Why not use a uranium radiation shield?
Well, it might weigh as much as 250 kg, and require a complete redesign of the dewar and satellite structure to support it during launch, and cost an arm and a leg, but why not? A uranium shield 2 cm thick would exclude a great many of the most troublesome energetic protons and might even save having to have a charge control system. The increased mass of the satellite would also improve the quality of drag free control. Nonetheless, we plan to use only the natural shielding of the satellite, to avoid the trouble and expense of a specially designed dewar, which could easily reach $30M or more. This natural shielding is the equivalent of a centimeter or two of aluminum.
