Geophysical Investigations of Mars and Mercury

我的研究重点是对太阳系中类地行星、卫星和小天体的地球物理研究。拟议的研究计划的主要目的是利用最近太空任务返回的数据，以解决与火星和水星的历史和现状有关的关键知识空白。这些研究的共同之处在于观测到的磁场对行星内部结构和演化以及大气和磁层过程提供了基本的限制。在水星和火星上，磁场产生于“内部来源”，如金属核心的流体运动和/或地壳岩石的磁化，以及“外部来源”，如行星表面高处产生的电流系统。由此产生的环境提供了关于每个行星内部的基本线索，在高层大气和行星周围的空间环境中发生的过程，以及这些内部和外部过程如何相互作用来塑造行星的演化。我们将利用信使号任务（2011-2015）的轨道数据研究水星地壳磁场的性质和历史。对地壳磁场的研究将阐明地壳磁化的分布和起源以及地核发电机的历史。提出的计划的一个新颖方面是量化与某些陨石坑相关的增强磁化是否反映了撞击传递的铁增强。这可以提供一种创新的方法来限制水星上的撞击物数量：即含铁与不含铁的撞击物的相对比例。我们还将开发水星的热演化模型，这一模型的关键动机是满足水星早期演化的三个限制条件：广泛的早期热流火山作用、实质性的行星收缩和发电机。对火星的研究旨在了解火星表面磁场时间变化的性质和起源，洞察号火星着陆器首次测量了火星表面磁场（2018年12月至今）。我们将利用这些数据，连同MAVEN任务（2014年11月至今）的卫星观测数据，来探测火星内部的电导率结构，这反过来又与内部温度、成分和挥发性含量有关。进一步的方面涉及使用地壳场模型、地表地质和撞击坑的记录来阐明火星发电机的历史以及地壳磁化的深度。拟议的研究计划是研究控制我们自己和其他太阳系行星演化的重要物理过程的关键，实用的方法。获得资助的人员将为国际行星任务作出贡献，并接受行星物理、计算和数据分析方面的高级培训，为在学术界、政府或私营工业中获得广泛的机会做好准备。

My research focuses on geophysical investigations of terrestrial planets, moons and small bodies in our solar system. The proposed research program is broadly aimed at exploiting data returned from recent space missions to address key knowledge gaps related to the histories and current states of Mars and Mercury. Common to the investigations are fundamental constraints offered by observed magnetic fields on planetary interior structure and evolution, as well as on atmospheric and magnetospheric processes. At Mercury and Mars, magnetic fields arise from "internal sources" such as fluid motions in the metallic core and/or magnetization of crustal rocks, and from "external sources" such as current systems generated high above the planet's surface. The resulting environments provide fundamental clues about each planet's interior, processes occurring in the upper atmosphere and the space environment around the planet, and how these internal and external processes interact to shape a planet's evolution. We will investigate the nature and history of Mercury's crustal magnetic field using orbital data from the MESSENGER mission (2011-2015). Investigations of crustal magnetic fields will elucidate the distribution and origin of magnetization in the crust and the history of the core dynamo. A novel aspect of the proposed program is to quantify whether enhanced magnetizations associated with some craters reflect impact-delivered iron enhancements. This can provide an innovative way to constrain the impactor population at Mercury: namely, the relative proportions of iron-bearing versus iron-free impactors. We will also develop thermal evolution models for Mercury, that are critically motivated by the challenge of satisfying three constraints on Mercury's early evolution: extensive early effusive volcanism, substantial planetary contraction and a dynamo. Studies of Mars aim to understand the nature and origin of time variations in the Martian surface magnetic field, measured for the first time by the InSight lander on Mars (Dec. 2018 - present). We will use these data, together with satellite observations from the MAVEN mission (Nov. 2014 - present), to probe the planet's interior electrical conductivity structure, that in turn is related to interior temperature, composition and volatile content. A further aspect involves using crustal field models, surface geology and the record of impact craters to elucidate the history of the Martian dynamo as well as the depths of crustal magnetization. The proposed research program is a key, practical approach to investigating important physical processes that govern the evolution of planets in our own and other solar systems. Funded personnel will contribute to international planetary missions and receive high-level training in planetary physics, computing and data analysis, preparing them for a broad range of opportunities in academia, government or private industry.