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.

长期以来，人们对火星上层大气的结构知之甚少，只有零星的测量数据，直到最近，美国宇航局的 MAVEN 和欧空局的火星快车和 ExoMars 航天器携带相关仪器访问了这颗行星，探索了大气层中 100 公里以上的区域。该行星的电离层是利用无线电掩星技术进行探索的，当航天器消失在行星后面时，深空网络会追踪和测量航天器发出的无线电信号。该技术允许推断电子密度的垂直剖面，但由于几何形状的本质，只能对黎明和黄昏区域进行采样，而不能对白天和夜间区域进行采样，而众所周知，这对于我们理解化学和传输过程至关重要（风） ）。为了克服这一限制，欧空局最近首次在火星航天器对航天器掩星中进行试验，对任何区域、白天和夜晚进行采样。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。他将从他之前在欧空局期间开发的一项技术开始，并以此为基础，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，学生除了开发出可用于未来行星探索的方法之外，还将获得电离层电子密度数据集，可以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且，通过使用和进一步开发该小组中可用的化学和传输模型，有助于确定塑造火星电离层的主要过程。