Planetary Defense Architectures for 2030 and Beyond

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 per-spective, 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 the efficacy of available mitigation (asteroid deflection) technologies. Effective Planetary Defense requires a long-term commitment to technology development, demonstrations, situational awareness, and operational readiness. Although it may not happen for some time, it is certain that the Earth will be impacted by an asteroid large enough (~50 m diameter or larger) to cause sig-nificant damage/loss of life. There exist >100,000 NEOs of this size or larger, which could lead to an impact like the 1908 airburst over Russia when a 40–60 m diameter asteroid flattened 2000 km2 of forest in Tunguska. If this had in-stead occurred over a modern city there clearly would have been mass casual-ties. With a moderate investment and long-term planning, we have the ability to protect the Earth from the majority of such threats. This paper summarizes some of the most important concepts, assuming that the recommendations in Ch 18 of Origins, Worlds, and Life: A Decadal Strategy for Planetary Sci-ence and Astrobiology 2023-2032 are fully-funded and operational systems may be deployed as soon as they are matured.

假设未来十年内对技术成熟化与风险降低演示投入适度资金，人类最早可在21世纪30年代起具备有效抵御小行星撞击威胁的能力。本文从工程视角出发，对这类行星防御（Planetary Defense, PD）系统之系统所涉及的核心属性与权衡方案进行了总结梳理。本文分析了各类作战场景，并针对现有小行星偏转减灾技术的效能开展对比分析，同时展示了全新的研究结果。构建有效的行星防御体系，需要长期投入技术研发、演示验证、态势感知与作战备勤相关工作。尽管这类事件短期内未必发生，但可以确定的是，地球终将遭遇直径约50米及以上、足以造成大规模破坏与人员伤亡的小行星撞击。目前已发现超过10万颗此类及更大尺寸的近地天体（Near-Earth Object, NEO），它们一旦撞击地球，可能引发类似1908年俄罗斯通古斯大爆炸的灾难：当时一颗直径40至60米的小行星在通古斯地区上空爆炸，夷平了2000平方公里的森林。倘若此类事件发生在现代都市，势必会造成大规模人员伤亡。通过适度投入与长期规划，人类具备保护地球免受绝大多数此类威胁的能力。本文总结了该领域的核心概念，前提是《起源、世界与生命：2023-2032行星科学与天体生物学十年战略》第18章中的相关建议能够获得全额资助，且相关作战系统在成熟后可立即部署。