CSST: A Giant Leap in Space Exploration and Sky Surveying

The Chinese Space Station Telescope (CSST), as a type of optical telescope, can capture the spectrum from near-ultraviolet to visible light. By combining a primary mirror with a large diameter and long focal length with an eyepiece that has a smaller diameter and shorter focal length, it achieves close-up imaging of distant objects. Its primary mirror has a diameter of two meters, comparable to that of the Hubble Space Telescope, but its field of view is more than 300 times larger than Hubble’s. This means that under the same conditions, while the Hubble Space Telescope can see one star, the CSST can see 300 stars.

In terms of appearance, the Chinese Space Station Telescope (CSST) is quite a giant, comparable in size to a large bus. It has a total length of 14 meters, stands nearly as tall as a four-story building, and has a maximum diameter of 4.5 meters. Its launch mass is approximately 16 tons. You might wonder why we need to send such a large instrument into space. This is because ground-based optical telescopes are affected by atmospheric turbulence, ionospheric refraction, the ozone layer, and the geomagnetic field when observing the starry sky. No matter how large a ground-based telescope is built, the images of the universe it captures are always somewhat blurry. However, with the CSST, we can resolve details of distant celestial bodies, helping us explore the cosmos more accurately.

As its name suggests, the core mission of the CSST is to conduct “sky surveys,” which means performing extensive surveys of celestial bodies in the universe. If we compare the entire universe to a massive painting, then the CSST is the best photographer, capable of capturing high-definition and detailed images of thousands of galaxies, providing us with a magnificent panoramic view of the universe. This observation mode means that the sky survey module of the CSST occupies most of its operational time, approximately 70%, according to researchers.

The sky survey module is equipped with 30 detectors, with a total of 2.5 billion pixels. Among these detectors, 18 are equipped with different "sunglasses"—filters—that can capture the appearance of celestial bodies in different wavelengths, creating a beautiful set of color photographs of the universe. The remaining 12 detectors are dedicated to faithfully recording spectra, capturing the spectral information of at least 1,000 celestial bodies with each exposure. The sky survey module will cover 40% of the entire sky, collecting high-quality data on nearly 2 billion galaxies during the project’s observation period, recording the spectacular scenery of the universe.

Bena Optics provided optical component solutions for the CSST, including a complete set of mirrors. These mirrors include aspherical and flat types, and are made from lightweight yet durable materials such as Zerodur or SiC. Bena Optics, in collaboration with CIOMP, is advancing the development of space exploration technology.

The Terahertz Module, Multi-Channel Imager, Integral Field Spectrograph, and Exoplanet Imaging Coronagraph are the precision measurement modules of the Chinese Space Station Telescope (CSST). Each of these devices has its own specialty, focusing on various scientific tasks such as the detection of exoplanets, spatially resolved spectral analysis of galaxy core regions, the study of neutral carbon in nearby galaxies, and observations of the cosmic ultra-deep field. These modules significantly enhance the observational precision of the telescope.