The era following the separation of CMB photons from matter, until the emergence of the first stars and galaxies, is known as the Cosmic Dark Ages. Studying the electromagnetic radiation emitted by neutral hydrogen having the 21 cm rest wavelength is the only way to explore this significant phase in the Universe’s history, offering opportunities to investigate essential questions about dark matter physics, the standard cosmological model and inflation. Due to cosmological redshift, this signal is now only observable at frequencies inaccessible from the Earth’s surface due to ionospheric absorption and reflection. With the Lunar Crater Radio Telescope (LCRT), we aim to conduct unprecedented measurements of the sky-averaged redshifted signal spectrum in the 4.7–47 MHz band, by deploying a 350 m diameter parabolic reflector mesh inside a lunar crater on the far side of the Moon and suspending a receiver at its focus. This work discusses the feasibility of the LCRT science goals through the development of a science model, with emphasis on post-processing techniques to extract the Dark Ages signal from the galactic foreground dominating the expected raw data. This model can be used to vary critical instrument and mission parameters to understand their effect on the quality of the retrieved signal.

This article is part of a discussion meeting issue ‘Astronomy from the Moon: the next decades (part 2)’.

CMB 光子与物质分离之后的时代，直到第一批恒星和星系的出现，被称为宇宙黑暗时代。研究具有 21 厘米静止波长的中性氢发出的电磁辐射是探索宇宙历史中这一重要阶段的唯一方法，为研究有关暗物质物理、标准宇宙学模型和膨胀的基本问题提供了机会。由于宇宙红移，该信号现在只能在由于电离层吸收和反射而无法从地球表面到达的频率下观测到。借助月球陨石坑射电望远镜 (LCRT)，我们的目标是通过在月球背面的月球陨石坑内部署直径 350 m 的抛物面反射器网格，对 4.7-47 MHz 频段的天空平均红移信号频谱进行前所未有的测量。月球并在其焦点处悬挂一个接收器。这项工作通过开发科学模型讨论了 LCRT 科学目标的可行性，重点是后处理技术，从主导预期原始数据的银河系前景中提取黑暗时代信号。该模型可用于改变关键仪器和任务参数，以了解它们对检索信号质量的影响。

本文是“月球天文学：未来几十年（第 2 部分）”讨论会议的一部分。