Citadel of the Green Death

At the coldly gleaming Experimental Station they flung this choice in Outlaw Joel Hakkyt's teeth: "Grinding, endless slavery on Asgard, that Alpha Centauri hell—or a writhing, screaming guinea-pig's death here?" He chose Asgard, naturally. But what was natural—on Asgard? - Summary by Robert Emmett Mcdowell