Comprehensive Modeling of the Effects of Hazardous Asteroids Mitigation Techniques

This proposal focuses on the computational modeling of outcomes from asteroid mitigation techniques that have been previously developed. The models to be implemented will enable these techniques to be evaluated accounting for the expected and predicted range of asteroid geophysical and dynamical properties. This is necessary and fundamental for the design and evaluation of mitigation experiments and attempts. It will also focus on the necessary technology for the detection of mitigation outcomes and use this as a fundamental metric in our models and evaluations. Our research will specifically focus on four objectives, listed below. Net Momentum Transfer: What is the distance displacement over time for a given technique? What geophysical parameters, such as porosity, most strongly control the b factor? What are the limiting factors on the efficiency of a given mitigation approach? Asteroid Body Response: Will the mitigation attempt break or fracture the asteroid? If the asteroid breaks, will it catastrophically shatter or split into components? After breakage will the components disperse, coalesce, or orbit? Deflection Detectability: For a given scenario how precise must tracking be to adequately detect deflection? What natural or mitigation induced effects will complicate this process? What set of close proximity operations are needed to measure the effect? Mapping of Sensitivity: What computational methodologies will best determine the statistical mapping between uncertain parameters and mitigation outcomes? How can these sensitivities be computed using the smallest number of numerical evaluations? With regard to NASA’s space technology roadmaps, this research addresses Planetary Safety (HEDS TABS 7.5.4). Identification of a fundamental limitation on the precision to which any energetic mitigation interaction with a hazardous asteroid can be supplied. Even if the shape model and material properties of a natural asteroid are perfectly known, the convolution of navigation delivery accuracy across the natural surface of an asteroid can yield uncertainties at the ~10% level in the delivered impulse (assuming a beta ~1), with this uncertainty increasing with increasing value of beta. This occurs due to the natural variation of an asteroid’s surface along with the physics of impacts within ~45 degrees of normal, as the bulk of the ejected material will depart normal to the local surface. Our survey of asteroid surfaces shows that over a likely impact uncertainty spot size (on the order of 50 m) there is variability in the surface normal direction commensurate with a ~10% error in delivered impulse. Similar results should hold for stand-off nuclear blasts. When material and model properties of the asteroid are also included, these uncertainties are naturally combined with these shape-based uncertainties. These findings are in a paper submitted for review to the Journal of Guidance, Control and Dynamics.