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Orbital Deflection of Comets by Directed Energy

Zhang, Qicheng and Lubin, Philip M. and Hughes, Gary B. (2019) Orbital Deflection of Comets by Directed Energy. Astronomical Journal, 157 (5). Art. No. 201. ISSN 1538-3881.

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Cometary impacts pose a long-term hazard to life on Earth. Impact mitigation techniques have been studied extensively, but they tend to focus on asteroid diversion. Typical asteroid interdiction schemes involve spacecraft physically intercepting the target, a task feasible only for targets identified decades in advance and in a narrow range of orbits—criteria unlikely to be satisfied by a threatening comet. Comets, however, are naturally perturbed from purely gravitational trajectories via solar heating of their surfaces, which activates sublimation-driven jets. Artificial heating of a comet, such as by a laser, may supplement natural heating by the Sun to purposefully manipulate its path and thereby avoid an impact. Deflection effectiveness 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 to assess the effectiveness and feasibility of using high-powered laser arrays in Earth orbit and on the ground for comet deflection. Simulation results suggest that a diffraction-limited 500 m orbital or terrestrial laser array operating at 10 GW for 1% of each day over 1 yr is sufficient to fully avert the impact of a typical 500 m diameter comet with primary nongravitational parameter A_1 = 2 × 10^(−8) au day^(−2). Strategies to avoid comet fragmentation during deflection are also discussed.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Zhang, Qicheng0000-0002-6702-191X
Hughes, Gary B.0000-0003-4739-8493
Additional Information:© 2019. The American Astronomical Society. Received 2017 April 3; revised 2019 March 20; accepted 2019 March 25; published 2019 April 30. We gratefully acknowledge funding from NASA California Space Grant grant NNX10AT93H and from NASA Innovative Advanced Concepts grants NNX15AL91G and NNX16AL32G as well as a generous gift from the Emmett and Gladys W. Fund in support of this research. We also thank the anonymous referee whose detailed comments and suggestions helped improve this manuscript. An earlier version of some of these results was presented at SPIE Optics + Photonics in August 2016 in San Diego, CA (Zhang et al. 2016a). Software: GNU Parallel (Tange 2011), gnuplot (Williams et al. 2017).
Funding AgencyGrant Number
California Space Grant ConsortiumUNSPECIFIED
Emmett and Gladys W. FundUNSPECIFIED
Subject Keywords:comets: general – methods: numerical
Issue or Number:5
Record Number:CaltechAUTHORS:20190430-104322857
Persistent URL:
Official Citation:Qicheng Zhang et al 2019 AJ 157 201
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95121
Deposited By: George Porter
Deposited On:01 May 2019 14:31
Last Modified:03 Oct 2019 21:10

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