During his first orbital flight in 2003, Yang Liwei heard a strange sound, as if someone was banging on the walls of his spacecraft, akin to a hammer hitting a metal bucket. Despite his checks through the porthole, the astronaut found no explanation. According to the online media Daily Galaxy, no source could be identified, inside or outside the device.
In the vacuum of space, no sound can normally travel. Without air, water, or solid particles to carry sound waves, silence is supposed to be absolute. How then could a noise reach Yang Liwei’s ears? For Professor Goh Cher Hiang, a specialist in space engineering, it is therefore impossible to hear such a sound. So where does it come from?
A recurring phenomenon
Yang Liwei was not the only one to experience this phenomenon: his successors, in 2005 and 2008, reported the same sounds. Aware of the anxiety this could cause, the first taikonaut had warned his colleagues in order to avoid any panic in flight.
Several hypotheses have since emerged. Some researchers raise the possibility that microdebris hit the capsule, producing this noise. But repeatedly? And only among taikonauts? Not entirely satisfactory.
Others believe that these hits could result from temperature variations that would cause the spacecraft’s metal walls to expand or contract. This would create clicking noises comparable to those that are sometimes heard in the frames of old houses. The noise could therefore come from the very structure of the Chinese vessels, which would explain why they were the only ones to report such a phenomenon.
However, no definitive explanation has been officially formulated to date. The phenomenon thus remains one of the fascinating mysteries of space exploration, for the moment limited to Chinese teams alone.
