Comparison of Planetary Defense Deflection Methods

Assuming relatively modest investment in the coming decade for technology maturation and risk reduction demonstration, the human race could have the ability to effectively defend itself against the threat of asteroid impact starting as soon as the 2030’s. In this paper we summarize from an engineering perspective, some of the most important attributes and trades involved of such a Planetary Defense (PD) system-of-systems. We consider operational scenarios and present new results comparing and contrasting simulated realizations of the efficacy of available mitigation (asteroid deflection) technologies, especially the trade between impulsive techniques (Kinetic Impact) and low-thrust concepts such as Ion Beam Deflection. New results from the successful DART mission indicate the momentum enhancement factor "beta" due to KI impact ejecta could be as high as 4 or 5; while this makes the deflection momentum transfer of KI more effective, it also increases the chance of disruption proportionally. If the delivered KI energy is limited to avoid the risk of disruption due to high values of beta, then the cases where KI is safe to use severely limit the effectivity of this method, whereas the Ion Beam Deflection (IBD) method does not suffer this limitation. Effective KI deflection also likely requires a precursor rendezvous mission to measure the target asteroid’s mass, whereas an IBD strategy inherently includes a rendezvous, simplifying the overall defensive operation. For these reasons and others, we suggest that IBD should be strongly considered for further analysis and potential technology demonstration risk reduction. We conclude by illustrating one such concept of a cost-effective IBD demonstration mission.