Photo: Matthias Kulka / The Image Bank / Getty Images
Nasa confirms that audio shared widely on social media of astronauts in distress was a simulation broadcast on its YouTube channel in error.
In the clip, intended to be used for training purposes, a voice said an astronaut on the International Space Station (ISS) had a "tenuous" chance of survival. The broadcast of the clip last night sparked speculation online about a possible emergency in space - but Nasa said all members of the ISS are safe.
The incident, which occurred at 23:28 BST, led some people to believe that a real astronaut was suffering from decompression sickness in space.
In fact, a six-hour spacewalk is set to begin this morning.
According to Nasa, "The crew members aboard the ISS were asleep at the time the audio was broadcast, in preparation of a spacewalk at 1300 BST on Thursday."
Coverage of the U.S. Spacewalk 90 begins at 8:00 a.m. EST.
Today's spacewalk has been cancelled due to a spacesuit discomfort issue.