Morris R. Jeppson's final steps before 'Little Boy' was dropped

The Atomic Bomb's Devastation 
 
This photograph, signed by Second Lieutenant Morris R. Jeppson, captures the near-total destruction of Hiroshima following the atomic bombing on August 6, 1945. Amid the devastation stands the skeletal ruin of the Hiroshima Prefectural Industrial Promotion Hall, now known as the Genbaku Dome (Atomic Bomb Dome). Once a symbol of progress and innovation, the building was mostly destroyed by blast, yet its central dome endured the vertical force of the explosion. Today, the Genbaku Dome stands in Hiroshima Peace Memorial Park.

The atomic bomb dropped on Hiroshima had a radius of destruction of approximately 1.6 km, with fires sweeping approximately 11.4 sq km. The bomb, detonated about 600 metres above ground, unleashed a blast pressure of 35 tons per sq meter with winds of over 400 meters per second. Nearly everything within the 1.6 km range was obliterated. The damage was instantaneous. 

Jeppson's Duty  

Morris Jeppson, then twenty-three years old, was the Weapon Test Officer. He was the last person to handle the bomb before its detonation. Just before the B-29 reached high altitude over the target area, he climbed into the unpressurized bomb bay and replaced three green safety plugs—each 'the size of a saltshaker,' as he would later describe them—with three red plugs. This seemingly routine switch was the final step in arming the bomb. The green plugs ensured safety during the flight, and now the red plugs made the weapon ready for use.

Jeppson was not alone. He worked alongside Navy Captain William “Deak” Parsons, the mission’s weaponeer, to perform the procedure. 'You had a job to do, you just did it,' Jeppson explained in 1995 during a reunion of the mission’s crew.  

The Story of the Safety Plugs 
 
After the mission finished, Jeppson retained a few of the safety plugs as mementos. In 2002 he auctioned off two of them for $167,500. The US government asserted that they were classified material and attempted—unsuccessfully—to prevent the sale.