Hull Echoes in Orbit: The Mysterious Tap of Shenzhou 5

During Shenzhou 5’s 21-hour mission, Chinese astronaut Yang Liwei reported a tapping sound on the hull that seemed neither external nor internal. With no signs of life or objects in sight and multiple theories proposed, experts suggested the noise could come from routine spacecraft temperature-driven expansion and contraction. Later flights Shenzhou 6 and 7 reportedly heard similar sounds, but the true source remains unknown, underscoring how space can still yield puzzling mysteries even on human missions.