NASA accidentally broadcast a simulation of astronauts being treated for decompression sickness on the International Space Station (ISS) on Wednesday, prompting speculation of an emergency in posts on social media.

About 6:28 p.m., The National Aeronautics and Space Administration’s (NASA) live YouTube channel broadcast audio that indicated a crew member was experiencing the effects of decompression sickness (DCS), NASA said on its official ISS X account.

A female voice asks crew members to “get commander back in his suit”, check his pulse and provide him with oxygen, later saying his prognosis was “tenuous”, according to copies of the audio posted on social media. NASA did not verify the recordings or republish the audio.

Several space enthusiasts posted a link to the audio on X with warnings that there was a serious emergency on the ISS.

“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,” the ISS account post said.

“There is no emergency situation going on aboard the International Space Station,” it added.

DCS, which is caused by nitrogen or other gas bubbles in the bloodstream due to a change in atmospheric pressure, can affect the central nervous system and is potentially fatal. It is commonly known as “the bends”.

Crew members on the ISS were in their sleep period at the time of the audio broadcast as they prepared for a spacewalk at 8 a.m. on Thursday, the ISS post said.

NASA’s ISS YouTube channel – at the time the audio was accidentally broadcast – now shows an error message saying the feed has been interrupted.