Direct detection and characterization of extrasolar planets has become possible with powerful new coronagraphs on ground-based telescopes. Space telescopes with active optics and coronagraphs will expand the frontier to imaging Earth-sized planets in the habitable zones of nearby Sun-like stars. Currently, NASA is studying potential space missions to detect and characterize such planets, which are dimmer than their host stars by a factor of 1010. One approach is to use a star-shade occulter. Another is to use an internal coronagraph. The advantages of a coronagraph are its greater targeting versatility and higher technology readiness, but one disadvantage is its need for an ultrastable wavefront when operated open-loop. Achieving this requires a system-engineering approach, which specifies and designs the telescope and coronagraph as an integrated system. We describe a systems engineering process for deriving a wavefront stability error budget for any potential telescope/coronagraph combination. The first step is to calculate a given coronagraph’s basic performance metrics, such as contrast. The second step is to calculate the sensitivity of that coronagraph’s performance to its telescope’s wavefront stability. The utility of the method is demonstrated by intercomparing the ability of several monolithic and segmented telescope and coronagraph combinations to detect an exo-Earth at 10 pc.

中文翻译：

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推导地球探测日冕仪的光学望远镜性能规格的方法

借助地面望远镜上功能强大的新型日冕仪，直接探测和表征太阳系外行星已成为可能。带有主动光学和日冕仪的太空望远镜将扩展边界，以成像附近太阳般恒星宜居区域中的地球大小的行星。目前，美国宇航局正在研究潜在的太空任务，以探测和表征这类行星，这些行星比其宿主恒星更暗，大约是1010倍。一种方法是使用恒星遮蔽物。另一种是使用内部日冕仪。日冕仪的优点是具有更大的瞄准通用性和更高的技术就绪性，但是一个缺点是在开环操作时需要超稳定的波前。要做到这一点，需要采用系统工程方法，它指定并设计了望远镜和日冕仪作为一个集成系统。我们描述了一种系统工程过程，用于为任何潜在的望远镜/日冕仪组合得出波前稳定性误差预算。第一步是计算给定日冕仪的基本性能指标，例如对比度。第二步是计算日冕仪性能对其望远镜的波前稳定性的敏感性。该方法的实用性通过相互比较几种整体式和分段式望远镜与日冕仪组合以10 pc探测外表地球的能力来证明。例如对比。第二步是计算日冕仪性能对其望远镜的波前稳定性的敏感性。该方法的实用性通过相互比较几种整体式和分段式望远镜与日冕仪组合以10 pc探测外表地球的能力来证明。例如对比。第二步是计算日冕仪性能对其望远镜的波前稳定性的敏感性。该方法的实用性通过相互比较几种整体式和分段式望远镜与日冕仪组合以10 pc探测外表地球的能力来证明。