Recently, the topic of exploration and colonization of Mars has emerged from science fiction. USA, Europe, Russia and
They are threatened by radiation.
Radiation from space. Why are people safe on Earth?
First of all, particles of energy that fly out of the sun as a result of giant solar eruptions are dangerous for people.
In addition to flares, huge clouds -coronal mass ejections - containing a billion tons of solar material, sometimes explode on the surface of the sun. Increasingly, scientists believe that coronal mass ejections play a dominant role in controlling the most powerful radiation from the Sun: solar energy particles or SEP (Solar energetic particles).
SEPs are particles (mostly protons, butalso electrons and ions) flying at such high speeds that some of them reach the Earth, 150 million km away, in less than an hour.
Radiation is the energy contained inelectromagnetic waves or carried by particles. Energy is transferred when a wave or particle collides with something else, such as an astronaut or a component in a spacecraft. SEPs are dangerous because they can pass through the skin, releasing energy and destroying cells or DNA in their path. Such damage can increase the risk of cancer later in life or, in extreme cases, cause acute radiation sickness in the short term.
Why are people safe on Earth?
On Earth, people are insured against this harm. But why?
Earth's protective "magnetic bubble" - magnetosphere- rejects most solar particles. The atmosphere also suppresses any particles that penetrate it. The International Space Station is moving in low Earth orbit while under the protection of the Earth, and the station's hull also helps protect the crew from radiation.
The Earth is in the center of a huge blue comet-shaped bubble.
Earth's magnetic bubble, called the magnetosphere,shown in blue. The magnetosphere provides a natural shield against cosmic radiation by deflecting most of the charged solar particles from the Earth.
Credit: Andøya Space Center / Trond Abrahamsen
But beyond Earth's magnetic reach, human explorers can face harsh radiation from space.
Astronaut protection strategy
The main strategy of the think tankwork in space - to use any available mass on the ship. They redistribute it in such a way as to fill in areas that are inadequately protected and direct the crew to well-protected areas.
The greater the mass between the crew and the radiation, theit is more likely that hazardous particles will transfer their energy before reaching the crew. On the Moon, astronauts can heap lunar soil or regolith over their hiding places, taking advantage of the natural protective materials of the environment. But when it comes to the design of a spacecraft, relying on its size for protection soon becomes expensive, as more propellant is required to launch more mass.
Johnson's team is working on developing methodsshielding without adding additional materials. Astronauts will not be able to fly in "special radiation shielding". The laws of distribution of payload on a ship are such that every object with which a team of astronauts flies must be multipurpose.
For the Orion spacecraft, they developeda plan for astronauts to build a temporary shelter from available materials at hand, including storage units already on board or supplies of food and water. If another storm breaks out on the Sun, as strong as during the era of the Apollo missions, Orion's crew will be safe and sound.
Jessica Vos (foreground), deputyOrion health and medical technology specialist and astronaut Anne McClain (background) demonstrate a radiation protection plan aboard a typical Orion spacecraft. During the SEP event, the crew will use storage bags aboard Orion to create a tight shelter from radiation.
Other teams at NASA are tackling the radiation problem withcreative solutions by developing technologies such as wearable vests and mass-increasing devices and electrically charged surfaces that deflect radiation.
Also, an experienced space designerspacesuits Amy Ross at NASA's Johnson Space Center in Houston is developing new suits for the Moon and Mars. It was the samples of her prototype spacesuit that went to Mars on the Perseverance mission for verification and analysis.
Perseverance has launched. How will it prepare us for the colonization of Mars?
How to protect yourself from the sun? Main problems
To protect astronauts from particle stormssolar energy, you need to know when such a storm will occur. But particle flows are fickle and difficult to predict. The nature of turbulent solar eruptions has not yet been fully understood.
Ideally, you could look at an activean area on the sun, see how it develops, and try to predict when the eruption will occur. The problem is that even if you could predict flares and coronal mass ejections, only a small fraction actually produces particles that are dangerous to astronauts.
Richardson
And if SPEs do appear, it is difficultpredict where they will go. The lines of force of the magnetic field are a highway for charged particles, but when the sun rotates, the roads turn into spirals. Some particles are knocked out due to the kinks of the field lines. As a result, they can spread throughout the solar system in the form of a huge foggy cloud.
The solar flare on August 7, 1972 wasrecorded by Big Bear Solar Observatory in California. This particular outbreak, known as the seahorse outbreak due to the shape of the bright areas, triggered a powerful SEP event that could harm astronauts if the Apollo mission had been in progress at the time.
Models to predict when will appearSEP are in the early stages of development. One of them uses the arrival of lighter, faster electrons to predict the flux of heavier protons that will follow, which are more dangerous.
Scientists rely on NASA's heliophysical missionsfor the development of space weather forecasting models. This helps position the spacecraft at different viewpoints between the Sun and Earth. Launched in 2018, NASA's Parker Solar Probe flies closer to the Sun than any other spacecraft before it. The spacecraft will track SEP near their source. This will be the key to unraveling how solar eruptions accelerate particles.
Time matters too. The sun goes through 11-year cycles of high and low activity. During solar maximum, the Sun is covered in areas of high magnetic voltage that are ready to erupt. During solar minimum, when there are few or no sunspots, eruptions are rare.
While scientists continue to improvetheir models, NASA's heliophysical spacecraft are already providing observations to give astronauts a complete picture, understanding and prediction of hazards. And, most importantly, permission to carry out missions. If there are no active sunspots on the Sun, scientists can say with confidence that there will be no solar flurry.
Another danger. Radiation from neighboring galaxies
The second type of cosmic radiationspreads even further than particles of solar energy. Galactic cosmic rays - particles of long gone exploding stars elsewhere in the Milky Way - constantly bombard the solar system at close to light speeds. If solar energy particles are a sudden downpour, then galactic cosmic rays are more like a steady drizzle. But drizzling rain can also be inconvenient.
The solar system is at the center of two large purple bubbles representing the heliosphere. Gold stripes are reflected everywhere.
This image shows the solar system andthe magnetic bubble of the Sun, the heliosphere that extends far beyond its limits. The bright stripes represent cosmic rays. During solar maximum, when the heliosphere gets stronger, it blocks more cosmic rays.
NASA Goddard Space Flight Center / Conceptual Imaging Lab
Cosmic rays tend to be moremore powerful than even the most energetic solar particles. The same spacecraft that protects the crew from solar energy particles will not be able to keep cosmic rays at a distance, so cosmic rays pose a serious problem, especially for long missions such as travel to Mars, which will take six to 10 months.
Although SEP is difficult to predict, galacticcosmic rays arrive at a constant speed. In one second, about 90 cosmic rays hit a point in space the size of a golf ball. Meanwhile, during a SEP downpour, there could be another 1,000 particles moving through that golf ball-sized space. This speed helps determine radiation limits and mission duration. In this is NASA's leading strategy to limit exposure to cosmic rays. NASA monitors astronauts' individual doses to ensure they are not exposed to excess radiation.
Cosmic rays are composed of heavy elementssuch as helium, oxygen or iron. Massive particles break atoms when they collide with something, be it an astronaut or the thick metal walls of a spacecraft. The impact causes a stream of additional particles - secondary radiation, which further exacerbates the danger of cosmic rays.
Exposure to cosmic rays is also associated withsolar cycle. In the relative calm of the solar minimum, cosmic rays easily penetrate the solar magnetic field. But during the solar maximum, the Sun's magnetic bubble intensifies with increased solar activity, pushing away some intruders from galaxies. Oddly enough, harmful radiation helps neutralize other hazardous radiation.
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