Global exploration of the upper atmosphere of Mars using radio occultation measurements

使用无线电掩星测量对火星高层大气进行全球探索

• 批准号: 2614496
• 金额: --
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2614496
• 关键词: Global; exploration; upper; atmosphere; Mars

The structure of the upper atmosphere of Mars has long remained poorly known, with only sporadic measurements available until recently, when Nasa's MAVEN and ESA's Mars Express and ExoMars spacecraft visited the planet with the relevant instrumentation to explore regions above 100 km in the atmosphere. The planet's ionosphere was explored using the technique of radio occultations, whereby a radio signal emitted from the spacecraft is traced and measured by the Deep Space Network as the spacecraft disappears behind the planet. This techniques allows vertical profiles of electron densities to be inferred, but by nature of the geometry only the dawn and dusk regions can be sampled, not the dayside and nightside regions which are known to be crucial for our understanding of chemistry and transport processes (winds). To overcome this limitation, ESA recently trialled for the first time ever at Mars spacecraft-to-spacecraft occultations, sampling any region, the dayside and the nightside. The PhD project will consist in exploring this new dataset which will be made available to us and analysed by the PhD student. He will start with a technique he previously developed during his time at ESA and build on that in order to obtain a robust and reliable technique for reducing past and future datasets. Thereby, the student, in addition to having developed a methodology which can be used in future planetary explorations, will obtain a dataset of ionospheric electron densities which can be further investigated for structural anomalies, including the effects of Mars' crustal magnetic fields on ionospheric structures and, by using and further developing chemistry and transport models available in the group, contribute towards identifying the main processes shaping the ionosphere of Mars.

火星上层大气的结构长期以来一直知之甚少，直到最近，NASA的MAVEN和欧空局的火星快车和ExoMars航天器带着相关仪器访问了火星，探索大气层中100公里以上的区域，才有零星的测量数据。使用无线电掩星技术对行星的电离层进行了探索，即当航天器消失在行星后面时，深空网络跟踪和测量航天器发出的无线电信号。这种技术可以推断出电子密度的垂直分布，但由于几何形状的性质，只能对黎明和黄昏区域进行采样，而不是对我们理解化学和传输过程（风）至关重要的昼侧和夜侧区域。为了克服这一局限性，欧空局最近首次在火星航天器对航天器的掩星试验中，对任何区域进行了采样，包括昼面和夜面。博士项目将包括探索这个新的数据集，该数据集将提供给我们并由博士生进行分析。他将从他以前在欧空局期间开发的技术开始，并在此基础上建立，以获得一种强大而可靠的技术来减少过去和未来的数据集。因此，该学生除了开发出可用于未来行星探索的方法外，还将获得电离层电子密度数据集，可进一步研究结构异常，包括火星地壳磁场对电离层结构的影响，并通过使用和进一步开发小组现有的化学和传输模型，有助于确定形成火星电离层的主要过程。