Galactic Radiation Can Cause Brain Degeneration

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Video: Galactic Radiation Can Cause Brain Degeneration

Video: Galactic Radiation Can Cause Brain Degeneration
Video: Space Radiation is Risky Business for the Human Body 2024, March
Galactic Radiation Can Cause Brain Degeneration
Galactic Radiation Can Cause Brain Degeneration
Anonim
Galactic radiation can cause brain degeneration
Galactic radiation can cause brain degeneration

A team of researchers from the University of Rochester Medical Center (URMC) in New York has announced the results of their research. Long-term astronauts in space, for example, during a flight to Mars, can lead to health problems due to galactic radiation. In particular, to brain degeneration, and possibly even the onset of Alzheimer's disease

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Earlier, in 2012, similar conclusions were reported by Russian scientists. As Natalia Teryaeva writes in the newspaper Ploshchad Mira, “if you fly on a Martian expedition in a modern spacecraft, the flight will take at least 500 days. During this period of space mission, the health of astronauts can be irrevocably lost.

This is evidenced by the results of studies by Russian radiobiologists and physiologists, which were discussed at the Joint Institute for Nuclear Research (JINR) at a visiting meeting of the Bureau of the Department of Physiology and Fundamental Medicine of the Russian Academy of Sciences.

Scientists see the greatest danger in galactic radiation: it can deprive a person of sight and reason, without which it will not be possible to fly to the target or return home.

The statements of researchers about the danger of heavy ions for the organism of astronauts are not speculative, they are based on data from accelerator experiments with animals carried out at the Laboratory of Radiation Biology of the Joint Institute for Nuclear Research (LRB JINR) in cooperation with the Institute of Biomedical Problems of the Russian Academy of Sciences (IMPB RAS), the Institute of Biochemistry RAS (IBCh RAS) and in collaboration with biologists from the American National Space Agency (NASA).

Heavy ions are scarier than protons

In deep space - beyond the Earth's magnetic field - dangerous cosmic radiation emanating from the depths of the galaxy lies in wait for man.

"Galactic cosmic rays are streams of elementary particles - light and heavy ions," explains Mikhail Panasyuk, director of the Skobeltsyn Research Institute of Nuclear Physics (SINP MSU). naked "nuclei. The reason for this is the interaction with matter in the process of their transfer in the Universe. The most common element of cosmic rays is hydrogen, its ions are protons. These particles are accelerated on shock waves - remnants of supernova explosions. Such stars do not explode in our Galaxy. more often than once in 30-50 years.

The flux of galactic cosmic ray particles is constant, in contrast to solar cosmic rays, which are generated on the Sun or in the interplanetary medium during solar flares. Because of this, the total contribution of solar cosmic rays over a long time is insignificant. But during solar flares (for several hours, days), the flux of solar cosmic rays can exceed the flux of galactic cosmic rays. In addition, the energy of particles of solar cosmic rays, as a rule, is less than that of particles of galactic cosmic rays. There are also extragalactic cosmic rays entering our Galaxy from other galaxies. Their energy is greater than that of galactic cosmic rays, but the fluxes are much less. Cosmic rays have a huge energy range: from 106 (1 MeV) to 1021 eV (1 ZeV).

Energy-mass spectrometers installed on space research satellites recorded the composition of cosmic rays. It turned out that a little less than one percent of all particles of galactic radiation are heavy ions with an energy of 300 - 500 MeV / nucleon - the nuclei of heavy chemical elements. The fraction of light and heavy ions of galactic radiation contains most of the ions of carbon, oxygen and iron - of these stable elements, stellar cores are formed as a result of the evolution of stars.

The results of measurements of space satellites served as the basis for further model calculations, which showed that outside the Earth's magnetosphere, about 105 heavy ions fall per square centimeter of area per year, and about 160 particles with a charge Z greater than 20 fall per day. every day just such a number of them will fall per square centimeter of the cosmonaut's body surface.

Space heavy ions are so energetic that they "pierce" the skin of a modern spacecraft in outer space, like cannonballs bombarding fine silk. Scientists of the Laboratory of Radiation Biology at JINR have found out how this can harm the health of the Earth's messengers on a long journey.

To Mars - by touch?

“We managed to understand why the same doses of different radiation (heavy ion flux, neutron, gamma radiation) cause different effects on living cells,” says the Director of the JINR LRB Corresponding Member of the Russian Academy of Sciences Evgeny Krasavin. different radiations are associated both with the physical characteristics of the radiation and with the biological properties of the living cell itself - its ability to repair DNA damage after irradiation. In experiments on heavy ion accelerators, we found that the most severe DNA damage occurs under the influence of heavy ions. rays (a beam of photons) and a beam of heavy ions can be imagined like this: to shoot a small shot from a gun into a wall is harm from X-rays, to shoot a cannonball at the same wall is destruction from one heavy ion. lose significantly more of their energy per unit more than their lighter cousins. That is why, passing through the cell, a heavy ion on its way produces great destruction. When a heavy particle passes through the cell nucleus, "cluster-type" lesions are formed with multiple breaks of chemical bonds in the DNA fragment. They cause various types of severe chromosomal damage in cell nuclei."

Further, the logic of reasoning of scientists was as follows. Hydrogen ions (protons) with an energy of 200 - 300 MeV / nucleon have time to run an 11 cm path in water before complete deceleration. The human body is 90% water. Extrapolating this result to a living human organism, we get the conclusion: even light ions on their way can damage thousands of cells in our body. In the case of heavy ions with a charge of more than 20, an even more deplorable result for health should be expected.

What human organs can be damaged by galactic heavy ions most severely and life-threatening?

- If you think about actively proliferating - rapidly renewing - body tissues, such as blood or skin, then their damage due to natural properties will quickly recover, - explains the director of LRB JINR Yevgeny Krasavin. - But on static tissues - the central nervous system, eyes, which do not have the natural ability to quickly repair damage, the constant flow of heavy ions will have a layering harmful effect, causing regular cell death. But the central nervous system and the eye are the control "chips" of our body.

In experiments on animals in Dubna, a group of radiobiologists led by Academician of the Russian Academy of Sciences Mikhail Ostrovsky studied the mechanisms of the effect of heavy ions on the structures of the eye - the lens, retina, and cornea. At the JINR accelerators, mice and solutions of crystallins (proteins) of their lens were irradiated with 100-200 MeV proton beams.

“The lens of the eye of humans and vertebrates is 90% composed of alpha-, beta- and gamma-crystallins,” Academician Ostrovsky said in his speech at a visiting meeting of the Bureau of the Department of Physical Physics of the Russian Academy of Sciences. “The content of these proteins in the lens is approximately the same, but they differ significantly in structure and molecular weight. Exposure to ultraviolet radiation or radiation can cause aggregation of crystallins - the appearance of opaque fibers in the lens. As a result of aggregation, large light-scattering conglomerates are formed, which lead to clouding of the lens, that is, to the development of cataracts. Passing through the lens of the eye, even single heavy ions after a while, they can cause it to become cloudy.

Return to Earth as a Homo sapiens

Least of all radiobiologists have studied the damaging effect of heavy ions on the central nervous system. According to NASA experts, during a Mars mission from 2 to 13 percent of nerve cells will be crossed by at least one iron ion. And one proton will fly through the nucleus of each cell of the body every three days. Therefore, there is a serious danger of irreversible violations of the behavioral reactions of the ship's crew. This jeopardizes the overall mission. The brain is a very delicate instrument, and disruption of small parts of it can lead to the loss of the functioning of the whole organism, as is the case in people who have had a stroke or in those who suffer from Alzheimer's disease.

At the NASA Space Radiation Laboratory in Brookhaven, using a beam of iron ions accelerated to an energy of 1 GeV / nucleon, galactic radiation was simulated on the heavy ion pre-accelerator of the RHIC collider at Brookhaven National Laboratory. The rat experiment was called a "cognitive test". A small solid area was placed in a round pool under a thin layer of opaque water. Laboratory rats - first healthy and then irradiated with beams of iron ions - were launched into this pool and monitored how quickly the animals could find this area and climb onto it. Healthy rats quickly found the site and walked towards it along the shortest path. Irradiation with heavy ions dramatically altered the cognitive functions (learning ability) of animals. A month after the irradiation, the behavior of the rat changed dramatically. She dodged, circled the pool for a long time, until she almost accidentally managed to feel the solid ground under her feet. The animal's thinking abilities were severely impaired. When rats were irradiated with X-rays and gamma radiation, no such effect was observed.

In order to imagine the possible consequences of irradiation of the human body with heavy ions, it is necessary to "play" the model of cosmic hazard on primates, the researchers say. Nevertheless, the harm from the effects of galactic radiation from heavy ions revealed in rodents is convincing enough not to think about it when planning to send people on a long flight to Mars.

How to avoid trouble

From what physicists and biologists know today, it follows that the risk of radiation damage to astronauts cannot be reduced to zero during more than a year's journey to Mars. Methods to reduce this risk exist so far in the form of ideas.

First idea: to plan a flight to Mars during the maximum solar cycle. At this time, the flux of galactic cosmic rays will be less due to the fact that the interplanetary magnetic field of the solar system will bend the trajectories of galactic cosmic rays, seeking to reduce the intensity of their particles and "sweeping" particles with energies less than 400 MeV / nucleon from the solar system.

The second idea is to significantly reduce the radiation dose from galactic radiation with the help of reliable protection of the ship and to provide in the structure of the ship a special compartment-shelter with more powerful protection from powerful streams of unpredictable solar wind. Already, new types of protective materials are being developed that would become more effective than currently used aluminum, for example, hydrogen-containing plastics such as polyethylene. With their help, it is possible to create a protection capable of reducing the radiation dose by 30 - 35% at a thickness of 7 cm. True, this is not enough, scientists believe, the thickness of the protective layer must be increased. And if it does not work, then significantly reduce the flight duration - say, at least to 100 days. One hundred days is a figure so far only intuitively justified. But in any case, you need to fly faster.

The third idea: to provide the pilots of the Martian spacecraft with effective anti-radiation drugs that could significantly strengthen the bonds between DNA proteins, reducing their vulnerability to heavy ion bombardment.

The fourth idea is to create an artificial magnetic field around the spacecraft, similar to the earth's magnetic field. There is a project of a superconducting toroidal magnet, inside and outside of which the field approaches zero, so as not to damage the health of astronauts. The powerful field of such a magnet should divert a large proportion of cosmic protons and nuclei from the spacecraft, and reduce the radiation dose by 3 - 4 times during the expedition to Mars. The prototype of such a magnet has already been created and will be used in an experiment to study cosmic rays on board the International Space Station.

Yet, until the ideas of protecting the Martian crew have not found their embodiment, there is only one way out, say radiobiologists: to conduct detailed radiobiological studies in terrestrial conditions on heavy ion accelerators, which, in terrestrial conditions, will simulate the damaging effect of high-energy heavy nuclei emanating from the depths of the galaxy. Among such unique accelerators are the Nuclotron of the JINR High Energy Physics Laboratory and the NICA collider complex being created on its basis. Scientists pin great hopes on the capabilities of these installations.

And if we are in a hurry to fly to Mars, then it is either time to build faster spaceships, or to leave the dreams of manned flights in deep space for the time being. Let the robots travel for now.

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