China's FAST Telescope Gets New Domestic Steel Ropes
In the mountains of Guizhou, the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) — the world's largest single-dish radio telescope — has recently completed a critical upgrade. Six giant steel wire ropes, totaling nearly 4,000 meters in length with each weighing over 6 tons, have been installed to replace the imported ones that had been in service. This marks the full domestication of FAST's core cable-driven system.
These six ropes are no ordinary cables. They serve as the eye muscles of the telescope, precisely controlling the 30-ton feed cabin — the eyeball that receives cosmic electromagnetic signals—to move with extreme accuracy across a 206-meter diameter area at a height of 140 meters. Each rope endures hundreds of bending and pulse load cycles every day, and must maintain its integrity for five years of high-intensity operation without a single wire break.
For years, FAST relied on imported ropes for this mission-critical component. In January 2023, the FAST team launched an independent R&D program. The breakthrough came in August 2025, after three rounds of iterative testing. To verify performance, the sample rope underwent 62,000 repeated bending cycles over pulleys and 200,000 pulse fatigue tests — a grueling qualification process that pushed the domestic product to its limits.
The newly installed ropes represent a full-chain domestic achievement — from raw materials to manufacturing processes to performance testing. According to Yao Rui, director of the FAST Measurement and Control Engineering Department, the R&D cost is roughly half that of the imported alternative. This is not just a simple replacement; the team collected baseline data before installation, will conduct a 24-hour static load test with the cabin suspended, and then move the cabin through all extreme positions to verify every performance indicator. After commissioning, the ropes will undergo a health check every six months.
For the wire rope industry, this achievement demonstrates that domestic products can meet the world's most demanding technical specifications — a milestone that extends far beyond astronomy.
