China's cosmic ambition: Space station telescope unveiled
Chinese scientists have unveiled details about their work on the Chinese Space Station Telescope (CSST), a modern observatory aimed at competing with the James Webb Telescope, built by NASA, ESA, and CSA. They note that it will be capable of remaining in orbit for decades.
China is developing a new state-of-the-art space telescope to rival the best currently operational observatories. Named the China Space Station Telescope (CSST), it will match the capabilities of the advanced James Webb Telescope (JWST), with the additional benefit of being serviceable and upgradeable directly in orbit.
Xuntian, the new Chinese space telescope
Its name is Xuntian, translating 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 commence operations. These large observatories have a wide range of scientific objectives, including conducting research in the universe to solve various cosmological mysteries.
The Chinese space telescope is scheduled for launch no earlier than 2026, and its main mirror will have a diameter of approximately 2 metres. Although this is slightly smaller 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 its primary goals will be 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, while comprising 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 extensive 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 appears 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 the time when the universe was still plasma, billions of years ago. Both phenomena are crucial for understanding cosmic evolution.
The CSST will complement other top-class instruments, enabling access to different areas of the universe 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 fly alongside each other, 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.
