On Saturday, NASA astronaut Butch Wilmore reported hearing unusual noises coming from a speaker inside the Starliner spacecraft.
“I’ve got a question about Starliner,” Wilmore radioed to Mission Control at the Johnson Space Center in Houston. “There’s a strange noise coming through the speaker … I don’t know what’s making it.”
Wilmore was unsure whether the noise was due to an anomaly in the connection between the International Space Station (ISS) and the Starliner or something else. He asked flight controllers in Houston if they could listen to the audio inside the spacecraft. A few minutes later, Mission Control responded that they were connected via a “hardline” to monitor the audio from Starliner, which has been docked to the ISS for nearly three months.
Wilmore, who was floating inside the Starliner, held his microphone up to the speaker. Shortly after, a distinctive pinging sound could be heard. “Alright Butch, that one came through,” Mission Control radioed back. “It was kind of like a pulsing noise, almost like a sonar ping.”
“I’ll do it one more time, and I’ll let y’all scratch your heads and see if you can figure out what’s going on,” Wilmore replied. The sonar-like sound repeated, and he added, “Alright, over to you. Call us if you figure it out.”
A recording of the audio and the conversation between Wilmore and Mission Control was captured and shared by Rob Dale, a meteorologist based in Michigan.
The source of the strange, somewhat eerie noise remains unclear. When Starliner travels to the space station, it maintains communication via a radio frequency system. However, once docked, communication switches to a hardline umbilical that carries audio.
Unusual sounds in space are not entirely new. For instance, during China’s first human spaceflight in 2003, astronaut Yang Liwei reported hearing a noise similar to an iron bucket being struck by a wooden hammer while in orbit. Later, scientists determined that the sound was due to small deformations in the spacecraft caused by pressure differences between its inner and outer walls.
This weekend’s sonar-like noises likely have a harmless explanation, and Wilmore did not seem alarmed. Still, these odd sounds are notable given the challenges Boeing and NASA have faced with Starliner’s debut crewed flight. These issues include significant helium leaks during flight and failing thrusters.
A week ago, NASA announced that, due to uncertainty about Starliner’s readiness, it would return to Earth without its original crew of Wilmore and Suni Williams.
Starliner is now scheduled to fly back to Earth autonomously on Friday, September 6. Wilmore and Williams will return to Earth next February aboard a Crew Dragon spacecraft, which is set to launch with just two astronauts later this month.