衍射帆H反转轨道：理论可行性、设计策略与应用

本文提出了一种利用面向太阳的衍射帆（SFDS）进行H反转撞击的行星防御方案，旨在克服传统反射帆在机动过程中的局限性。通过一阶段和二阶段衍射角策略，该方法显著提升了撞击速度并缩短了任务时长。以毁神星（Apophis）为例的模拟验证了该方案在快速响应和高动能防御方面的优势。

arXiv:2608.04596v2 Announce Type: replace Abstract: With the growing threat of near-Earth asteroid, planetary defense serves as a vital shield against catastrophic disasters. Kinetic impact utilizing an angular momentum reversal (H-reversal) trajectory of a solar sail is a highly advantageous defense approach. However, traditional reflective sails (RS) are constrained during these maneuvers by attitude-thrust coupling and a degradation of solar radiation pressure utilization at the high cone angles required for transverse acceleration. To enhance impact performance and simplify control, this paper proposes an H-reversal impact scheme utilizing a Sun-facing diffractive sail (SFDS) under a one-stage diffraction angle {\theta}d strategy and a two-stage {\theta}d strategy. The feasible parameter spaces for both strategies were mapped using the hodograph method. Tailored trajectory design methods were established for both strategies based on the feasibility analysis. Apophis impact scenario was considered, and the corresponding trajectories were constructed. Simulations demonstrate that the one-stage {\theta}d SFDS outperforms RS through a 21% increase in the impact velocity and a 35% decrease in the mission duration. Furthermore, the proposed two-stage {\theta}d strategy yields an additional 9km/s gain in impact velocity. By utilizing SFDS H-reversal trajectories, this research establishes an emergency planetary defense framework characterized by rapid response and high kinetic