China is preparing to launch a powerful space telescope that could surpass the Hubble in some aspects. The telescope, named Xuntian, which means “surveying the heavens” in English, is expected to begin scientific operations in 2024.
Xuntian is still in the prototype stage of development, according to Xu Shuyan, the chief designer of the Xuntian Optical Facility and Researcher from the National Astronomical Observatories of the Chinese Academy of Sciences. He said that all subsystems, units, and components are ready for assembly and testing, and then the development of the telescope sample and the flying parts will start. “After this, we will conduct the joint test with the Xuntian platform and the test at the launch base before it is launched,” Xu told China Central Television (CCTV).
Xuntian is also known as the Chinese Space Station Telescope or the Chinese Survey Space Telescope (CSST). It is a bus-sized spacecraft with a two-meter (6.6 foot) diameter primary mirror. It is an ultraviolet-optical space telescope that will share the same orbit as China’s Tiangong space station. This will allow Tiangong astronauts to dock the telescope with the space station for maintenance and upgrades as needed. Xuntian has a nominal mission lifetime of 10 years, but it could be extended.
Xuntian has a 2.5-billion-pixel camera that can capture high-resolution images of various celestial bodies and deep-field survey observations. It also has five observation instruments: the Xuntian module, the integral field spectrograph, the multichannel imager, the extrasolar planetary imaging coronagraph, and the terahertz module.
Xuntian aims to outperform Hubble in some aspects. Hubble is currently the world’s most advanced optical telescope, operated by NASA. However, Xuntian has a field of view that is 300 times larger than Hubble’s, which means it can see more of the sky at once. Li Ran, a project scientist on the CSST Scientific Data Reduction System team, compared Xuntian’s capabilities to Hubble’s using an analogy of imaging a flock of sheep. “Hubble may see a sheep but the CSST sees thousands, all at the same resolution,” Li said.
Xuntian is expected to make breakthroughs in cosmology, dark matter and dark energy, the Milky Way galaxy and other neighboring galaxies, star formation and evolution, and exoplanets. Zhou Jianping, the chief designer of China’s space program, said that Xuntian is “the most important scientific project since the launch of our country’s space station program” and “a scientific facility that the Chinese astronomical community has eagerly anticipated”.
However, some researchers outside China have expressed doubts about Xuntian’s claims to surpass Hubble. They said that more detailed information about Xuntian’s specific capabilities and specifications is needed to evaluate its potential to do similar or better investigations than Hubble.
Xuntian is scheduled to be launched next year on a Long March 5B rocket. It will be China’s first large space telescope ever and one of its most ambitious space projects. It will join China’s growing space assets, such as its space station, its lunar rover, and its Mars probe.
