Misty Castle II: Direct Course (1983)
Pre-Direct Course (1982)
Date: 7 October 1982
Location: PHETS, White Sands Missile Range
Explosive Charge: 24 tons, ANFO
Objectives
Primary Objective: Ascertain the feasibility of executing a height-of-burst event and to test selected prototype dust phenomenology experiments.
Secondary Objective I: Define the operational requirements for constructing a height-of-burst test bed for the upcoming Direct Course event.
Secondary Objective II: Describe the reaction of the support tower (fragmentation) to the blast.
Secondary Objective III: Document blast fidelity identifying anomalies.
Secondary Objective IV: Evaluate new diagnostic procedures.
Secondary Objective V: Record dust effects.
Secondary Objective VI: Record test environment conditions.
Event Summary
Pre-Direct Course was a 24-ton ANFO height-of-burst detonation executed on 7 October 1982 at White Sands Missile Range. The high-explosive charge consisted of 24 tons of bulk ANFO poured into a 11.8-foot diameter spherical fiberglass and balsawood container and mounted at a height of 57 feet atop a steel tower. Pre-Direct Course served as a 1/3 scale model for the upcoming Direct Course test. The site immediately around Pre-Direct Course ground zero was divided into sections that replicated varying surface conditions:
-Clean Line: Paved with concrete and asphalt, similar to normal building areas
-Normal Line: Section with compacted earth
-Dust Line: Covered with loose sand for small particle debris testing
Conducted as a precursor to Direct Course, the event was successful in producing the intended height-of-blast effects, although container debris affected shock wave propagation.
Direct Course (1983)
Date: 26 October 1983
Location: PHETS, White Sands Missile Range
Explosive Charge: 609 tons, ANFO
Objectives
Primary Objective: Provide an airblast and ground shock environment for the United States and allied foreign government-sponsored experiments designed to determine the response of tactical and strategic weapon system, communications equipment, aircraft, vehicles, and a variety of structures.
Secondary Objective I: Provide a thermal environment (in addition to airblast) for several experiments to study synergistic effects.
Secondary Objective II: Record the airblast and ground shock environment.
Secondary Objective III: Record the effects simulating a nuclear airburst explosion.
Secondary Objective IV: Increase the weapons effects data base.
Event Summary
One year after the Pre-Direct Course event, WSMR prepared its PHETS facilities for Direct Course, the primary height-of-burst experiment. To produce the blast, a 609-ton charge of ANFO was placed in a fiberglass sphere with a diameter of 35.1 feet at a height of 165.7 feet. This charge was intended to produce a blast similar to that of a 1 kiloton nuclear weapon. Like previous tests, Direct Course included 10 thermal radiation source units to mimic the combined heat and blast effects as seen in an actual nuclear detonation.
“Sphere and 300-foot crane preparing to place column and copper tower in sphere, 12 July 1983.” 
The Direct Course sphere was suspended in a strong net and then placed on top of a tower. 
“The fiberglass sphere is lifted in preparation for placement on top of the tower. The upper 70 feet of the tower and sphere were lifted together by a large crane.” 
“The 35-foot diameter sphere was filled with 600 tons of a mixture of ammonium nitrate and fuel oil (ANFO), using the cement bucket on top of the tower.” 
This color photograph shows the sphere being inspected at the top of the tower. Guide wires surround the tower to secure it against heavy winds that are typical in the northern range.
Like Pre-Direct Course, the test site was divided into radial sections with varying surface conditions. However, Direct Course did not include a full section of concrete and asphalt. Instead, the sections included a specially prepared dust section, a compacted soil section, and an undisturbed, or natural, section. Several dozen organizations participated in the event, with over 200 individual experiments being conducted.
One particularly interesting experiment in Direct Course was conducted by the Ballistic Research Laboratory on Soviet armor and vehicles. Eight Soviet combat vehicles and cargo trucks were placed side-on to the explosion to maximize the effects of the airblast. These included:
- 1x T-62 main battle tank
- 1x BTR-60PB armored personnel carrier
- 2x BRDM-2 armored scout cars
- 2x ZIL-157 cargo trucks
- 2x GAZ-66 cargo trucks
A total of 18 mannequins were placed in crew member positions.
The Direct Course detonation caused a ball of heat and pressure to expand rapidly outwards from its tower. In front of the explosion are TRS units. 
“Direct Course explosion from Ground Zero, 26 October 1983. Photographs by Frank Trevino, White Sands Missile Range.” 
The dust and debris cloud begins its rise over the testbed. 
The dust and debris cloud continues to rise. It begins to form the iconic mushroom cloud that is more typically associated with nuclear explosions rather than conventional high explosives. 
The mushroom cloud towers over the Direct Course testbed. In the lower right, the plumes created by the TRS units begin to dissipate.
Although most of the Direct Course experiments performed as expected, the event suffered problems such as the failure of 6 (out of 10) thermal radiation source units and greater than expected free-field overpressures caused by unusually high detonation velocities in the charge. Some of the experiments relying on heat were exposed to thermal radiation sources after the explosion took place. Although this could simulate the results of blast effects and heat separately, this partial solution was unable to create the blast and thermal conditions that would occur simultaneously after a thermonuclear detonation.
I enjoyed reading the information provided and researched for all the Misty Castle projects. I appreciate the Museum putting this together for all the men and women who worked on the Stallion side of the range on these projects.