报告摘要：In the decameter and hectometer wave bands (hereafter referred to as the ultra-long wavelength bands), ground-based observations face significant challenges due to the reflection, absorption and refraction of the ionosphere, and abundant radio frequency interference, leaving this spectral range largely unexplored to date. In this talk, I will introduce the Discovering the Sky at the Longest wavelength project (DSL), also known by its Chinese nameHongmeng (meaning the Primordial Universe). This is a cislunar orbit ultralong wavelength observatory, made up by a mother satellite, and 9 daughter satellites deployed by a single rocket launch. Operating in the radio-quiet zone on the far side of the Moon that naturally shields terrestrial interference, this satellite constellation will conduct pioneering interferometric imaging and global spectrum surveys. This ambitious mission aims to acquire the first substantial dataset of high-resolution, high-precision ultra-long wavelength observations in human history. This presentation will review the development of ultra-long wavelength astronomy, outline the Hongmeng Project's configuration, and discuss its scientific prospects in key areas including the Cosmic Dark Ages and Cosmic Dawn the Epoch, quasars and radio galaxies, Galactic structure and interstellar medium, as well as solar and planetary studies. Colleagues and students across relevant disciplines are warmly invited to join the Hongmeng science team and contribute to groundbreaking research in ultra-long wavelength radio astronomy.

主讲人简介：Xuelei Chen received his Ph.D. from Columbia University in 1999. He did postdoctoral research in the Ohio State University and the KITP of UC Santa Barbara before joining the faculty of the National Astronomy Observatories, Chinese Academy of Science (NAOC). He is the Director of the Division of Extragalactic Astronomy and Cosmology, and PI of the Cosmic Dark Matter and Dark Energy Research Group in NAOC. He is the leader of the Tianlai 21cm intensity mapping project, and the Hongmeng project. He has co-authored more than 230 research papers.