Schumann Resonances as a tool to constrain the depth of Titan's buried water ocean: Re-assessment of Huygens observations and preparation of the EFIELD/Dragonfly experiment
{"title":"Schumann Resonances as a tool to constrain the depth of Titan's buried water ocean: Re-assessment of Huygens observations and preparation of the EFIELD/Dragonfly experiment","authors":"Paul Lagouanelle, Alice Le Gall","doi":"arxiv-2407.21529","DOIUrl":null,"url":null,"abstract":"Among the lines of evidence for a buried ocean on Titan is the possible\ndetection, in 2005, by the Permittivity, Wave and Altimetry (PWA) analyzer on\nboard the ESA Huygens probe of Schumann-like Resonances (SR). SR are Extremely\nLow Frequency electromagnetic waves resonating between two electrically\nconductive layers. On Titan, it has been proposed that they propagate between\nthe moon's ionosphere and a salty subsurface water ocean. Their\ncharacterization by electric field sensors can provide constraints on Titan's\ncavity characteristics and in particular on the depth of Titan's ocean which is\nkey to better assess Titan's habitability. For this work we have developed a\nnumerical model of Titan's electromagnetic cavity as well as a surrogate model\nto conduct simulations and sensitivity analyses at a low computational cost.\nThis surrogate model is used both to re-assess PWA/Huygens measurements and to\npredict the future performance of the EFIELD experiment on board the NASA\nDragonfly mission. We demonstrate that the PWA/Huygens measurements, in\nparticular due to their low spectral resolution, do not bring any meaningful\nconstraint on Titan's ocean depth. On the other hand, the finer resolution of\nthe EFIELD experiment and its ability to capture several harmonics of SR should\nprovide more robust constraints on Titan's internal structure, especially if\nthe electrical properties of the ice crust and the atmosphere can be better\nconstrained.","PeriodicalId":501209,"journal":{"name":"arXiv - PHYS - Earth and Planetary Astrophysics","volume":"24 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv - PHYS - Earth and Planetary Astrophysics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2407.21529","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
Among the lines of evidence for a buried ocean on Titan is the possible
detection, in 2005, by the Permittivity, Wave and Altimetry (PWA) analyzer on
board the ESA Huygens probe of Schumann-like Resonances (SR). SR are Extremely
Low Frequency electromagnetic waves resonating between two electrically
conductive layers. On Titan, it has been proposed that they propagate between
the moon's ionosphere and a salty subsurface water ocean. Their
characterization by electric field sensors can provide constraints on Titan's
cavity characteristics and in particular on the depth of Titan's ocean which is
key to better assess Titan's habitability. For this work we have developed a
numerical model of Titan's electromagnetic cavity as well as a surrogate model
to conduct simulations and sensitivity analyses at a low computational cost.
This surrogate model is used both to re-assess PWA/Huygens measurements and to
predict the future performance of the EFIELD experiment on board the NASA
Dragonfly mission. We demonstrate that the PWA/Huygens measurements, in
particular due to their low spectral resolution, do not bring any meaningful
constraint on Titan's ocean depth. On the other hand, the finer resolution of
the EFIELD experiment and its ability to capture several harmonics of SR should
provide more robust constraints on Titan's internal structure, especially if
the electrical properties of the ice crust and the atmosphere can be better
constrained.
2005年,欧空局惠更斯探测器上的珀耳帖率、波和高度测量(PWA)分析仪可能探测到了类似舒曼共振(SR)的现象,这也是土卫六上埋藏有海洋的证据之一。SR是在两个导电层之间产生共振的极低频电磁波。在土卫六上,有人认为它们是在月球电离层和咸水洋之间传播的。电场传感器对它们的描述可以为土卫六的空隙特征,特别是土卫六海洋的深度提供约束条件,这对于更好地评估土卫六的宜居性至关重要。在这项工作中,我们开发了一个土卫六电磁空腔数值模型和一个代用模型,以便以较低的计算成本进行模拟和敏感性分析。这个代用模型既可用于重新评估PWA/惠更斯测量结果,也可用于预测NASADragonfly任务中的EFIELD实验的未来性能。我们证明,PWA/惠更斯测量数据,特别是由于其光谱分辨率较低,并不能对土卫六的海洋深度带来任何有意义的限制。另一方面,EFIELD 实验更精细的分辨率及其捕捉 SR 的若干谐波的能力应该能够对土卫六的内部结构提供更有力的约束,特别是如果冰壳和大气层的电特性能够得到更好的约束的话。