19 September 2016 Simulations of directed energy comet deflection
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Abstract
Earth-crossing asteroids and comets pose a long-term hazard to life and property on Earth. Schemes to mitigate the impact threat have been studied extensively but tend to focus on asteroid diversion while neglecting the possibility of a comet threat. Such schemes often demand physically intercepting the target by spacecraft, a task feasible only for targets identified decades in advance in a restricted range of orbits. A threatening comet is unlikely to satisfy these criteria and so necessitates a fundamentally different approach for diversion. Comets are naturally perturbed from purely gravitational trajectories through solar heating of their surfaces which activates sublimation-driven jets. Artificial heating of a comet, such as by a high-powered laser array in Earth orbit, may supplement natural heating by the Sun to purposefully manipulate its path to avoid an impact. The effectiveness of any particular laser array for a given comet depends on the comet's heating response which varies dramatically depending on factors including nucleus size, orbit and dynamical history. These factors are incorporated into a numerical orbital model using established models of nongravitational perturbations to evaluate the effectiveness and feasibility of using high-powered laser arrays in Earth orbit or on the ground to deflect a variety of comets. Simulation results suggest that orbital arrays of 500m and 10GW operating for 10 min=d over 1 yr may be adequate for mitigating impacts by comets up to ~500m in diameter. Continuously operating ground-based arrays of 100m and 10GW may be similarly effective when appropriately located.
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Qicheng Zhang, Qicheng Zhang, Philip M. Lubin, Philip M. Lubin, Gary B. Hughes, Gary B. Hughes, } "Simulations of directed energy comet deflection", Proc. SPIE 9981, Planetary Defense and Space Environment Applications, 998108 (19 September 2016); doi: 10.1117/12.2235711; https://doi.org/10.1117/12.2235711
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