Chinese Astronaut Yang Liwei made history when he became China's first astronaut (known as a “taikonaut”) on October 16, 2003. When Yang flew into space aboard the Shenzhou 5 spacecraft, China became the third country to independently send an astronaut into space (behind the U.S. and Russia). But something weird happened during his historic journey into space, and he's just now starting to talk about it.
“Anon-causal situation I have met in space is a knock that appeared from time to time,” said Yang. “It neither came from outside nor inside the spaceship, but sounded like someone is knocking the body of the spaceship just as knocking an iron bucket with a wooden hammer.”
Yang said that he felt nervous when hearing the sound. He looked out the porthole to try to find the cause, but found nothing there. Because it's always best to double check and make sure that a giant alien isn't attacking your spacecraft!
As if an unexplained knocking sound wasn't already eerie enough, the same sound was also heard by the Shenzouh 6 spacecraft in 2005 and then again by the Shenzhou 7 spacecraft in 2008. Because once wasn't enough!
Yang warned the astronauts of Shenzhou 6 and Shenzhou 7 that they could hear the sound. "Before entering space, I have told them that the sound is a normal phenomenon, so there is no need to worry,"said Yang. Uh...yeah...a weird space sound is completely normal....
Scientists are offering many possible explanations for the scary sound, and none of them are aliens. Everything has been speculated from space debris to the sound of the spacecraft cooling. Although, the obvious explanation is still aliens.
“If it is knocking, there could be something physical ‘hitting’ the spacecraft carrying the astronaut," said Professor Goh Cher Hiang, an expert in space engineering at the National University of Singapore. However, Hiang also stressed that this was "speculative."
Wee-Seng Soh, a colleague of Hiang offers a different possible explanation of the sound. It could be, "a result of expansion or contraction of the spaceship, especially since the temperature of the spaceship’s exterior could change considerably within the orbit." But no matter how you try to explain it, it's still creepy!
This isn't the first time that a mystery sound was heard in space. The Apollo 10 astronauts reported hearing an unexplained whistling sound on their trip around the moon in 1969. The astronauts described the sound as an " outer-space type music" and was heard when they reached the dark side of the moon. No, it wasn't Pink Floyd.
"The radio technicians (rather than the UFO fans) had a ready explanation for it: It was interference between the Lunar Module's and Command Module's VHF radios," said Michael Collins, an Apollo 11 astronaut who heard similar noise when he was on his mission.