American Institute of Aeronautics and Astronautics 1 Blast Designs For Neo Destruction and Deflection Leslie Gertsch 1 , Jason Baird 2 , and Paul Worsey 3 University of Missouri-Rolla, Rolla, Missouri, United States 65409-0660 Large-scale blasting techniques developed for terrestrial construction and mining could, if applied to a threatening NEO, ensure its transformation into fragments too small (<50 meters across) to survive passage through Earth’s atmosphere. Additionally, this approach could impart impulses to deflect the NEO. This approach would also be responsive to ongoing characterization of the NEO. Four NEOs were selected to illustrate the range of blast design and mitigation outcomes possible: Asteroids Itokawa, 1986 DA, and Eros, and comet Wild2. This paper addresses the overall concept for operations and discusses key features of the approach that are normally outside the realm of aerospace engineering. I. Introduction HETHER asteroid or comet, many near-Earth objects (NEOs) have the potential to impact the Earth at some future time. Many have in the past. Prevention of such an impact is the topic of this conference; this paper discusses the application of distributed-energy means – explosives, whether conventional or nuclear – to this end. Rather than salvation being delivered in a single burst of energy, this approach distributes destructive energy within carefully selected parts of a threatening NEO. The advantage is responsiveness to unexpected spatio-temporal changes in NEO properties, and the ability to select the desired maximum fragment size. The fragmentability of a NEO depends on its physical structure and the type of material it comprises. This is true regardless of the fragmentation method used. A mechanical classification proposed by Ref. 1 divides NEOs into four broad groups based on their components and structure, focused on how readily they can be broken up: Group 0. Ice composites – very weak, containing ices with or without organic compounds. Group 1. Friable rock – similar to Group 0, but with no volatile components. Also weak. Group 2. Hard rock – strong and brittle, the most similar to materials encountered in terrestrial mining and excavation practice. Group 3. Metallic: 3a. Massive metal – may be ductile. 3b. Rock-metal composites – would fracture mainly at rock-metal interfaces. In addition to the fragmentability of a natural body in space, its size also affects the fragmentation techniques that can be applied. Although a mountain can be reduced to sand one pickaxe blow at a time, the time required would be prohibitive. More efficient means are needed. Therefore, Ref. 2 described an additional classification, one based on size expressed as the number of separate blasts * required to fully deal with a threatening NEO: Class 1. Requires only one blast of a few to several hundred charges. A single human-robotic team is needed for blast design and construction. Class 2. Requires between two and five simply layered blasts. One to several teams are needed, depending on the mitigation speed required. Class 3. Requires more than five blasts, with significant complexity, including multiple layers of blasts. Many human-robotic teams needed. 1 Assistant Professor (Geological Engineering), Rock Mechanics and Explosives Research Center, 1006 Kingshigh- way, AIAA Member, GertschL@umr.edu. 2 Associate Professor (Mining Engineering), Rock Mechanics and Explosives Research Center, 1006 Kingshighway, AIAA Member, jbaird@umr.edu. 3 Professor (Mining Engineering), Rock Mechanics and Explosives Research Center, 1006 Kingshighway, pworsey@umr.edu. * A blast is the initiation of one or more charges linked by a network of detonators. W