... during its first years, Mercury had been so close to the sun that its temperature was driven high enough to permit a subatomic thermo-nuclear reaction. The reaction had shorn some elements of their electrons and left a thin coating of material composed almost entirely of neutrons. The nuclite was incredibly dense. It could be handled only in low gravity because of its weight. But nothing else provided the shielding ... — Rip Foster Rides the Gray Planet • Blake Savage
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