All you need is a couple of meters of water or earth. The base would be inside the comet at complete safety anyway, and detection can warn you to get inside in

All you need is a couple of meters of water or earth. The base would be inside the comet at complete safety anyway, and detection can warn you to get inside in case of increased sun activity. It is really easy if you have just a little material: http://en.wikipedia.org/wiki/Radiation_protection#Shielding http://en.wikipedia.org/wiki/Radiation_protection#Shielding