What is the unusual sound emanating from Boeing’s Starliner spacecraft?

update: A statement was sent to SpaceNews’ Jeff Faust.NASA said the sound had stopped and explained why: “The feedback from the speakers was the result of an audio configuration between the space station and Starliner,” NASA said. “The space station’s audio system is complex, with multiple interconnected spacecraft and modules, and it is common for noise and feedback to occur.” They added that the feedback had no technical impact to the crew or spacecraft operations.

The ill-fated mission to the International Space Station (ISS) aboard Boeing’s Starliner spacecraft has run into trouble once again. The two astronauts, Butch Wilmore and Sunita Williams, who only recently learned they would be staying on the ISS until at least February, began hearing strange noises coming from the Boeing spacecraft over the weekend.

“We’re hearing some strange noises coming from the speakers,” Wilmore told Mission Control in Houston, Texas, on August 31. Recorded by an enthusiast“We don’t know what caused it.”

Mission Control told Wilmore they would investigate the regular pulsating noise. New ScientistBoeing referred requests for comment to NASA, which did not immediately respond.

The Starliner spacecraft delivered Wilmore and Williams to the ISS on June 5, but a thruster failure and helium leak made the planned return trip with passengers deemed too risky.

The noise has puzzled space industry experts and mission control. “It’s very strange,” one person said. Martin Barstow Professor at the University of Leicester in the UK. “I’ve never been on a spacecraft, so I have no idea.”

Social media posts have speculated about the possibility of sonar interference, but say such interference couldn’t come from outside the capsule because sound waves cannot travel in space. Jonathan Aitken “I don’t think it’s a big deal,” said the researcher at the University of Sheffield in the UK. “The bigger question for me is whether it’s a single speaker that’s making the noise, or the whole communications system.”

To investigate the source of the noise, Barstow recommends a thorough inspection of the aircraft. “Find out where there are microphones that might be providing input and isolate them,” he says. “But the sound could also be coming from the audio system electronics.”

Barstow noted that the regular but occasionally erratic nature of the pulse may support the idea that this is a problem with electronic interference.

This hypothesis is Phil Metzger “Electromagnetic interference (EMI) is very common and difficult to eliminate,” said John F. Kennedy, a professor at the University of Central Florida who helped test the ISS intercom system as co-founder of NASA’s Swamp Works research facility at the Kennedy Space Center in Florida. He wrote to X.

Metzger said: New ScientistIn response to an interview request from SpaceX, astronaut John McClellan explained on social media that the interference could be coming from outside the Starliner: “During one test, we heard a noise that we tracked down to its source and found to be coming from a power inverter that is part of the test facility and not the spacecraft,” he wrote. “We believe that the noise on Starliner was due to electromagnetic interference leaking into something like an audio cable with a loose braid at the connector interface.”

What to do about it is another matter: Wilmore’s radio communications with Mission Control suggest that neither he nor Williams were overly concerned about the noise, but were confused as to its source.

There’s no rush to find out what the problem is, since Starliner is scheduled to return to Earth on its own on September 6. “I don’t think it’s significant since there won’t be a crew on board, but anything unusual should always be investigated,” Barstow said. “It might shed some light on an underlying problem.”