美国国家航天局（NASA）的祸神星（Pandora）任务开启系外行星与宿主星研究

祸神星（Pandora）是美国国家航天局（NASA）最新的系外行星（exoplanet）任务，也是该局天体物理学（Astrophysics）先驱者（Pioneer）计划中首个发射的卫星（satellite），目前正在对太阳系（solar system）之外的世界及其环绕的恒星（star）进行独特的观测。该任务将确定至少20颗系外行星的大气构成，包括是否存在霾、云和水。

Pandora, NASA’s newest exoplanet mission and the first satellite to launch through the agency's Astrophysics Pioneers program, is now making unique observations of worlds beyond our solar system and the stars they orbit. The mission will determine the atmospheric make-up of at least 20 exoplanets, including the presence of hazes, clouds, and water.

“祸神星的数据将有助于填补我们在行星及其宿主星（host star）知识方面的重大空白，因为目前我们无法完全确定恒星的光线如何影响系外行星大气成分的测量，”美国国家航天局（NASA）戈达德航天中心（Goddard Space Flight Center）的祸神星首席研究员Elisa Quintana在马里兰州格林贝尔特表示，“我们设计祸神星航天器及其深入的观测计划，正是为了更好地理解这一棘手问题。”

“Pandora’s data will help close a major gap in our knowledge about planets and their host stars because, right now, we can’t be entirely sure how the star’s light affects measurements of what makes up exoplanet atmospheres,” said Elisa Quintana, Pandora’s principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We designed the Pandora spacecraft and its in-depth observing program to better understand this vexing issue.”

该任务的结果将为解读美国国家航天局（NASA）韦布空间望远镜（James Webb Space Telescope）的测量数据，以及未来专注于寻找宜居世界的观测台奠定坚实基础。事实上，祸神星的近红外探测器（infrared detector）正是最初为韦布望远镜开发的一台备用设备。

The results of the mission will lay a firm foundation for interpreting measurements by NASA’s James Webb Space Telescope, as well as future observatories focused on finding habitable worlds. In fact, Pandora’s near-infrared detector is a spare originally developed for Webb.

“航天器运行状况良好，所有仪器表现都达到了我们的预期，”加利福尼亚州劳伦斯利物莫国家实验室（Lawrence Livermore National Laboratory）的祸神星副项目经理Jordan Karburn说，“我们团队在整个调试过程中的辛勤工作得到了回报，现在我们可以充满信心地开始科学研究了。”

"The spacecraft is healthy and all of the instruments are performing as well as we could have hoped,” said Jordan Karburn, Pandora’s deputy project manager at Lawrence Livermore National Laboratory in California. “Our team’s hard work throughout the commissioning process has paid off, and we can now confidently start science."

祸神星于1月11日发射进入近地轨道（low earth orbit），是一颗由美国国家航天局（NASA）天体物理学先驱者计划资助的雄心勃勃的小型卫星（SmallSat）。先驱者计划旨在通过快节奏、低成本且对失败容忍度高于常规的任务，探索关于宇宙（universe）的重大问题。

Launched into low Earth orbit on Jan. 11, Pandora is an ambitious small satellite (SmallSat) funded by NASA’s Astrophysics Pioneers program. Pioneers are designed to explore compelling questions about the universe with fast-paced, low-cost missions that require a higher-than-usual tolerance for failure.

三个因素使祸神星独一无二。它携带了一台直径约18英寸（45厘米）的新型全铝望远镜（telescope），将同时在可见光（visible light）和红外光谱（infrared spectrum）下研究行星及其宿主星，并且观测目标的时间将比韦布等旗舰级观测台所能做到的要长得多。

Three factors make Pandora unique. It carries a novel all-aluminum telescope about 18 inches (45 centimeters) in diameter, it will study planets and their host stars simultaneously in both visible and infrared light, and it will observe targets for a much longer time than flagship observatories like Webb are able to.

当行星从我们的视角看去经过其恒星前方时，望远镜可以对行星的大气进行采样。在这一被称为凌（transit）的过程中，部分星光在到达我们这里之前会掠过行星的大气层。当这些光线与大气分子相互作用时，它们的化学指纹就会嵌入其中。对于每种分子，天文学家（astronomer）都能在特征波长处观察到亮度下降。

Telescopes can sample a planet’s atmosphere in systems where the planet passes in front of its star as seen from our perspective. During this event, called a transit, some starlight skims the planet’s atmosphere before making its way to us. As this light interacts with atmospheric molecules, their chemical fingerprints become embedded in it. For each molecule, astronomers see brightness dips at characteristic wavelengths.

但我们的仪器也会看到来自整颗恒星的光，而不仅仅是掠过行星的那部分。恒星表面（stellar surface）并不均匀。它们拥有被称为光斑（faculae）的更热、更亮的区域，以及类似于太阳黑子的更冷、更暗的区域。随着恒星的旋转，这两者都会生长、缩小并改变位置。

But our instruments also see light from the whole star, not just what grazes the planet. Stellar surfaces aren’t uniform. They sport hotter, brighter areas called faculae and cooler, darker regions similar to sunspots. Both can grow, shrink, and change position as the star rotates.

“水是我们为了了解系外行星大气成分和物理条件所能测量的最重要的分子之一，”马萨诸塞州剑桥市麻省理工学院（Massachusetts Institute of Technology）的团队成员Benjamin Rackham说，“但恒星上的特征可能会扭曲我们正在寻找的水信号。祸神星旨在将行星和恒星的信号分离开来，帮助我们更准确地了解行星，并为最终研究可能孕育生命的行星奠定基础。”

“Water is one of the most important molecules we can measure to understand the composition and physical conditions of an exoplanet atmosphere,” said Benjamin Rackham, a team member at the Massachusetts Institute of Technology in Cambridge. “But features on the star can distort the water signal we’re searching for. Pandora is designed to disentangle the signals from the planet and the star, helping us to understand the planets more accurately and laying the groundwork for the eventual study of planets that could harbor life.”

祸神星的望远镜由利物莫实验室和新罕布什尔州基恩市的康宁特种材料公司（Corning Specialty Materials）联合开发，其探测器构成了任务的核心。探测器将同时捕捉恒星在可见光下的亮度和近红外光谱，同时在行星凌日时获取行星的近红外光谱。在其为期一年的主要任务过程中，祸神星将对至少20颗系外行星进行10次长达24小时的持续凝视观测，每次观测都包含一次凌日。

Pandora’s telescope, jointly developed by Livermore and Corning Specialty Materials in Keene, New Hampshire, and its detectors make up the mission’s heart. The detectors will capture the star’s brightness in visible light and its near-infrared spectrum at the same time, while also obtaining a near-infrared spectrum from the planet when it transits the star. Over the course of its year-long primary mission, Pandora will observe at least 20 exoplanets 10 times with a long-duration stare covering 24 hours, with a transit included in each observation.

“祸神星的优势在于它能够在多个波长下对目标进行长时间观测，这是高需求的旗舰任务（如韦布）无法经常做到的，”美国国家航天局（NASA）戈达德航天中心的任务项目科学家Knicole Colón表示，“结合祸神星和韦布的数据，将使科学家能够独特地确定恒星表面的性质，并清晰地分离出恒星和行星的信号。”

“Pandora’s advantage is its ability to observe targets for extended periods at multiple wavelengths, something high-demand flagship missions like Webb cannot regularly do,” said Knicole Colón, the mission’s project scientist at NASA Goddard. “Combining Pandora and Webb data will uniquely enable scientists to determine the properties of stellar surfaces and cleanly separate star and planetary signals.”

祸神星任务由美国国家航天局（NASA）戈达德航天中心领导。劳伦斯利物莫国家实验室提供任务的项目管理和工程支持。祸神星的望远镜由康宁公司制造，并与利物莫实验室合作开发，后者还开发了成像探测器组件、任务控制电子设备以及所有配套的热和机械子系统。红外传感器由美国国家航天局（NASA）戈达德航天中心提供。蓝色峡谷技术公司（Blue Canyon Technologies）提供了卫星平台，执行了航天器的组装、集成和环境测试，并提供任务运行支持。美国国家航天局（NASA）位于加州硅谷的艾姆斯研究中心（Ames Research Center）负责任务的数据处理（data processing）。祸神星的科学数据可在美国国家航天局（NASA）系外行星档案库中获取，该档案库由加州理工学院的IPAC运营。亚利桑那大学领导祸神星的任务运行并为其科学计划做出贡献。许多其他大学也为科学团队提供了支持。

Pandora is led by NASA’s Goddard Space Flight Center. Lawrence Livermore National Laboratory provides the mission’s project management and engineering. Pandora’s telescope was manufactured by Corning and developed collaboratively with Livermore, which also developed the imaging detector assemblies, the mission’s control electronics, and all supporting thermal and mechanical subsystems. The infrared sensor was provided by NASA Goddard. Blue Canyon Technologies provided the bus, performed spacecraft assembly, integration and environmental testing, and is providing mission operations support. NASA’s Ames Research Center in California’s Silicon Valley performs the mission’s data processing. Pandora’s science data is available at the NASA Exoplanet Archive, which is operated by IPAC at the California Institute of Technology in Pasadena. The University of Arizona leads mission operations for Pandora and contributes to its science program. Many additional universities also support the science team.

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To learn more about the Pandora mission, please visit: