Astronauts in space spooked by mysterious knocking sound that no one can explain
China's first astronaut says he heard mysterious knocks during his first flight in space - but no one has been able to explain the cause of them.
Astronaut Yang Liwei said the strange noises left him feeling very nervous and he looked out into the vast emptiness of space but couldn't see anything out of the ordinary.
Mr Yang, now a major general in China's Air Force, said it sounded like someone was knocking the body of the spaceship, comparing the noise to that of a hammer hitting an iron bucket.
The 51-year-old's unexplained experience has raised all kinds of theories, including aliens , and he said he has never heard the sound again since returning to earth.