Alone in space, a Chinese astronaut heard a sound he should never have heard

More than twenty years ago, Yang Liwei, the first Chinese man in space, reported hearing an unsettling sound inside his capsule. The phenomenon, which appears to defy the basic laws of physics, continues to baffle scientists to this day.

In the vast silence of orbit, any unexpected noise could trigger panic. That’s exactly what happened in 2003, when Yang Liweithe first taikonaut, embarked on his historic mission.

During the flight, he was startled by a strange knocking sound that echoed through his spacecraft, a Shenzhou 5 capsule — a moment that would become one of the most enduring mysteries of space flights.

“It sounded like someone knocking on the hullas if you were hitting an iron bucket with a wooden hammer”, said Yang in an interview with , in 2016. “The noise It didn’t come from inside or outside the ship“, said the taokonaut, unable to identify its origin.

Determined to find an explanation, Yang peered out the window, looking for signs of impact or damage. Could it be a mechanical problem? A structural flaw? Or something external?

Nothing seemed out of the ordinary — and yet the sound continued, rhythmic and distinct. Over time, the taikonaut learned to live with the noise, which he ended up classifying as a “normal phenomenon”.

Physics and engineering theories

According to physics, Yang’s experience should have been impossible. “Sound waves need a medium — air, water or solid matter — to propagate,” explained the professor Goh Wior Chera specialist in space engineering at the National University of Singapore, in an interview with .

But In the vacuum of space there is no medium that transports the sound. Following this logic, Yang I shouldn’t have heard anything at all. So what actually caused the noise inside your spaceship?

Scientists have suggested several possible explanations. The simplest is that it had been a physical impact. “If it was a crash, perhaps some object hit the spacecraft,” said Goh, although he acknowledged that the theory is speculative and practically impossible to confirm.

Yang Liwei, the first Chinese in space

While orbiting hundreds of kilometers above Earth, spacecraft face constant threats from micro-debris — small fragments that move speeds sufficient to drill through metal. But no sign of a collision was ever found during Yang’s mission.

Another theory, from the professor Wee-Seng Sohalso from Singapore, points to the violent temperature changes to which spacecraft are subject.

“It could be the shell expanding or contracting as it goes through extreme temperature changes,” he said. If true, the noise could simply be theom of the ship’s materials bending under thermal stress.

Others also heard

Perhaps the most curious thing of all is the fact that Yang was not alone. Chinese media later reported that outros taikonautasduring missions in 2005 and 2008 also heard the same mysterious knock.

Yang even warned future astronauts before launch: “Don’t be alarmed if you hear him — tit happened to me too“.

Over time, the “ghost beat” has become almost a tradition in Chinese space flights, and went from being a reason for fear to becoming an accepted part of the lives of taikonauts in orbit.

In addition to the taikonauts, NASA astronauts also heard strange sounds in space. In May 1969, during a test flight for the Apollo 11 moon landing, astronauts Thomas Stafford, John Young e Eugene CernaThey also didn’t hear a high-pitched “whistling” sound as they orbited the far side of the Moon, out of contact with Earth. They jokingly referred to the sound as “space music”.

NASA’s explanation? Radio interference between the lunar module and command module systems. But even that answer left some scientists unconvinced, particularly because the tone and rhythm were so unusual.

After all, what do astronauts really hear in the vacuum of space? And why is science, usually so capable of identifying physical causes, unable to explain something so strangely tangible? Without concrete evidence, the mystery endures, reminding us that even the silence of space may have its secrets.