NASA has identified the source of the strange, “sonar-like” sounds coming from Boeing’s Starliner capsule and says the noises have now stopped.
In an emailed statement, a NASA spokesperson told DailyMail.com the cause was “an audio mismatch between the space station and Starliner.”
The space agency had been searching for the source of the sounds since Saturday, when stranded astronaut Butch Wilmore radioed the Johnson Space Center in Houston to report a mysterious pulsating sound coming from one of the spacecraft’s speakers.
“I have a question about Starliner. There’s a strange sound coming through the speaker and I don’t know if you can connect to the Starliner… I don’t know what’s causing it,” he said.
A problem with the audio configuration could mean many different things, but a retired NASA scientist told DailyMail.com that NASA is likely referring to a signal feedback loop.
Astronaut Butch Wilmore reported Saturday that “strange” sonar-like sounds were coming from Boeing’s Starliner capsule.
“It could be that the electronics present happened to produce a pulsating effect when there was feedback,” former NASA planetary physicist Phillip Metzger, who previously tested intercom systems on the International Space Station, told DailyMail.com.
An audio feedback loop occurs when an audio signal is sent from an input to an output and then back to itself, creating a sound loop.
Often it sounds like a constant howling or screeching sound that gets louder as the repetition continues, which is very different from the constant pulsating sound Wilmore heard.
“But depending on the electronics, that might not happen,” Metzger said. “Depending on the type of filtering they have, it might produce a different effect.”
So it is still plausible that this sound comes from a feedback loop.
Both Metzger and NASA confirmed that this issue would not affect Starliner’s other systems, pose any safety risks, or disrupt the spacecraft’s functionality.
Before NASA’s statement, Metzger speculated on X, formerly Twitter, that the noise could be caused by electromagnetic interference, or EMI.
2/2 For the space station I tested the intercom systems among other things. Electromagnetic interference (EMI) is common and difficult to eliminate. During a test we heard noise that we eventually traced to the transducers that were part of the test facility, not even in…
—Dr. Phil Metzger (@DrPhiltill) September 1, 2024
EMI occurs when stray electromagnetic signals enter an electronic system, such as Starliner’s hearing system, he explains.
The cables in a spacecraft’s electronic systems are wrapped in braided “shielding” that prevents EMI from entering the system.
But sometimes these shields can break. This is especially common at a system’s connectors — “that’s the weak point where things tend to break,” Metzger said.
Shielding can fail due to vibration, which can cause a braided wire to rub against the machine and fray over time. Or it can be a design or manufacturing issue, he explained.
“When that small, fine braided material breaks, it creates an opening that allows the signal to get in,” Metzger said.
It’s still possible that the unusual sounds coming from Starliner’s speaker were caused by EMI, but based on NASA’s explanation, Metzger thinks a feedback loop is an equally likely explanation.
This audio issue should not affect Starliner’s ability to undock from the ISS and begin its unmanned return to Earth on September 6.
“The space station’s audio system is complex and requires multiple spacecraft and modules to be connected together. It is common for noise and feedback to occur,” NASA said in a statement.
This latest technical issue occurs just four days before Starliner is set to undock from the ISS and begin its unmanned return to Earth, meaning astronauts Sunita Williams and Butch Wilmore will have to remain on the ISS for at least another six months.
Wilmore and Williams have been stuck on the ISS since June 6, when they arrived aboard the Boeing spacecraft for a week-long stay.
Starliner was plagued by helium leaks and booster problems before, during and after launch. On August 24, NASA officials determined that the malfunctioning spacecraft was unfit to return the crew to Earth.
Wilmore and Williams will remain on the ISS until February 2025, when they can hitch a ride home on SpaceX’s Crew Dragon spacecraft.
As for Starliner, NASA has selected a date and time no later than September 6 at 6:04 p.m. ET to undock the spacecraft from the ISS and return it to Earth.
Provided weather at the landing site is good, Starliner will autonomously undock from the ISS and begin a six-hour flight to White Sands Space Harbor in New Mexico, a desert landing target.
After landing, the aircraft will be returned to Boeing’s Starliner factory at Kennedy Space Center.