Observing the Atmospheres and Surfaces of Earth Analogs

近几十年来，人们发现了数千颗围绕其他恒星运行的行星。这些世界是如此遥远，以至于在最好的情况下，它们看起来像是未分辨的点，但我们仍然可以仅仅基于光盘集成的光来了解它们。事实上，它们在详细观测方面的不足之处，在数量和多样性上都有所弥补：系外行星为我们提供了解决行星科学中的难题的杠杆，包括大气环流、云形成和地球化学循环。 詹姆斯·韦伯太空望远镜(JWST)是美国宇航局将于2018年秋季发射的6.5米红外望远镜。这将是第一个能够描述温带类地系外行星大气层的仪器，也是直到21世纪中叶才能测量其热发射的唯一望远镜。加拿大准备在使用JWST进行系外行星观测方面处于领先地位，我提议的研究计划将最大限度地提高我们设计、减少和分析过境温带陆地观测的能力。通过与L大学的JWST/NIRISS团队密切合作，我们将帮助他们设计和实施他们对凌日行星的保证时间观测，我的团队将准备申请和分析将于2019年公开的提前发布科学。 继JWST之后的下一个旗舰，广域红外巡天望远镜(WFIRST)，将配备日冕仪，在反射光中对附近的行星系统进行成像。即使行星在图像中是未分辨的点，它们的亮度和颜色也会随着旋转和轨道运动将不同的表面特征带入视野而变化。我的团队将帮助确定测量行星倾角和构建表面图所需的测量精度、时间分辨率和光谱分辨率。第二代基于空间的高对比度成像将专注于围绕附近恒星运行的地球双胞胎。外部地图学将帮助我们了解这些行星是否像我们在地球上一样具有板块构造和不稳定的旋回，因此将是建立这些世界长期宜居的关键一步。

Thousands of planets have been discovered orbiting other stars in recent decades. These worlds are so distant that they appear as unresolved dots in the best of cases, but we can still learn about them based solely on disc-integrated light. Indeed, what they lack in detailed observations, they make up for in quantity and diversity: exoplanets provide us with leverage to crack hard problems in planetary science including atmospheric circulation, cloud formation, and geochemical cycling. The James Webb Space Telescope (JWST) is a 6.5 meter infrared telescope that NASA will launch in fall 2018. It will be the first instrument capable of characterizing the atmospheres of temperate terrestrial exoplanets, and the only telescope capable of measuring their thermal emission until the mid 21st century. Canada is poised to be a leader in the use of JWST for exoplanet observations and my proposed research program will maximize our ability to design, reduce and analyze observations of transiting temperate terrestrials. By working closely with the JWST/NIRISS team at l'Université de Montréal, we will help them design and implement their Guaranteed Time Observations of transiting planets, and my group will be prepared to apply for and analyze Early Release Science, which will become public in 2019. The next flagship after JWST, the Wide Field Infrared Survey Telescope (WFIRST), will be equipped with a coronagraph for imaging nearby planetary systems in reflected light. Even though planets will be unresolved dots in the images, their brightness and color will vary as rotational and orbital motion bring different surface features into view. My group will help determine the measurement precision, time resolution, and spectral resolution necessary to measure planetary obliquity and construct surface maps. The second generation of space-based high-contrast imaging will focus on Earth twins orbiting nearby stars. Exo-cartography will help us understand whether these planets have plate tectonics and volatile cycles like we have on Earth, and will therefore be a key step in establishing the long-term habitability of these worlds.