China's new cosmic eye to rival James Webb telescope
Chinese scientists have unveiled details about their work on the Chinese Space Station Telescope (CSST), a modern observatory designed to compete with the James Webb Telescope, developed by NASA, ESA, and CSA. They emphasize that it will have the capability to remain operational in orbit for decades.
China is developing a cutting-edge space telescope to rival the best currently operational observatories. Named the China Space Station Telescope (CSST), it is expected to match the capabilities of the advanced James Webb Telescope (JWST) and, additionally, can be serviced and upgraded directly in orbit.
Xuntian, the new Chinese space telescope
The telescope is called Xuntian, which translates from Mandarin as "surveying the heavens", aptly describing its mission. Scientists have published new details about the project in the scientific article repository arXiv under the title: "Future Cosmology: New Physics and Opportunity from the China Space Station Telescope (CSST)."
CSST will join the ranks of modern telescopes, such as Euclid, launched by the European Space Agency in July 2023; the Nancy Grace Roman Space Telescope, which is in the final stages of launch preparation; and the Vera C. Rubin Observatory, a massive ground-based installation that will soon begin operations. These major observatories have a wide range of scientific objectives, including conducting research on the universe to solve various cosmological mysteries.
The Chinese space telescope is slated for launch no earlier than 2026, and its main mirror will have a diameter of approximately 6.6 feet. Although this is slightly less than the width of the Hubble Telescope's mirror, the advanced optics of the CSST will allow it to achieve a field of view at least 300 times greater than Hubble's.
Uncovering the mysteries of the cosmos
Thanks to its capabilities, the CSST will conduct numerous significant tests and measurements. One of the primary goals is to measure an effect known as weak gravitational lensing. Light from distant galaxies is slightly distorted by small curvatures in space created by other galaxies. By mapping hundreds of thousands of galaxies, researchers hope to create detailed maps of matter distribution in the universe. These maps may help scientists understand the mysteries of dark matter, which, despite making up most of the matter in the universe, does not interact with light and thus cannot be directly observed.
On a larger scale, the CSST will engage in studying the statistics of voids and galaxy clusters. Voids are massive empty spaces between galaxies, while clusters are groups of galaxies. The properties of these structures—their size and distance from each other—depend on the nature of dark energy, a mysterious substance that seems to accelerate the expansion of the universe.
Additionally, the CSST will search for supernovae and measure baryon acoustic oscillations. Supernovae serve as constant reference points to distant galaxies, while baryon oscillations are remnants from when the universe was still plasma, billions of years ago. Both phenomena are crucial for understanding cosmic evolution.
The CSST will complement other top-tier instruments, enabling access to different areas of the universe and at various distances. There is hope that all four world-class telescopes will coordinate their efforts.
The telescope will be close to the Tiangong space station
However, the CSST has another significant advantage. It is no coincidence that its name includes the word "station": once launched, it will share an orbit with the Chinese space station Tiangong. Although they won't always be aligned, their orbits will regularly bring them closer together. This facilitates the Chinese space agency’s ability to service the telescope, replace instrument modules, and even perform upgrades—which will be impossible for other space telescopes. While other devices will have a limited operational time, the CSST can provide valuable cosmological data for many more decades.
