According to a report and a statement made by a Russian Space Forces official, the International Space Station may have suffered a with a piece of space debris. Astronauts awoke to the gut-wrenching sound of metal scraping against metal, which lasted for a period of about one second. However, subsequent examination with an externally-mounted camera revealed , leading authorities to believe the sound was caused by equipment shifting internally.
This incident brings back memories of Mir's near-disaster with the Progress resupply vessel, back in 1997. While there is a Russian Soyuz permanently docked to the ISS, strange sounds are not the nicest thing to wake up to in a vacuum.
Despite assuasions by the Russian authorities, the incident doesn't quite add up. The of a piece of space junk 11mm in diameter is around 5.71kms-1, so an external impact of anything larger than a fingernail would tear a hole in the side of the craft large enough to depressurise the cabin - which doesn't seem to be the case. This leads to the conclusion that a sound akin to a tin can eminated from the interior of the cabin, which we can assume is not something regularly associated with life on board the ISS (this isn't , after all).
It's a sobering thought that the amout of space junk in high orbit around this planet is increasing , with millions of tiny, hull-piercing projectiles whizzing around as frictionless flotsam. If internal movement was to blame, hopefully there was no serious payload failure aboard the USD $90bn scientific laboratory.