A Unified Understanding of the Earth's Radiation Environment

对地球辐射环境的统一认识

• 批准号: NE/Z000157/1
• 负责人: Sarah Glauert
• 金额: $ 126.28万
• 依托单位: British Antarctic Survey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FZ000157%2F1
• 关键词: Unified; Understanding; Earth; Radiation; Environment

Our society is increasingly reliant upon technological infrastructure that orbits in the harsh and highly dynamic radiation environment of near-Earth space. Low-cost access to space is driving a rapid increase in the number of satellites on orbit (e.g., Starlink, Oneweb), many of which use electronics that are untested during active solar conditions, such as the upcoming solar maximum in 2024-2025. This proposal will make a significant advance in the understanding of the radiation environment in which these satellites operate.Space was a £16.5 Bn UK industry in 2019/2020 and severe space weather was added to the National Risk Register in 2011, owned by the Met Office who provide space weather services to the satellite industry. However, current forecasting models, including the BAS Radiation Belt Model (BAS-RBM) that provides forecasts to the Met Office and European Space Agency, only forecast the highest energy electrons and the associated risk of damage from internal charging. The Met Office currently has no capability to forecast the lower energy electrons that can cause surface charging damage and be energised to become so-called 'killer' electrons.The radiation environment is highly dynamic and includes several different populations of electrons, identified by their energy ranges. The lowest energy electrons form the background plasma, medium energy electrons are found in the ring current, and the highest energy electrons form the radiation belts. These have historically been studied independently but the populations are interdependent, and recent research has highlighted that they need to be studied as a single system. For example, the highest energy killer electrons are produced when lower energy electrons are energised by electromagnetic waves. These waves are generated by the medium energy electrons and the acceleration is most effective in regions with a depleted background plasma. This proposal aims to establish how the populations and their interactions contribute to the variability of the radiation environment. We will determine which solar wind conditions produce the most effective wave-electron interactions, quantify the role of realistic magnetic fields on the loss and energisation of electrons, and determine how the interactions of the different populations affect the radiation environment in key types of space weather events. This will significantly increase our understanding of the conditions that lead to radiation environments that may damage satellites.These studies require a combination of data analysis and modelling. A few models can study multiple populations, but they all initially addressed a single population using an appropriate framework for that population. Extending to include another population meant incorporating an additional framework, introducing interpolation errors and inconsistencies. For example, although these models use realistic magnetic field models for part of the calculation, they assume a dipole magnetic field to model the wave-electron interactions. Building on our BAS-RBM experience, we will adopt a novel approach using a unifying framework for all three populations that can also include realistic magnetic and electric fields. To be consistent we will also develop the first comprehensive characterisations of wave-electron interactions in realistic magnetic fields. Using observations from spacecraft such as the Van Allen Probes, together with this new modelling framework, we will address the causes of variability in the radiation environment. The model created for these studies will also be able to provide improved predictions of the conditions leading to internal charging on satellites and a new ability to address surface charging.

我们的社会越来越依赖于在近地空间恶劣和高度动态辐射环境中运行的技术基础设施。低成本进入太空正在推动轨道上卫星数量的迅速增加（例如，Starlink，Oneweb），其中许多使用的电子设备在活跃的太阳能条件下未经测试，例如即将到来的2024-2025年太阳能极大期。这一提议将使对这些卫星运行的辐射环境的理解取得重大进展。在2019/2020年，太空是英国165亿英镑的产业，2011年，严重的太空天气被添加到国家风险登记册，该登记册由气象局拥有，为卫星产业提供空间天气服务。然而，目前的预测模型，包括向英国气象局和欧洲航天局提供预测的BAS辐射带模型（BAS-RBM），只能预测最高能量的电子和内部充电造成的相关损害风险。英国气象局目前没有能力预测低能量电子，这些电子可能会导致表面充电损坏并被激发成为所谓的“杀手”电子。辐射环境高度动态，包括几种不同的电子群，根据其能量范围进行识别。最低能量的电子形成背景等离子体，中等能量的电子被发现在环电流，和最高能量的电子形成辐射带。历史上这些都是独立研究的，但群体是相互依存的，最近的研究强调它们需要作为一个单一系统来研究。例如，当较低能量的电子被电磁波激发时，会产生最高能量的杀手电子。这些波由中等能量电子产生，并且加速在具有耗尽背景等离子体的区域中是最有效的。该提案旨在确定人口及其相互作用如何促成辐射环境的可变性。我们将确定哪些太阳风条件产生最有效的波-电子相互作用，量化现实磁场对电子损失和激发的作用，并确定不同人群的相互作用如何影响关键类型空间天气事件中的辐射环境。这将大大增加我们对导致可能损坏卫星的辐射环境的条件的了解，这些研究需要数据分析和建模相结合。一些模型可以研究多个群体，但它们最初都是使用针对该群体的适当框架来处理单个群体。扩大到包括另一个人口意味着纳入一个额外的框架，引入插值误差和不一致。例如，虽然这些模型使用真实的磁场模型进行部分计算，但它们假设偶极磁场来模拟波-电子相互作用。在我们的BAS-RBM经验的基础上，我们将采用一种新的方法，对所有三种人群使用统一的框架，其中还可以包括现实的磁场和电场。为了保持一致，我们还将首次全面描述真实磁场中的波-电子相互作用。我们将利用货车艾伦探测器等航天器的观测结果，以及这一新的建模框架，探讨辐射环境变化的原因。为这些研究创建的模型还将能够改进对导致卫星内部充电的条件的预测，并提供解决表面充电的新能力。