The most likely explanation for what had happened next was that one of the robots crawling around in that area maintaining the shape of the nozzle had become contaminated with a mixture of alpha-emitting fuel fleas and beta-emitting daughters, and tracked the material to a location where it had been transferred to the glove of a space suit—possibly by a mechanism as simple as a spacewalker reaching down to brush some ice from the claw of a Grabb, or planting a foot in a location where a contaminated Grabb had stepped. The contamination had then been brought into the command module when the spacewalker came indoors. They might not even have known about the burst fuel rod, so they might not have been checking for contamination. Or, as suggested by Sean’s note, their Geiger counters might have broken down, one by one, rendering them blind to the presence of radioactivity in their environment. In any case, the particles had spread around the command module. Some men had inhaled them, some had swallowed them. They hadn’t been healthy to begin with.