The Dark Ages and Cosmic Dawn are largely unexplored windows on the infant Universe (z ~ 200–10). Observations of the redshifted 21-cm line of neutral hydrogen can provide valuable new insight into fundamental physics and astrophysics during these eras that no other probe can provide, and drives the design of many future ground-based instruments such as the Square Kilometre Array (SKA) and the Hydrogen Epoch of Reionization Array (HERA). We review progress in the field of high-redshift 21-cm Cosmology, in particular focussing on what questions can be addressed by probing the Dark Ages at z > 30. We conclude that only a space- or lunar-based radio telescope, shielded from the Earth’s radio-frequency interference (RFI) signals and its ionosphere, enable the 21-cm signal from the Dark Ages to be detected. We suggest a generic mission design concept, CoDEX, that will enable this in the coming decades.

黑暗时代和宇宙黎明在很大程度上是婴儿宇宙（z ~ 200-10）未探索的窗口。对中性氢红移 21 厘米线的观测可以为这些时代的基础物理学和天体物理学提供其他探测器无法提供的宝贵新见解，并推动许多未来地面仪器的设计，例如平方公里阵列（SKA） ）和再电离阵列（HERA）的氢时代。我们回顾了高红移 21 厘米宇宙学领域的进展，特别关注通过探测 z > 30 的黑暗时代可以解决哪些问题。我们的结论是，只有基于太空或月球的射电望远镜才能屏蔽地球的射频干扰 (RFI) 信号及其电离层使得来自黑暗时代的 21 厘米信号能够被检测到。我们建议采用通用任务设计概念 CoDEX，该概念将在未来几十年内实现这一目标。