CAREER: Atmospheric Electricity on Earth and Mars

地球大气层中自然发生的闪电在很短的时间内释放出巨大的能量。闪电最常发生在雷暴期间，因为云中积聚了静电荷。在火星上也发现了闪电，据信是由沙尘暴造成的。虽然由于大气压力低，这种闪电不像在地球上那么常见，但火星上的金属物体就像避雷针一样，对仪器来说是一种危险。火星表面机器人探险者的增加增加了这种放电的可能性，增加了仪器的风险，也增加了人类探索的可能性。这项CAREER研究概述了一项为期五年的努力，旨在研究具有代表性的地球和火星大气条件下放电的物理学和可观测性。研究人员建议进行一项综合研究，将理论和实验结合起来，集中研究在6到1013毫巴压力范围内的空气中产生的放电，以检查从热、圆柱形或球形电极开始的放电与在表层岩石和沙粒摩擦充电中观察到的电气化之间的差异。主要目的是进一步加深我们对不同环境中放电物理的理解。特别是，本研究旨在解决以下行星电的突出问题：(1)几何因素能否充分解释理论和观测到的闪电起始阈值之间的差异？(2)建模是否有助于评估以瞬态发光事件或假定的火星闪电形式发生的大气击穿的性质（发光、飘带、引线）？(3)摩擦增压是否会引发这种非常规放电？研究计划旨在：•产生一个新的，广义模型的电子雪崩从热圆柱形或球形电极发起的公式，•创建一个三维分形模型的外星放电和估计他们的电荷和偶极矩，•在一个规模的火星尘埃事件的电气化进行定量测量，•传播学术研究以外的学术机构通过天文学在Tap会谈，•利用乐高头脑风暴创建夏令营，通过创新和吸引人的方法向中学生介绍编程和空间科学。这个项目的成功将直接影响到未来探测地外大气电的仪器的设计，通过识别由非常规闪电引起的最可测量的变化。它还将有助于评估从地表物体开始排放的风险，特别是在火星探索的框架内。它将通过为期5天的夏令营、公开讲座和非正式场所的讲座，加强学术研究与当地社区之间的关系。通过这些任务，研究者将接触到所有年龄和水平的受众，并寻求激励下一代科学家和工程师。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Naturally occurring lightning in the Earth atmosphere releases tremendous amount of energy in a very short time. Lightnings most commonly occur during thunderstorms as electrostatic charges accumulate in clouds. Lightnings have also been found to occur on Mars, believed to be created by dust storms. Though not as common as on Earth because of low atmosphere pressure, such lightnings can be a hazard to instruments on Mars with metal objects acting like a lightning rod. The multiplication of robotic explorers at the surface of the planet has increased the chances of such electric discharges, increasing risks for instruments and an ever-more likely human-exploration.This CAREER research outlines a five-year effort to study the physics and observability of electrical discharges in atmospheric conditions representative of Earth and Mars. The investigators suggest a comprehensive study combining theory and experiments centered on discharges produced in air at pressures ranging from 6 to 1013 mbar, to examine the differences between discharges started from a hot, cylindrical or spherical electrode, and the electrification observed in the tribocharging of regoliths and sand grains. The principal objective is to further our understanding of the physics of electrical discharge in diverse environments. In particular, this research seeks to resolve the following outstanding issues in planetary electricity: (1) Can geometric factors adequately explain the difference between theoretical and observed lightning initiation thresholds? (2) Can modeling help assess the nature (glow, streamer, leader) of atmospheric breakdown occurring in the form of Transient Luminous Events or putative Martian lightning? (3) Can tribocharging lead to the initiation of such non-conventional discharges?The research plan aims to: • produce the formulation of a new, generalized model of electron avalanche initiated from a hot cylindrical or spherical electrode,• create a 3-D fractal models of extraterrestrial discharges and estimates of their electric charges and dipole moments,• make quantitative measurements of the electrification in a scaled Martian dust event,• disseminate of academic research outside academia through Astronomy on Tap talks, and• create a summer camp using LEGO Mindstorms to introduce middle-schoolers to programing and space science through an innovative and engaging approach.The success of this project will directly impact the design of future instruments for the detection of extraterrestrial atmospheric electricity by identifying the most measurable changes due to non-conventional lightning. It will also help to assess the risk of initiating discharges from surface objects in particular in the framework of Martian exploration. It will strengthen the relationship between academic research and the local community, through the 5-day summer camp, public lectures, and talks at informal venues. Through these tasks, the investigator will reach audiences of all ages and levels and seek to inspire the next generation of scientists and engineers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.