Detection of Earth-like planets around nearby stars using a petal-shaped occulter
Detection of Earth-like planets around nearby stars using a petal-shaped occulter
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DOI：
10.1038/nature04930
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发表时间：
2006-07
期刊：
影响因子：
64.8
通讯作者：
W. Cash
中科院分区：
文献类型：
--
作者：
W. Cash
直接观测类地行星是非常具有挑战性的，因为它们的母恒星比它们亮1010倍，但距离它们只有几分之一弧秒。在太空中，大气层的闪烁会使光线模糊不清，但望远镜中的光散射和衍射问题仍然存在。这两个被提出的解决方案--日冕仪的另一个有吸引力的变化是在望远镜外面放置一个遮蔽物，在星光进入光路之前就将其阻挡。然而，在实际规模的任务中，遮蔽物周围或通过遮蔽物的衍射和散射的有效抑制是有限的。在这里，我报告一个掩模设计，将实现所需的抑制，并可以建立与现有的技术。日冕仪紧凑的使命架构被用来取代两个航天器的不便，但令人生畏的光学挑战被直径30至50米的简单可展开薄片所取代。当这样一个掩星器在至少一米口径的望远镜下编队飞行时，可以看到和研究距离恒星10秒差距的类地行星。
Direct observation of Earth-like planets is extremely challenging, because their parent stars are about 1010times brighter but lie just a fraction of an arcsecond away. In space, the twinkle of the atmosphere that would smear out the light is gone, but the problems of light scatter and diffraction in telescopes remain. The two proposed solutions—a coronagraph internal to a telescope and nulling interferometry from formation-flying telescopes—both require exceedingly clean wavefront control in the optics. An attractive variation to the coronagraph is to place an occulting shield outside the telescope, blocking the starlight before it even enters the optical path. Diffraction and scatter around or through the occulter, however, have limited effective suppression in practically sized missions,,. Here I report an occulter design that would achieve the required suppression and can be built with existing technology. The compact mission architecture of a coronagraph is traded for the inconvenience of two spacecraft, but the daunting optics challenges are replaced with a simple deployable sheet 30 to 50 m in diameter. When such an occulter is flown in formation with a telescope of at least one metre aperture, terrestrial planets could be seen and studied around stars to a distance of ten parsecs.