【摘要】 系外地球科学卫星(ET)将通过采用空间大视场超高精度测光这一关键技术在国际上率先突破生命起源中的系外地球存在及其演化这一重大前沿科学问题. ET卫星将在日地拉格朗日L2点晕(Halo)轨道部署由6台广角凌星望远镜和1台微引力透镜望远镜构成的空间天文台,结合凌星法和微引力透镜法,利用空间超大视场和超高精度的光学测光观测,首次发现富有重要意义、被广泛关注的系外地球,并确定其发生率,对目前了解甚少的类地行星和流浪行星进行国际上第一次大规模的种群普查,首次发现流浪地球,并确定其发生率,揭示类地行星和流浪行星起源,为地外生命探寻提供候选者和新方向. ET卫星的观测结果、统计研究以及和对理论的检验将回答系外地球在宇宙中有多普遍,类地行星是如何形成和演化的,流浪行星又是如何起源的这些亟待解决的前沿科学问题.对ET卫星发现的系外地球样本的后随观测,将精确测量其质量、密度和大气成分,有助于深入分析宜居性特征.此外,对ET新发现的大量各种系外行星样本的研究,以及对理论的检验将推动这些种类的行星形成和演化规律的更深入认识, ET的大量高精度、高频次和长基线测光数据将推动星震学、银河系考古学、时域天文学、双星和双星黑洞等领域的研究.更多还原

【Abstract】 The Earth 2.0(ET) mission will pioneer the international breakthrough in the frontier scientific issue of the existence and evolution of Earth 2.0s(or exo-Earths) in the origin of life by adopting the key technology of ultra-high precision photometry with a large field of view in space. The ET mission will deploy a space observatory consisting of six wide-field transit telescopes and one micro-lensing telescope in a halo orbit at the Sun-Earth Lagrange L2 point. Combining transit and micro-lensing methods, utilizing the ultra-large field of view and ultra-high precision optical photometry observations in space, the ET mission will for the first time discover historically significant Earth 2.0s and determine their occurrence rate. It will conduct the first large-scale survey of terrestrial-like and free-floating planets, discover free-floating Earth-mass planets and measure their occurrence rates, reveal the origins of Earth-like and free-floating planets, and provide candidates and new directions for the search for extraterrestrial life. The observational results, statistical studies, and theoretical tests of the ET mission will answer pressing frontier scientific questions such as “How common are Earth-like planets in the universe”, “How do Earth-like planets form and evolve” and “How do free-floating planets originate”. Follow-up observations of the Earth 2.0 samples discovered by the ET mission will precisely measure their mass, density, and atmospheric composition, contributing to an in-depth study of their habitability characteristics. Moreover, the study of the large number of various exoplanet samples newly discovered by ET, as well as tests of theories, will promote a deeper understanding of the formation and evolution of these types of planets. ET’s abundant high-precision, high-cadence, and long-baseline photometric data will advance research in fields such as asteroseismology, Galactic archaeology, time-domain astronomy,binary stars, and binary black holes.更多还原