The Nuclear Retarc Sulky: An Upside Down Crater
Abstract
Sulky, an 85-ton nuclear cratering experiment, was detonated 90 ft below the surface in the dry basalt of Buckboard Mesa, Nevada Test Site on 18 December 1964 as part of the U.S. Plowshare Program. The resulting mound, called a retarc (crater spelt backward), was roughly symmetrical with an average radius of 100 ft, beyond which the ground surface was flexed and fractured for at least another 100 ft. The mound contained a central pit averaging 29 ft in radius and 21 ft high with the floor 9 ft above surface ground zero. The resulting measurements and analysis achieved the original objective of helping to define the nuclear rock cratering curve beyond optimum depth of burst. Viewed from the surface the Sulky mound appeared as a jumbled pile of basalt blocks sized by pre existing joint surfaces. However, trenches cut through the mound revealed a well defined structure below the surface. Beginning in 1987 a new effort by DNA/AFWL/USGS mapped in detail the structure exposed by the trenches and individual basalt blocks on and beyond the mound. With good stratigraphic control provided by preshot corings, basalt layers were mapped across the mound showing upthrusting increasing inward until intersected by the central pit which is actually an ejection pit and the primary source of the jumbled blocks covering the mound surface. New analysis of the high speed cinema followed the mound rise and then tracked many of the individual ejecta blocks exiting at high angles from the central portion of the mound, the ejection pit . Close correlation of these data provided an excellent benchmark for both centrifuge experiments and 2 D continuum and discrete element simulations which bounded the observables. Together the synthesis of all these efforts provided a dynamic link for better understanding the formation of the Sulky retarc and show just how close Sulky was to being a classical crater.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 2010
- Accession Number
- ADA560596
Entities
People
- Eric J. Rinehart
- James R. Rocco
- Jeffrey M. Thomsen
- Robert W. Henny
Organizations
- Defense Threat Reduction Agency