Ground zero soil sampling: Trinity, 1945

At Trinity—the world's first nuclear weapons testing site—large quantities of soil were drawn into the fireball to redeposit either downwind as radioactive fallout or in the near‐field as a unique, anthropogenic silicate glass trinitite . Manhattan Project physicists and chemists came to see soils at the Trinity site as a useful medium to assess the explosive power of the weapon they had developed. They devised ingenious ways to enter the high radiation field of the post‐detonation crater at Ground Zero in order to sample soil bearing the radioisotope footprint of the fireball. A blend of out‐of‐the‐box thinking, battle‐proven US Army military hardware, gutsy geotechnical improvisation and emerging environmental radioactivity analytical capabilities provided the answers needed by strategists at this critical stage in the Second World War.