The world's largest and most sensitive single-dish radio telescope—the Five-hundred-meter Aperture Spherical Telescope (FAST), nicknamed "China Sky Eye" — has recently reached a key milestone: six domestically-made steel wire ropes, totaling nearly 4,000 meters in length and each tipping the scales at over 6 tons, are replacing the imported ones. Think of FAST as a colossal eye scanning the heavens, and the feed cabin is its "eyeball." Just as our eyes rely on six extraocular muscles working in concert to rotate smoothly and lock onto targets, FAST's 30-ton feed cabin is precisely steered and tracked across the telescope's massive reflective surface by six cable-driven steel wire ropes. Suspended 140 meters in the air, these six ropes work together to position the "eyeball" in real time across a 206-meter range. The demands on them are punishing: each rope endures hundreds of bending cycles and pulse loads every single day, requiring exceptional fatigue resistance — they must operate continuously for five years without failure to keep FAST running at peak performance. The independent R&D of these ropes started in January 2023. To test their performance, the research team ran sample ropes repeatedly 62,000 times on pulleys and conducted 200,000 pulse fatigue tests, with loads impacting cyclically between 120 kN and 400 kN. After 3 rounds of iterative experiments, the feed-driving steel wire ropes for FAST finally succeeded in August 2025. The replacement work is expected to last until late June.