Modelling the acceleration, transport and loss of radiation belt electrons to protect satellites from space weather (Rad-Sat)

在过去10年中，在轨运行的卫星数量从450颗增加到1300多颗。我们比以往任何时候都更加依赖这些卫星，用于各种应用，如移动的电话、电视信号、互联网、导航和金融服务。所有这些卫星的设计都必须能够承受空间恶劣的辐射环境，设计寿命可长达15年或更长。空间天气事件可使地球货车艾伦辐射带的电子辐射水平增加五个数量级，造成卫星充电、卫星运行中断，有时还造成卫星损失。例如，2003年，据估计，在一次被称为万圣节风暴的大型空间天气事件中，至少有10%的运行卫星出现异常（故障1）。因此，必须了解辐射水平如何以及为什么变化如此之大，以便工程师和企业能够评估影响并制定缓解措施。美国宇航局货车艾伦探测器和THEMIS卫星任务的新结果表明，波粒相互作用在高能电子的加速、传输和损失中起着主要作用，因此辐射带的变化也是如此。该提案汇集了来自英国各地的科学家以及来自保险和卫星服务部门的利益相关者。我们将处理来自货车艾伦探测器和THEMIS等科学卫星的数据，以获得四种非常重要的波的信息，这些波被称为磁声波，无线电波被称为等离子体层嘶嘶声，闪电产生的哨声和发射波。我们将使用数据，理论和模型来确定波的特性以及它们在空间天气事件中的变化。我们将进行研究，以评估由于每种波类型使用准线性理论的电子的加速，运输和损失。我们将使用模拟来测试与准线性理论相比，非线性效应是否会导致更多的粒子加速和损失。我们将分析超低频范围内的压缩磁声波，并确定它们在磁场中传输电子的有效性，以及传输是否扩散。我们将把这些研究的结果纳入我们最先进的全球辐射带模型，以模拟已知的空间天气事件，并将结果与数据进行比较，以突出波的重要性并改进模型。我们还将包括当地时间的影响，并将损失率与来自地面和其他卫星的数据进行比较，以约束模型。我们将使用现有的辐射带模型和MHD模型模拟极端空间天气事件，以便我们能够评估波在辐射带快速形成中的作用，例如在1991年发生的不到2分钟的时间内。我们将建立一个由空间保险、卫星运营商和预报员组成的利益攸关方社区，他们将为我们的研究提供投入，并将结果用于风险评估、异常解决和业务规划。该项目将提供新的经处理的数据、更好的预报能力和专门知识，以支持联合王国政府为国家风险登记册2评估严重空间天气，并支持卫星工业的发展。坎农，P，S.，等（2013），极端空间天气：对工程系统和基础设施的影响，皇家工程学院，伦敦，SW1A 2WH.2。内阁办公室，（2012年），国家民事紧急情况风险登记册，白厅，伦敦SW1A 2WH，www.cabinetoffice.gov.uk。

Over the last 10 years the number of operational satellites in orbit has grown from 450 to more than 1300. We rely on these satellites more than ever before for a wide range of applications such as mobile phones, TV signals, internet, navigation and financial services. All these satellites must be designed to withstand the harsh radiation environment in space for a design life that can be as long as 15 years or more. Space weather events can increase electron radiation levels by five orders of magnitude in the Earth's Van Allen radiation belts causing satellite charging, disruption to satellite operations and sometimes satellite loss. For example, in 2003 it was estimated that at least 10% of all operational satellites suffered anomalies (malfunctions1) during a large space weather event known as the Halloween storm. It is therefore important to understand how and why radiation levels vary so much so that engineers and business can assess impact and develop mitigation measures. New results from the NASA Van Allen Probes and THEMIS satellite missions show that wave-particle interactions play the major role in the acceleration, transport and loss of high energy electrons and hence the variability of the radiation belts. This proposal brings together scientists from across the UK with stakeholders from the insurance and satellite services sector. We will process data from scientific satellites such as Van Allen Probes and THEMIS to obtain information on four very important type of waves known as magnetosonic waves, and radio-waves known as plasmaspheric hiss, lightning generated whistlers and transmitter waves. We will use data, theory and models to determine the properties of the waves and how they vary during space weather events. We will conduct studies to assess the acceleration, transport and loss of electrons due to each wave type using quasi-linear theory. We will use simulations to test whether nonlinear effects result in more particle acceleration and loss compared to quasi-linear theory. We will analyse compressional magnetosonic waves in the ultra-low frequency range and determine their effectiveness for transporting electrons across the magnetic field, and whether the transport is diffusive or not. We will incorporate the results of these studies into our state-of-the-art global radiation belt model to simulate known space weather events, and compare the results against data to highlight the importance of the waves and improve the model. We will also include local time effects and compare loss rates against data from the ground and other satellites to constrain the model. We will simulate extreme space weather events using our existing radiation belt model, and an MHD model so that we can assess the role of waves in the rapid formation of a radiation belt such as occurred in 1991 in less than 2 minutes. We will develop a stakeholder community consisting of space insurance, satellite operators and forecasters who will provide input to our research and who will use the results for risk assessment, anomaly resolution and operational planning. The project will deliver new processed data, a better forecasting capability and expertise that will support the UK Government assessment of severe space weather for the National Risk Register2 and the growth of the satellite industry.1. Cannon, P, S., et al. (2013), Extreme Space Weather: Impacts on Engineered Systems and Infrastructure, Royal Academy of Engineering, London, SW1A 2WH.2. Cabinet Office, (2012), National risk register of civil emergencies, Whitehall, London SW1A 2WH, www.cabinetoffice.gov.uk.