Astronomy is now entering a golden era with multi-messengers and big data. We will make giant leaps in our understanding of the universe. In the next decade, astronomers will embark on many ambitious surveys, such as the Rubin Observatory (LSST) led by the US and the Chinese 2m Space Telescope (CSST), which will produce images of hundreds of billions of objects. However, most of these surveys will only produce pictures (images), but lack follow-up spectroscopic surveys. Since spectroscopy can provide more detailed information on elemental abundances, distances and radial velocities of distant objects, astronomers urgently need a wide-field spectroscopic survey machine to further probe the mysteries of the Universe.
Currently at Tsinghua, we are leading an international effort, seeded by private funding, to build a 6.5m MUltiplexed Survey Telescope (MUST); the telescope will be sited at Leng Hu, Qinghai province, China. When construction is completed, the telescope will have survey capability an order of magnitude better than any existing facility. It will perform diverse forefront research, including dark energy/dark matter, time-domain astrophysics (including gravitational wave cosmology), galaxy formation and evolution, and extrasolar planets/Earth 2.0. It will also spur world-class technology developments on fiber, optical detectors, and etc.