China’s Five-hundred-meter Aperture Spherical Radio Telescope (FAST), the world’s largest single-dish radio telescope.
It has reached a significant technological milestone by replacing a key structural component with domestically developed technology for the first time.
According to the National Astronomical Observatories of the Chinese Academy of Sciences, six massive steel cables each weighing over six tons and stretching to a total length of nearly 4,000 meters are currently being replaced as part of a major upgrade and maintenance operation expected to continue through late June.
These high strength cables are essential to the telescope’s operation, as they support and control the movement of FAST’s feed cabin. A central component responsible for collecting astronomical signals. Suspended in mid-air, the 30-tonne cabin is precisely maneuvered using the cable system, enabling it to shift, rotate and maintain extreme positioning accuracy above the telescope’s reflective dish.
Operating at a height of approximately 140 meters and spanning a working range of 206 meters, the system requires continuous precision control. Each cable is subjected daily to intense mechanical stress, including repeated bending cycles and high-impact pulse loads.
Engineers emphasize that the cables must remain structurally intact without a single wire break for at least five years to ensure uninterrupted scientific performance.
Since its commissioning in 2016, FAST had relied on imported steel cable technology, with a previous replacement cycle completed in 2021. The latest upgrade marks a shift toward full domestic capability in a critical area of telescope engineering.
To ensure reliability and safety, researchers conducted extensive validation tests on the newly developed cables, including more than 62,000 repeated pulley motion simulations and around 200,000 pulse fatigue stress tests. These rigorous assessments were designed to replicate real operational conditions and confirm long-term durability.
By August 2025, the domestically produced cables had successfully passed multiple rounds of iterative testing, confirming their readiness for deployment.
Scientists involved in the project stated that this achievement strengthens supply chain independence while also advancing China’s broader capabilities in high precision materials engineering.
Beyond the telescope itself, the breakthrough is seen as a foundational step in building a complete technological ecosystem covering material science, manufacturing processes, evaluation systems, and industrial testing standards.
Experts suggest the innovation could serve as a reference model for other large scale scientific infrastructure projects in the future. The newly manufactured cables have now been delivered to the FAST site, where installation work is underway and expected to be completed by the end of June.
With this milestone, FAST not only sharpens its view of the universe but also signals a new era of self-reliant scientific engineering at the highest level of precision astronomy.
