Nasa has confirmed 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 on Wednesday evening sparked speculation online about a possible emergency in space – but Nasa said all members of the ISS are safe.
“This audio was inadvertently misrouted from an ongoing simulation where crew members and ground teams train for various scenarios in space and is not related to a real emergency,” it said on the ISS X page.
Private firm SpaceX also posted on social media to say there was no emergency aboard the ISS.
The incident, which occurred at 23:28 BST, led some people to believe that a real astronaut was suffering from decompression sickness in space.
It was made all the more believable because, unlike fake audio which usually appears first from spurious sources, this was broadcast on an official Nasa channel.
In the audio being shared on social media, a person asks the ISS crew to help get an astronaut into his spacesuit, to check his pulse, and to provide him with oxygen.
Though Nasa confirmed the audio was shared in error, it did not independently verify the recordings being shared online were the same that it broadcast.
Decompression sickness, also known as “the bends”, is a problem typically associated with scuba diving, which bubbles form inside the body due to a change in external pressure.
Astronauts follow protocols to remove nitrogen from the body to prevent this from happening in space.
According to Nasa, its crew members aboard the ISS were asleep at the time the audio was broadcast, in preparation of a spacewalk at 1300 BST on Thursday.
It says this will still go ahead as originally planned.