Cosmonauts receive a dose of radiation 200 times more per day than a person on Earth. If we compare it with a medical X-ray study, it turns out that the daily dose of radiation for an astronaut is 0.6 millisieverts, which is 5-6 sessions of chest examination. On Earth, the natural background radiation consists mainly of gamma radiation, in space - of charged particles. Elements of the periodic table are accelerated to tens, hundreds of gigaelectronvolts, so they can pierce several meters of the thickness of the protective coating.
Studies have been conducted on the health of astronauts to see if they get cancer more often than other people. We concluded that no, but this study has very little statistics: there are not so many astronauts. Of course, radiation shortens life, because it leads to premature aging of the body. And for the astronauts to remain young and healthy, radiation standards have been invented. In Russia, this is 1,000 millisieverts in a lifetime, while an astronaut is allowed to receive no more than 200 millisieverts per year.
From the point of view of modern standards, it is impossible to constantly be in space: a person will receive the maximum dose of radiation in 4 years (4 x 200 = 800 mSv, another 200 mSv is a reserve for unforeseen circumstances). The record-breaking astronauts spent about 850 days in space. If all the standards are followed, which is monitored by the radiation safety service of manned space flights, then the life of cosmonauts will be reduced by no more than 2.5-3 years.
It is worth considering that the level of radiation in space is not constant and changes due to solar proton events, which increase the radiation dose received by the astronaut. Current manned flights are in low orbit (as experts say, in an orbit with a mid-latitude inclination). There, under the protection of the magnetosphere, the dose from flares is weakened by several hundred times, so the radiation dose for the day when a solar proton event occurs increases by a maximum of 10–15 times. The situation changes dramatically if we are outside the magnetosphere (about 10 Earth radii) or closer to the poles at low latitudes. In these areas, the magnetosphere does not protect us in any way, solar flares begin to pose a real danger, since the radiation dose increases 200–300 times compared to the undisturbed period. This causes the immediate effects of radiation exposure: dizziness, nausea, loss of appetite, deterioration in working capacity - this is a dangerous phenomenon for an astronaut. Fortunately, powerful flares are quite rare - once or twice per solar cycle (11 years), and their maximum duration does not exceed two days.
In different compartments of the spacecraft, the radiation dose is different, the readings may differ even inside the human body. First of all, you need to learn how to control the level of radiation: cosmonauts have various dosimeters, sensors, which can be used to obtain information about radiation exposure. Depending on solar activity, we recommend that the crew stay in those compartments of the space station where the radiation dose is lower - these are compartments that do not protrude from the hull.
In the radiation safety service for manned space flights, we proposed to protect cosmonauts by placing a special product on a thin outer wall. The protective curtain is a "mattress" with space napkins - gauze cloth soaked in water and sealed in a plastic bag. Wet wipes replace the shower for astronauts; they can not only be stored at the station, but used as an additional layer of water that protects the astronaut from radiation in the compartments. Water and plastic plates trap secondary particles - neutrons, and the radiation dose is absorbed more efficiently.
Vyacheslav Shurshakov, Candidate of Physical and Mathematical Sciences, Senior Researcher, IBMP, Radiation Safety Service for Manned Space Flights