Testing the asteroid Pallas as the parent body of the active NEA Phaethon

原行星是令人着迷的天体，提供了在行星上观察到的一种特殊的地质过程的例子，例如火山作用、构造和分化，但在一个特殊的环境中，低于1000公里的天体没有发展成完整的行星。观察表明，(2)帕拉斯填补了(1)谷神星和(4)灶神星之间的空白。黎明号任务探测的原行星谷神星和灶神星具有相似的地质学特征，表面引力相似。虽然灶神星的密度比富含水的谷神星的无水组成要高得多，但帕拉斯的密度也更高，但尚不清楚是因为最初的水分含量较小，还是由于水分损失。帕拉斯提供了一个案例研究，让我们对这类天体有一个新的、更完整的理解，这些天体与典型的小行星非常不同，是行星的前身，并且经历了行星过程。重要的是，这是建议的近地小行星(3200)法埃顿的母体，命运+任务将对其进行调查。以帕拉斯为重点，拟议的项目目标是完成五个科学目标，重点是密度、成分、结构和年代学。A.通过对孔隙率的演化进行建模，并在计算的最终体积密度与Pallas的最终体积密度之间推导出匹配，从Pallas的体积密度和类似CM的表面成分推导出Pallas的沉积时间。B.确定哪些内部成分和结构与水化(次)表面一致，例如，水化表面是否意味着地幔和地壳中的高冰份，方法是计算温度和孔隙度的演变并得出材料的强度和成分。C.对于A.和B.D.中约束的参数，约束Pallas的大地测量性质的演变，例如，MOI系数和自转速度。D.通过比较Phaethon的S物理性质与Pallas获得的物理性质，确定是否可以从Pallas产生具有Phaethon S物理性质的天体，假设Phaethon是其母小行星的单个碎片。E.确定Pallas的热演化是否与CM、CY或Tagish Lake球粒陨石的热年代学记录一致，即Pallas是否可能是这两个群中任何一个的母体，方法是将计算的热演化与这些陨石群的现有数据进行拟合。该项目旨在弥合谷神星和灶神星之间在我们对原行星的理解上的差距，调查帕拉斯是否可能是菲埃顿的母行星，并通过建模研究支持命运+太空任务。

Protoplanets are fascinating bodies that provide a special sort of examples of geological processes observed on planets, e.g., volcanism, tectonics, and differentiation, yet in a special setting of sub-1000 km bodies that did not develop to full planets. Observations suggest that (2) Pallas fills a gap between (1) Ceres and (4) Vesta. Protoplanets Ceres and Vesta explored by the Dawn mission have comparable geology given similar surface gravities. While Vesta is much denser due to its anhydrous composition than the water-rich Ceres, Pallas is also denser, but it is unclear if due to an initially smaller water content, or water loss. Pallas offers a case study for a new and much more complete understanding of this class of objects which are very different from typical small asteroids, are precursors of planets, and have undergone planetary processes. Importantly, it is the suggested parent body of the near-Earth asteroid (3200) Phaethon that will be investigated by the Destiny+ mission. Focusing on Pallas, the proposed project targets to complete five science objectives focused on density, composition, structure, and chronology. A. Derive the accretion time of Pallas from its bulk density and a CM-like surface composition by modelling the evolution of the porosity and deriving a match between the calculated final bulk density and that of Pallas. B. Determine which internal composition and structure are consistent with a hydrated (sub-) surface, e.g., if the hydrated surface implies a high ice fraction in the mantle and crust, by calculating the evolution of the temperature and porosity and deriving the strength and composition of the material. C. Constrain the evolution of geodetic properties of Pallas, e.g., MOI coefficient and spin velocity, for the parameters constrained in A. and B. D. Determine if an object with Phaethon´s physical properties can be produced from Pallas for the assumption that Phaethon is a single fragment of its parent asteroid by comparing Phaethon´s physical properties with those obtained for Pallas. E. Determine if the thermal evolution of Pallas is compatible with the thermo-chronological record of CM, CY, or Tagish Lake chondrites, i.e., if Pallas can be the parent body of either of these groups, by fitting the thermal evolution calculated to the data available for these meteorite groups. The project aims to closing the gap between Ceres and Vesta in our understanding of protoplanets, to investigating if Pallas can be the parent asteroid of Phaeton, and to supporting the Destiny+ space mission with modeling studies.