Yang Liwei, was the first Chinese to go into space in 2003, sent by China’s space program. In a recent interview with a Chinese television network released by Xinhua news agency, Yang said he heard a noise similar to “a wooden hammer beating against an iron cube”.
This news has always been a mystery over the years since no official explanation for what happened has ever been found. At the time, Yang was a bit nervous and decided to look through the hatch of the ship looking for the source of the noise, but never found an explanation for that mysterious sound.
Try as he might, he could never decipher what it was, and the astronaut never could reproduce the sound on Earth so that they could help him find a logical answer to what he had heard.
Predictably, the story about the mysterious noise in space caught the attention of the Chinese media, who, after all, whacked Yang’s ship when he was alone, thousands of miles from Earth?
Some theories have emerged in the search for explanations, one of which was that, as sound waves propagate mechanically as a vibration and need a medium (liquid, solid or gaseous) for travel, they may have created this sound.
Another example of this would be the sound of thunder traveling through the air, or the sonar, which makes it in the water.
“Although interplanetary (and interstellar) space is not completely empty, gas molecules and dust grains are so scattered that they do not form a continuous medium that allows sound waves to be transmitted directly”, said Professor Monica Grady for Academic site The Conversation, Department of Planetary and Space Science, UK Open University.
“If it was knocking, it could be something physical that was stuck to the spacecraft carrying the astronaut”, Professor Goh Cher Hiang, a specialist at the National University of Singapore, explained to the BBC, explaining that this is just speculation.
But his colleague Wee-Seng Soh has a different explanation, he suggests that the noise may have been “the result of the expansion or contraction of the spacecraft, especially when the outside temperature of the spacecraft may have changed considerably once it entered orbit”.
Another explanation would be the air pressure, so, according to the Chinese press, the sound was also heard later by astronauts who participated in missions between the years 2005 and 2008.
Yang spoke of his experience to his successors so that they would not be surprised or worried about the sound he had heard. In this way, and although he never found an accurate explanation, Yang eventually surrendered and defined this sound as “a normal phenomenon”.
Last November, when the astronaut attended an activity held at a school in Ningbo City, Zhejiang Province, students asked some questions about this topic.
Yang said his best explanation is that the sound was a consequence of the reaction of air pressure, which caused changes in the structure of the spacecraft as it leaves the Earth’s atmosphere and move into space, Xinhua reported.
He added that air escaping from objects inside the space dome could also cause noise and that hearing sound in space is not uncommon, just as it is not uncommon to find an explanation for them.
In 1969, during the NASA mission that orbited the Moon, the astronauts described a strange sound as they passed the dark side of the satellite and could not explain. They described it by saying it sounded like a whistle, which they understood as the music of space.
NASA later said that it would only be some interference.
Yang’s days as an astronaut were long gone, spent 21 hours, 22 minutes, 45 seconds in space, and now integrates People’s Liberation Army Air Force (PLAAF) as Major General.