What are Cosmic Rays?

Cosmic rays , also known as cosmic rays , are charged high-energy subatomic particles from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray comes from the history that was once thought to be electromagnetic radiation. The primary primary cosmic rays (particles coming from deep space and the atmosphere) are generally stable particles on Earth, such as protons, nuclei, or electrons. However, a very small proportion are stable antimatter particles, such as positrons or antiprotons, and the remaining small part is an active area of research.

Henry Becler

In 1912, German scientist Victor Hans brought

Solar modulation refers to the process by which the sun or solar wind changes the intensity and energy spectrum of the Milky Way cosmic rays entering the solar system. When the sun is active, the galaxy's cosmic rays will enter the solar system less than when it is quiet. For this reason, the Milky Way cosmic rays follow the 11-year cycle as the sun, but the difference is that intense solar activity corresponds to low cosmic rays (entering the solar system) and vice versa.

About 4.6 billion years ago, the earth

The origin of cosmic rays usually refers to the main components of cosmic rays-various

Gas barrier

Although when the cosmic rays reach the earth, there will be an atmosphere to block part of the radiation, but the intensity of the ray stream is still very large, which is likely to have a certain degree of impact on air traffic. For example, the control and navigation systems used on modern aircraft are quite sensitive.

Humans still can't say exactly where cosmic rays are generated, but it is generally believed that they may come from

In 1903,

Direct detection method The cosmic rays below 1014eV have a sufficiently large flux, and a particle detector with an area of about square meters can be used to directly detect the original cosmic rays. This type of detector requires

Cosmic Ray Alien Life Evolution

Cosmic rays are constantly bombarding Earth, and a new study suggests that this invisible, high-energy particle flow may play a key role in determining the existence of life on other planets.

More than 100 years after its discovery, cosmic rays still haunt scientists. This high-energy particle flow propagates through space at almost the speed of light. Some of these particles carry 100 million times more energy than the energy achieved by the most powerful accelerator on Earth. Cosmic rays are nucleus streams, the main component of which is protons, which are hydrogen nuclei.

When cosmic rays bombard the Earth's atmosphere, they produce a series of secondary particle streams, including muons, a type of subatomic particle that is similar to electrons but has a much larger mass. Part of this particle flow will reach the ground, endangering life on the ground and in the ocean. In fact, muons can even penetrate the surface rock and soil layers after tens of meters.

Scientists are investigating the effects that cosmic rays may have on the habitability of distant exoplanets. Over the past 20 years, scientists have discovered hundreds of exoplanets using ground and space telescope equipment, which has raised hopes that some form of extraterrestrial life may exist in those exoplanets. Researchers' interest is particularly focused on exoplanets located in so-called "habitable zones", where the planets are at a reasonable distance from the star, allowing water to exist on its surface in liquid form. On Earth, liquid water has bred rich life forms.

Researchers believe that the level of radiation a planet is exposed to will affect its livability. Although the external radiant flux experienced by a planet, the flux from its "sun" is much higher than the cosmic rays from the galaxy, but the particle energy of the latter is much higher than the photon and proton flux in solar radiation Energy so that it has an impact that cannot be ignored.

The author of the study, Dimitra Atri, is an astrophysicist from the Blue Marble Space Science Institute, a non-profit made up of scientists from around the world Research institute. Researchers have paid attention to two important factors that may affect the planet's radiation dose, including the strength of its magnetic field and the thickness of the atmosphere.

"I started thinking about it when I was studying Mars and the Earth. These two planets are close neighbors, but Mars is a barren planet, but Mars is deserted. Why?" He said. : "The main reason is that compared to Earth, Mars has a high environmental radiant flux. This is because Mars' atmosphere is almost negligible compared to Earth. By Earth's standards, it is very thin. In addition, Mars is also very thin. There is no global magnetic field, so it accordingly lacks the protective layer facing the cosmic rays like Earth. So I think it is this difference that has led to the completely different fate of two originally similar planets. "

The researchers simulated different planetary scenarios, from planets that lack magnetic fields completely to planets with strong magnetic fields like Earth; from planets with very thin atmospheres to planets with dense atmospheres like Earth. "We know that the earth's magnetic field protects us from cosmic rays, and we also think that cosmic rays are a factor that significantly affects the radiation flux of the ground environment," said Aitley.

However, unexpectedly, Aitley said: "We found that the planet s atmospheric thickness is the factor that has a more important role in the planet's surface radiant flux." He said: "If you take the Earth as an example, you will use the Earth s magnetic field Completely removed, then the radiation flux we are exposed to the environment will triple, which is a very large increase, but despite this, this will not pose a serious threat to our survival. However, if you retain the magnetic field, but Decreasing the Earth s atmospheric concentration by a factor of 10 would increase the radiant flux we receive by two orders of magnitude. "

Scientists now tend to think that exoplanets orbiting red dwarfs are ideal places to search for alien life, because such stars are relatively faint, and their number is the largest in the universe, accounting for about the total number of stars in the universe. About 80%. However, statistical studies have shown that exoplanets in habitable zones that are relatively close to red dwarfs appear to be more inclined to have weaker magnetic fields. This tendency is particularly evident in a class of exoplanets called "super-earths" . The so-called "super-earth" refers to those rocky planets with a mass less than 10 times the mass of the earth. Astrobiologists believe that the weaker magnetic fields of these planets may make them unsuitable for life, but this discovery shows that weaker magnetic fields may not pose a big problem.

Aitley said that further research in the future will look at how the increasing radiation flux will affect the evolution of life. He said, "The main research method of the existing research on the effect of radiation dose on organisms is to use very high radiation doses to examine how the organisms will be harmed and die in such an environment. But I think systematic investigation is gradually progressing. "The response of organisms in an environment of elevated radiation doses will better provide a reference for studying the effects of cosmic rays on habitable environments."

Atelier and his colleagues have detailed their findings in the October issue of Astrobiology. ^[5]

Cosmic ray space manned flight

Cosmic rays are affected by the Earth s atmosphere, and the natural background radiation of a single person on the ground is only 0.3-0.4 mSv / y. Outside the atmosphere, about one proton or more nucleus per second passes through the area the size of a nail. In total, about 5000 ions per second penetrate the astronaut's body, breaking the chemical bonds in the body and causing a series of ionization reactions. In cosmic rays, a few heavier nuclei cause more damage than protons, because the ability to break a chemical bond is proportional to the square of the charge. For example, iron nucleus does 676 times more damage than protons. According to NASA estimates, astronauts receive 250 mSv of radiation in space in the solar system each year, and about one-third of the body's DNA is cut by cosmic rays. The lunar surface is 70-120mSv / y, the low-Earth orbit is 100mSv / y, and the Van Allen radiation zone is 15 Sv / y. The sun also releases a large number of protons and heavy atomic nuclei, ejecting near the speed of light, sometimes exceeding Sv within an hour, which is a lethal dose for astronauts without barriers. ^[6]