NASAs Mission Control is investigating a mysterious sound coming from inside Boeings troubled Starliner spacecraft after one of the two astronauts stranded in space due to issues with the spacecraft reported it.

NASA astronaut Butch Wilmore radioed Mission Control in Houston on Saturday to flag the sounds that he said were coming from a speaker inside the Starliner space capsule, Ars Technica first reported .

Ive got a question about Starliner, Wilmore says in a recording of his call, published by meteorologist Rob Dale. Theres a strange noise coming through the speaker. I dont know whats making it.