What Is China's Xuntian Space Telescope?

A New Eye on the Universe

When China's Xuntian space telescope — whose name means "surveying the sky" — lifts off atop a Long March 5B rocket in late 2026, it will mark one of the most significant moments in the history of observational astronomy. Developed by the Chinese Academy of Sciences and the China Manned Space Agency, Xuntian (also called the Chinese Space Station Telescope, or CSST) is designed to do something no telescope has done before at its resolution: photograph nearly half the entire sky in breathtaking detail.

Key Specs: Size Is Not Everything

At first glance, Xuntian seems modest. Its primary mirror measures 2 meters across — slightly smaller than the Hubble Space Telescope's 2.4-meter mirror. But the comparison stops there. Xuntian's defining feature is its field of view, which is 300 to 350 times wider than Hubble's. Where Hubble peers at tiny patches of sky in extraordinary depth, Xuntian will sweep across vast swaths of the cosmos in a single glance.

Powering that wide gaze is a 2.5-billion-pixel camera — one of the largest ever flown in space. Over a planned 10-year mission, the telescope will survey roughly 17,500 square degrees of sky, covering up to 40% of the total celestial sphere. The result will be a dataset of hundreds of billions of galaxies, stars, and transient phenomena.

Five Instruments, Five Windows on the Cosmos

Xuntian carries five first-generation scientific instruments:

• Survey Camera — the main instrument, responsible for wide-field imaging across near-ultraviolet to near-infrared wavelengths
• Terahertz Receiver — detects long-wavelength radiation from cool gas and dust in galaxies
• Multichannel Imager — provides simultaneous observations across multiple wavelength bands
• Integral Field Spectrograph — splits light into spectra across an extended area, crucial for studying galaxy kinematics
• Cool Planet Imaging Coronagraph — designed to block starlight and directly image cold exoplanets orbiting other stars

Together, these instruments let astronomers peel back different layers of the universe in a single mission.

What Xuntian Is Hunting For

The telescope's primary science drivers are two of the deepest mysteries in physics: dark matter and dark energy. Dark matter — invisible mass that holds galaxies together — makes up about 27% of the universe's total energy content. Dark energy, the mysterious force accelerating the universe's expansion, accounts for roughly 68%. Neither has ever been directly detected.

Xuntian will probe both using a technique called weak gravitational lensing, which measures how massive structures bend light from distant galaxies. By mapping tiny distortions across billions of galaxy images, scientists can reconstruct the invisible web of dark matter and track how dark energy has shaped cosmic structure over billions of years. According to Universe Today, researchers hope to achieve percentage-level precision on dark energy's properties — a significant leap over current measurements.

A Telescope That Can Be Repaired

One of Xuntian's most unusual engineering choices is where it lives. Rather than sitting in a distant, unreachable orbit like the James Webb Space Telescope, Xuntian will co-orbit with China's Tiangong space station at roughly 400 kilometers altitude. It will fly independently most of the time, but periodically dock with Tiangong so that Chinese astronauts can swap out instruments, perform maintenance, and install upgrades.

This design could dramatically extend the telescope's operational life — potentially for decades, according to Live Science. Hubble has survived largely because astronauts serviced it five times; JWST has no such option. Xuntian is built with servicing as a core feature from the start.

Global Science — With Caveats

China has indicated that Xuntian's data will be released to the international scientific community, with official data products planned for release every two years, according to Aerospace America. The telescope's survey will complement contemporaneous missions including the European Space Agency's Euclid telescope, NASA's Nancy Grace Roman Space Telescope, and the Vera C. Rubin Observatory in Chile.

However, some Western astronomers have expressed uncertainty about the specifics of data access for researchers outside China. Geopolitical tensions add a layer of complexity to what could otherwise be a landmark moment for open science.

Why It Matters

Xuntian represents a coming-of-age for Chinese space astronomy. The combination of Hubble-class resolution, an enormous field of view, and the ability to be serviced indefinitely positions the telescope to become one of the most productive astronomical instruments ever built. Whether its discoveries are shared openly with the world will determine not just its scientific legacy — but the future of global astronomical collaboration.