The 2m-aperture Chinese Space Station Telescope (CSST) is a major science project of China Manned Space Program. It is planned to launch in 2025 and has a nominal mission lifetime of 10 years. During observations, the CSST will fly independently at a large distance from the space station. It can dock with the space station for servicing as scheduled or as needed. With a Cook-type three-mirror anastigmat design, the CSST can achieve superior image quality within a large field of view (FoV), which gives it an advantage for survey observations.
The CSST will be equipped with 5 first-generation instruments including a Survey Camera, a Terahertz Receiver, a Multichannel Imager, an Integral Field Spectrograph, and a Cool Planet Imaging Coronagraph. Its primary task is to carry out a high-resolution large-area multiband imaging and slitless spectroscopy survey covering the wavelength range of 255 nm to 1000 nm. It will take the Survey Camera roughly 7 years of operation accumulated over 10 years of orbital time to image roughly 17,500 square degrees of the sky in NUV, u, g, r, i, z, and y bands and take slitless spectroscopy of the same sky in 3 bands. The point-source 5σ limiting magnitudes in g and r bands can reach 26 (AB mag) or higher. The spectral resolution (R=λ/Δλ) of the slitless spectrograph is specified to be on average no less than 200, and the wide-band-equivalent limiting magnitudes in GV (400-620 nm) and GI (620-1000 nm) bands will be 23 or higher. Deep fields will be selected for more observations to reach at least one magnitude deeper than the wide-area survey. In this talk, I will give an overview of the project and discuss its potential for cosmological studies.