loaded with electrodes which stimulate the foot, and the brain is under the impression that the body is walking: An MRI reveals that the systems associated with the tension and relaxation of muscles become operational. Similar shoes, by the way, are currently used in Russia by hospitals for immobilized patients.

Kisses and goodbyes

A separate seat on the spacecraft is occupied by the battle against infections. Germs and microbes are particularly dangerous for astronauts, as during prolonged travel their immune system is substantially weaker. Shorter journeys do not have such a significant impact, and the immune system is completely restored shortly after returning to Earth.

"On the ISS (International Space Station), sterility is not really present in the sense that we think it is," notes Samarin. "It is provided at the launch complex: During the preparation of the ship for launch, all accessible surfaces are treated with a disinfecting solution, all vents and systems are "aired out", and despite all of that, when the ship enters orbit, astronauts note the appearance of dust! The astronauts bring their own flora aboard with them, where it settles on the walls of living quarters, begins to reproduce, mutate, deteriorates the stations, wires, windows. In general, our "friends" the germs eat everything — glass, iron ..."

Russian cosmonaut Sergey Ryazanskiy and a Russian spacesuit aboard the ISS in 2013 — Photo: NASA

In the 1970s the Deputy Minister of Health of the USSR, who was in charge of the space program was Avetik Burzanyan. He was very worried that the astronauts could pick up an infection upon returning to Earth, and always protested during landing, when the astronauts kissed those who greeted them. What if one of them is sick?! As a result, Burzanyan introduced a restricted observational period: an astronaut was to leave for 21 days prior to the launch and after landing, to be stationed at Baikonur, Kazakhstan, and no one had the right to kiss them. Today the observational period is still maintained, but it's a bit more flexible.

Now scientists are striving to understand if recovery is possible after prolonged flights affected by a radiation field. Today we know that long-term space flights negatively affect both the innate and the acquired immune systems. These changes affect deeply rooted mechanisms of the body — on the cellular and genetic levels, which are involved in the development of immune responses. One of the Russian laboratories established that if the flight lasts from four to 14 months, it can lead to long-term stress, and then to over-exhaustion of the immune system. This is precisely why astronauts are at a high risk of developing diseases associated with impaired immunoreactivity.


The signal "Alert, Attention, danger!" means that a solar flare has occurred, and the astronauts stationed on the ISS must immediately relocate to special cabins that are equipped to protect against radiation.

"This signal is not a daily occurrence, and usually, the entire dose of radiation that the crew receives is comparable to that of nuclear power plant operators," says Samarin. "But the ISS is in low orbit, meaning it is reliably protected by Earth's own radiation belts. During a flight to Mars the ship would undergo a powerful influence of cosmic radiation, what will happen to the crew and the equipment, we still don't fully know." Biophysicists proved that exposure to radiation primarily affects the nervous system, but apart from that mutations can occur in any cells, as particles break apart our DNA.

The most interesting program Roscosmos plans to carry out in the coming years is the "Bion-M2" satellite mission in 2019 to determine what happens to a living organism under high-energy radiation (until now, all experiments have taken place on Earth). The spacious module will "transport" geckos, mice, snails, fruit flies and other animals into high orbit of 500 kilometers. Another satellite (also carrying live specimen) plans to enter an elliptical orbit 200,000 kilometers away from Earth. It is believed that after these missions we would have a clearer understanding of the possibility of living in space, and just how much more work our bodies need in the meantime.