The knocking of the door outside the ship made the Chinese astronaut bewildered

Sounds like "hammering on iron buckets" made China's first astronaut to fly to space feel very confused and worried.

Chinese astronaut Yang Liwei shared hearing the mysterious knockings of a space flight, China Central Television reported yesterday.

Astronaut Yang Liwei sits in the Shenzhou 5. spacecraft compartment (Photo: China.org.cn).

Yang, born in 1965 in Liaoning, was the first astronaut to fly to space in China. On October 16, 2003, Yang stepped out of the spacecraft after 21 hours of space flight, becoming the 241th in the world in outer space.

"A strange situation I have encountered in the universe is the occasional knock , " Yang recalls of the flight.

Yang explained that the knock appeared very unexpectedly and without any rhythm. "It doesn't have to come from inside the spacecraft or the outer space, but it sounds like someone knocks on the spacecraft's body, similar to using a wooden hammer to knock on a bucket of iron , " Yang said.

Yang said he was worried when he heard the sound, and approached the window on the spaceship to find out the cause but found nothing unusual. After returning to Earth, Yang told the technicians about the mysterious sound, trying to replicate with some tools. However, he had never heard the same sound.

Astronauts on the Shenzhou 6 spacecraft and Shenzhou 7 also heard a knock. " Before flying to space, I told them that sound is a normal phenomenon, so there's no need to worry , " Yang said.