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Space radiation is emitted by the Sun, other stars and other high energy objects outside the Earth’s atmosphere. This radiation bombards the Earth on a regular basis but we never really pay attention to it except for the UV rays from the Sun. The reason why this is so is because the Earth has several natural barriers that protect us from the worst kinds of radiation.
If you remember from your elementary or high school science class, radiation comes in varying strengths. The three types are alpha, beta, and gamma radiation. The energy particles associated with each have different energy levels. The best illustration is what materials they can penetrate. Alpha particle are the weakest. They can be easily blocked by a piece of paper or skin. Beta particles are stronger and can penetrate the skin. This is where we see the effects of radiation. It can strike DNA causing spontaneous mutations. However aluminum and other substances of similar density can deflect these particles. The strongest radiation particles of all are gamma particles. This is the most common type of radiation in space. Only the most dense substances can stop them and even then they are absorbed upon contact.
The Earth’s atmosphere is the main shield that protects protects us from space radiation. It works in two ways: first, it uses its natural magnetic field called the magnetosphere to redirect dangerous particles away from the surface. Radiation is made of high energy atomic particles so the Earth’s magnetic field deflects them. The second way the Earth protects us is with the density of our atmosphere; the remaining radiation that gets past our magnetosphere gets absorbed by the lower levels of the atmosphere. This leaves only the weakest and more beneficial types of radiation behind.
Space radiation is a major concern for practical interplanetary and eventually interstellar flight. Naturally man made craft don’t have the perfect defenses that the Earth has with its magnetosphere and atmosphere. This puts astronauts at risk every time there is a solar storm or if they pass planets with high levels of radiation like Jupiter – even the background radiation of space is potentially dangerous in the long run. Fortunately, scientists are coming up with technologies that can protect human beings and space craft from damaging radiation. One of the inventions we currently use is a satellite that acts as an early warning system. This technology gives orbiting astronauts a few minutes to find shelter in the Space Station or shuttle. Another new technology creates an artificial ionic shield, mimicking the Earth’s magnetosphere, to redirect dangerous particles away from astronauts. These technologies will help make deep human space exploration possible in the future.
If you liked this article there are others on the subject you might enjoy. There is an article that goes into depth about the Ion Shield. Another article talks about a study NASA is doing to study the effects of radiation on astronauts.
There are also other resources you can check out on the web. The NASA websites have great articles. One is a general article about radiation and another is about four proposals NASA is reviewing to deal with it.
You can also listen to Astronomy Cast. The July 4, 2009 Question episode has some interesting information.