Deflection driven evolution of asteroid impact risk under large uncertainties

The threat of asteroid impacts on the Earth can be mitigated through deflection missions. The deflection capability has previously been omitted in asteroid impact risk analysis work that quantifies impact damage on the Earth. Here we investigate the effect of pre-designed deflection missions on the risk profile of the fictitious impact scenario 2019 PDC. The impact risk analysis is based on a statistical approach. We sample orbital and physical property distributions that provide a complete representation of possible impact scenarios. Three pre-designed kinetic impactor deflection missions are considered in separate simulations. The deflection mission imposes a deflection ΔV on the asteroid and the impulse enhancement factor β is calculated as part of the analysis. The post-deflection impact risk is compared to the undeflected risk situation. Variations in physical and orbital properties make the outcome of deflection missions uncertain. It can therefore be inadequate to label deflection mission outcomes in binary terms of success and failure. Instead, defining a satisfactory risk reduction goal and scaling the deflection mission capability to deliver this risk reduction is more accurate. In addition, the results highlight dilemmas that decision-makers would face in an asteroid threat scenario. By implementing a deflection mission, the potential impact point of the asteroid is moved, threatening new populations and potentially increasing damage in case of an impact.