Lethal untrackable debris objects pose the highest risk to the sustainability of the space environment, and thus, shall be included in the assessment of the long-term effect of mitigation and remediation measures to the space debris problem. The introduction of centimetre-sized particles in the debris evolutionary models represents a challenge from a computational cost point of view. To answer this need, this work proposes a novel probabilistic debris environment propagator. The method classifies the objects population into intact objects and fragmentation debris. The evolution of the former population is retrieved through an individual definition of each object’s mission profile. A continuum approach is adopted for the characterisation of the fragments, whose density distribution in orbital elements is propagated in time through the continuity equation. The intrinsic computational efficiency of the density-based fragments cloud models is leveraged to make the method agnostic to the lowest fragments size considered. A second classification of the population of intact objects into species, such as payloads, rocket bodies, mission related objects and constellations, ensures a faithful replication of their orbit evolution. Fragmentation debris caused by intact objects explosion and accidental fragments-intact object collision are included in a probabilistic fashion at the detected fragmentation epoch, to account for their feedback effect onto the environment. The model is applied to estimate the evolution of the space debris population in low-Earth orbit up to 200 years from the reference epoch, with and without the inclusion of a future launch traffic pattern, and considering a different fulfilment of the post-mission disposal phase.

中文翻译：

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近地轨道空间碎片环境基于密度的演化模型

致命的、无法追踪的碎片物体对空间环境的可持续性构成最高风险，因此，应将其纳入对空间碎片问题缓解和补救措施的长期效果的评估中。从计算成本的角度来看，在碎片演化模型中引入厘米大小的颗粒是一个挑战。为了满足这一需求，这项工作提出了一种新颖的概率碎片环境传播器。该方法将对象群体分类为完整对象和碎片碎片。以前群体的进化是通过每个物体的任务概况的单独定义来检索的。采用连续介质方法来表征碎片，其轨道元素中的密度分布通过连续性方程随时间传播。利用基于密度的碎片云模型的固有计算效率，使该方法与所考虑的最低碎片大小无关。对完整物体群体进行第二次分类，如有效载荷、火箭主体、任务相关物体和星座，确保忠实地复制其轨道演化。由完整物体爆炸和意外碎片与完整物体碰撞引起的碎片碎片以概率方式包含在检测到的碎片时期，以解释它们对环境的反馈影响。该模型用于估计从参考历元起长达 200 年的近地轨道空间碎片数量的演变，包括或不包括未来的发射交通模式，并考虑任务后处置的不同实现方式阶段。