This article traces the transformation of the earth by nuclear testing from a bounded site of experiment into a “laboratory planet.” Focusing on the Amchitka nuclear testing program in the Aleutian Islands (1965–1971), it examines how Cold War weapons research assembled islands, oceans, atmospheres, and animal bodies into a distributed experimental apparatus. The underground detonations of Long Shot, Milrow, and Cannikin did not simply test weapons; they instrumented an entire geophysical milieu through seismic networks, environmental monitoring, and biological experimentation. Marine animals, geological strata, atmospheric particles, and ocean waters functioned as sensing media that registered detonation effects as a continuous stream of measurable data. In this way, the island and its surrounding environment were transformed into a computational machine for translating the violence of the blast wave into information. The article argues that this configuration exemplifies a broader “geotechnical” condition in which geopolitical power and geophysical processes become structurally coupled, producing a planetary-scale laboratory in which the earth itself becomes both experimental environment, instrument of calculation, and medium of power.