Ground-based observations of Jupiter (and Saturn) in support of the NASA Juno mission

支持 NASA 朱诺号任务的木星（和土星）地面观测

• 批准号: 2445854
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2445854
• 关键词: Ground; based; observations; Jupiter; Saturn

The clouds of the Solar System's Gas Giants (Jupiter and Saturn) are amongst the most beautiful and complex phenomena displayed by the planets. Their spatial distribution reveals the forces and energy exchange mechanisms (e.g., moist convection) shaping the banded appearance of the planetary weather layers; their vertical structure tells us about the composition and cloud microphysics; and their colour reveals the chemical alteration of aerosols in a giant planet atmosphere. While most clouds are white, the clouds of Jupiter and Saturn are coloured with various hues of yellow and red, but the nature of these colours, or 'chromophores,' has yet to be determined, and remains an enduring mystery.The NASA Juno mission arrived at Jupiter in July 2016 and entered into a series of elliptical polar orbits designed to probe Jupiter's interior structure through measurement of its gravity and magnetic fields and remote sensing of its deep atmosphere. Juno's highly elliptical orbit minimises the damaging effects of Jupiter's extremely harsh radiation belts, but means that its UV, visible and near-IR observations are mostly of Jupiter's poles, while microwave observations using the MWR instrument are mostly confined to narrow north-south swaths during perijove (closest approach) passes that lack the global spatial context necessary to interpret them properly. Hence, a global campaign is under way to provide Earth-based observational support for Juno, in which our group closely involved making observations with the MUSE instrument at ESO's Very Large Telescope (VLT) in Chile. The MUSE (Multi Unit Spectroscopic Explorer) instrument provides an unprecedented opportunity to study the clouds, dynamics and composition of the giant planet atmospheres at a spatial and spectral resolution never before possible. MUSE measures spectral 'cubes' in which each pixel of the 300 x 300 field of view is a complete spectrum covering the range spectral 480 to 930 nm. These 'cubes' allow us to map the spatial distribution of the clouds and colouring agents, estimate cloud top levels and determine spatial variations of ammonia abundance. While other ground-based and space-based instruments can provide partial coverage of these wavelengths (usually as images in discrete filters), only MUSE provides the unique combination of spatial and spectral coverage, which makes it a very powerful tool for studying clouds in giant planet atmospheres. Analysis of existing MUSE observations has been used to model the distribution of cloud, chromophores and ammonia in Jupiter's atmosphere, but Jupiter's atmosphere continues to develop and the Juno mission is set to observe for several more years. Hence, continuing observations are vital and more are planned or remain waiting to be processed. At longer wavelengths, instruments such as VLT/VISIR provide thermal mapping that can be used to determine the vertical and spatial distribution of temperature and gaseous abundances. A set of MUSE observations was made within a few minutes of a set of VISIR observations on one night in 2018 and provides a golden opportunity to link cloud features to observed thermal anomalies. We envision that our VLT/MUSE programme could extend to further observations of Saturn also to compare and contrast these two worlds. In addition to these ground-based facilities, NASA's James Webb Space Telescope (JWST), scheduled for launch in 2021, is planned to make many observations of the gas giants over a wide wavelength range that will need to be understood and interpreted.In this project, the student will analyse existing VLT/MUSE Jupiter observations and participate in proposing and reducing further measurements, gaining excellent experience in telescopic observational data analysis and gaining a deep insight into the atmospheric circulation and cloud formation on these worlds. The spectral cubes will be analysed with our sophisticated multiple-scattering radiative transfer model, NEMESIS. Given the t

太阳系的气态巨行星（木星和土星）的云是行星上最美丽、最复杂的现象之一。它们的空间分布揭示了力和能量交换机制（如湿对流）形成的行星天气层的带状外观；它们的垂直结构告诉我们组成和云的微物理；它们的颜色揭示了巨大行星大气中气溶胶的化学变化。虽然大多数云是白色的，但木星和土星的云却呈现出各种黄色和红色的色调，但这些颜色的性质，或“发色团”，尚未确定，仍然是一个持久的谜。美国宇航局的朱诺号探测器于2016年7月抵达木星，进入了一系列椭圆极轨道，旨在通过测量木星的重力和磁场以及遥感木星的深层大气来探测木星的内部结构。朱诺号的高椭圆轨道最大限度地减少了木星极其恶劣的辐射带的破坏性影响，但这意味着它的紫外线、可见光和近红外观测主要是在木星的两极，而使用MWR仪器的微波观测主要局限于近日点（最接近）通过时狭窄的南北狭长地带，缺乏正确解释它们所必需的全球空间背景。因此，一项为朱诺提供地面观测支持的全球运动正在进行中，我们的团队密切参与了在智利的ESO甚大望远镜（VLT）上使用MUSE仪器进行观测。MUSE（多单元光谱探测器）仪器提供了一个前所未有的机会，以前所未有的空间和光谱分辨率研究巨大行星大气的云层、动力学和组成。MUSE测量光谱“立方体”，其中300 x 300视场的每个像素都是一个完整的光谱，覆盖光谱范围为480至930 nm。这些“立方体”使我们能够绘制云和着色剂的空间分布，估计云顶水平并确定氨丰度的空间变化。虽然其他地基和天基仪器可以提供这些波长的部分覆盖（通常作为离散滤波器中的图像），但只有MUSE提供独特的空间和光谱覆盖组合，这使其成为研究巨行星大气中云的非常强大的工具。对现有MUSE观测数据的分析已被用于模拟木星大气中云、发色团和氨的分布，但木星的大气仍在继续发展，朱诺号任务还将继续观测几年。因此，持续的观察是至关重要的，更多的观察正在计划中或等待处理。在较长的波长，仪器如VLT/VISIR提供热测绘，可用于确定温度和气体丰度的垂直和空间分布。在2018年的一个晚上，一组MUSE观测在一组VISIR观测的几分钟内完成，为将云特征与观测到的热异常联系起来提供了一个绝佳的机会。我们设想我们的VLT/MUSE计划可以扩展到对土星的进一步观测，也可以比较和对比这两个世界。除了这些地面设施外，美国宇航局计划于2021年发射的詹姆斯·韦伯太空望远镜（JWST）计划在很宽的波长范围内对这些气体巨星进行许多观测，这些观测需要被理解和解释。在这个项目中，学生将分析现有的VLT/MUSE木星观测数据，并参与提出和减少进一步的测量，获得望远镜观测数据分析的优秀经验，并深入了解这些世界的大气环流和云形成。光谱立方体将用我们复杂的多重散射辐射传输模型NEMESIS进行分析。给定t