Shot Wheeler was the 17th atomic test of Operation Plumbbob, detonated on 6 September 1957 from a balloon at 500 feet above Yucca Flat, Nevada Test Site. The photograph — AEC catalog number AEC-57-5821, credited to Lookout Mountain Laboratory, USAF — documents the fireball milliseconds after detonation. Clearly visible are the dark spike-like streaks radiating outward from the base of the fireball: the so-called Rope Trick Effect. As the initial burst of thermal radiation from the fireball travels outward at the speed of light, it is absorbed by the metal cables suspending the device from the balloon. The cables superheat and vaporize almost instantaneously, before the fireball itself has expanded to engulf them. The vaporized metal forms channels of dense, opaque plasma that appear as dark filaments against the intensely luminous fireball — a fleeting physical record of the detonation's first microseconds, frozen here by the camera.