China will launch its flagship space telescope at the end of 2023, which is expected to provide wider and clearer images of space, and expand human knowledge about the evolution of universe, according to scientists.

　　The telescope, namely Chinese Space Station Telescope (CSST), is a space-based optical observatory for astronomers to carry out sky surveys, capturing a general map or images of the sky.

　　The size of CSST is equal to a bus, with a length equal to a height of a three-story building. Its two-meter aperture is almost the same as the Hubble Space Telescope, but its field of view is 350 times larger than Hubble, said Liu Jifeng, deputy director of National Astronomical Observatories of China (NAOC).

　　The field of view refers to the sky's area a telescope can capture at one time.

　　Li Ran, project scientist of the CSST Scientific Data Reduction System said that Hubble's field of view is approximately one percent of the size of a fingernail held at arms length, so it has only observed a tiny fraction of the sky in 30 years.

　　The CSST is more suitable for survey observations since it can complete large-scale scans of the universe more quickly, said Zhan Hu, project scientist of the CSST Optical Facility.

　　The CSST is likely to be the largest space telescope for astronomy in the near-ultraviolet and visible in the decade before 2035, said Zhan.

　　The telescope is installed with five instruments including a Survey Camera, whose main focal plane is equipped with 30 units of 81-megapixel detectors, each bigger than the Hubble's, said Li.

　　"If photographing a flock of sheep, Hubble may see one sheep but the CSST can see thousands, all at the same resolution," he said.

　　As China's most expensive space astronomy facility, its main objective is to address the most basic problems about the universe, such as the evolution of galaxies, dark matter and dark energy. CSST will take pictures of 40 percent of the sky and transmit massive data back to the Earth that scientists all over the world can study, said Li.

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　　The telescope will fly independently in the same orbit with China's space station, but keep a large distance apart. It can dock with the space station for refueling and maintenance when necessary, which can extend its mission lifespan.

　　The in -orbit construction of China's space station is scheduled to be complete by 2022 and CSST is expected to start scientific operations in 2024, with a designed mission lifespan of 10 years.