John Wieneke was an American physicist who worked at Los Alamos during the Manhattan Project. Wieneke later worked on the post-war nuclear program at the Nevada test site in the 1950s. During Operation Tumbler-Snapper in 1952, an atomic bomb failed to start during a planned test. Wieneke was part of the team that had to go up the test tower to see what went wrong, under no guarantee that the bomb would not go off at any moment.