Unexplained Sound in Space: What a Chinese Astronaut Discovered After 20 Years

Space has always fascinated us, and its mysteries often inspire stories in books and movies. One memorable moment comes from “Doctor Who.” In an episode called “Listen,” the Doctor hears unexplained knocks while exploring a deserted spaceship. It’s a thrilling example of how strange sounds in space can captivate our imagination.

In real life, a Chinese astronaut named Yang Liwei experienced something similar during his historic flight aboard the Shenzhou 5 in 2003. He reported hearing a strange knocking sound that he couldn’t identify. This noise wasn’t just a one-time incident. Astronauts on subsequent missions, Shenzhou 6 in 2005 and Shenzhou 7 in 2008, also reported hearing it—a perplexing mystery that has puzzled scientists for two decades.

Interestingly, NASA has recorded sounds from space, such as the eerie noises from black holes. These recordings help scientists understand celestial phenomena. However, the Shenzhou knocks remain unexplained, leaving a lingering question mark.

The Curious Incident of the Shenzhou 5

Yang Liwei’s flight lasted 21 hours, and during that time, he heard the same knocking sound—a thud akin to wood hitting metal. Though he searched for answers, the source remained elusive. What’s even stranger is that astronauts in later missions reported the exact same sound without any explanation as to why it occurred. This resembles experiences from the Apollo 10 mission in 1969 when astronauts heard odd whistling sounds while orbiting the Moon.

In many cases, scientists find the reasons behind odd noises. For instance, the sounds from Apollo 10 were traced back to radio interference. In contrast, the Shenzhou knocking has yet to be clearly identified, stirring curiosity among both scientists and space enthusiasts.

Theories Behind the Mystery Sound

Why do these sounds occur? Expert Goh Cher Hiang from the National University of Singapore weighed in, explaining that sound needs a medium—like air or metal—to travel. This leaves scientists pondering the possibilities.

One theory suggests that space debris could be making contact with the spacecraft. Another possibility is that the temperature changes between space and Earth might cause the ship to expand or contract, leading to knocking noises. Lastly, the sound could be air escaping from various objects on the ship. While all these theories offer insights, none have definitively explained the mystery.

The fact that this knocking was heard across three missions over five years adds to the intrigue. It reminds us that even as we explore space, its mysteries continue to surprise us. This sense of wonder is precisely what drives humanity to delve deeper into the cosmos.