The Chemistry and Physics of Titan's Upper Atmosphere Revealed by the Atacama Large Millimeter/submillimeter Array

土星的卫星泰坦的大气层是由氮和碳等分子以及其他元素组成的，这些分子存在于像地球这样的岩石行星的早期大气层中。我们研究土卫六的大气层，以了解更多关于地球大气层的早期历史。卡西尼号航天器绘制了简单的碳和氮分子，揭示了许多随着土卫六季节变化而变化的分子模式。然而，这些只是土卫六大气中分子类型的一小部分，我们没有覆盖整个土卫六的大气。 这是卡西尼号运行的最后一年。与卡西尼号同时使用新的阿塔卡玛大型毫米/亚毫米阵列（阿尔马）射电望远镜天文台，天文学家将使用射电望远镜和航天器完全观察土卫六的大气层。他们将绘制土卫六大气层中分子类型和数量的第一张三维地图。然后，他们将对结果进行建模，以了解大气中的分子是如何产生、运输和随时间变化的。来自华盛顿地区少数民族学校的物理学和天文学本科生将在美国宇航局戈达德太空飞行中心的首席研究员的投入和支持下进行独立的太阳系研究。土星的卫星土卫六有一个厚厚的氮和碳丰富的大气层，丰富的复杂的有机分子。它是原始地球（包括早期地球）的潜在类似物。美国宇航局卡西尼号航天器上的仪器提供了较小的碳氢化合物和腈的地图，揭示了许多复杂的，季节性变化的分子丰度模式。然而，这些观测只追踪了土卫六分子清单的一小部分，并且在空间和时间上的覆盖范围不完整。了解土卫六大气气体的形成和演化是确定其他原始行星大气中分子库存的关键一步。阿塔卡马大型毫米/亚毫米阵列（阿尔马）是一个革命性的工具，用于探测和瞬时日光半球映射土卫六的气体。在卡西尼号运行的最后一年，阿尔马将与卡西尼号同时使用，以提供泰坦大气层的完整视图。这项研究将为土卫六上的多种分子物种绘制第一张瞬时的、空间分辨的三维分子丰度图，从而为理解行星大气的基本物理和化学提供新的严格测试。对这些地图的解释将有助于生成更详细的化学模型，以深入了解分子物质的全球生产，运输和演变，特别是在泰坦的中高层大气中研究较少。同位素丰度比将有助于限制化学途径，并追踪土卫六氢和氮的起源和演变。首席研究员将指导来自华盛顿地区少数民族服务机构的物理学和天文学本科生，他们将在美国宇航局的戈达德太空飞行中心进行独立的太阳系研究。

The atmosphere of Saturn's moon Titan is composed of molecules such as nitrogen and carbon and other elements that were present in the early atmospheres of the rocky planets like Earth. We study Titan's atmosphere to learn more about the early history of the Earth's atmosphere. Cassini spacecraft has mapped simple carbon and nitrogen molecules, revealing many patterns of molecules that change with the changing seasons of Titan. These are, however, only a small number of the types of molecules in Titan's atmosphere, and we do not have coverage of the atmosphere across all of Titan. This is Cassini's last year of operation. Using the new Atacama Large Millimeter/submillimeter Array (ALMA) radio telescope observatory at the same time as Cassini, the astronomers will observe Titan's atmosphere completely using both the radio telescopes and the spacecraft. They will make the first 3-dimensional maps of the types and amounts of molecules in Titan's atmosphere. They will then model the results to learn about how the molecules in the atmosphere are produced, transported, and changed with time. Undergraduate physics and astronomy students from minority-serving schools in the Washington DC area will conduct independent Solar System research with the principal investigator's input and backing at NASA's Goddard Space Flight Center.Saturn's moon Titan has a thick nitrogen and carbon-rich atmosphere, abundant in complex organic molecules. It is a potential analogue for primitive terrestrial bodies (including the early Earth). Instruments onboard NASA's Cassini spacecraft have provided maps of the smaller hydrocarbons and nitriles, revealing many complex, seasonally-varying molecular abundance patterns. These observations, however, trace only a small subset of Titan's molecular inventory, and have incomplete spatial and temporal coverage. Understanding the formation and evolution of Titan's atmospheric gases is a key step in determining the molecular inventories present in other primitive planetary atmospheres. The Atacama Large Millimeter/submillimeter Array (ALMA) is a revolutionary tool for the detection and instantaneous daylight-hemisphere mapping of Titan's gases. ALMA will be used concurrently with Cassini during its final year of operation to provide complete views of Titan's atmosphere. This research will produce the first instantaneous, spatially-resolved 3-dimensional molecular abundance maps for multiple molecular species on Titan, allowing new and rigorous tests for understanding the basic physics and chemistry of planetary atmospheres. Interpretation of these maps will help generate more detailed chemical models to provide insight into the global production, transport and evolution of molecular material, particularly in Titan's less well-studied middle and upper atmospheres. Isotope abundance ratios will help constrain chemical pathways and trace the origin and evolution of Titan's hydrogen and nitrogen. The principal investigator will mentor undergraduate physics and astronomy students from minority-serving institutions in the Washington DC area, who will conduct independent Solar System research at NASA's Goddard Space Flight Center.