Man first flew into space in 1961, but even half a century later there are no exact answers to questions about how exactly space flight and prolonged stay in conditions of minimal gravity or weightlessness affects the human body.
In a new study, scientists decided to study the changes in the astronauts’ bodies a little deeper, almost at the molecular level.
Irreversible changes
A study of the health of astronauts after a long stay in space showed that there are a number of changes that greatly affect their health both during the flight and after. Many astronauts, after a certain period of time spent in zero gravity, are unable to regain their previous levels of physical fitness.
This is because microgravity conditions strain the human body and lead to its weakening. For example, the heart weakens due to loss of mass, since in weightlessness the blood is distributed differently and the heart beats slower.
In addition, bone mass density decreases due to the fact that the body is not affected by Earth's gravity. Changes in bone mass are observed already in the first two weeks in zero gravity, and after a long stay in space, it is almost impossible to restore the previous state of the tissue.
Changes in the body's immune system and in the metabolic process are especially strong.
Immune system
The immune system suffers from the fact that weightlessness is an extremely new condition for humans in terms of evolutionary development. For hundreds of thousands of years, humans have not encountered microgravity conditions and have proven to be extremely genetically unprepared for them.
Because of this, the immune system perceives weightlessness as a threat to the entire body as a whole and tries to use all possible defense mechanisms at once.
In addition, in conditions of isolation from familiar conditions, the human body is faced with a minimum amount of bacteria, viruses and microbes, which also negatively affects the immune system.
Metabolism
Changes in metabolism occur for a number of reasons. Firstly, the body's endurance decreases and muscle mass is lost due to the lack of physical activity that the body is accustomed to in gravity conditions.
Secondly, due to decreased endurance and aerobic exercise, the body consumes less oxygen and breaks down less fat.
Third, due to changes in the cardiovascular system, less oxygen reaches the muscles through the blood.
All this suggests that the human body is going through a difficult period of adaptation to the conditions of a long stay in space. However, how exactly and why do changes occur in the body?
Study of blood composition
Studies of the condition of astronauts before, during and after space missions have shown that changes occur in the immune system, muscle tone, metabolism and body temperature regulation, but scientists still do not understand the mechanisms that stimulate these changes.
It turns out that space flight reduces the content of various protein groups in the human body. Some of them quickly return to normal, but others find it much more difficult to reach a pre-flight state.
Progress of the study
To study the effect that prolonged stay in orbit in microgravity has on the levels of proteins in the blood, scientists studied the blood plasma of 18 Russian cosmonauts who had been on long-term missions on the International Space Station.
The first plasma sample was collected a month before the flight, the second sample was collected immediately after landing, and the final sample was collected a week after the mission.
In certain cases, astronauts took and studied samples themselves while on the ISS to provide more accurate indicators of how the levels of certain proteins in their blood were changing.
Results
Just 24% of the protein groups analyzed were found in lower abundance immediately after landing on Earth and after seven days.
Conclusions
Studying the difference in the content of proteins in the blood is one of the ways in which it is possible to explain some of the changes that occur in the body of an astronaut who has been in weightlessness for a long time.
For example, the study authors concluded that almost all of the 24% of proteins whose concentrations changed during space travel were associated with just a few body processes, such as fat metabolism, blood clotting and immunity.
Illustration copyright AP Image caption It's hard to look as good in real space as Sandra Bullock did in the movies.
Many people dream of flying into orbit, to the Moon, and even beyond. But those who actually go into space face a number of health risks.
According to the doctor from the cult TV series “Star Trek” Leonard McCoy (aka Chiropper, aka Bony), “space is disease and danger wrapped in darkness and silence.” And he is right in many ways. Traveling in space can make you weak, tired, sick and, with a certain degree of probability, suffering from depression.
"We're not designed to survive in the vacuum of space; our evolution didn't include that," says Kevin Fong, founder of the Center for the Study of Medicine in Extreme Environments, Space and High Altitudes at University College London and author of Life's Limit. death and the possibilities of the human body."
Let's imagine that you are lucky enough to fly into space. And now you are lying in a chair and counting the seconds until the start. What should you expect from your body? How will it behave in the coming minutes, hours, days and months? We asked scientists, engineers and astronauts about this, who know from experience what happens to a person under conditions when our body is in a completely artificial, alien situation. How to deal with this?
10 seconds after start. Possible loss of consciousness
The spacecraft separates from the launch complex, and the acceleration increases to 4G. You feel four times heavier than your normal weight. You are pressed into the chair, it is very difficult to even move your hand.
"Overload causes blood to shift to the legs, and to stay conscious we need to keep the blood flowing to the brain," John Scott, a senior scientist at the Human Performance Laboratory, explained to me when I visited QinetiQ's centrifuge in Farnborough in southern England. .
Due to the fact that the blood drains from the head, military pilots, even at relatively low g-forces, experience a gray veil before their eyes. True, in modern manned spacecraft, for example, in the Russian Soyuz, the astronaut’s position is chosen in such a way (with legs raised) to direct blood from the legs to the chest and further to the head.
10 minutes after start. Nausea
“The first thing astronauts complain about is nausea and vomiting,” says Fong. The lack of gravity affects our inner ear, which is responsible for our sense of balance, coordination and spatial orientation. “And it [the lack of gravity] reduces the ability to track moving objects,” he adds.
In some astronauts, in addition to minor changes in vision, swelling of the optic nerve, changes in the retina, and deformation of the eyeball were discovered. William Jeffs,NASA
Even if you ignore the balls of vomit floating around the capsule in zero gravity, "space sickness" can cause weakness and inability to perform assigned tasks.
One such incident nearly derailed the Apollo lunar program. During Apollo 9, the first test of the lunar lander in orbit, Rusty Schweikart was initially unable to complete some of the assigned tasks, and the duration of the spacewalk had to be shortened.
Anousheh Ansari, who became the first female space tourist, also said she had to deal with nausea, vomiting and disorientation.
Two days after the start. Swollen face
I recently interviewed Canadian astronaut Chris Hadfield. According to him, in orbit his nose was constantly stuffy. In space it is as if we are constantly standing on our heads; fluid accumulates in the upper part of the body. The result is facial swelling. It looks like your legs swell on a long flight.
They are overstimulated from being in space, they work in shifts, and they also have to get used to sleeping in a sleeping bag, strapped to the wall
“Our body pushes fluid upward,” explains Fong. “When we find ourselves in zero gravity, the body's systems continue to work, and since they do not meet resistance in the form of gravity, the tissues of the head swell.”
But the fact that you will look fatter than usual is not a problem. Recent research also suggests that spaceflight may affect vision. Researchers from the University of Texas examined astronauts using MRI scanners, and two-thirds of those examined had abnormalities.
“We have not yet found out the reasons for this,” admits NASA spokesman William Jeffs. “In addition to minor changes in vision, some astronauts were found to have swelling of the optic nerve, changes in the retina, and deformation of the eyeball. Possibly due to increased intracranial pressure.”
A week after the start. Decreased muscle and bone mass
When there is no gravity, our body begins to degrade.
Illustration copyright Thinkstock Image caption Before you decide to take your first step on Mars, take care of your bones and muscles!“Many systems in our body require gravity to function properly,” explains Fong. “In some experiments, rats lost up to a third of their muscle mass over seven to ten days of flight—which is a lot!” The heart muscle also degrades.
When you're in orbit, like the International Space Station, this isn't such a big deal. But let's imagine that you are planning a flight to Mars. You land 200 million kilometers from home, and your crew can't walk...
Since the beginning of the space age, scientists have puzzled over how to help astronauts maintain physical fitness. Each ISS crew member devotes an hour a day to cardio training and another hour to strength training. Despite this, when they return to Earth after a six-month watch in orbit, they find it difficult to walk.
The lack of gravity also affects the bones. They dissolve - almost literally. "In some weight-bearing areas, there was a loss of 1-2% per month," says Fong. "That's a very significant loss of bone tissue and a huge amount of calcium that ends up in the blood."
For future explorers about to set foot on Mars for the first time, this could be a major hurdle. It would be a shame if such an important step for humanity ends with a banal broken leg.
Two weeks after the start. Insomnia
"Insomnia is one of the most common problems," says Fong. "Astronauts' circadian rhythms, their daylight cycle, everything goes wrong." In an orbit where the Sun rises every 90 minutes, astronauts have difficulty adjusting to the lack of natural night.
In addition, they are overstimulated from being in space, they work in shifts, and they also have to get used to sleeping in a sleeping bag, strapped to the wall.
To combat sleep deprivation, the ISS is equipped with separate sleeping compartments that can be darkened to simulate nighttime. A new LED lighting system is being tested to reduce the unnatural harshness of light on board the station.
A year after the start. Diseases
There is growing evidence that spaceflight has harmful effects on the immune system. NASA researchers have discovered that the white blood cells of fruit flies in orbit are less effective at ingesting foreign microorganisms and fighting off infection than those of genetically identical flies left on Earth.
In deep space, for example, on the way to the Moon or Mars, the possibility of receiving a lethal dose of radiation becomes increasingly real.
This study is supported by other studies. Other insects, mice and salamanders in space become more vulnerable to disease. Most likely, it is again due to the lack of gravity.
Exposure to cosmic radiation provides even more cause for concern. Astronauts often report "seeing" bright flashes of light. The reason is cosmic rays passing through their brains. And this despite the fact that the ISS rotates in a fairly low orbit, and the Earth’s atmosphere partly protects the station’s inhabitants from hard cosmic radiation. But in deep space, for example, on the way to the Moon or Mars, the possibility of receiving a lethal dose of radiation becomes increasingly real. This can make long flights too dangerous.
However, observations of Apollo astronauts, who spent several days in deep space aboard a poorly protected capsule, did not reveal an increased likelihood of developing cancer.
Two years after the start. Depression
You survived takeoff, overcame nausea, learned to sleep in space and are doing exercises so that upon arrival on Mars you can confidently step onto its surface. You are in excellent physical shape. But how do you feel psychologically?
In June 2010, the European Space Agency and Russia's Institute of Biomedical Problems sent six people on a 520-day "flight to Mars." The flight simulation took place on the outskirts of Moscow in a mock-up of a spaceship. The stress associated with long-haul flights and the problems caused by isolation were examined.
How to solve the psychological problems of people locked in a cramped automated tin can, drinking processed urine and watching endless airless space through the windows?
The trip to Mars went well. It was an exciting adventure and the crew had a lot to do. The “walk on Mars” also went well. The most difficult part was the final part of the flight - the return to Earth. Daily tasks became burdensome and crew members became easily irritated. The days passed slowly. In general, the participants were overcome by boredom.
How to solve the psychological problems of people locked in a cramped automated tin can, drinking processed urine and watching endless airless space through the windows? Space agency specialists continue to work on this task.
“The mental health of our astronauts has always been as important to us as their physical health,” says Jeffs. “Ongoing behavioral training, research and improvements in communication technologies are all designed to help prevent any potential problems.”
To do this, first of all, you need to recruit the right people into the crews. An astronaut having a nervous breakdown is the worst thing that can happen.
Long years of evolution have adapted us to life in conditions of stable earth gravity. The atmosphere gives us protection and allows us to breathe. Probably, some version of artificial gravity will partly solve the problem, but space in any case poses a serious threat to human health.
Next year, NASA plans to launch a year-long experiment on the ISS to study in more detail the effects of long-duration spaceflight on astronauts. In the meantime, anyone who decides to leave the relatively safe orbit of our planet and go to other worlds must remember: there is no doctor on Earth yet like the iconic character from Star Trek. The technology that he used during his service in Starfleet is also missing.
About the author. Richard Hollingham is a journalist and host of the Space Explorers podcast. He edits Space:UK magazine for the British Space Agency, is a launch commentator for the European Space Agency and presents science programs on BBC Radio.
The original article in English can be read on the website.
When exploring the abyss of space, the most important question becomes: how will the human body behave in space? During the flight to distant planets and stars, environmental conditions will not resemble those on Earth in which people evolved. Currently, there are two protections - the spacecraft and the spacesuit. The first defense involves life support systems - air, water, food, maintaining the required temperature, counteracting radiation and small meteorites. The second protection ensures human safety in outer space and on the surface of a planet with a hostile environment.
The space medicine industry has existed for a long time. It is developing rapidly, and its goal is to study the health of astronauts who spend long periods in outer space. Doctors are trying to figure out how long people can survive in extreme conditions and how quickly they can adapt to earthly conditions after returning from a flight.
The human body requires a certain amount of oxygen in the air. Its minimum concentration (partial pressure) is 16 kPa (0.16 bar). If the pressure is lower, the astronaut may lose consciousness and die from hypoxia. In a vacuum, gas exchange in the lungs proceeds as usual, but leads to the removal of all gases, including oxygen, from the bloodstream. After 9-12 seconds, such blood reaches the brain, and the person loses consciousness. Death occurs after 2 minutes.
Blood and other fluids contained in the body boil at a pressure below 6.3 kPa (the vapor pressure of water at body temperature). This condition is called ebullism. The steam is capable of inflating the body to 2 times its normal size. But the body’s tissues have good elasticity and are quite porous, so there will be no tears. It should also be taken into account that the blood vessels, due to their internal pressure, will restrain ebullism, so some of the blood will remain in a liquid state.
To reduce ebullism, there are special protective suits. They are effective at pressures up to 2 kPa and prevent bloating at altitudes above 19 km. The spacesuits use 20 kPa of pure oxygen. This is enough to maintain consciousness, but the evaporation of gases contained in the blood can still cause decompression sickness and gas embolisms in an unprepared person.
People cannot exist outside the magnetosphere, and therefore the human body in space is exposed to high levels of radiation. During a year of work in low-Earth orbit, an astronaut receives a radiation dose that is 10 times higher than the annual dose on Earth. Radiation damages lymphocytes that maintain the immune system at proper levels.
In addition, cosmic rays in galactic space can provoke cancer of any organs. They can also damage an astronaut's brain, which can lead to Alzheimer's disease. Therefore, doctors are developing special protective drugs to reduce the risk of negative events to an acceptable level. Still, it must be said that interplanetary missions outside the Earth's magnetosphere are extremely vulnerable. Here you need to take into account powerful solar flares. They can cause radiation sickness in astronauts, which means death.
In mid-2013, NASA experts reported that a manned mission to Mars could involve a high radiation risk. In September 2017, NASA reported that radiation levels on the surface of Mars had doubled. This was associated with the aurora, which turned out to be 25 times brighter than previously observed. This happened due to an unexpected and powerful solar storm.
Human organs subject to physiological changes in space
Now let's talk about the effects of weightlessness on the human body in space. Short-term exposure to microgravity causes spatial adaptation syndrome. It is expressed mainly in nausea, as the vestibular system is upset. With prolonged exposure, health problems arise, and the most significant are the loss of bone and muscle mass, and the functioning of the cardiovascular system slows down.
The human body is mainly composed of liquid. Thanks to gravity, it is distributed in the lower body, and there are many systems to balance this situation. In zero gravity, the liquid is redistributed to the upper half of the body. For this reason, astronauts experience swelling on their faces. The disturbed balance distorts vision, and changes in the sense of smell and touch are also recorded.
What is interesting is that many bacteria feel much better in space than on Earth. In 2017, it was found that in zero gravity, bacteria become more resistant to antibiotics. They adapt to the space environment in ways that are not observed on Earth.
Because weightlessness increases the amount of fluid in the upper body, intracranial pressure increases. Pressure increases on the back of the eyeballs, thereby affecting their shape. This effect was discovered in 2012, when astronauts returned to earth after a month in space. Deviations in the functioning of the visual apparatus could become a serious problem for future missions, including a mission to Mars.
The solution here could be an artificial gravity system. However, even with a complex gravity system installed on a starship, a state of relative microgravity may remain, and, therefore, the risks associated with it will remain.
The psychological consequences associated with prolonged stay in space have not yet been clearly analyzed. There are analogues on Earth. These are Arctic research stations and submarines. For such teams, changing the environment is a great stress. And its consequences are anxiety, depression and insomnia.
Sleep quality in space is poor. This is explained by the change in dark and light cycles and poor lighting inside the ship. And poor sleep affects neurobiological reactions and leads to psychological stress. Dreams may be disrupted by mission demands and high noise levels from operating equipment. 50% of astronauts receive sleeping pills and at the same time sleep 2 hours less than on Earth.
A study of long-term stay in space showed that the first 3 weeks are the most critical for astronauts. It is during this period that the human body adapts to extreme environmental changes. But the coming months are also difficult. However, the missions are not long enough to judge long-term physiological effects and changes.
A flight to Mars and back, taking into account modern technologies, will take at least 18 months. But now no one can say how the human body will behave in space for a year and a half, and even in the absence of a magnetosphere. Only one thing is clear: the ship must contain a huge number of diagnostic instruments and medical supplies. Only in this case will the crew’s performance remain at the proper level.
Boundless outer space is a hostile environment for humans. It contains countless unknown dangers. But, despite everything, people are determined to conquer space. Therefore, scientific work in this direction is carried out tirelessly. Technologies are being developed that include artificial gravity and bioregenerative life support systems. All this should reduce future risks to nothing and enable people to colonize the galactic abyss.
Vladislav Ivanov
Immunity is the body’s ability to resist invasion by foreign organisms. The immune system is a very complex entity: it consists of several internal organs (red bone marrow, thymus, which is located in the upper part of the chest), lymph nodes and the spleen. All these organs secrete a large number of specialized cells (lymphocytes, eosinophils, neutrophils and others), which find a foreign microorganism or cell and begin to attack it.
The main functions of acquired immunity are performed by lymphocytes, which are divided into two types: T-lymphocytes and B-lymphocytes.
T-lymphocytes have a very wide spectrum of action (strengthen the immune response, destroy damaged cells of their own body, activate B-lymphocytes and other types of active cells of the immune system).
A team of scientists led by Brian Krushian from NASA's NASA Space Center. decided to find out how a long stay in space affects the functioning of the human immune system. Such studies had never been carried out before: experts only had information about how the human body, which spent a short period of time in space, protects itself from diseases. The results of the scientists' work were published in NPJ Microgravity.
The study involved 23 astronauts (18 men and 5 women) working on the International Space Station, with an average age of 53 years. Sixteen cosmonauts arrived at the ISS on Russian Soyuz spacecraft and spent about six months in space. The remaining seven people were delivered to the ISS by American shuttles. The missions of five cosmonauts lasted more than a hundred days, two lasted less than two months.
Before the flight (180 and 45 days before it), scientists took blood from all subjects for analysis and found out how many cells responsible for the functioning of the immune system were produced in it.
Those cosmonauts who spent about six months on the ISS took their blood three more times: two weeks after arrival, in the second or third month of their stay on the station, and at the end of the mission.
These blood samples were brought to Earth and also examined by specialists from the Space Center. Lyndon Johnson.
As a result of the work, it turned out that the immune system of people who were in a state of weightlessness for about six months works much worse than that of others:
her ability to produce T lymphocytes was significantly reduced, her white blood cell count was impaired, and her ability to recognize foreign microorganisms and cells was suppressed.
Scientists claim that the results of their work mean: a long stay in space significantly weakens the body’s immunity, which can create additional difficulties and problems with staying in orbit. It is worth noting that after a person returns to Earth, the immune system is not restored immediately, as evidenced by analyzes of blood samples taken immediately after landing and after a month of life on Earth.
So far, researchers cannot name the exact reasons for the weakening of the immune system: it could be the general stress received by the body during the flight to the ISS, or the disrupted functioning of the body’s biological clock, or being in a state of weightlessness.
Previously, scientists have already found out how weightlessness affects the condition of the skin of living organisms - the article was published in the same journal NPG Microgravity. Because the astronauts complained of dry and itchy skin, it was decided to send mice into orbit and return them to Earth 91 days later, after which the condition of the rodents' skin was analyzed. It must be said that the rodents participating in the experiment became the first living creatures in the world - with the exception of humans, of course - to spend such a long time in weightlessness.
Six laboratory mice were delivered to the International Space Station using the Discovery shuttle. After returning, scientists examined their skin and found out: after three months in space
she became significantly thinner (by 15%), and the fur began to grow differently.
(The hair follicles of the astronaut mice were in an active stage of work, while their functioning at that time should have been slower.) The changes affected the work of the genes that were responsible for the work of the follicles. In addition, researchers found that the skin of rodents began to produce 42% more collagen than the skin of “terrestrial” mice.
Mice also helped researchers understand why people's vision deteriorates in space: the corresponding work was done by American and Russian researchers, and the main participants in the experiment were rodents who spent 30 days in space on the Russian Bion-M No. 1 spacecraft. The results were published in The Journal of Applied Physiology.
Cosmonauts who spend short periods of time in zero gravity complain of vision problems that arise - which, however, disappear after returning to Earth. However, if the stay in orbit was long, vision is not restored on its own. Lead study author Michael Delp comments: “When astronauts go into space, they are willing to sacrifice their physical health to do so. However, few people usually want to risk their eyesight.”
After the return of Bion-M, the mice were taken to the Institute of Medical and Biological Problems, where a team of scientists, led by and, began a detailed examination of their health. As a result of the work, it turned out that vision problems arise due to disruption of the blood vessels. Under conditions of gravity, blood circulating through the vessels and arteries tends downward, towards the legs, and this state is natural for our body. In microgravity (weightlessness) conditions
the fluid cannot move downward due to gravity, and too much blood enters the brain. This harms the functioning of the blood vessels, in particular those that ensure the normal functioning of the eyes.
Scientists say they will look for ways to combat this problem.
The results of the work prove that significant changes can occur in the human body while in space, including genetic ones, which require detailed study.
Today, perhaps, even a small child knows about the fact that weightlessness is observed in space. Numerous science fiction films about Space have contributed to such widespread dissemination of this fact. However, in reality, few people know why there is weightlessness in Space, and today we will try to explain this phenomenon.
False Hypotheses
Most people, having heard the question about the origin of weightlessness, will easily answer it by saying that such a state is experienced in Space for the reason that the force of gravity does not act on bodies there. And this will be a completely wrong answer, since the force of gravity acts in Space, and it is this force that holds all cosmic bodies in their places, including the Earth and the Moon, Mars and Venus, which inevitably revolve around our natural luminary - the Sun.
Having heard that the answer is incorrect, people will probably pull out another trump card from their sleeves - the absence of an atmosphere, the complete vacuum observed in Space. However, this answer will not be correct either.
Why is there weightlessness in space?
The fact is that the weightlessness that astronauts on the ISS experience arises due to a whole combination of various factors.
The reason for this is that the ISS orbits the Earth at a tremendous speed exceeding 28 thousand kilometers per hour. This speed affects the fact that the astronauts on the station cease to feel Earth’s gravity, and a feeling of weightlessness is created relative to the ship. All this leads to the fact that the astronauts begin to move around the station exactly as we see in science fiction films.
How to simulate weightlessness on Earth
It is interesting that the state of weightlessness can be artificially recreated within the Earth’s atmosphere, which, by the way, is being successfully done by specialists from NASA.
NASA has such an aircraft on its balance sheet as the Vomit Comet. This is a completely ordinary airplane, which is used to train astronauts. It is he who is able to recreate the conditions of being in a state of weightlessness.
The process of recreating such conditions is as follows:
- The airplane sharply gains altitude, moving along a pre-planned parabolic trajectory.
- Reaching the top point of the conventional parabola, the airplane begins a sharp downward movement.
- Due to a sharp change in the trajectory of movement, as well as the flight of the aircraft downward, all people on board begin to experience conditions of weightlessness.
- Having reached a certain point of descent, the airplane levels its trajectory and repeats the flight procedure, or lands on the surface of the Earth.
