Cosmic radiation

One of the major negative biological factors of outer space, along with gravity, is radiation. But if the situation with the gravity on different bodies in the Solar system (e.g. on the moon or Mars) will be better than the ISS, with radiation, things are more complicated.

On the origin of cosmic radiation is of two types. It consists of galactic cosmic rays (GCR) and heavy positively charged protons emanating from the Sun. These two types of radiation interact with each other. In the period of solar activity, the intensity of galactic rays decreases, and Vice versa. Our planet is protected from solar wind by the magnetic field. In spite of this, some of the charged particles reaches the atmosphere. The result is a phenomenon known as the Aurora Borealis. High-energy GCR almost stopped by the magnetosphere, but they do not reach the Earth’s surface in dangerous quantities due to its dense atmosphere. The orbit of the ISS is above the dense layers of the atmosphere, but inside the radiation belts of the Earth. Because of this, the level of space radiation on the station is much higher than on Earth, but substantially lower than in the open space. Its protective properties of the Earth’s atmosphere pribliziteljny 80-cm layer of lead.

The only reliable source of data on the radiation dose that can be obtained during long-term space flights and on the surface of Mars, the RAD instrument is on the research station Mars Science Laboratory, better known as Curiosity. To understand how accurate its data, let’s look at the ISS.

In September 2013 in the journal Science published an article on the results of the tool RAD. On a comparative chart, built by the jet propulsion Laboratory of NASA (organization is not connected with the experiments conducted on the ISS, but it works with the RAD tool the Mars Curiosity Rover), stated that for six months in near-earth space station man receives a dose of radiation, approximately equal to 80 mSv (millisieverts). But in the edition of the University of Oxford from 2006 (ISBN 978-0-19-513725-5) States that in a day an astronaut on the ISS gets an average of 1 mSv, i.e. half-yearly dose should be 180 mSv. As a result, we see tremendous variation in the estimates of exposure have been studied in low Earth orbit.

Main solar cycles have a period of 11 years, and because GCR and solar wind are interrelated, for statistically reliable observations to study data about the radiation in different parts of the solar cycle. Unfortunately, as mentioned above, all the data we have about radiation in outer space have been collected in the first eight months of 2012 unit MSL on its way to Mars. Information about radiation on the planet’s surface accumulated them over the years. This does not mean that data is incorrect. Just need to understand that they can reflect only characteristics a limited period of time.

Last tool RAD data were published in 2014. As reported by scientists from the jet propulsion Laboratory of NASA for a six-month stay on the surface of Mars the person will receive an average radiation dose of about 120 mSv. This figure is midway between the lower and upper estimates of radiation dose to the ISS. During the trip to Mars, if he will take six months, the radiation dose will be 350 mSv, i.e. in 2-4,5 times more than the ISS. During the flight MSL have been through five solar flares moderate power. We don’t know what dose will receive the astronauts on the moon, as in the days of the Apollo program was not conducted experiments studying cosmic radiation separately. Its effects have been studied only in conjunction with the effects of other negative phenomena, such as the effects of lunar dust. However, it can be assumed that the dose will be higher than on Mars, because the Moon is not protected even a weak atmosphere, but lower than in the open space, because the man in the moon will be irradiated only the “top” and “sides”, but not under my feet./

In conclusion, it can be noted that radiation is a problem that will require solutions in the case of the colonization of the Solar system. However, the widely held view that radiation environment outside the Earth’s magnetosphere does not allow to make long-term space flights, is simply not true. For the flight to Mars will have to install a protective coating or a residential unit of the complex migratory space, or on a separate specially protected “storm” compartment in which astronauts can wait out the proton showers. This does not mean that developers will have to use a complex anti-radiation system. In order to significantly reduce exposure enough insulation coating that is used on rockets and space ships to protect against overheating during braking in the Earth’s atmosphere.

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