The United States and nuclear-policy experts on Wednesday marked the 80th anniversary of the Trinity explosion—the world’s first atomic bomb test—conducted at 5:29 a.m. on 16 July 1945 in the New Mexico desert. The plutonium device, which produced a blast of roughly 20 kilotons, ushered in the nuclear age and cleared the way for the bombings of Hiroshima and Nagasaki three weeks later. To coincide with the anniversary, the National Security Archive released an expanded collection of declassified reports, photographs and films. Newly highlighted documents show the test scattered radioactive material across some 1,100 square miles—traces were measured as far as Colorado—while internal memoranda detailed early concerns about public-health and legal fallout. Local lawmakers and residents, including the Tularosa Downwinders, used the milestone to press for broader compensation under the recently re-authorised Radiation Exposure Compensation Act. Although Congress extended the program this year, many New Mexicans exposed to Trinity fallout remain outside its remit. The commemoration comes amid renewed debate over whether the United States should resume underground nuclear testing as it modernises its arsenal. A Science News review published in March said most physicists argue computer modelling and sub-critical experiments make full tests unnecessary, warning that a single detonation could spur a global testing cascade.