NASA on Saturday Astronaut Butch Wilmore noticed strange sounds coming from a speaker inside the Starliner spacecraft.
“I have a question about Starliner,” Wilmore radioed to Mission Control at Johnson Space Center in Houston. “There’s a strange sound coming out of the speaker… I don’t know what’s causing it.”
Wilmore said he wasn’t sure if there was some weird thing going on in the connection between the station and the spacecraft that was causing the noise, or if it was something else. He asked flight controllers in Houston to see if they could listen to the sound inside the spacecraft. A few minutes later, Mission Control responded by radio that they were hard-wired to listen to the sound inside the Starliner, which has been docked to the International Space Station for nearly three months.
Wilmore, apparently floating in the Starliner, pressed a microphone against a speaker inside the Starliner. A miniature time later, there was a distinctive pinging sound. “Okay, Butch, we got it,” Mission Control radioed Wilmore. “It was kind of a pulsing sound, almost like a sonar ping.”
Listen to a recording of the sounds heard by Butch Wilmore.
“I’ll do it again and let you all scratch your heads and see if you can figure out what’s going on,” Wilmore replied. The strange sonar-like sound repeated itself. “Okay, now it’s your turn. Call us if you figure it out.”
Cosmic Singularity
This audio recording and Wilmore’s conversation with Mission Control, was captured and shared by Michigan meteorologist Rob Dale.
It wasn’t immediately clear what was causing the strange and somewhat disturbing noise. As the Starliner flies to the space station, it maintains communication with the space station using a radio frequency system. Once docked, however, there is a rigid umbilical cord that carries sound.
Astronauts occasionally notice such oddities in space. For example, during China’s first spaceflight in 2003. said astronaut Yang Liwei heard what sounded like an iron bucket being struck with a wooden hammer in orbit. Scientists later realized that the noise was caused by slight deformations of the spacecraft caused by the pressure difference between its inner and outer walls.
The sonar sounds this weekend likely have a benign cause, and Wilmore certainly didn’t sound nervous. Still, the odd sounds are worth noting given the challenges Boeing and NASA have encountered during Starliner’s debut crewed flight, including significant helium leaks in flight and engine failures. NASA announced last week that because of uncertainty about Starliner’s flight capabilities, it would return home without its original crew of Wilmore and Suni Williams.
Starliner is now set to return to Earth autonomously on Friday, September 6Wilmore and Williams will return to Earth in February next year, flying aboard Crew Dragon spaceship The launch is scheduled for the second half of the month, with just two astronauts on board.
This story originally appeared on Ars Technica.