the blast was visible for about 5 minutes. The explosion had also been slightly obscured to the crew at Johnston Island by cloud coverage. The blast from Orange did not cause the large communication interruption that Teak had caused, but some commercial flights to Hawaii were said to have lost contact with air traffic controllers for a short period of time. Surface tests Of the 35 nuclear tests in Operation Hardtack I, four were surface burst shots: Cactus, Koa, Quince and Fig. These tests took place from May to August 1958, all at the Enewetak Atoll. Surface tests inherently present the potential for more radioactive exposure issues than the high-altitude or underwater detonations. This is because there is more material present to be converted to radioactive debris by excess neutrons due to the proximity to the Earth's surface, and due to the soil and other minerals excavated from the craters created by these blasts. The existence of this extra material allows for larger radioactive particles to be created and lifted into the blast cloud, falling back to the surface as fallout.Though surface and near-surface tests have a higher probability of radioactive exposure problems, the radioactive elements have significantly shorter residence times when injected into the atmosphere. As radioactive clouds from surface-type tests reach heights of around at maximum, and thus cannot extend higher than the lower stratosphere, the residence times can be up to 13 years less than the high-altitude blasts. During original concept planning in 1954, Enewetak was supposed to be the location of the smaller tests conducted during Operation Hardtack I. Due to poor weather conditions and policy changes in 1958, five of the UCRL tests which were planned to be conducted at the Bikini Atoll were moved to Enewetak. This included the later two surface blast devices in the Quince and Fig tests. Cactus The Cactus test took place May 6, 1958 at approximately 0615. An land-surface type shot was detonated on a platform at the northern tip of Runit, Enewetak in the second of the 35 tests for Operation Hardtack I.The initial cloud from the explosion reached as high as within the first ten minutes, and settled at around by 20 minutes after detonation. The nuclear fallout prediction map proved to be accurate in determining the span and the intensity of the resultant fallout.Measured peak intensity of fallout reached at hour three directly above blast site