A eerie, sonar-like sound is now emanating from a speaker on the Starliner

Starliner is set to undock from the International Space Station and begin its return journey to Earth uncrewed in just a few days, but it seems to still have a few surprises up its sleeve. Astronaut Butch Wilmore recently reported an unexplained “strange noise” coming from a speaker in the spacecraft, sparking curiosity and intrigue among NASA’s Mission Control team.

During a conversation captured in an audio clip shared on a NASASpaceflight forum by meteorologist Rob Dale, Wilmore can be heard discussing the mysterious sound. The noise, which starts at the 45-second mark, has a steady pulsing beat that left Wilmore and the team puzzled. “I don’t know what’s making it,” Wilmore admitted.

Once Mission Control confirmed they could hear the sound as well, Wilmore brought his mic closer to the speaker, allowing the flight controller in Houston to describe it as “almost like a sonar ping.” After playing the sound for a few more seconds, Wilmore concluded the call, noting that everything else seemed normal on board. Mission Control sought clarification, asking if the noise was indeed emanating from the speaker in Starliner and if there were any other unusual sounds or configurations present, to which Wilmore responded that everything else appeared to be in order.

The source of the strange noise remains a mystery. Starliner, built by Boeing, has been docked at the ISS since early June, with engineers working tirelessly to address any issues from its previous crewed flight. As Starliner prepares to depart for Earth on September 6, it will leave behind its current crew, Wilmore and NASA astronaut Suni Williams, who will continue their work on the ISS until SpaceX provides them with a ride home in 2025.