Picture for representation
Picture for representation Reuters

Strange sounds during space flight experienced by Chinese astronauts have come up as interesting sidebars to mushrooming rumours about alien life and UFOs. Yang Liwei, China's first astronaut, revealed in a recent interview that he heard a mysterious knock - like a wooden hammer hitting an iron bucket, during his flight in space in 2003.

The Astronaut said he was baffled by the sound which appeared suddenly without any reason, reported Xinhua news agency, citing China Central Television. "A non-causal situation I have met in space is a knock that appeared from time to time," said Yang.

He further said that "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."

It was also reported that the astronaut, who is a major general now, mustered the courage and went to inspect the porthole. However, he did not find anything that could have possibly made the sound.

What is more shocking is that it is not only Yang who heard the sound. Spaceflight mission Shenzhou 6 and Shenzhou 7 astronauts have also heard the sound but even they failed to come up with any possible explanation.

"Before entering space, I have told them that the sound is a normal phenomenon, so there is no need to worry," said the astronaut.

Yang did not give up hope of finding the source of the noise and asked around technicians about the mysterious sound once he returned to earth. He even tried to explain the sound with instruments, however, he said that he neither could recreate the sound nor heard the exact sound again.

Yang Liwe,i who was born in Liaoning province's Suizhong County in 1965, became the first person sent into space by the Chinese space program in 2003.