A Chinese astronaut described a mysterious sound in space (3 photos)

China's first astronaut (or taikonaut) reported hearing a sound during his historic mission that baffled scientists. It remains unknown what Yang Liwei heard.





Taikonaut Yang Liwei launched aboard the Shenzhou-5 spacecraft in 2003. And the first Chinese astronaut ever returned to Earth with an intriguing story about a mysterious knocking sound, according to the Express.

During his 21-hour mission, he orbited the Earth 14 times before landing safely in Mongolia.

However, during his space journey, Yang heard something completely unbelievable: a sharp, constantly repeating "knock." He examined the capsule, looked out the window, and studied the panels, but was unable to locate the source of the sound, even though it continued.

He claimed the sound was coming not from inside the capsule, but from outside, from the vacuum of space, where, theoretically, sound should not travel at all.

Later, Yang told reporters: "The sound was like a blow to the hull, like someone hitting an iron bucket with a wooden hammer."

He remained calm and continued his mission, trying to ignore the knock.

Upon returning to Earth, engineers examined the spacecraft for clues, but found nothing that could explain the noise.



However, Yang wasn't the only one who heard the strange sound. Chinese media later reported that crews on later missions, including flights in 2005 and 2008, also recorded the same phantom knock. Before launch, Yang even warned the rookies, advising them not to be alarmed if they felt like space was knocking on their door.

Possible explanations included the collision of tiny microparticles with the hull, leaving no visible traces. Although this seemed plausible, no evidence was found during Yang's mission.

Other theories included thermal cracks, caused by sudden temperature changes every 90 minutes in orbit, and structural or mechanical vibrations caused by pressure systems, valves, flywheels, or attitude control thrusters.

Newer Chinese spacecraft are equipped with additional sensors, and every unusual squeak or vibration is recorded. But until the data provides a definitive answer, Yang's "thump-thump" remains one of the most intriguing unsolved mysteries of spaceflight.