Planet Earth is protected from cosmic radiation by a combination of active and passive shields. Together they reduce the absorbed dose by a factor of 50 when compared to the levels absorbed by astronauts on the International Space Station.
The passive component is provided by
a) the shadow of the planet Earth itself, which reduces the flux by a factor of two, as well as
b) the atmosphere, which is equivalent to the thickness of 3.5 meters of aluminium also providing significant protection.
The active component is provided by the Earth’s magnetic field, which bends away the low energy components of Cosmic Rays providing the remaining protection.
The effectiveness of the magnetic deflection of Earth’s magnetic field is shown in this video (click on image below), since the large flux of energetic solar particles coming from the Sun cannot reach our planet. The SR2S protection system will act in a similar way: thanks to the combined effect of the passive and active shields designed to protect the habitation module, astronauts will be able to travel for longer distances in deep space without exceeding the permitted dose levels and protected from the deadly effects of sudden solar events. An SR2S spacecraft will be a microscopic Earth environment traveling to deep space.
The clip is available to download at different resolutions from: http://svs.gsfc.nasa.gov/vis/a000000/a003900/a003902/