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What is space radiation and how does it affect humans in space?

asked 2016-05-23 06:01:15 -0500

Rob Mueller gravatar image

What are Galactic Cosmic Radiation (GCR) and Solar Particle Events (SPE)? How do they affect humans traveling in space? Why does it not affect us on earth?

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answered 2016-08-24 00:48:48 -0500

DrPhiltill gravatar image

Having lived on Earth, we have a distorted view of reality. The normal situation of reality is to exist in a bath of radiation. This is normal for almost all of space. The Earth is an unusual little pond because the radiation gets stopped by our thick atmosphere and protective global magnetic shield.

So first, radiation is the normal condition of space. Second, it consists of high velocity particles, traveling near the speed of light. (Primarily when we talk about space radiation we mean the particles that have mass, although there is also photon radiation consisting of x-rays, gamma rays, etc.) These massive particles include electrons, protons, heavier nuclei including helium, lithium, etc., all the way up the atomic chart. The majority of the nuclei are iron or smaller nuclei, because iron is the heaviest element made in normal stars. These particles are blown out from stars as part of their solar wind or in other stellar events. If they were simply stellar wind, then they would not be very dangerous because that is actually fairly low energy, lower velocity radiation. However, these particles get accelerated in space, perhaps by the shockwaves where stars had previously exploded -- i.e., supernova remnants. This slingshots the particles to higher velocity. A particle may shoot through many supernova remnants so it goes to higher and higher velocities. This is known as Galactic Cosmic Radiation. It is a very low density bath of radiation throughout the universe, but it is at extremely high energies/high velocities, so it is very hard to protect astronauts against it. The long, accumulated exposure to this bath can cause an astronaut to have a higher than normal risk of getting cancer at some point in their lives, and it can affect their eyes and brains and other organs. It is a slow, cumulative damage to the body.

There's another source of high velocity radiation, and that is from our sun. The sun is mostly putting out just ordinary solar wind, which is low energy and easily stopped by the skin of a spacecraft, so solar wind is no danger. However, the sun occasionally ejects particles in more energetic ways. It can have solar flares, and it can have coronal mass ejections. The solar flares can shoot out a brief burst of very high energy particles -- electrons, protons, and some heavier nuclei -- that are hard to stop and also at very dense fluxes. Thus, they can cause an astronaut very quickly. The astronaut exposed to a solar flare could get acute radiation sickness and die within a couple weeks. The coronal mass ejections (CMEs) also send out a large flux of particles, but the original speed of these is not very fast. However, this "burp" from the sun is a very dense plasma that contains magnetic fields, and just like the supernova remnants it causes particles to accelerate and go shooting out from the plasma at very high energy. A CME may take several days to travel from ... (more)

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answered 2016-08-24 01:19:44 -0500

Flipper gravatar image

Our atmosphere, ozone-layer and such absorbs and reflects light. It does protect us. Some cosmic rays get in and it's good for us in small dosages. 15 minutes in the sun, per day, is enough to supply our bodies with sufficient Vitamin D. We just have to limit our exposure to the Sun. Light is radiation.

Now, when we leave our protective Earth, there is no protection for us. We need to shield our bodies (and ship's components) from the interstellar radiation.

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answered 2016-08-24 13:48:41 -0500

Pascal Le Dramont gravatar image

updated 2016-08-24 22:20:26 -0500

Rob Mueller gravatar image

The radiation high energy particle releases from our sun are also known as Solar Particle Events (SPE).

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answered 2016-08-24 14:15:57 -0500

Rob Mueller gravatar image

SPE can be detected by spacecraft staged in orbit, and the alarm can be raised, telling the astronaut crew to seek shelter.

Galactic Cosmic Rays (GCR) are always present and omni-directional, and permanent shielding must be invented to protect the crew in space. Anything containing hydrogen provides a good shield e.g water, polyethylene, H2 propellant.

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Asked: 2016-05-23 06:01:15 -0500

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Last updated: Aug 24 '16