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

阿塔卡马大型毫米/亚毫米阵列揭示了土卫六高层大气的化学和物理

• 批准号: 1613987
• 负责人: Martin Cordiner
• 金额: $ 21.15万
• 依托单位: Catholic University of America
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1613987&HistoricalAwards=false
• 关键词: Chemistry; Physics; Titan; Upper; Atmosphere

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.

土星泰坦的气氛由氮和碳等分子以及其他元素等分子组成，这些元素在岩石行星的早期大气中存在。我们研究泰坦的大气层，以了解有关地球大气层的早期历史的更多信息。卡西尼航天器已绘制了简单的碳和氮分子，揭示了许多分子的模式，这些分子随着泰坦的变化而变化。但是，这些只是泰坦大气中的少数分子类型，我们在所有泰坦的大气中都没有覆盖。 这是卡西尼运营的最后一年。与卡西尼（Cassini）同时，使用新的Atacama大毫米/亚毫米阵列（ALMA）射电望远镜观测站，天文学家将使用射电望远镜和航天器完全观察到泰坦的大气层。他们将制作泰坦大气中分子类型和数量的前3维图。然后，他们将对结果进行建模，以了解如何随着时间的推移产生，运输和更改大气中的分子。华盛顿特区地区的少数派服务学校的本科生物理学和天文学学生将在NASA的Goddard太空飞行中心进行独立的太阳能系统研究。Saturn'sMoon Titan具有厚实复杂的有机分子。它是原始陆生物（包括早期地球）的潜在类似物。 NASA的Cassini航天器上的仪器提供了较小的碳氢化合物和硝化液的地图，显示出许多复杂的，季节性的分子丰度模式。但是，这些观察结果仅追踪一小部分泰坦分子库存，并且具有不完全的空间和时间覆盖范围。了解泰坦大气气体的形成和演变是确定其他原始行星大气中存在的分子清单的关键步骤。 Atacama大毫米/亚毫米阵列（ALMA）是革命性的工具，用于检测和瞬时的日光 - 泰坦气体映射。阿尔玛（Alma）将在卡西尼（Cassini）的最后一年与卡西尼（Cassini）一起使用，以提供泰坦大气的完整视图。这项研究将为泰坦的多个分子物种提供第一个瞬时，空间分辨的三维分子丰度图，从而提供了新的和严格的测试，以理解行星气氛的基本物理和化学。对这些地图的解释将有助于生成更详细的化学模型，从而深入了解分子材料的全球生产，运输和演变，尤其是在泰坦较少研究的中层和上层大气中。同位素丰度比率将有助于限制化学途径并追踪泰坦氢和氮的起源和进化。首席研究员将指导来自华盛顿特区少数派服务机构的本科生和天文学学生，他们将在NASA的Goddard太空飞行中心进行独立的太阳能系统研究。