Collaborative Research: Cubesat--Ionospheric Scintillation Explorer (ISX)

合作研究：立方体卫星——电离层闪烁探测器（ISX）

• 批准号: 1445500
• 负责人: John Bellardo
• 金额: $ 44.81万
• 依托单位: California Polytechnic State University Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1445500&HistoricalAwards=false
• 关键词: Collaborative; Research; Cubesat; Ionospheric; Scintillation

This project is to design, develop, construct, operate and analyze the results of a spacecraft CubeSat mission named "Ionospheric Scintillation eXplorer" (ISX). Ionospheric scintillation refers to random fluctuations in amplitude and phase of radio signals traversing a region of turbulence in the ionosphere. It impacts the power and phase of the radio signal and is caused by small-scale (kilometer to centimeters) structure in the ionospheric electron density along the signal path. Ionospheric scintillation affects trans-ionospheric radio signals up to a few GHz in frequency and, thus, can have detrimental impacts on satellite-based communication and navigation systems, such as GPS-based systems, and also on scientific instruments requiring observations of trans-ionospheric radio signals, e.g. for radio astronomy. The physics behind the generation of the plasma irregularity structures that cause scintillation is not fully understood, largely due to a lack of adequate observations. An obvious consequence of this is that neither does a reliable capability exist for the prediction or mitigation of the effects of scintillations on radio waves. ISX will generate an extensive dataset for applying diffraction radio imaging, which enables the prediction of scintillations at any frequency determined from the imaged structure, and potentially the mitigation of distorted signals by canceling phase fluctuations. Another broader impact of the proposed project is that it is a pilot effort to provide global, space-based monitoring of ionospheric radio wave distortion using signals of opportunity available worldwide. While a single spacecraft cannot provide real-time monitoring, it can show the way for a constellation of spacecraft to provide such a space weather service in the future. Scintillation effects occur predominantly in the equatorial region in ionospheric density structures termed Equatorial Spread F (ESF). The main goal of this project is to provide new observations on the structure of scintillation-scale ionospheric irregularities associated with ESF. Specifically, ISX will simultaneously record scintillation patterns of multiple ground-based digital television (DTV) carrier signals. Scintillation patterns for a unique set of experimental geometries will be compared to determine how far along the magnetic field the turbulence maps, which is crucial observational data on the three-dimensional electrodynamics of these sub-km structures.During the lifecycle of the project, it will provide extensive student training opportunities, including student involvement through Cal Poly spacecraft design classes and funded graduate students. Each year, 20-40 students will be involved in the design, fabrication, and flight of this mission. Cal Poly has flown many student satellite missions; the proposed effort will leverage the heritage and experience from all of these.This project addresses the science question: To what distance along a flux tube does an irregularity of certain transverse-scale extend? It has been difficult to measure the magnetic field-alignment of scintillation-scale turbulent structures because of the difficulty of sampling a flux tube at multiple locations within a short time. This measurement is now possible due to the worldwide transition to DTV, which presents unique signals of opportunity for remote sensing of ionospheric irregularities from numerous vantage points. DTV spectra, in various formats, contain phase-stable, narrowband pilot carrier components that are transmitted simultaneously. A 4-channel radar receiver will simultaneously record up to 4 spatially separated transmissions from the ground. For most experimental geometries, the corresponding transmitter-satellite lines-of-sight will cross the same magnetic flux tube within 1-10 s, a reasonably short time to assume "frozen" irregularities. Correlations of amplitude and phase scintillation patterns corresponding to multiple points on the same flux tube will be a measure of the spatial extent of the structures along the magnetic field. A subset of geometries where two or more transmitters are aligned with the orbital path will be used to infer the temporal development of the structures. The radio receiver is based on the instrument developed and successfully demonstrated on the previous Radio Aurora eXplorer (RAX) NSF CubeSat project.

该项目旨在设计、开发、建造、运行和分析名为“电离层闪烁探测器”（ISX）的立方体卫星任务的结果。电离层闪烁是指穿越电离层湍流区域的无线电信号在振幅和相位上的随机波动。它影响无线电信号的功率和相位，是由信号路径上电离层电子密度的小尺度（千米到厘米）结构引起的。电离层闪烁影响频率高达几千兆赫的跨电离层无线电信号，因此可能对基于卫星的通信和导航系统（例如基于全球定位系统）以及需要观测跨电离层无线电信号的科学仪器（例如用于射电天文学的仪器）产生有害影响。导致闪烁的等离子体不规则结构的产生背后的物理学还没有完全理解，很大程度上是由于缺乏足够的观测。这样做的一个明显后果是，既不存在可靠的能力来预测或减轻闪烁对无线电波的影响。ISX将为应用衍射射电成像生成一个广泛的数据集，该数据集能够预测从成像结构确定的任何频率的闪烁，并可能通过消除相位波动来减轻扭曲信号。拟议项目的另一个更广泛的影响是，它是一项试点工作，利用世界各地可用的机会信号，提供全球性的、基于空间的电离层无线电波失真监测。虽然单个航天器无法提供实时监测，但它可以为未来航天器星座提供此类空间天气服务指明道路。闪烁效应主要发生在赤道地区的电离层密度结构中，称为赤道扩散F （ESF）。该项目的主要目标是提供与ESF相关的闪烁尺度电离层不规则结构的新观测结果。具体来说，ISX将同时记录多个地面数字电视（DTV）载波信号的闪烁模式。将比较一组独特的实验几何图形的闪烁模式，以确定湍流图沿磁场的距离，这是这些亚千米结构的三维电动力学的关键观测数据。在项目的整个生命周期中，它将为学生提供广泛的培训机会，包括通过加州理工学院的航天器设计课程和资助研究生的学生参与。每年，20-40名学生将参与这个任务的设计、制造和飞行。加州理工学院已经执行了许多学生卫星任务；提议的努力将利用所有这些的遗产和经验。这个项目解决了一个科学问题：沿通量管的某个横向尺度的不规则延伸到什么距离？由于难以在短时间内对一个磁通管在多个位置进行采样，对闪烁尺度湍流结构的磁场走向测量一直是一个难题。由于全球向数字电视的过渡，这种测量现在成为可能，这为从许多有利位置遥感电离层不规则现象提供了独特的信号。各种格式的数字电视频谱包含同步传输的相位稳定的窄带导频载波分量。一个4通道雷达接收机将同时记录多达4个来自地面的空间分离传输。对于大多数实验几何，相应的发射机-卫星的视线将在1-10秒内穿过相同的磁通管，这是一个相当短的时间来假设“冻结”不规则。对应于同一磁通管上多个点的振幅和相位闪烁模式的相关性将是沿磁场的结构空间范围的度量。其中两个或多个发射机与轨道路径对齐的几何形状的子集将用于推断结构的时间发展。无线电接收机是基于在以前的射电极光探测器（RAX） NSF立方体卫星项目上开发并成功演示的仪器。